Thompson J, Peltola KJ, Koskinen PJ, Jänne OA, Palvimo JJ. Attenuation of androgen receptor-dependent transcription by the serine/threonine kinase Pim-1.
J Transl Med 2003;
83:1301-9. [PMID:
13679438 DOI:
10.1097/01.lab.0000087585.03162.a3]
[Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Androgens play a key role in the regulation of the normal prostate as well as in the promotion and progression of prostate cancer. Recently, an oncogenic serine/threonine kinase, Pim-1, was reported to be overexpressed in prostate cancer. To elucidate whether Pim-1 is capable of modulating androgen signaling, we studied the effects of Pim-1 on androgen receptor (AR)-dependent transcription. Under transient transfection conditions, Pim-1 attenuated transcriptional activity of AR in a dose-dependent fashion in PC-3, HeLa, and COS-1 cells, whereas a kinase-negative mutant of Pim-1, Pim-1(K67M), showed no repressive activity. In contrast, ectopic expression of Pim-1 did not influence the activity of endogenous AR in LNCaP cells. This was, however, not a result of the T877A mutation present in AR of LNCaP cells, because that AR mutant was repressed by Pim-1 as efficiently as wild-type AR when expressed in PC-3 prostate cancer cells. Pim-1 inhibited AR mutants devoid of the ligand-binding domain or the core amino-terminal transactivation function but failed to influence the DNA binding of AR. Because we found no evidence for phosphorylation of AR by Pim-1 or for direct interaction between these proteins, Pim-1 is likely to influence AR activity via an indirect mechanism, possibly involving phosphorylation of a coregulator and/or a component of the transcription machinery. Overexpression of Pim-1 may thus attenuate androgen response during progression of prostate cancer in a cell context-dependent fashion.
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