Login to Access Video or Poster Abstract: MP83-18
Sources of Funding: none.

Introduction

Under androgen deprivation therapy (ADT), 21-carbon steroids (C21s), such as progesterone (P4) and glucocorticoids, accumulate in men with prostate cancer (PCa). Accumulated C21s could stimulate the progesterone receptor (PGR) or glucocorticoid receptor (GR) on PCa cells, and a relationship between these stimulations and castration resistance in PCa has been suggested. However, although the intra-tumoral metabolism of C21s in PCa cells exists, it is not known whether intracrine C21s are implicated in PCa progression. In this study, we showed that 20β-dihydro-5α-dihydroprogesterone (20β-OHDHP), a C21 and a metabolite of P4, was synthesized in PCa cells and was able to directly stimulate the androgen receptor.

Methods

LNCaP cells expressing mutant AR (mAR) and VCaP cells expressing wild-type AR (wAR) were incubated in the presence of several agents. After incubation, cell growth was determined by the MTS assay, PSA levels were determined by an enzyme immunoassay, C21 and androgen levels were measured by LC-MS, gene expression was analyzed by qRT-PCR, and AR-related signaling was determined by a reporter assay.

Results

The presence of 20β-OHDHP synthesis from pregnenolone (P5) and the absence of androgen synthesis from P5 or 20β-OHDHP were observed in both cells. With the addition of 20β-OHDHP to the medium, both cells were promoted in a concentration-dependent manner and were able to continuously proliferate or simply survive. In both cells, the expression of AR-related genes, such as KLK3, TMPRSS2, and FKBP5, increased in the presence of 20β-OHDHP and RLU increased in a concentration-dependent manner; however, the expression of GR-related genes, such as SGK1, NR3C1 and PGR, decreased. The stimulation of 20β-OHDHP was inhibited by the addition of bicalutamide, which blocks androgens from binding to AR.

Conclusions

Under ADT, 20β-OHDHP synthesized in PCa cells accelerates their own growth due to the stimulation of both wAR and mAR. This pathway may be an interesting candidate for targeted therapy.

Funding

none.