Regulation of Bcl-2 expression by dihydrotestosterone in hormone sensitive LNCaP-FGC prostate cancer cells.
ABSTRACT Up-regulation of the anti-apoptotic bcl-2 proto-oncogene is associated with androgen independent prostate cancer progression. This observation suggests that the expression of bcl-2 may be negatively regulated by androgens in prostate cancer cells.
The expression of the proto-oncogene bcl-2 was assessed in the hormone sensitive prostate cancer cell line LNCaP-FGC in the presence and absence of a physiological concentration of 1 nM. dihydrotestosterone (DHT). Sequence analysis of the bcl-2 promoter regions demonstrated the presence of 2 potential androgen response elements. Transient transfections of luciferase reporter constructs containing these potential androgen response elements into LNCaP-FGC cells in the presence and absence of DHT were performed. Steady-state transcripts of bcl-2 were assessed using RNase protection assays.
Cells cultured in charcoal stripped serum in the presence of DHT resulted in down-regulation of bcl-2 protein. Down-regulation of bcl-2 protein and mRNA by DHT was inhibited by coincubation with the antiandrogen bicalutamide, an agent that competitively inhibits binding of DHT to androgen receptor. Luciferase reporter constructs containing candidate androgen response elements were transrepressed in the presence of DHT. Bcl-2 mRNA was also down-regulated by DHT and this down-regulation could not be abolished by cycloheximide.
Together these results suggest that the suppression of bcl-2 expression by DHT in hormone sensitive LNCaP-FGC prostate cancer cells occurs directly. In addition, these results provide a possible mechanistic basis for the up-regulation (derepression) of bcl-2 observed in hormone independent prostate cancers.
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ABSTRACT: The prostate gland is under androgen control. The aim of the present study was to evaluate the expression of two genes that are regulators of the cell cycle, the p53 and p21 genes, in human non-transformed epithelial prostatic cells (HNTEPs) treated with different concentrations of hormones. Samples of prostate tissue were obtained from 10 patients between 60 and 77 years of age. HNTEP cells were grown in basal medium and treated with dihydrotestosterone (DHT) in different conditions for 4 h. A low concentration of DHT resulted in a significant increase in cell growth; this effect was eradicated by addition of the antiandrogen hydroxyflutamide. Furthermore, the low concentration of DHT induced lower mRNA levels in the p53 and p21 genes in HNTEP cells. In turn, high DHT concentrations induced a significant increase in the expression of the p53 and p21 genes. The present data suggest that the p53 and p21 genes play a role in the control of responsiveness and androgen dose-dependent cell proliferation in HNTEP cells. Further studies are required to assess the intracellular signaling pathway regulated by p53 and p21 under the influence of androgens and its implications for the pathophysiology of prostate diseases.International Journal of Molecular Medicine 07/2012; · 1.88 Impact Factor
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ABSTRACT: BCL-2 is an integral protein of the external mitochondrial membrane that inhibits cell apoptotic death. We investigated the effect of androgen deprivation therapy (ADT) on BCL-2 expression in prostate cancer tissues. We studied BCL-2 expression in vivo in prostate cancer tissues obtained from patients who underwent radical prostatectomy after neoadjuvant ADT, by Northern and Western blot analysis, and immunohistochemistry. Moreover, gene transcriptional activity was also measured by nuclear run-on experiments. We demonstrated an increase of BCL-2 mRNA expression in patients who underwent neoadjuvant ADT for 1 month in comparison to patients who had not received any therapy. Moreover, we demonstrated that there were no significant modifications of BCL-2 mRNA levels in patients who underwent neoadjuvant ADT for 3 and 6 months. Furthermore, BCL-2 protein levels in patients who underwent neoadjuvant ADT for 1 month were upregulated in comparison to patients who had not received any therapy. Immunohistochemical analysis showed a strong positivity of prostate cells depending on ADT administration for 1 month. Finally, transcriptional activity was not modified in patients who underwent neoadjuvant ADT, suggesting the absence of hormonal regulation on BCL-2 gene expression at the transcriptional level. Our data show that short-term administration of ADT interferes with BCL-2 expression, suggesting that androgen-mediated mechanisms may act through BCL-2-mediated apoptotic pathways. Moreover, since short-term ADT administration does not interfere with BCL-2 expression at the transcriptional level, the androgen-mediated mechanisms involving BCL-2 pathways, probably act at the post-transcriptional level.International Journal of Oncology 07/2011; 39(5):1233-42. · 2.77 Impact Factor