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Soluble factors derived from stroma activated androgen receptor phosphorylation in human prostate LNCaP cells: Roles of ERK/MAP kinase
Author(s) -
Shigemura Katsumi,
Isotani Shuji,
Wang Ruoxiang,
Fujisawa Masato,
Gotoh Akinobu,
Marshall Fray F.,
Zhau Haiyen E.,
Chung Leland W. K.
Publication year - 2009
Publication title -
the prostate
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.295
H-Index - 123
eISSN - 1097-0045
pISSN - 0270-4137
DOI - 10.1002/pros.20944
Subject(s) - lncap , stromal cell , mapk/erk pathway , cancer research , androgen receptor , prostate cancer , endocrinology , biology , androgen , kinase , medicine , protein kinase a , dihydrotestosterone , microbiology and biotechnology , cancer , hormone
BACKGROUND Accumulated evidence suggests stromal–epithelial interactions are critical to the progression of prostate cancer. In this study, we characterized AR phosphorylation in LNCaP cells co‐cultured with the conditioned medium (CM) from human prostate stromal fibroblasts. METHODS CM harvested from prostate stromal fibroblasts was added to LNCaP cells, and both anchorage‐dependent and ‐independent growth was determined. Status of AR phosphorylation at Ser‐81 and Ser‐213 was assessed by immunoblot analysis. ERK kinase activity was measured using MBP‐2 protein as the substrate. RESULTS The growth of LNCaP cells on plastic dishes increased by 1.7‐fold upon exposure to stromal CM or androgen, and their combination resulted in additive growth (2.4‐fold). Anchorage‐independent growth of LNCaP cells in soft agar, however, was induced synergistically at 80‐fold by both stromal CM and androgen. Stromal CM or androgen alone induced LNCaP cell growth by 10‐ and 26‐fold, respectively. We observed ERK kinase inhibitor, U0126, but not phosphatidylinositol 3‐kinase (PI‐3K), LY294002, or protein kinase A (PKA) inhibitor, H‐89, inhibited stromal CM or androgen‐induced PSA promoter luciferase activities, and anchorage‐independent growth of LNCaP cells. Our results demonstrated for the first time how stromal CM acts in synergy with androgen by activation of ERK kinase and AR phosphorylation at Ser‐81 but not Ser‐213, for AR‐regulated PSA promoter and anchorage‐independent growth of human prostate cancer cells. CONCLUSIONS A stromal factor‐activated ERK pathway mediated by AR phosphorylation at Ser‐81 could be responsible for stimulating the growth of human prostate cancer cells. Prostate 69: 949–955, 2009. © 2009 Wiley‐Liss, Inc.