c-Jun NH(2)-terminal kinase mediates leptin-stimulated androgen-independent prostate cancer cell proliferation via signal transducer and activator of transcription 3 and Akt.
Obesity is associated with advanced prostate cancer. Here we demonstrate that in mouse prostate cancer TRAMP-C1 cells epididymal fat extracts from high-fat diet-fed obese mice stimulate androgen-independent cell growth more significantly than those from low-fat diet-fed lean mice or genetically obese leptin-deficient ob/ob mice in correlation with leptin concentrations. This result suggests that obesity promotes androgen-independent prostate cancer cell growth via adipose leptin. We have reported that added leptin stimulates androgen-independent prostate cancer cell proliferation through c-Jun NH(2)-terminal kinase (JNK). As with JNK, signal transducer and activator of transcription 3 (STAT3) and Akt are implicated in androgen-independent prostate cancer. In this study, we identify novel interaction of these three molecules in leptin-stimulated androgen-independent cell proliferation. Leptin activates JNK, STAT3 and Akt in a biphasic manner with a similar time-course. Pharmacological JNK inhibition suppresses leptin-stimulated DNA binding activity, as well as Ser-727 phosphorylation, of STAT3. Since JNK upregulates STAT3 activity via Ser-727 phosphorylation, JNK mediates leptin-stimulated STAT3 activation through Ser-727 phosphorylation. Moreover, JNK inhibition impairs leptin-stimulated Ser-473 phosphorylation of Akt that is required for its activation. Thus, JNK is involved in leptin-stimulated Akt activation. These findings together indicate that JNK mediates leptin-stimulated androgen-independent prostate cancer cell proliferation via STAT3 and Akt.
Miyazaki
Toshiaki
T
Department of Surgical Research, Beckman Research Institute of the City of Hope, Duarte, CA 91010-3000, USA.
Bub
Jeffrey D
JD
Iwamoto
Yoshiki
Y
D052436:Adipose Tissue, White / Q000737:chemistry; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D004247:DNA / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015870:Gene Expression / Q000235:genetics; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020738:Leptin / Q000276:immunology / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008820:Mice, Obese; D008954:Models, Biological; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D011471:Prostatic Neoplasms / Q000378:metabolism* / Q000473:pathology; D011485:Protein Binding / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D054411:Receptors, Leptin / Q000235:genetics; D050796:STAT3 Transcription Factor / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014020:Tissue Extracts / Q000494:pharmacology
D000906:Antibodies; D004791:Enzyme Inhibitors; D020738:Leptin; D000081082:Phosphoinositide-3 Kinase Inhibitors; D054411:Receptors, Leptin; D050796:STAT3 Transcription Factor; D014020:Tissue Extracts; D004247:DNA; D051057:Proto-Oncogene Proteins c-akt; D048031:JNK Mitogen-Activated Protein Kinases