Regulation of Akt/FOXO3a/GSK-3β/AR Signaling Network by Isoflavone in Prostate Cancer Cells

Abstract

We have previously shown that genistein could inhibit Akt activation and down-regulate AR (androgen receptor) and PSA (prostate-specific antigen) expression in prostate cancer (PCa) cells. However, pure genistein showed increased lymph node metastasis in an animal model, but such an adverse effect was not seen with isoflavone, suggesting that further mechanistic studies are needed for elucidating the role of isoflavone in PCa. It is known that FOXO3a and GSK-3β, targets of Akt, regulate cell proliferation and apoptosis. Moreover, FOXO3a, GSK-3β, and Src are AR regulators and regulate transactivation of AR, mediating the development and progression of PCa. Therefore, we investigated the molecular effects of isoflavone on the Akt/FOXO3a/GSK-3β/AR signaling network in hormone-sensitive LNCaP and hormone-insensitive C4-2B PCa cells. We found that isoflavone inhibited the phosphorylation of Akt and FOXO3a, regulated the phosphorylation of Src, and increased the expression of GSK-3β, leading to the down-regulation of AR and its target gene PSA. We also found that isoflavone inhibited AR nuclear translocation and promoted FOXO3a translocation to the nucleus. By electrophoretic mobility shift assay and chromatin immunoprecipitation assay, we found that isoflavone inhibited FOXO3a binding to the promoter of AR and increased FOXO3a binding to the p27KIP1 promoter, resulting in the alteration of AR and p27KIP1 expression, the inhibition of cell proliferation, and the induction of apoptosis in both androgen-sensitive and -insensitive PCa cells. These results suggest that isoflavone-induced inhibition of cell proliferation and induction of apoptosis are partly mediated through the regulation of the Akt/FOXO3a/GSK-3β/AR signaling network. In conclusion, our data suggest that isoflavone could be useful for the prevention and/or treatment of PCa. We have previously shown that genistein could inhibit Akt activation and down-regulate AR (androgen receptor) and PSA (prostate-specific antigen) expression in prostate cancer (PCa) cells. However, pure genistein showed increased lymph node metastasis in an animal model, but such an adverse effect was not seen with isoflavone, suggesting that further mechanistic studies are needed for elucidating the role of isoflavone in PCa. It is known that FOXO3a and GSK-3β, targets of Akt, regulate cell proliferation and apoptosis. Moreover, FOXO3a, GSK-3β, and Src are AR regulators and regulate transactivation of AR, mediating the development and progression of PCa. Therefore, we investigated the molecular effects of isoflavone on the Akt/FOXO3a/GSK-3β/AR signaling network in hormone-sensitive LNCaP and hormone-insensitive C4-2B PCa cells. We found that isoflavone inhibited the phosphorylation of Akt and FOXO3a, regulated the phosphorylation of Src, and increased the expression of GSK-3β, leading to the down-regulation of AR and its target gene PSA. We also found that isoflavone inhibited AR nuclear translocation and promoted FOXO3a translocation to the nucleus. By electrophoretic mobility shift assay and chromatin immunoprecipitation assay, we found that isoflavone inhibited FOXO3a binding to the promoter of AR and increased FOXO3a binding to the p27KIP1 promoter, resulting in the alteration of AR and p27KIP1 expression, the inhibition of cell proliferation, and the induction of apoptosis in both androgen-sensitive and -insensitive PCa cells. These results suggest that isoflavone-induced inhibition of cell proliferation and induction of apoptosis are partly mediated through the regulation of the Akt/FOXO3a/GSK-3β/AR signaling network. In conclusion, our data suggest that isoflavone could be useful for the prevention and/or treatment of PCa. Androgen and AR (androgen receptor) are required for both normal prostate development and prostate carcinogenesis. Androgen ablation therapy for prostate cancer, although initially effective, nearly always leads to treatment failure and progression to hormone-refractory prostate cancer (HRPC), 2The abbreviations used are: HRPC, hormone-refractory prostate cancer; PCa, prostate cancer; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; IGF, insulin-like growth factor; PBS, phosphate-buffered saline; siRNA, small interfering RNA; EMSA, electrophoretic mobility shift assay; ChIP, chromatin immunoprecipitation. for which there is no curative therapy. It is still unclear how the prostate cancer cells progress to androgen independence. However, more evidence indicates that the mechanism involved in the escape of prostate cancer (PCa) from androgen control include mutation and overexpression of the AR gene or ligand-independent AR activation by other signaling pathways, including Akt and Src (1Chen C.D. Welsbie D.S. Tran C. Baek S.H. Chen R. Vessella R. Rosenfeld M.G. Sawyers C.L. Nat. Med. 2004; 10: 33-39Crossref PubMed Scopus (1976) Google Scholar, 2Guo Z. Dai B. Jiang T. Xu K. Xie Y. Kim O. Nesheiwat I. Kong X. Melamed J. Handratta V.D. Njar V.C. Brodie A.M. Yu L.R. Veenstra T.D. Chen H. Qiu Y. Cancer Cell. 2006; 10: 309-319Abstract Full Text Full Text PDF PubMed Scopus (288) Google Scholar, 3Asim M. Siddiqui I.A. Hafeez B.B. Baniahmad A. Mukhtar H. Oncogene. 2008; 27: 3596-3604Crossref PubMed Scopus (70) Google Scholar, 4Wen Y. Hu M.C. Makino K. Spohn B. Bartholomeusz G. Yan D.H. Hung M.C. Cancer Res. 2000; 60: 6841-6845PubMed Google Scholar). Most HRPC cells express AR and the androgen-inducible PSA (prostate-specific antigen), suggesting that AR signaling plays an important role in the development and progression of HRPC (5Heinlein C.A. Chang C. Endocr. Rev. 2004; 25: 276-308Crossref PubMed Scopus (1323) Google Scholar). In prostate epithelial cells, ligand-free AR is sequestered in the cytoplasm. Binding of androgen to the AR induces AR conformational change. The AR then forms a homodimer and is phosphorylated. This phosphorylation stabilizes the ligand-AR complex, allowing its translocation to the nucleus for its activity (6Edwards J. Bartlett J.M. BJU Int. 2005; 95: 1320-1326Crossref PubMed Scopus (110) Google Scholar). The activated AR then initiates gene transcription by binding to specific androgen-response elements in the promoter regions of target genes, including PSA. More evidences have shown that instead of androgen, other molecules in cell signaling pathways can also transactivate AR (7Balk S.P. Urology. 2002; 60: 132-138Abstract Full Text Full Text PDF PubMed Scopus (237) Google Scholar). It has been found that Akt and Src can phosphorylate the AR and transactivate the activity of AR (3Asim M. Siddiqui I.A. Hafeez B.B. Baniahmad A. Mukhtar H. Oncogene. 2008; 27: 3596-3604Crossref PubMed Scopus (70) Google Scholar, 4Wen Y. Hu M.C. Makino K. Spohn B. Bartholomeusz G. Yan D.H. Hung M.C. Cancer Res. 2000; 60: 6841-6845PubMed Google Scholar). In addition, Akt has also been found to phosphorylate AR and suppress AR transactivation (8Lin H.K. Yeh S. Kang H.Y. Chang C. Proc. Natl. Acad. Sci. U. S. A. 2001; 98: 7200-7205Crossref PubMed Scopus (340) Google Scholar). Further study has shown that Akt pathway can suppress AR activity in androgen-dependent LNCaP cells with low passage numbers; however, Akt can also enhance AR activity in LNCaP cells with high passage numbers, suggesting that Akt pathway may have distinct mechanisms to modulate AR functions in various stages of prostate cancer cells (9Lin H.K. Hu Y.C. Yang L. Altuwaijri S. Chen Y.T. Kang H.Y. Chang C. J. Biol. Chem. 2003; 278: 50902-50907Abstract Full Text Full Text PDF PubMed Scopus (156) Google Scholar). Therefore, Akt could be an important regulator of AR required for the progression of PCa cells to HRPC. The activated Akt can inhibit apoptosis and promote cell survival by direct phosphorylation of its downstream targets (10Franke T.F. Hornik C.P. Segev L. Shostak G.A. Sugimoto C. Oncogene. 2003; 22: 8983-8998Crossref PubMed Scopus (1001) Google Scholar). FOXO3a (Forkhead transcription factor class O3a) is one of the main targets of activated Akt. By binding to the nuclear importer, active FOXO3a translocates to the nucleus, binds to DNA, and promotes the transcription of its target genes, including p27KIP1, inducing either cell cycle arrest or apoptosis (11Burgering B.M. Kops G.J. Trends Biochem. Sci. 2002; 27: 352-360Abstract Full Text Full Text PDF PubMed Scopus (624) Google Scholar). However, activated Akt regulates transcription of FOXO3a target genes through phosphorylation of FOXO3a, leading to the release of FOXO3a from DNA and translocation to the cytoplasm (11Burgering B.M. Kops G.J. Trends Biochem. Sci. 2002; 27: 352-360Abstract Full Text Full Text PDF PubMed Scopus (624) Google Scholar, 12Brunet A. Bonni A. Zigmond M.J. Lin M.Z. Juo P. Hu L.S. Anderson M.J. Arden K.C. J. Cell. Full Text Full Text PDF PubMed Scopus Google Scholar). It has been found that FOXO3a also promotes the transcription of AR L. Xie S. Altuwaijri S. J. Kim Chen Y.T. Hu Y.C. L. Chang C. J. Biol. Chem. 2005; Full Text Full Text PDF PubMed Scopus Google Scholar). Therefore, signaling to important in the development and progression of HRPC. is main Akt target gene involved in the induction of apoptosis and cell cycle arrest (10Franke T.F. Hornik C.P. Segev L. Shostak G.A. Sugimoto C. Oncogene. 2003; 22: 8983-8998Crossref PubMed Scopus (1001) Google Scholar). also cell survival through regulation of one of the molecules in signaling A. Cell. PubMed Scopus Google Scholar). Moreover, is an AR regulator that activity of AR, a network with S. H. Oncogene. 2006; 25: PubMed Scopus Google Scholar, Kim J. P. G. A. Chen L. M. J. J. Biol. Chem. 2004; Full Text Full Text PDF PubMed Scopus Google Scholar). In addition, Src, one of the important can Akt through the regulation of Yang H. Oncogene. 2005; PubMed Scopus Google and transactivate AR through the phosphorylation of AR Z. Dai B. Jiang T. Xu K. Xie Y. Kim O. Nesheiwat I. Kong X. Melamed J. Handratta V.D. Njar V.C. Brodie A.M. Yu L.R. Veenstra T.D. Chen H. Qiu Y. Cancer Cell. 2006; 10: 309-319Abstract Full Text Full Text PDF PubMed Scopus (288) Google suggesting that Src is also a of the Akt/FOXO3a/GSK-3β/AR signaling network. These suggest that Akt/FOXO3a/GSK-3β/AR signaling network may important in the development and progression of HRPC. Therefore, specific of the molecules in signaling network by a could be important for HRPC cells, and such a could be useful for the prevention and/or treatment of not PCa but HRPC and We and have previously found that one of the active found in a effect on various including PCa S. J. Google Scholar, Y. S. M. Oncogene. PubMed Scopus Google Scholar). We have also that genistein induces growth inhibition and apoptosis in PCa cells through the down-regulation of Akt Y. Cancer Res. 2002; Google AR, and PSA O. 2002; PubMed Scopus Google Scholar). Moreover, Y. O. M. M. M.C. B. Cancer 2004; Google from our have found that pure genistein could lymph node in an of PCa by however, such a was not found isoflavone was used S. M. J. O. Int. J. PubMed Scopus Google Scholar). These suggest that isoflavone is more for cancer prevention and treatment however, no such studies have been to to the effect and molecular mechanisms of on the Akt/FOXO3a/GSK-3β/AR signaling network in PCa cells, in HRPC cells. we found that one of the could inhibit the growth of prostate cancer cells through the inhibition of signaling Y. Z. Kong S. S. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus (110) Google Scholar). we for the that isoflavone is a class of for inducing growth inhibition and cell in both androgen-sensitive LNCaP and C4-2B PCa cells, which is partly mediated through the regulation of Akt/FOXO3a/GSK-3β/AR we that isoflavone pure genistein be for the prevention and/or treatment of PCa but in HRPC, for which there is no curative therapy. and PCa cell including LNCaP and C4-2B cells, in with and in a and by and from the of was in to a The of isoflavone we in to the of genistein in the isoflavone It has been that the of genistein in can to a of to M.G. T. J.M. S.H. J. 2002; PubMed Scopus Google and that prostate can genistein isoflavone in PCa A. A. S. H. 2006; PubMed Scopus Google Scholar). Therefore, we and isoflavone to and for in was from and from and used for or by and LNCaP and C4-2B PCa cells in the cells in with isoflavone, or isoflavone for cells with the cells to an assay, previously Y. S. O. Cancer Res. 2005; PubMed Scopus Google and a assay the and to the The growth inhibition of LNCaP and C4-2B cells by isoflavone treatment was with and for of and C4-2B PCa cells with isoflavone, or isoflavone for cells with and in for The cells then with for and a or We also the cells in control or or cells the cell assay to the previously Y. S. O. Cancer Res. 2005; PubMed Scopus Google Scholar). The activity of in was by the assay the The and activation of also by The induction of apoptosis by isoflavone treatment of LNCaP and C4-2B PCa cells was with of and and C4-2B PCa cells with isoflavone for and treatment and the cells in and The cell was and through a small of the cells for cell the cell was and the was The was in and the by was nuclear The in the was by a assay and to immunoprecipitation by of or and of and for the The was then in and for and was used for and C4-2B cells with or isoflavone for or cell of the cells was by the cells in and In of and nuclear also The was by the assay cell and or nuclear to previously Y. S. O. Cancer Res. 2005; PubMed Scopus Google Scholar). The of was and by The of control was by the of control to the with Akt activated and by Cancer The or was LNCaP and C4-2B PCa cells the cells and with by treatment with isoflavone for the and nuclear from and cells and to the and LNCaP PCa cells with Akt or control by of the from The of Akt, GSK-3β, and PSA expression was by C4-2B cells also with AR, and control and for The effects of on cell proliferation by an and C4-2B PCa cells on and with isoflavone for then with for with PBS, and with in for The cells then with or with PBS, the cells with or for and with a and the and was to the activity of FOXO3a binding to AR or p27KIP1 promoter in and cells. LNCaP and C4-2B PCa cells with isoflavone for nuclear from cells was and to DNA binding and we previously Y. S. O. Cancer Res. 2005; PubMed Scopus Google Scholar). The of which AR or p27KIP1 promoter with a FOXO3a DNA binding are for AR and for p27KIP1 L. Xie S. Altuwaijri S. J. Kim Chen Y.T. Hu Y.C. L. Chang C. J. Biol. Chem. 2005; Full Text Full Text PDF PubMed Scopus Google Scholar, T. T. I. Biochem. J. 2000; PubMed Scopus Google Scholar, and M. Sci. Scholar). FOXO3a was also to the of FOXO3a DNA binding assay was to the effect of isoflavone on FOXO3a binding to AR or p27KIP1 promoter an in LNCaP and C4-2B PCa cells with isoflavone for and the cells in cell and on for The and in nuclear and on for the nuclear to an DNA of and was the assay of with FOXO3a The FOXO3a DNA with for and the and from The DNA and DNA then and and the DNA and the AR promoter p27KIP1 promoter data to the and the of AR or p27KIP1 promoter DNA was by was by and of FOXO3a of and of AR and by have previously that genistein the phosphorylation of Akt in PCa cells and the expression of PSA in LNCaP PCa cells Y. Cancer Res. 2002; Google Scholar, O. 2002; PubMed Scopus Google Scholar). further isoflavone could suppress the expression of PSA through the inhibition of Akt phosphorylation and the of AR, we the effects of isoflavone on Akt, FOXO3a, and AR in and We that phosphorylation of Akt, FOXO3a, and AR was by in PCa cells, However, isoflavone inhibited the phosphorylation of Akt, FOXO3a, and AR in the cytoplasm and nucleus of C4-2B and LNCaP PCa cells and Moreover, isoflavone the of Akt, FOXO3a, and AR phosphorylation by of Akt both and was inhibited by isoflavone and we found that isoflavone inhibited the phosphorylation of FOXO3a both and and in LNCaP and C4-2B PCa cells We have also that the of FOXO3a was increased in nuclear isoflavone treatment suggesting that the increased of FOXO3a in both the cytoplasm and nucleus of PCa cells could a of active FOXO3a in the nuclear to inhibit cancer cell further the effects of isoflavone on FOXO3a and AR, we studies Akt We found that Akt the of Akt, and PSA to the effects of isoflavone, suggesting that the effect of isoflavone on FOXO3a and AR is mediated through the Akt We also the PCa cells to a of isoflavone for a and results suggesting that the down-regulation of by isoflavone in our studies was not the of cell In addition, we also found that AR expression and isoflavone AR expression and phosphorylation both and and we the effects of isoflavone on FOXO3a and AR Akt with Akt and activated Akt we of and in the cytoplasm and nucleus of C4-2B PCa cells and We also AR phosphorylation in nucleus and increased of PSA in the Akt and we found that isoflavone could the of and PSA by Akt or activated Akt and increased the of FOXO3a in the nuclear and By we found that isoflavone inhibited the of Akt and FOXO3a in the cytoplasm and nucleus of PCa cells and with Akt and in FOXO3a phosphorylation by isoflavone We also found that isoflavone the of FOXO3a and AR complex, which could inhibit FOXO3a in both the and nuclear and suggesting that of active FOXO3a in the nuclear in cells could be with the and effects of Moreover, we found that isoflavone the expression of from and to and with the down-regulation of AR by By we that binding to was increased isoflavone treatment and also inhibited the phosphorylation of and increased the phosphorylation of and suggesting that isoflavone could signaling to inhibit PCa cell AR could also be by activated Src, we investigated the effects of isoflavone on Src signaling to further to the molecular mechanism of of of Src by we found that isoflavone the expression of Src Moreover, the of which is activated of Src, was by isoflavone However, the of which Src was increased These are with the down-regulation of Akt and AR signaling by isoflavone both AR and FOXO3a are transcription that regulate the transcription of target genes in the nuclear we further investigated the nuclear of AR and FOXO3a by isoflavone of AR and of FOXO3a by we found that isoflavone the of nuclear AR however, the nuclear FOXO3a was increased isoflavone treatment we PCa cells to isoflavone for We that AR was nuclear AR was suggesting the inhibition of AR nuclear translocation by Moreover, isoflavone treatment for the of both and nuclear AR with the results from We also the expression of one of the nuclear and the of with AR or FOXO3a in and PCa cells. We found that isoflavone the of in LNCaP and C4-2B PCa cells More we found that isoflavone inhibited binding to AR with the data from and and the effects of isoflavone on the nuclear of However, we increased binding of to FOXO3a and and increased of FOXO3a in nuclear isoflavone with the data from FOXO3a functions a transcription which is known to regulate the transcription of its target genes, including AR and p27KIP1, we the effects of isoflavone on the activity of AR and p27KIP1 regulated by of p27KIP1 by EMSA, we found that isoflavone increased the activity of FOXO3a binding to p27KIP1 promoter DNA in C4-2B PCa cells assay the that isoflavone FOXO3a binding to the p27KIP1 promoter in in PCa cells and Moreover, we found an increased of p27KIP1 of isoflavone treatment in LNCaP and C4-2B PCa cells with the data from and we found that of PCa cells to isoflavone for a the nuclear translocation of p27KIP1 suggesting that isoflavone cell proliferation partly through the nuclear of of AR by to the data on p27KIP1, EMSA, we found that isoflavone inhibited the activity of FOXO3a binding to AR promoter DNA in C4-2B PCa cells suggesting the effect of isoflavone on the transcription of The data from the assay showed that isoflavone treatment FOXO3a binding to the AR promoter in in C4-2B PCa cells and By we found the down-regulation of AR expression by isoflavone treatment and with the results from and FOXO3a, GSK-3β, p27KIP1, Src, and AR are important in Akt and AR signaling that regulate cell we the effects of isoflavone on cell proliferation and apoptosis. of and of by through of Akt/FOXO3a/GSK-3β/AR of proliferation we found that which Akt, promoted cell proliferation in LNCaP and C4-2B PCa cells and isoflavone inhibited cell proliferation and cell proliferation and By for cells, we more and in C4-2B and LNCaP PCa cells with control suggesting that isoflavone could apoptosis. cell we a apoptosis We found that cancer cells from apoptosis isoflavone apoptosis and of LNCaP and C4-2B PCa cells from apoptosis further the induction of apoptosis by isoflavone, we activity and We found increased activity of and the and active in cells. Moreover, AR also inhibited the proliferation of prostate cancer cells, p27KIP1 promoted cell growth These results are with our on the of Akt, FOXO3a, and AR by or isoflavone treatment suggesting that the inhibition of cell proliferation and induction of apoptosis by isoflavone is partly mediated by the regulation of Akt/FOXO3a/GSK-3β/AR signaling apoptosis. C4-2B and LNCaP PCa cells with isoflavone, or isoflavone for cell was by and in cell assay with activity assay with and for of is an important in the Akt signaling pathway H. 2006; PubMed Scopus Google Scholar). The to control FOXO3a is phosphorylation of FOXO3a by Akt. The of FOXO3a is one of the that cancer cells or cell our of we found that isoflavone inhibited the phosphorylation and activation of Akt, leading to the of Moreover, isoflavone also increased nuclear translocation of FOXO3a, leading to the of FOXO3a in the nuclear of cells. These results suggest that isoflavone regulates the activity of FOXO3a through the regulation of FOXO3a phosphorylation and nuclear It has been shown that FOXO3a regulates the transcription of p27KIP1 and AR by binding to L. Xie S. Altuwaijri S. J. Kim Chen Y.T. Hu Y.C. L. Chang C. J. Biol. Chem. 2005; Full Text Full Text PDF PubMed Scopus Google Scholar, Y. X. L. K. S.P. B. Biol. Cell. 2005; PubMed Scopus Google Scholar). and assay, we found that isoflavone was to FOXO3a binding to p27KIP1 promoter and suppress FOXO3a binding to the AR promoter, resulting in the increased p27KIP1 expression and AR of p27KIP1 promoter activity and expression by FOXO3a regulation could to the growth inhibition and cell that we have in PCa cells, in It has been that FOXO3a AR expression L. Xie S. Altuwaijri S. J. Kim Chen Y.T. Hu Y.C. L. Chang C. J. Biol. Chem. 2005; Full Text Full Text PDF PubMed Scopus Google AR P. H. S. G. Cell. Biol. 2003; PubMed Scopus Google a to a AR and The of AR and isoflavone treatment suggest that isoflavone could the resulting in the inhibition of AR transactivation It is important to that the of transcription for a specific gene chromatin promoter and DNA binding the regulation of including and B. R. 2000; PubMed Scopus Google Scholar). FOXO3a DNA binding could also be by the in chromatin and such GSK-3β, leading to increased FOXO3a binding to the p27KIP1 promoter and binding to the AR In addition, the alteration of p27KIP1 by isoflavone treatment could also be to the activity of previously A. Biochem. 2003; PubMed Scopus Google Scholar). Therefore, further are required for the and effect molecules isoflavone-induced cell is that cell cycle and apoptosis in the Akt signaling also with to regulate cell proliferation through It has been shown that activated Akt and A. J. Biol. Chem. 2003; 278: Full Text Full Text PDF PubMed Scopus Google Scholar). Akt is can phosphorylate and leading to the inhibition of cell survival by signaling S. H. Oncogene. 2006; 25: PubMed Scopus Google Scholar, H. Cell. 2006; Full Text Full Text PDF PubMed Scopus Google Scholar). In we found that isoflavone treatment phosphorylation and increased expression and suggesting that isoflavone could down-regulate However, the regulation of signaling is a and mechanistic studies that are in our has been that can suppress the activity of AR Kim J. P. G. A. Chen L. M. J. J. Biol. Chem. 2004; Full Text Full Text PDF PubMed Scopus Google Src can AR Z. Dai B. Jiang T. Xu K. Xie Y. Kim O. Nesheiwat I. Kong X. Melamed J. Handratta V.D. Njar V.C. Brodie A.M. Yu L.R. Veenstra T.D. Chen H. Qiu Y. Cancer Cell. 2006; 10: 309-319Abstract Full Text Full Text PDF PubMed Scopus (288) Google Scholar). also can a with AR binding to the PSA promoter to PSA transcription S. C. L.R. Z. R. Oncogene. 27: PubMed Scopus Google Scholar). In we increased expression of and active Src, AR, and PSA in PCa cells. More we found that isoflavone inhibited AR phosphorylation and These results suggest that isoflavone could inhibit cell survival through the regulation of signaling study by other also showed that genistein in could inhibit Akt activation and activity in PCa model, evidence of isoflavone effect in PubMed Scopus Google and results are with our Akt, FOXO3a, p27KIP1, GSK-3β, and Src are molecules in and with other to regulate cell survival and apoptosis K. Res. 2006; PubMed Scopus Google Scholar, M. C.L. L. J. Biol. 2006; PubMed Scopus Google Scholar, C. M. S. M. H. R. J. P. C. J.M. Oncogene. 2006; 25: PubMed Scopus Google Scholar). Moreover, of AR that AR transactivation L. Xie S. Altuwaijri S. J. Kim Chen Y.T. Hu Y.C. L. Chang C. J. Biol. Chem. 2005; Full Text Full Text PDF PubMed Scopus Google Scholar, Kim J. P. G. A. Chen L. M. J. J. Biol. Chem. 2004; Full Text Full Text PDF PubMed Scopus Google Scholar, S. Cancer Res. 2000; 60: Google Scholar). It is that there is Akt, FOXO3a, p27KIP1, GSK-3β, Src, and Therefore, the Akt/FOXO3a/GSK-3β/AR signaling network to in the control of PCa cell growth and apoptosis. In the we found that isoflavone its effects on of molecules of signaling The effect of isoflavone could from the inhibition of Akt activation and of of in signaling leading to the inhibition of AR transactivation and PSA expression in both androgen-sensitive and -insensitive PCa cells More has been found that Akt, FOXO3a, and regulators in the development of PCa by regulation of the of AR and other genes S. H. Oncogene. 2006; 25: PubMed Scopus Google Scholar, B. A. H. Y. Xu P. PubMed Scopus Google Scholar, A.M. Cancer Res. 2005; PubMed Scopus Google Scholar). We found that the isoflavone in the that we have used could regulate molecules and down-regulation of AR transactivation and of suggesting that isoflavone could be used for the prevention and/or treatment of PCa, HRPC. The of pure or with the isoflavone for the regulation of Akt/FOXO3a/GSK-3β/AR signaling pathways are needed to the role of a in the isoflavone that is for the adverse effect of pure genistein in PCa, and studies are in our which could be important for further to the molecular mechanism of of isoflavone for the prevention and/or treatment of PCa in the It is known that growth factor Akt and AR L. D.H. S. Int. J. PubMed Scopus Google Scholar, P. Cell. Biol. 2000; PubMed Scopus Google suggesting that and could cell growth and inhibit apoptosis. we found that isoflavone the and Akt and AR activation and cell proliferation and more cell also Akt downstream genes, including FOXO3a, GSK-3β, and p27KIP1, to the of Akt, resulting in the down-regulation of These results suggest that isoflavone-induced inhibition of cell proliferation and induction of cell are in to the regulation of the Akt/FOXO3a/GSK-3β/AR signaling network. molecular mechanistic data also suggest that isoflavone could be a for the prevention and/or treatment of PCa but for HRPC.