Effects of leptin on leptin receptor isoform expression and proliferative activity in human normal prostate and...

Results of studies on the expression of leptin and its receptors in the human prostate gland and human prostate cell lines are contradictory. Regarding this, we carefully reinvestigated this issue using human normal prostate (PrEC, PrSC, PrSMC) and prostate cancer (DU145, LNCaP, PC3) cell lines. Expression of leptin receptor isoforms was assessed by qPCR while the effects of leptin on cell proliferative activity was determined by real-time cell analyzer (RTCA). Expression of the leptin receptor variant 1 was not detected in LNCaP and PrSMC cell lines, but it was found in the remaining cell lines. In contrast, in all examined cell lines, isoforms 1-3 and 2 and 4 of the leptin receptor were found. The expression of isoforms 3 and 6 of the leptin receptor was observed in PC3, PrEC, PrSMC and PrSC cell lines, but not in LNCaP and DU145 cells. Expression of the leptin receptor isoforms 4-6 and 5 was not demonstrated in any of the tested cell lines. We also studied the effects of leptin on the expression of its receptor isoforms in all tested cell lines. At a wide range of concentrations, leptin did not change the expression of leptin receptor variant 1 in the DU145, PrEC and PC3 cell lines. In contrast, in the PrSC cell line, leptin significantly increased the expression of this gene. In all prostate cell lines tested, leptin did not alter the expression levels of variants 1-3 of the leptin receptor isoforms. Leptin did not alter the expression of isoforms 2 and 4 of the leptin receptor in the PC3 and LNCaP cell lines. In the DU145 and PrEC cell lines, leptin inhibited expression of these receptor isoforms while an opposite effect was noted in the PrSC cells. Leptin did not affect the expression level of variants 3 and 6 of its receptor in the PrEC and PC3 cell lines. However, in PrSMC cells, leptin inhibited the expression of variants 3 and 6 of its receptor, while in the PrSC cell line this cytokine significantly increased their expression levels. As assessed by RTCA, leptin stimulated the proliferative activity of DU145 cells, but inhibited this activity in LNCaP cells. At all concentrations tested, leptin did not change the proliferation rate of the PC3, PrEC and PrSMC cells. In contrast, leptin notably stimulated the proliferative activity of the PrSC (prostate stromal cell) cell line. Thus, our study demonstrated that in all tested human normal prostate and prostate cancer cell lines, transcription variants 4, 5 and 6 of the leptin receptor were not expressed. Leptin receptor transcription variants 1, 2 and 3 showed differential expression, which was present in the PC3, PrEC and PrSC cell lines. Our data also suggest that the stimulatory effects of leptin on proliferative activity of the studied cell lines require the expression of leptin receptor variant 1 in the affected cells.