Molecular mechanism of adaphostin-mediated G1 arrest in prostate cancer (PC-3) cells: signaling events mediated by hepatocyte growth factor receptor, c-Met, and p38 MAPK pathways.
Adaphostin (NSC680410), a small molecule congener of tyrphostin AG957, has been demonstrated previously to have significant anti-proliferative effects in several leukemia models. However, this effect of adaphostin in adherent cells/solid tumor models has not been examined. In this study, we investigated the anti-proliferative effects of adaphostin in the human prostate cancer cell line PC-3. Specifically, we explored the potential molecular mechanism(s) by which adaphostin elicits its anti-proliferative effect(s). We demonstrate that adaphostin inhibits the proliferation of PC-3 cells by inducing a G(1) phase cell cycle arrest. This adaphostin-induced G(1) arrest was associated with an increase in the expression of p21 and p27 and a decrease in the expression of G(1)-specific cyclins (cyclin A, D1, and D3) and cyclin-dependent kinases 4 and 6. Consequently, a dramatic decrease in the phosphorylation of retinoblastoma protein was also observed. Additionally, we found that adaphostin treatment induced a decrease in the phosphorylation of nucleophosmin, a major nuclear phosphoprotein, and that this decreased phosphorylation was a result of the p21- and p27-mediated inactivation of cyclin E-cyclin-dependent kinase 2 complex kinase activity. Furthermore, we have determined that the adaphostin-mediated cell cycle arrest of PC-3 cells is dependent upon activation of the p38 MAPK. We also demonstrate that the hepatocyte growth factor receptor-c-Met is involved in the adaphostin-mediated signaling events that regulate p38 MAPK. Taken together, these results identify for the first time a signaling cascade of adaphostin-mediated G(1) phase-specific cell cycle arrest in PC-3 cells. These findings suggest that the tyrphostin member has a broader spectrum of activity than originally predicted.
Mukhopadhyay
Indranil
I
Laboratory of Clinical Trials Unit, Division of Cancer Treatment and Diagnosis, NCI, National Institutes of Health, Bethesda, Maryland 20892, USA.
Sausville
Edward A
EA
Doroshow
James H
JH
Roy
Krishnendu K
KK
D000218:Adamantane / Q000031:analogs & derivatives* / Q000494:pharmacology; D001483:Base Sequence; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D019927:Cyclin E / Q000378:metabolism; D051357:Cyclin-Dependent Kinase 2 / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000378:metabolism; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000235:genetics / Q000378:metabolism; D016193:G1 Phase / Q000187:drug effects; D006801:Humans; D006873:Hydroquinones / Q000494:pharmacology*; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008297:Male; D008954:Models, Biological; D009687:Nuclear Proteins / Q000378:metabolism; D056489:Nucleoplasmins; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D019859:Proto-Oncogene Proteins c-met / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
C493956:CDKN1A protein, human; D019927:Cyclin E; D050759:Cyclin-Dependent Kinase Inhibitor p21; D006873:Hydroquinones; C404397:NSC 680410; D009687:Nuclear Proteins; D056489:Nucleoplasmins; D010750:Phosphoproteins; D034741:RNA, Small Interfering; D050760:Cyclin-Dependent Kinase Inhibitor p27; D019859:Proto-Oncogene Proteins c-met; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2; D048051:p38 Mitogen-Activated Protein Kinases; D000218:Adamantane