![[Feedback]](/icons/banner/feedbackACT.gif){kind=icon}
![[For Subscribers]](/icons/banner/subscriberACT.gif){kind=icon}
![[Archive]](/icons/banner/archiveACT.gif){kind=icon}
![[Search]](/icons/banner/searchACT.gif){kind=icon}
![[Contents]](/icons/banner/tocACT.gif){kind=icon}
|
|
|
|
|
||
4
*
Molecular Cell and Developmental Biology Section and
Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712
4To whom correspondence should be addressed. E-mail: surangi{at}mail.utexas.edu.
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
|---|
KEY WORDS: • estrogen signaling • phytoestrogen • breast cancer progression • FAK activity • Akt activity • phosphorylation • antioxidant activity
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
|---|
). The antioxidant activities of polyphenols are well recognized and may be responsible for various health benefits. Free radicals are produced by pollutants in our food, water and air; oxidation-reduction reactions of lipids and metal ions; and continuous mitochondrial electron transport reactions in the body. Catechins in green and black tea and red wine can defuse these aggressive superoxide, alkyl and hydroxyl free radicals by providing an electron, thereby preventing attack on DNA and other cell components. If not deactivated, the aggressive radicals produce free radical chain reactions, potentially leading to heart disease, stroke, memory loss and cancer. In one step, catechins help subvert these health problems by converting damaging free radicals to inactive compounds while themselves becoming low-energy harmless catechin free radicals. In addition to being powerful antioxidants, catechins such as epigallocatechin gallate (EGCG)5
in green tea absorb ultraviolet light in the 280–320-nm range, preventing the promotion of photo-induced skin cancer. EGCG also has substantial inhibitory effects in vivo against a wide variety of tumors and in vitro against cancer cell lines (2
–5
). Another effective antioxidant polyphenol is resveratrol, which is found in high concentration in red wine as well as in peanuts and grape skins (6
). trans-Resveratrol may prevent cancer by inhibiting cancer growth, tumor angiogenesis and cell invasion (7
–15
).
Some of these compounds have estrogenic (and antiestrogenic) activity and are commonly referred to as phytoestrogens. Soybeans are the main dietary source of two isoflavonoids: genistein and daidzein. These compounds may affect cancer progression as a result of their effects on apoptosis, cell cycle progression, growth and differentiation as well as their antioxidant and antiangiogenic effects. Genistein affects cellular function via inhibition of 17ß-steroid oxidoreductase (an enzyme necessary for estrogen synthesis) and tyrosine-specific protein kinases. Genistein also modulates the activity of topoisomerase II, enzymes involved in phosphoinositide turnover and transforming growth factor-ß (TGFß) signaling cascades (16
–22
). The exact effect of phytoestrogens on breast cancer cells and tumors is concentration dependent, where growth is stimulated at low concentrations (0.1–10 µmol/L) and inhibited at high concentrations (20–100 µmol/L) (23
–26
).
Estrogenic compounds regulate gene transcription via two specific intracellular estrogen receptors (ERs): ER
and ERß. The general scheme of estrogen action involves diffusion into the cytosol, binding to ERs and activation of gene expression (27
,28
). Overexpression of ER is considered to be a predictive and prognostic factor in breast cancer (29
,30
). Consequently, inhibition of ER has become a major strategy for preventing and treating breast cancer (31
–35
). Loss of ER expression is common in malignant progression of breast cancer, making traditional therapy with selective ER modifiers ineffectual. Therefore much effort is directed toward designing novel therapeutic strategies to combat alternative signaling pathways, such as epidermal growth factor receptor signaling, that are dysregulated during breast cancer progression (36
).
The mode of action of the common mammalian estrogen 17ß-estradiol (E2) in regulating cell proliferation as well as tumorigenesis via gene transcription is well established. One method to evaluate estrogenic genomic effects of compounds and crude mixtures is to measure the ability of compounds to bind to ER and to activate estrogen-responsive genes (37
). Using a yeast-based ER transactivational reporter system, we investigated the estrogenic properties of compounds, monitored complex plant extracts and isolated novel estrogenic compounds via activity-guided fractionation (38
,39
).
Recent literature, however, indicates that E2 exerts additional nongenomic effects on cell signaling. Such rapid nongenomic effects have been reported for a variety of cell types, such as bone, neuronal, mammary, ovarian and cardiovascular cells (40
–42
). These cells contain plasma membrane ERs that can cross-activate a variety of signaling cascades, including those mediated by G protein–coupled receptors and tyrosine kinase–type growth factor receptors. Rapid cellular responses to estrogen activate both Gs and Gq type G proteins, leading to stimulation of adenylate cyclase and phospholipase C, which in turn activate protein kinase A, protein kinase C and intracellular Ca2+ fluxes (42
–45
). E2-bound ER associates with the regulatory subunit of phosphatidylinositol-3-kinase (PI3-K) and activates the survival factor Akt (protein kinase B) (46
,47
) as well as stimulating growth factor receptor activity (48
). These effects of E2 signaling stimulate cell proliferation via activation of mitogen-activated protein kinase (MAPK) cascades (42
,43
). Activation of the tyrosine kinases Src and Shc by ER has also been linked to direct stimulation of MAPK signaling (49
). Moreover, E2 has been shown to affect the tyrosine phosphorylation status of key signaling intermediates such as c-Src and focal adhesion kinase (FAK) in both ER-positive (+) and ER-negative (-) breast cancer cell lines (50
). Recent studies have shown that MAPK signaling not only affects gene transcription leading to tumorigenesis but also may promote cancer cell invasion (51
,52
). Therefore E2 signaling to MAPK cascades may be relevant for breast cancer malignancy. The true complexity of estrogen signaling is only now beginning to be elucidated, and even less is known about the nongenomic effects of the vast array of related estrogenic compounds.
In this study the soybean phytoestrogens genistein and daidzein and resveratrol from red wine were chosen to investigate the relevance of nongenomic activity of flavonoids in breast cancer progression. Genistein and daidzein bind to and transactivate both ER and ERß and have been extensively studied for their potential health benefits (39
,53
,54
). In addition to attenuating cell growth via ER, genistein has been shown to block the proliferation of normal and cancer cells stimulated by growth factor and cytokine. High concentrations of genistein act as a tyrosine kinase inhibitor; this function may underlie its anticancer effects (17
,18
,37
). However, in one study the antiproliferative effect of genistein was shown to be uncoupled from its effect as a tyrosine kinase inhibitor, possibly acting via TGFß signaling (19
,55
). More studies are needed to fully evaluate the estrogenic, antiestrogenic and tyrosine kinase inhibitory effects of genistein on breast cancer progression.
Resveratrol is structurally similar to the synthetic estrogen diethylstilbestrol and binds to and activates ER ( and ß) to exert both estrogenic and antiestrogenic effects (56
–60
). The antitumor activity of resveratrol is mediated by MAPKs [i.e., extracellular signal-regulated protein kinases, c-jun NH (2
)-terminal kinases and p38 kinase]. Resveratrol-induced p38 MAPK-mediated p53 activation has been implicated in inhibition of cell cycle progression and initiation of apoptotic pathways (61
–64
). Recently, the stimulatory effect of resveratrol on apoptosis was also demonstrated in a novel mitochondrial pathway controlled by Bcl-2 (65
). Moreover, resveratrol inhibits tumor promoting agent- or UV-induced activity of the activator protein 1 transcription factor through inhibition of c-Src nonreceptor tyrosine kinase and MAPK pathways (66
).
These studies implicate phytoestrogens not only in mediation of genomic effects via ER but also in more rapid signaling cascades. In this study, the effects of phytoestrogens on the activation status of signaling proteins known to control breast cancer cell survival, proliferation and invasion were monitored in ER(+) metastatic and ER(-) nonmetastatic human breast cancer cell lines. Activation of PI3-K, which catalyzes the phosphorylation of phosphatidylinositol-4,5-bisphosphate to generate phosphatidylinositol-3,4,5-bisphosphate (PIP3), is a key event during signal transduction via cell surface receptors (67
). PIP3-induced activation of phosphoinositide-dependent kinase mediates the phosphorylation (in Ser 473 and Thr 308) and activation of Akt. Activated Akt initiates downstream signaling cascades that promote cell survival and proliferation potentially leading to cancer malignancy (68
,69
). FAK is a tyrosine kinase that is recruited to the membrane in response to tyrosine kinase–type growth factor and integrin receptor activation. Activation of FAK by phosphorylation in Tyr 397 triggers various kinase signaling cascades, including activity by Src and Shc, nonreceptor tyrosine kinases and MAPKs. Similarly, these events increase cell proliferation, motility and invasion (52
,70
,71
).
|
MATERIALS AND METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
|---|
Human breast cancer cell lines T47D and MDA-MB-231 were maintained in Dulbecco’s modified Eagle’s medium (DMEM) [10% fetal bovine serum (FBS)] at 37°C with 5% CO2. Before stimulation with estrogenic compounds, cells were washed with phenol red–free DMEM. Approximately 3 x 105 cells/well were transferred to 6-well plates and grown for 48 h in phenol red–free DMEM with 10% FBS. Next, cells were starved in phenol red–free DMEM for 24 h before stimulation. Cells were stimulated for 15 min with either E2 (Sigma Chemical Co., St. Louis, MO), genistein, daidzein or trans-resveratrol (LKT Laboratories, St. Paul, MN). E2 was used at a concentration of 10 nmol/L, and phytoestrogens were used at 1, 50, or 100 µmol/L. Dimethylsulfoxide was added as a vehicle for unstimulated controls.
Western blot analysis.
Cells were disrupted in lysis buffer (20 mmol/L Tris-HCl, pH 7.5), 150 mmol/L NaCl, 1 mmol/L EGTA, 1 mmol/L EDTA, 2.5 mmol/L sodium pyrophosphate, 50 mmol/L sodium fluoride, 1 mmol/L dithiothreitol, 10% glycerol, 1% Nonidet P-40, 0.5% deoxycholate, and protease inhibitors) at 4°C. Lysates were centrifuged at 16,000 x g; the proteins in the supernatant were eluted with Laemmli’s sample buffer and separated on 10% sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) gels. Proteins were transferred to polyvinylidene fluoride membranes, blocked and probed with specific primary antibodies. Detection was accomplished using alkaline phosphatase–conjugated secondary antibody and developed with nitro blue tetrazolium/5-bromo-4-chloro-3-indolyl phosphate reagent (Pierce Chemical, Rockford, IL). Anti-Akt and anti–phospho-Akt (Ser-473) antibodies were purchased from Cell Signaling, MA. Anti-FAK or anti–phospho-FAK (Tyr-397) antibodies were purchased from Upstate Biotechnology (Lake Placid, NY). The density of positive bands was quantified using NIH Image software; the results were averaged.
We calculated the the ratio of the amount of phosphorylated-Akt (P-Akt), as detected with anti–phospho-Akt antibody, to the amount of total Akt, as detected with anti–Akt antibody. Similarly, we calculated the ratio of the amount of phosphorylated-FAK (P-FAK), as detected with anti–phospho-FAK antibody, to the amount of total FAK, as detected by anti–FAK antibody. The relative activity for both Akt and FAK was calculated and plotted onto a graph relative to values for unstimulated controls (i.e., the difference between the the ratio of P-Akt to Akt with stimulation and the ratio of P-Akt to Akt without stimulation divided by the the ratio of P-Akt to Akt without stimulation) for each compound tested.
|
RESULTS AND DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
|---|
The nongenomic effects of estrogen on activation of critical oncogenic signaling molecules are just beginning to be examined. Most studies have focused only on the effects of phytoestrogens at the gene transcription level after prolonged (>24 h) exposure (72
–75
). Very little is known about the effects of phytoestrogens on activation of short-term signaling cascades as well as their effect on prevention of breast tumorigenesis and cancer progression. Reversible protein phosphorylation is one of the most prevalent mechanisms for covalent modification of proteins during signal transduction and control of cellular processes (76
). Therefore as a preliminary step toward phosphoproteomic profiling the effects of dietary phytoestrogens in breast cancer progression, we focused on the rapid activation of key signaling proteins by phosphorylation in ER(+) and ER(-) breast cancer cell lines.
The concentrations of estrogenic compounds that we used were in agreement with previous concentrations of phytoestrogens used to induce gene transcription via both ER and ERß (77
). Our experimental design of adding low, medium and high concentrations of phytoestrogens was intended to differentiate the effects of phytoestrogens as estrogenic, antiestrogenic and tyrosine inhibitory compounds. Our approach of using two breast cancer cell lines with differential ER status—ER(+) T47D cells and ER(-) MB-231—that express low levels of ERß (78
–82
) enabled an evaluation of the ER dependency of the observed effects. Comparison of the total phosphoproteomic profiles of unstimulated or stimulated T47D or MB-231 whole-cell lysates by Western blotting with antibodies specific to phosphoserine or phosphotyrosine demonstrated significant differences in the phosphorylation status of a number of proteins (data not shown).
Activation of Akt by phytoestrogens.
The phosphorylation status and thus activation of Akt in response to estrogenic compounds were monitored in breast cancer cells by Western blotting of unstimulated or stimulated cell lysates with antiphosphoserine 473 Akt antibody to determine phospho-Akt levels or an anti-Akt antibody to determine total Akt levels. In ER(+) T47D cells, E2, genistein and daidzein activated Akt. Interestingly, resveratrol decreased Akt phosphorylation in a concentration-dependent fashion (Fig. 1
). In contrast, in ER(-) MDA-MB-231 cells, all estrogenic compounds except genistein at high concentrations (100 µmol/L) activated Akt. Daidzein had a marked effect on Akt activation in MB-231 cells (Fig. 2
). These results agree with a recent report that demonstrated increased Akt activity in response to E2 with the same MB-231 cell line (47
).
|
|
–85
) and, more recently, in both ER(+) and ER(-) human breast cancer cell lines (47
,86
). A study on Akt activation in the myocardium reported that E2 and genistein elevated nuclear phospho-Akt activation (87
). Therefore our observation of activated Akt in response to E2 agrees with published reports.
Our results demonstrate that the effects of estrogenic compounds on Akt activation differed depending on the ER status of breast cancer cells. The inhibitory action of resveratrol in the ER(+) T47D cells, but not in ER(-) MB-231 cells, indicates that this effect was probably ER dependent. In MCF-7 ER(+) breast cancer cells, the same range of resveratrol (10–50 µmol/L) antagonizes the E2-mediated gene expression and growth-stimulatory effect (12
) and induces p53-mediated apoptosis (61
). In MCF-7 and MVLN breast cancer cells, resveratrol demonstrated a biphasic effect by increasing growth at medium concentrations (10 and 25 µmol/L) and decreasing growth at a high concentration (50 µmol/L). Low concentrations (0.1 and 1 µmol/L) had no effect on cell growth (88
). These results agree with our observations that low concentrations of resveratrol demonstrate little or no effect on Akt activity, whereas higher (50 and 100 µmol/L) concentrations demonstrate striking inhibitory effects. More studies using concentrations in the 10–25 µmol/L range are necessary to evaluate whether medium concentrations of resveratrol increase Akt activity in ER(+) breast cancer cells.
In one study, resveratrol decreased hepatocyte growth factor–induced cell scattering and invasion in hepatocellular carcinoma cells independent of Akt activation (15
). However, for the first time in breast cancer cells, we demonstrate that resveratrol directly modulates Akt activity. Activated Akt is a strong cellular survival signal that protects cells from apoptosis by phosphorylation of the proapoptotic Bcl-2 family member Bad, which is then sequestered and degraded (68
,69
). Resveratrol induces p53 activity that leads to activation of the proapoptotic Bcl-2 family member Bax (61
–64
). Thus resveratrol-mediated downregulation of Akt activity coupled with activation of proapoptotic signaling is predicted to act as a strong signal to suppress growth and activate apoptosis in ER(+) breast tumors.
Activation of FAK by phytoestrogens.
We also monitored the effect of phytoestrogens on FAK activity in breast cancer cells. In the ER(+) T47D cell line, 15-min stimulation with E2, genistein or daidzein increases phospho-FAK levels, whereas resveratrol decreases the levels (Fig. 3
). The ER(-) MB-231 cell line demonstrated increased FAK phosphorylation in response to all phytoestrogens tested (Fig. 4
). Similar results were obtained by immunoprecipitations of stimulated cell lysates using an antiphosphotyrosine antibody followed by Western blotting with an anti-FAK antibody (data not shown).
|
|
, 4)
. This may reflect the general perplexity in the field regarding the exact mechanism of action of genistein as a tyrosine kinase inhibitor or an antiestrogen (89
). Traditional studies using genistein as a tyrosine kinase inhibitor have added genistein to cells in serum or phenol red–containing media, which contain estrogenic compounds (37
,90
). Others have shown that the antiproliferative effects of genistein are estrogen dependent, including inhibition of estrogen-induced protein tyrosine kinase activity (91
). Some studies have concentrated on long-term effects of genistein on the phosphotyrosine status of proteins, where the reported inhibition of protein tyrosine kinases may result from alterations in kinase expression (18
).
Daidzein, the other major isoflavone in soy that differs structurally from genistein only by the lack of a hydroxyl group, was selected to enable the analysis of effects that may be distinct from the tyrosine kinase inhibitory effects of genistein. These two structurally related phytoestrogens are thought to have discrete target sites and mechanisms in their growth inhibitory action on breast cancer cells (75
). In a previous study using MB-468 breast cancer cells, genistein demonstrated a concentration-dependent biphasic effect on cell cycle progression, whereas daidzein was not effective at high concentrations (92
). Our results demonstrate that both daidzein and genistein increased FAK phosphorylation at low, medium and high concentrations. Unstimulated and stimulated cell lysates of ER(+) T47D and ER(-) MB-231 were probed with an antiphosphotyrosine antibody or immunoprecipitated with an antiphosphotyrosine antibody and probed with a different antiphosphotyrosine antibody to detect overall trends of phosphorylation in response to phytoestrogens (data not shown). In these experiments, daidzein increased whereas high concentrations of genistein decreased overall tyrosine phosphorylation. Therefore the enhanced phospho-FAK levels in the presence of high concentrations of daidzein may reflect a general effect of daidzein on activation of a protein tyrosine kinase or inactivation of a protein phosphatase.
In ER(-) MB-231 cells, all phytoestrogens tested increased FAK activity (Fig. 4)
. In contrast, resveratrol reduced FAK phosphorylation in ER(+) T47D cells (Fig. 3)
. This result may indicate that FAK activation by soy phytoestrogens is not dependent on ER. A single study that investigated the effect of estrogen on FAK activity in breast cancer used the nonmetastatic ER(+) MCF-7 human breast cancer cells. These cells were cultured for 7 d in the presence of E2 at 1 nmol/L, which resulted in decreased tyrosine phosphorylation of FAK. The E2-induced effect was blocked by the ER antagonist 4-hydroxytamoxifen at 100 nmol/L, indicating that dephosphorylation of FAK is an ER-mediated event. E2 treatment also resulted in a reduced association between FAK and paxillin, a focal complex protein that mediates contact between integrin receptors and the actin cytoskeleton (93
). Thus, unlike as shown here, long-term exposure to E2 may exert genomic effects on tyrosine kinases or phosphatases that affect FAK activity.
The anti–phospho-FAK antibody that specifically interacts with the phosphotyrosine residue 397 consistently detected two bands: one at 125 kDa and the other at 90 kDa. Our 125 FAK antibody, which was raised against the carboxyl-terminal residues 748-1053, did not detect the amino-terminal 90-kDa fragment. The 125-kDa and 90-kDa phospho-FAK bands probably correspond to calpain digestion of the full-length FAK (125 kDa) to a 90-kDa fragment that still contains the phosphotyrosine 397 residue (94
). Both fragments were quantified for total phospho-FAK analysis. Unfortunately, the reported data only reflect levels of 125-kDa full-length FAK. Ongoing experiments are focusing on the detection of nonphosphorylated FAK using an additional antibody raised against the amino terminus of FAK.
The tyrosine kinase Src activates calpain proteases that digest FAK during transformation and invasion (70
,95
,96
). Calpain-deficient embryonic fibroblasts reduce cell migration, implying that the cleavage products observed in our breast cancer cells have invasive potential (97
). Interestingly, Src and thus Shc and MAPK signaling are activated by nongenomic actions of E2 (86
,98
,99
). We are currently investigating the possible regulation of focal adhesion turnover by estrogenic compounds via Src-mediated calpain activity.
FAK activation by phosphorylation results in cell proliferation, motility and invasion (51
,52
,70
,71
). Decreased phosphorylation levels and reduced association between FAK and paxillin have been suggested as important steps leading to the loss of stable focal contacts and loss of growth inhibition during tumorigenesis (50
). However, a recent study demonstrated that dephosphorylation of FAK and down-regulation of FAK activity by EGFR induction initiated tumor cell invasion (100
). Our results that demonstrate phytoestrogen-mediated FAK phosphorylation and cleavage in ER(+) and ER(-) breast cancer cells (Figs. 3
, 4)
may indicate potential modulation of cell migration by phytoestrogens. Rapid turnover of focal adhesions by regulation of FAK activity via both phosphorylation and calpain cleavage has been implicated in cell migration and invasion through the extracellular matrix (70
,93
,96
,101
). Therefore the observed differences in FAK activity in response to estrogenic compounds may be relevant to control of breast cancer progression.
Summary.
E2 plays a critical role in the initiation and progression of breast and gynecological cancers and has been implicated in modulation of breast cancer cell invasion and metastasis (102
–104
). Phytoestrogens are known to act as agonists or antagonists of E2 and may protect against some cancers, cardiovascular disease and osteoporosis, as well as to prevent the undesirable symptoms of menopause (105
–108
). Interest in the potential benefits of phytoestrogen consumption continues to increase; however, use of phytoestrogens in prevention of breast and uterine cancer or as a "natural" alternative to hormone replacement therapy remains controversial (18
,106
,109
–116
). Although phytoestrogens are thought to protect against breast cancer by regulating ER and growth factor signaling pathways (18
,117
), their exact mechanism of action needs to be evaluated (118
). Moreover, because of the lack of relevant information, the increased use of phytoestrogens in human diet does not consider nongenomic modes of phytoestrogen action at the cellular and molecular level.
The present data indicate that soybean phytoestrogens increase phosphorylation of both Akt and FAK, molecules that promote cancer cell survival and invasion, whereas the red wine phytoestrogen resveratrol inhibits FAK and Akt activity in an ER-dependent manner. Our novel data demonstrate that genistein, in addition to its effect as a tyrosine kinase inhibitor and an antiestrogen via ER, may also have ER-independent effects on breast cancer cells. With a similar panel of ER(+) and ER(-) breast cancer cell lines, the antiproliferative effects of genistein were shown to be dependent on E2, thus leading the authors to conclude that antiestrogenic effects of genistein were only operative in ER(+) breast cancer cell lines (91
). However, others have suggested that genistein can inhibit growth and induce apoptosis in ER(-) highly metastatic MB-435 breast cancer cells via down-regulation of ErbB-2 and Bcl-2 and decreased matrix metalloproteinase secretion (119
). The present study suggests that the soy phytoestrogens genistein and daidzein may exert additional effects on breast cancer cell survival, proliferation and invasion via activation of Akt and FAK.
Our data on the effects of resveratrol in ER(+) and ER(-) breast cancer cells support the well-established properties of resveratrol as an ER-dependent antagonist of estrogenic effects that inhibit cellular events associated with tumor initiation, promotion and progression (9
,59
,120
). However, studies performed using ER-transfected cell lines have shown that resveratrol acts as a mixed agonist and antagonist. In the absence of E2, resveratrol was shown to exert mixed estrogen agonist-antagonist activities in T47D and MCF-7 ER(+) breast cancer cell lines (37
). For the first time, the present study demonstrates ER-dependent and -independent effects of resveratrol on Akt and FAK activity in breast cancer cells. Interestingly, all estrogenic compounds tested increased Akt and FAK activity in the metastatic ER(-) breast cancer cell line. Shorter ERß isoforms have been detected in the ER(-) MDA-MB-231 cells that express low levels of ERß (81
,82
). Thus the stimulatory effects of phytoestrogens on Akt and FAK activity in MB-231 cells may be mediated by ERß. Although the exact mechanism by which phytoestrogens modulate Akt and FAK activity remains to be elucidated, our results are intriguing and may be pertinent to concerns of varied estrogenic effects during breast cancer progression.
A comprehensive evaluation of nongenomic signaling by phytoestrogens will be achieved by confirming our results in a wider range of human breast cancer cell lines at different stages of breast cancer progression. Many kinases and phosphatases involved in modulation of signaling events have been implicated in a variety of pathological conditions including cancer predisposition (121
). Therefore the phosphoproteins identified in our studies may represent a rich source of potential targets for therapeutic intervention in treatment and prevention of breast cancer as well as markers for early detection of malignant breast cancer.
|
FOOTNOTES |
|---|
2 Supported by NIH/NCA Grant R21CA83957–01A1 awarded to S. F. D. and Welch Foundation Grant No. F-130 awarded to T. J. M.
3 Delia M. Brownson and Nicolas G. Azios contributed equally to this work.
5 Abbreviations used: DMEM, Dulbecco’s modified Eagle’s medium; E2, 17ß-estradiol; EGCG, epigallocatechin gallate; ER, estrogen receptor; FAK, focal adhesion kinase; FBS, fetal bovine serum; MAPK, mitogen-activated protein kinase; P-FAK, phosphorylated-FAK; PI3-K, phosphatidylinositol-3-kinase; PIP3, phosphatidylinositol-3,4,5-bisphosphate; SDS-PAGE, sodium dodecyl sulfate–polyacrylamide gel electrophoresis; TGFß, transforming growth factor-ß.
|
LITERATURE CITED |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
|---|
1. Yang, C. S., Landau, J. M., Huang, M. T. & Newmark, H. L. (2001) Inhibition of carcinogenesis by dietary polyphenolic compounds. Annu. Rev. Nutr. 21:381-406.[Medline]
2. Yang, C. S., Prabhu, S. & Landau, J. (2001) Prevention of carcinogenesis by tea polyphenols. Drug Metab. Rev. 33:237-253.[Medline]
3. Yang, C. S., Maliakal, P. & Meng, X. (2002) Inhibition of carcinogenesis by tea. Annu. Rev. Pharmacol. Toxicol. 42:25-54.[Medline]
4. Katiyar, S. K., Bergamo, B. M., Vyalil, P. K. & Elmets, C. A. (2001) Green tea polyphenols: DNA photodamage and photoimmunology. J. Photochem. Photobiol. B 65:109-114.[Medline]
5. Kavanagh, K. T., Hafer, L. J., Kim, D. W., Mann, K. K., Sherr, D. H., Rogers, A. E. & Sonenshein, G. E. (2001) Green tea extracts decrease carcinogen-induced mammary tumor burden in rats and rate of breast cancer cell proliferation in culture. J. Cell Biochem. 82:387-398.[Medline]
6. Burns, J., Yokota, T., Ashihara, H., Lean, M. E. & Crozier, A. (2002) Plant foods and herbal sources of resveratrol. J. Agric. Food Chem 50:3337-3340.[Medline]
7. Nigdikar, S. V., Williams, N. R., Griffin, B. A. & Howard, A. N. (1998) Consumption of red wine polyphenols reduces the susceptibility of low-density lipoproteins to oxidation in vivo.. Am. J. Clin. Nutr. 68:258-265.[Abstract]
8. Soleas, G. J., Grass, L., Josephy, P. D., Goldberg, D. M. & Diamandis, E. P. (2002) A comparison of the anticarcinogenic properties of four red wine polyphenols. Clin. Biochem. 35:119-124.[Medline]
9. Jang, M., Cai, L., Udeani, G. O., Slowing, K. V., Thomas, C. F., Beecher, C. W., Fong, H. H., Farnsworth, N. R., Kinghorn, A. D., Mehta, R. G., Moon, R. C. & Pezzuto, J. M. (1997) Cancer chemopreventive activity of resveratrol, a natural product derived from grapes. Science (Washington,D.C.) 275:218-220.
10. Igura, K., Ohta, T., Kuroda, Y. & Kaji, K. (2001) Resveratrol and quercetin inhibit angiogenesis in vitro. Cancer Lett. 171:11-16.[Medline]
11. Bhat, K. P. & Pezzuto, J. M. (2002) Cancer chemopreventive activity of resveratrol. Ann. N.Y. Acad. Sci. 957:210-229.[Medline]
12. Lu, R. & Serrero, G. (1999) Resveratrol, a natural product derived from grape, exhibits antiestrogenic activity and inhibits the growth of human breast cancer cells. J. Cell. Physiol. 179:297-304.[Medline]
13. Hsieh, T. C., Burfeind, P., Laud, K., Backer, J. M., Traganos, F., Darzynkiewicz, Z. & Wu, J. M. (1999) Cell cycle effects and control of gene expression by resveratrol in human breast carcinoma cell lines with different metastatic potentials. Int. J. Oncol. 15:245-252.[Medline]
14. Bove, K., Lincoln, D. W. & Tsan, M. F. (2002) Effect of resveratrol on growth of 4T1 breast cancer cells in vitro and in vivo. Biochem. Biophys. Res. Commun. 291:1001-1005.[Medline]
15. De Ledinghen, V., Monvoisin, A., Neaud, V., Krisa, S., Payrastre, B., Bedin, C., Desmouliere, A., Bioulac-Sage, P. & Rosenbaum, J. (2001) Trans-resveratrol, a grapevine-derived polyphenol, blocks hepatocyte growth factor-induced invasion of hepatocellular carcinoma cells. Int. J. Oncol. 19:83-88.[Medline]
16. Li, Y., Upadhyay, S., Bhuiyan, M. & Sarkar, F. H. (1999) Induction of apoptosis in breast cancer cells MDA-MB-231 by genistein. Oncogene 18:3166-3172.[Medline]
17. Polkowski, K. & Mazurek, A. P. (2000) Biological properties of genistein. A review of in vitro and in vivo data. Acta Pol. Pharm. 57:135-155.[Medline]
18. Barnes, S., Boersma, B., Patel, R., Kirk, M., Darley-Usmar, V. M., Kim, H. & Xu, J. (2000) Isoflavonoids and chronic disease: mechanisms of action. Biofactors 12:209-215.[Medline]
19. Kim, H., Peterson, T. G. & Barnes, S. (1998) Mechanisms of action of the soy isoflavone genistein: emerging role for its effects via transforming growth factor beta signaling pathways. Am. J. Clin. Nutr. 68:1418S-1425S.[Abstract]
20. Yan, L., Yee, J. A., McGuire, M. H. & Graef, G. L. (1997) Effect of dietary supplementation of soybeans on experimental metastasis of melanoma cells in mice. Nutr. Cancer 29:1-6.[Medline]
21. Menon, L. G., Kuttan, R., Nair, M. G., Chang, Y. C. & Kuttan, G. (1998) Effect of isoflavones genistein and daidzein in the inhibition of lung metastasis in mice induced by B16F-10 melanoma cells. Nutr. Cancer 30:74-77.[Medline]
22. Dixon-Shanies, D. & Shaikh, N. (1999) Growth inhibition of human breast cancer cells by herbs and phytoestrogens. Oncol. Rep. 6:1383-1387.[Medline]
23. Miodini, P., Fioravanti, L., Di Fronzo, G. & Cappelletti, V. (1999) The two phyto-oestrogens genistein and quercetin exert different effects on oestrogen receptor function. Br. J. Cancer 80:1150-1155.[Medline]
24. Ju, Y. H., Allred, C. D., Allred, K. F., Karko, K. L., Doerge, D. R. & Helferich, W. G. (2001) Physiological concentrations of dietary genistein dose-dependently stimulate growth of estrogen-dependent human breast cancer (MCF-7) tumors implanted in athymic nude mice. J. Nutr. 131:2957-2962.
25. Sathyamoorthy, N. & Wang, T. T. (1997) Differential effects of dietary phyto-oestrogens daidzein and equol on human breast cancer MCF-7 cells. Eur. J. Cancer 33:2384-2389.
26. Wang, C. & Kurzer, M. S. (1997) Phytoestrogen concentration determines effects on DNA synthesis in human breast cancer cells. Nutr. Cancer 28:236-247.[Medline]
27. Katzenellenbogen, B. S., Choi, I., Delage-Mourroux, R., Ediger, T. R., Martini, P. G., Montano, M., Sun, J., Weis, K. & Katzenellenbogen, J. A. (2000) Molecular mechanisms of estrogen action: selective ligands and receptor pharmacology. J. Steroid Biochem. Mol. Biol. 74:279-285.[Medline]
28. Safe, S. (2001) Transcriptional activation of genes by 17 beta-estradiol through estrogen receptor-Sp1 interactions. Vitam. Horm. 62:231-252.[Medline]
29. Dickson, R. B. & Stancel, G. M. (2000) Estrogen receptor-mediated processes in normal and cancer cells. J. Natl. Cancer Inst. Monogr. 27:135-145.
30. Fuqua, S. A. (2001) The role of estrogen receptors in breast cancer metastasis. J. Mammary Gland Biol. Neoplasia 6:407-417.[Medline]
31. Robertson, J. F. (2002) Estrogen receptor downregulators: new antihormonal therapy for advanced breast cancer. Clin. Ther. 24:A17-A30.
32. Fabian, C. J. & Kimler, B. F. (2001) Chemoprevention for high-risk women: tamoxifen and beyond. Breast J 7:311-320.[Medline]
33. Salih, A. K. & Fentiman, I. S. (2001) Breast cancer prevention: present and future. Cancer Treat. Rev. 27:261-273.[Medline]
34. Park, W. C. & Jordan, V. C. (2002) Selective estrogen receptor modulators (SERMS) and their roles in breast cancer prevention. Trends Mol. Med. 8:82-88.[Medline]
35. Pritchard, K. I. (2001) Breast cancer prevention with selective estrogen receptor modulators: a perspective. Ann. N.Y. Acad. Sci. 949:89-98.[Medline]
36. Kurokawa, H. & Arteaga, C. L. (2001) Inhibition of erbB receptor (HER) tyrosine kinases as a strategy to abrogate antiestrogen resistance in human breast cancer. Clin. Cancer Res. 7:4436s-4442s.
37. Sudbeck, E. A., Ghosh, S., Liu, X. P., Zheng, Y., Myers, D. E. & Uckun, F. M. (2001) Tyrosine kinase inhibitors against EGF receptor-positive malignancies. Methods Mol. Biol. 166:193-218.[Medline]
38. Lee, S.-J., Chung, H.-Y., Maier, C. G.-A, Wood, A. R., Dixon, R. A. & Mabry, T. J. (1998) Estrogenic flavonoids from Artemsia vulgaris L. J. Agric. Food Chem. 46:3325-3329.
39. Bystrom, A. M. (2002) Estrogenic Activity of Flavonoids from Cyperus alopecuroides Rottb. (Cyperaceae). MA Thesis 2002:32 The University of Texas Austin .
40. Belcher, S. M. & Zsarnovszky, A. (2001) Estrogenic actions in the brain: estrogen, phytoestrogens, and rapid intracellular signaling mechanisms. J. Pharmacol. Exp. Ther. 299:408-414.
41. Gray, G. A., Sharif, I., Webb, D. J. & Seckl, J. R. (2001) Oestrogen and the cardiovascular system: the good, the bad and the puzzling. Trends Pharmacol. Sci. 22:152-156.[Medline]
42. Coleman, K. M. & Smith, C. L. (2001) Intracellular signaling pathways: nongenomic actions of estrogens and ligand-independent activation of estrogen receptors. Front. Biosci. 6:D1379-D1391.[Medline]
43. Kelly, M. J. & Levin, E. R. (2001) Rapid actions of plasma membrane estrogen receptors. Trends Endocrinol. Metab. 12:152-156.[Medline]
44. Levin, E. R. (2001) Cell localization, physiology, and nongenomic actions of estrogen receptors. J. Appl. Physiol. 91:1860-1867.
45. Filardo, E. J. (2002) Epidermal growth factor receptor (EGFR) transactivation by estrogen via the G-protein-coupled receptor, GPR30: a novel signaling pathway with potential significance for breast cancer. J. Steroid Biochem. Mol. Biol. 80:231-238.[Medline]
46. Castoria, G., Migliaccio, A., Bilancio, A., Di Domenico, M., de Falco, A., Lombardi, M., Fiorentino, R., Varricchio, L., Barone, M. V. & Auricchio, F. (2001) PI3-kinase in concert with Src promotes the S-phase entry of oestradiol-stimulated MCF-7 cells. EMBO J 20:6050-6059.[Medline]
47. Tsai, E. M., Wang, S. C., Lee, J. N. & Hung, M. C. (2001) Akt activation by estrogen in estrogen receptor-negative breast cancer cells. Cancer Res. 61:8390-8392.
48. Martin, M. B., Franke, T. F., Stoica, G. E., Chambon, P., Katzenellenbogen, B. S., Stoica, B. A., McLemore, M. S., Olivo, S. E. & Stoica, A. (2000) A role for Akt in mediating the estrogenic functions of epidermal growth factor and insulin-like growth factor I. Endocrinology 141:4503-4511.
49. Kousteni, S., Bellido, T., Plotkin, L. I., O’Brien, C. A., Bodenner, D. L., Han, L., Han, K., DiGregorio, G. B., Katzenellenbogen, J. A., Katzenellenbogen, B. S., Roberson, P. K., Weinstein, R. S., Jilka, R. L. & Manolagas, S. C. (2001) Nongenotropic, sex-nonspecific signaling through the estrogen or androgen receptors: dissociation from transcriptional activity. Cell 104:719-730.[Medline]
50. Bartholomew, P. J., Vinci, J. M. & DePasquale, J. A. (1998) Decreased tyrosine phosphorylation of focal adhesion kinase after estradiol treatment of MCF-7 human breast carcinoma cells. J. Steroid Biochem. Mol. Biol. 67:241-249.[Medline]
51. Santen, R. J., Song, R. X., McPherson, R., Kumar, R., Adam, L., Jeng, M. H. & Yue, W. (2002) The role of mitogen-activated protein (MAP) kinase in breast cancer. J. Steroid Biochem. Mol. Biol. 80:239-256.[Medline]
52. Schaller, M. D. (2001) Biochemical signals and biological responses elicited by the focal adhesion kinase. Biochim. Biophys. Acta 1540:1-21.[Medline]
53. Kuiper, G. G., Lemmen, J. G., Carlsson, B., Corton, J. C., Safe, S. H., van der Saag, P. T., van der Burg, B. & Gustafsson, J. A. (1998) Interaction of estrogenic chemicals and phytoestrogens with estrogen receptor beta. Endocrinology 139:4252-4263.
54. Casanova, M., You, L., Gaido, K. W., Archibeque-Engle, S., Janszen, D. B. & Heck, H. A. (1999) Developmental effects of dietary phytoestrogens in Sprague-Dawley rats and interactions of genistein and daidzein with rat estrogen receptors alpha and beta in vitro. Toxicol. Sci. 51:236-244.
55. Peterson, G. (1995) Evaluation of the biochemical targets of genistein in tumor cells. J. Nutr. 125:784S-789S.
56. Bhat, K. P., Lantvit, D., Christov, K., Mehta, R. G., Moon, R. C. & Pezzuto, J. M. (2001) Estrogenic and antiestrogenic properties of resveratrol in mammary tumor models. Cancer Res. 61:7456-7463.
57. Bhat, K. P. & Pezzuto, J. M. (2001) Resveratrol exhibits cytostatic and antiestrogenic properties with human endometrial adenocarcinoma (Ishikawa) cells. Cancer Res. 61:6137-6144.
58. Henry, L. A. & Witt, D. M. (2002) Resveratrol: phytoestrogen effects on reproductive physiology and behavior in female rats. Horm. Behav. 41:220-228.[Medline]
59. Bhat, K. P. L., Kosmeder, J. W. & Pezzuto, J. M. (2001) Biological effects of resveratrol. Antioxid. Redox Signal. 3:1041-1064.[Medline]
60. Bagchi, D., Das, D. K., Tosaki, A., Bagchi, M. & Kothari, S. C. (2001) Benefits of resveratrol in women’s health. Drugs Exp. Clin. Res. 27:233-248.[Medline]
61. She, Q. B., Bode, A. M., Ma, W. Y., Chen, N. Y. & Dong, Z. (2001) Resveratrol-induced activation of p53 and apoptosis is mediated by extracellular-signal-regulated protein kinases and p38 kinase. Cancer Res. 61:1604-1610.
62. She, Q. B., Huang, C., Zhang, Y. & Dong, Z. (2002) Involvement of c-jun NH(2)-terminal kinases in resveratrol-induced activation of p53 and apoptosis. Mol. Carcinog. 33:244-250.[Medline]
63. Shih, A., Davis, F. B., Lin, H. Y. & Davis, P. J. (2002) Resveratrol induces apoptosis in thyroid cancer cell lines via a MAPK- and p53-dependent mechanism. J. Clin. Endocrinol. Metab. 87:1223-1232.
64. Dong, Z. (2000) Effects of food factors on signal transduction pathways. Biofactors 12:17-28.[Medline]
65. Tinhofer, I., Bernhard, D., Senfter, M., Anether, G., Loeffler, M., Kroemer, G., Kofler, R., Csordas, A. & Greil, R. (2001) Resveratrol, a tumor-suppressive compound from grapes, induces apoptosis via a novel mitochondrial pathway controlled by Bcl-2. FASEB J 15:1613-1615.
66. Kong, A. N., Yu, R., Hebbar, V., Chen, C., Owuor, E., Hu, R., Ee, R. & Mandlekar, S. (2001) Signal transduction events elicited by cancer prevention compounds. Mutat. Res. 480–481:231-241.
67. Katso, R., Okkenhaug, K., Ahmadi, K., White, S., Timms, J. & Waterfield, M. D. (2001) Cellular function of phosphoinositide 3-kinases: implications for development, homeostasis, and cancer. Annu. Rev. Cell Dev. Biol. 17:615-675.[Medline]
68. Storz, P. & Toker, A. (2002) 3'-phosphoinositide-dependent kinase-1 (PDK-1) in PI 3-kinase signaling. Front. Biosci. 7:d886-d902.[Medline]
69. Nicholson, K. M. & Anderson, N. G. (2002) The protein kinase B/Akt signalling pathway in human malignancy. Cell Signal 14:381-395.[Medline]
70. Hauck, C. R., Hsia, D. A. & Schlaepfer, D. D. (2002) The focal adhesion kinase-a regulator of cell migration and invasion. IUBMB Life 53:115-119.[Medline]
71. Parsons, J. T., Martin, K. H., Slack, J. K., Taylor, J. M. & Weed, S. A. (2000) Focal adhesion kinase: a regulator of focal adhesion dynamics and cell movement. Oncogene 19:5606-5613.[Medline]
72. Le Bail, J. C., Champavier, Y., Chulia, A. J. & Habrioux, G. (2000) Effects of phytoestrogens on aromatase, 3beta and 17beta-hydroxysteroid dehydrogenase activities and human breast cancer cells. Life Sci. 66:1281-1291.[Medline]
73. Ju, Y. H., Carlson, K. E., Sun, J., Pathak, D., Katzenellenbogen, B. S., Katzenellenbogen, J. A. & Helferich, W. G. (2000) Estrogenic effects of extracts from cabbage, fermented cabbage, and acidified brussels sprouts on growth and gene expression of estrogen-dependent human breast cancer (MCF-7) cells. J. Agric. Food Chem. 48:4628-4634.[Medline]
74. Cappelletti, V., Fioravanti, L., Miodini, P. & Di Fronzo, G. (2000) Genistein blocks breast cancer cells in the G(2)M phase of the cell cycle. J. Cell Biochem. 79:594-600.[Medline]
75. Balabhadrapathruni, S., Thomas, T. J., Yurkow, E. J., Amenta, P. S. & Thomas, T. (2000) Effects of genistein and structurally related phytoestrogens on cell cycle kinetics and apoptosis in MDA-MB-468 human breast cancer cells. Oncol. Rep. 7:3-12.[Medline]
76. Oda, Y., Nagasu, T. & Chait, B. T. (2001) Enrichment analysis of phosphorylated proteins as a tool for probing the phosphoproteome. Nat. Biotechnol. 19:379-382.[Medline]
77. An, J., Tzagarakis-Foster, C., Scharschmidt, T. C., Lomri, N. & Leitman, D. C. (2001) Estrogen receptor beta-selective transcriptional activity and recruitment of coregulators by phytoestrogens. J. Biol. Chem. 276:17808-17814.
78. Dotzlaw, H., Leygue, E., Watson, P. H. & Murphy, L. C. (1999) Estrogen receptor-beta messenger RNA expression in human breast tumor biopsies: relationship to steroid receptor status and regulation by progestins. Cancer Res. 59:529-532.
79. Cao, S., Hudnall, S. D., Kohen, F. & Lu, L. J. (2000) Measurement of estrogen receptors in intact cells by flow cytometry. Cytometry 41:109-114.[Medline]
80. Vladusic, E. A., Hornby, A. E., Guerra-Vladusic, F. K., Lakins, J. & Lupu, R. (2000) Expression and regulation of estrogen receptor beta in human breast tumors and cell lines. Oncol. Rep. 7:157-167.[Medline]
81. Fuqua, S. A., Schiff, R., Parra, I., Friedrichs, W. E., Su, J. L., McKee, D. D., Slentz-Kesler, K., Moore, L. B., Willson, T. M. & Moore, J. T. (1999) Expression of wild-type estrogen receptor beta and variant isoforms in human breast cancer. Cancer Res. 59:5425-5428.
82. Tong, D., Schuster, E., Seifert, M., Czerwenka, K., Leodolte, S. & Zeillinger, R. (2002) Expression of estrogen receptor beta isoforms in human breast cancer tissues and cell lines. Breast Cancer Res. Treat. 71:249-255.[Medline]
83. Ivanova, T., Mendez, P., Garcia-Segura, L. M. & Beyer, C. (2002) Rapid stimulation of the PI3-kinase/Akt signalling pathway in developing midbrain neurones by oestrogen. J. Neuroendocrinol. 14:73-79.[Medline]
84. Simoncini, T., Genazzani, A. R. & Liao, J. K. (2002) Nongenomic mechanisms of endothelial nitric oxide synthase activation by the selective estrogen receptor modulator raloxifene. Circulation 105:1368-1373.
85. Hisamoto, K., Ohmichi, M., Kanda, Y., Adachi, K., Nishio, Y., Hayakawa, J., Mabuchi, S., Takahashi, K., Tasaka, K., Miyamoto, Y., Taniguchi, N. & Murata, Y. (2001) Induction of endothelial nitric-oxide synthase phosphorylation by the raloxifene analog LY117018 is differentially mediated by Akt and extracellular signal-regulated protein kinase in vascular endothelial cells. J. Biol. Chem. 276:47642-47649.
86. Duan, R., Xie, W., Li, X., McDougal, A. & Safe, S. (2002) Estrogen regulation of c-fos gene expression through phosphatidylinositol-3-kinase-dependent activation of serum response factor in MCF-7 breast cancer cells. Biochem. Biophys. Res. Commun. 294:384-394.[Medline]
87. Camper-Kirby, D., Welch, S., Walker, A., Shiraishi, I., Setchell, K. D., Schaefer, E., Kajstura, J., Anversa, P. & Sussman, M. A. (2001) Myocardial Akt activation and gender: increased nuclear activity in females versus males. Circ. Res. 88:1020-1027.
88. Basly, J. P., Marre-Fournier, F., Le Bail, J. C., Habrioux, G. & Chulia, A. J. (2000) Estrogenic/antiestrogenic and scavenging properties of (E)- and (Z)-resveratrol. Life Sci. 66:769-777.[Medline]
89. Ye, R., Bodero, A., Zhou, B. B., Khanna, K. K., Lavin, M. F. & Lees-Miller, S. P. (2001) The plant isoflavonoid genistein activates p53 and Chk2 in an ATM-dependent manner. J. Biol. Chem. 276:4828-4833.
90. Kagami, S., Urushihara, M., Kondo, S., Loster, K., Reutter, W., Tamaki, T., Yoshizumi, M. & Kuroda, Y. (2001) Requirement for tyrosine kinase-ERK1/2 signaling in alpha 1 beta 1 integrin-mediated collagen matrix remodeling by rat mesangial cells. Exp. Cell Res. 268:274-283.[Medline]
91. Shao, Z. M., Shen, Z. Z., Fontana, J. A. & Barsky, S. H. (2000) Genistein’s "ER-dependent and independent" actions are mediated through ER pathways in ER-positive breast carcinoma cell lines. Anticancer Res. 20:2409-2416.[Medline]
92. Schultze-Mosgau, M. H., Dale, I. L., Gant, T. W., Chipman, J. K., Kerr, D. J. & Gescher, A. (1998) Regulation of c-fos transcription by chemopreventive isoflavonoids and lignans in MDA-MB-468 breast cancer cells. Eur. J. Cancer 34:1425-1431.
93. Panetti, T. S. (2002) Tyrosine phosphorylation of paxillin, FAK, and p130CAS: effects on cell spreading and migration. Front. Biosci. 7:d143-d150.[Medline]
94. Carragher, N. O., Levkau, B., Ross, R. & Raines, E. W. (1999) Degraded collagen fragments promote rapid disassembly of smooth muscle focal adhesions that correlates with cleavage of pp125(FAK), paxillin, and talin. J. Cell Biol. 147:619-630.
95. Carragher, N. O., Westhoff, M. A., Riley, D., Potter, D. A., Dutt, P., Elce, J. S., Greer, P. A. & Frame, M. C. (2002) v-Src-induced modulation of the calpain-calpastatin proteolytic system regulates transformation. Mol. Cell Biol. 22:257-269.
96. Perrin, B. J. & Huttenlocher, A. (2002) Calpain. Int. J. Biochem. Cell Biol. 34:722-725.[Medline]
97. Dourdin, N., Bhatt, A. K., Dutt, P., Greer, P. A., Arthur, J. S., Elce, J. S. & Huttenlocher, A. (2001) Reduced cell migration and disruption of the actin cytoskeleton in calpain-deficient embryonic fibroblasts. J. Biol. Chem. 276:48382-48388.
98. Song, R. X., McPherson, R. A., Adam, L., Bao, Y., Shupnik, M., Kumar, R. & Santen, R. J. (2002) Linkage of Rapid Estrogen Action to MAPK Activation by ER alpha-Shc Association and Shc Pathway Activation. Mol. Endocrinol. 16:116-127.
99. Santen, R., Jeng, M. H., Wang, J. P., Song, R., Masamura, S., McPherson, R., Santner, S., Yue, W. & Shim, W. S. (2001) Adaptive hypersensitivity to estradiol: potential mechanism for secondary hormonal responses in breast cancer patients. J. Steroid Biochem. Mol. Biol. 79:115-125.[Medline]
100. Lu, Z., Jiang, G., Blume-Jensen, P. & Hunter, T. (2001) Epidermal growth factor-induced tumor cell invasion and metastasis initiated by dephosphorylation and downregulation of focal adhesion kinase. Mol. Cell Biol. 21:4016-4031.
101. Petit, V. & Thiery, J. P. (2000) Focal adhesions: structure and dynamics. Biol. Cell. 92:477-494.[Medline]
102. Carolin, K. A. & Pass, H. A. (2000) Prevention of breast cancer. Crit. Rev. Oncol. Hematol. 33:221-238.[Medline]
103. Rochefort, H., Platet, N., Hayashido, Y., Derocq, D., Lucas, A., Cunat, S. & Garcia, M. (1998) Estrogen receptor mediated inhibition of cancer cell invasion and motility: an overview. J. Steroid Biochem. Mol. Biol. 65:163-168.[Medline]
104. Cavalieri, E. L. & Rogan, E. G. (2002) A unified mechanism in the initiation of cancer. Ann. N.Y. Acad. Sci. 959:341-354.[Medline]
105. Breithofer, A., Graumann, K., Scicchitano, M. S., Karathanasis, S. K., Butt, T. R. & Jungbauer, A. (1998) Regulation of human estrogen receptor by phytoestrogens in yeast and human cells. J. Steroid Biochem. Mol. Biol. 67:421-429.[Medline]
106. Setchell, K. D. & Cassidy, A. (1999) Dietary isoflavones: biological effects and relevance to human health. J. Nutr. 129:758S-767S.
107. Tikkanen, M. J. & Adlercreutz, H. (2000) Dietary soy-derived isoflavone phytoestrogens. Could they have a role in coronary heart disease prevention?. Biochem. Pharmacol. 60:1-5.[Medline]
108. Wiseman, H. (2000) The therapeutic potential of phytoestrogens. Exp. Opin. Investig. Drugs 9:1829-1840.
109. Kurzer, M. S. & Xu, X. (1997) Dietary phytoestrogens. Annu. Rev. Nutr. 17:353-381.[Medline]
110. Brandi, M. L. (1997) Natural and synthetic isoflavones in the prevention and treatment of chronic diseases. Calcif. Tissue Int. 61(suppl. 1):S5-S8.
111. Horn-Ross, P. L., John, E. M., Lee, M., Stewart, S. L., Koo, J., Sakoda, L. C., Shiau, A. C., Goldstein, J., Davis, P. & Perez-Stable, E. J. (2001) Phytoestrogen consumption and breast cancer risk in a multiethnic population: the Bay Area Breast Cancer Study. Am. J. Epidemiol. 154:434-441.
112. Baber, R. J., Templeman, C., Morton, T., Kelly, G. E. & West, L. (1999) Randomized placebo-controlled trial of an isoflavone supplement and menopausal symptoms in women. Climacteric 2:85-92.[Medline]
113. Adlercreut, H., Mazur, W., Stumpf, K., Kilkkinen, A., Pietinen, P., Hulten, K. & Hallmans, G. (2000) Food containing phytoestrogens, and breast cancer. Biofactors 12:89-93.[Medline]
114. Brzezinski, A. & Debi, A. (1999) Phytoestrogens: the "natural" selective estrogen receptor modulators?. Eur. J. Obstet. Gynecol. Reprod. Biol. 85:47-51.[Medline]
115. Messina, M. J. & Loprinzi, C. L. (2001) Soy for breast cancer survivors: a critical review of the literature. J. Nutr. 131:3095S-3108S.
116. Glazier, M. G. & Bowman, M. A. (2001) A review of the evidence for the use of phytoestrogens as a replacement for traditional estrogen replacement therapy. Arch. Intern. Med. 161:1161-1172.
117. Lamartiniere, C. A., Cotroneo, M. S., Fritz, W. A., Wang, J., Mentor-Marcel, R. & Elgavish, A. (2002) Genistein chemoprevention: timing and mechanisms of action in murine mammary and prostate. J. Nutr. 132:552S-558S.
118. Goldwyn, S., Lazinsky, A. & Wei, H. (2000) Promotion of health by soy isoflavones: efficacy, benefit and safety concerns. Drug Metab. Drug Interact 17:261-289.[Medline]
119. Li, Y., Bhuiyan, M. & Sarkar, F. H. (1999) Induction of apoptosis and inhibition of c-erbB-2 in MDA-MB-435 cells by genistein. Int. J. Oncol. 15:525-533.[Medline]
120. Savouret, J. F. & Quesne, M. (2002) Resveratrol and cancer: a review. Biomed. Pharmacother. 56:84-87.[Medline]
121. Smith, A. & Ashworth, A. (1998) Cancer predisposition: where’s the phosphate?. Curr. Biol. 8:R241-R243.[Medline]
This article has been cited by other articles:
|
|
 |
|
  D. Ung and S. Nagar Variable Sulfation of Dietary Polyphenols by Recombinant Human Sulfotransferase (SULT) 1A1 Genetic Variants and SULT1E1 Drug Metab. Dispos., May 1, 2007; 35(5): 740 - 746. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. R. Yance Jr and S. M. Sagar Targeting Angiogenesis With Integrative Cancer Therapies Integr Cancer Ther, March 1, 2006; 5(1): 9 - 29. [Abstract] [PDF]
|
|
|
|
 |
|
 P. Totta, F. Acconcia, F. Virgili, A. Cassidy, P. D. Weinberg, G. Rimbach, and M. Marino Daidzein-Sulfate Metabolites Affect Transcriptional and Antiproliferative Activities of Estrogen Receptor-{beta} in Cultured Human Cancer Cells J. Nutr., November 1, 2005; 135(11): 2687 - 2693. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M Maggiolini, A G Recchia, D Bonofiglio, S Catalano, A Vivacqua, A Carpino, V Rago, R Rossi, and S Ando The red wine phenolics piceatannol and myricetin act as agonists for estrogen receptor {alpha} in human breast cancer cells J. Mol. Endocrinol., October 1, 2005; 35(2): 269 - 281. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. J. Ferguson, E. Kurowska, D. J. Freeman, A. F. Chambers, and D. J. Koropatnick A Flavonoid Fraction from Cranberry Extract Inhibits Proliferation of Human Tumor Cell Lines J. Nutr., June 1, 2004; 134(6): 1529 - 1535. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Boscolo, A. d. Signore, E. Sabbioni, M. Di Gioacchino, L. Di Giampaolo, M. Reale, P. Conti, R. Paganelli, and M. Giaccio Effects of Resveratrol on Lymphocyte Proliferation and Cytokine Release Ann. Clin. Lab. Sci., April 1, 2003; 33(2): 226 - 231. [Abstract] [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
