Effect of an angiotensin II type 1 receptor blocker on caveolin-1 expression in prostate cancer cells

Abstract

Introduction: Caveolin-1, the major structural protein of caveolae, interacts directly with the AT1 receptor. The biological functions of caveolin-1 in cancer are compound, multifaceted, and depend on cell type, tumour grade and cancer stage. The AT1-R-caveolin complex in caveolae may coordinate angiotensin II (Ang II) induced signalling. The aim of this study was to determine the effect of the angiotensin II receptor type 1 blocker candesartan on caveolin expression in human metastatic prostate adenocarcinoma cells PC-3.

Material and methods: WST-1 and BrdU assays were used as indicators of cell viability and proliferation after angiotensin II and/or candesartan stimulation. Real-time RT-PCR and western blot were used to study the effect of Ang II and/or candesartan on the expression of Cav-1 and AT1-R in PC-3 cells.

Results: We found that the expression of caveolin-1 mRNA in the PC-3 cells treated with CV was significantly decreased in comparison with the control (2.9 ±0.17, 4.7 ±0.6, p < 0.05), whereas a higher caveolin-1 mRNA expression was observed in those after Ang II treatment (6.0 ±0.43, 4.7 ±0.6, p < 0.05). Protein analysis indicate that the expression of caveolin-1 protein in the PC-3 cells treated with candesartan was significantly decreased when compared with the control (0.69 ±0.05, 1.6 ±0.12, p < 0.05), whereas higher caveolin-1 protein expression was observed after Ang II treatment (2.5 ±0.20, 1.6 ±0.12, p < 0.05).

Conclusions: These results provide new information on the action of candesartan and may improve the knowledge about AT1 receptor inhibitors, which can be potentially useful in prostate cancer therapy.

Keywords: angiotensin II; angiotensin II type 1 receptor; candesartan; caveolin-1; prostate cancer.

Figure 1

AT1-R expression in prostate cancer cells and inhibition of cell proliferation by candesartan in PC-3 cells. A – Total RNA from prostate adenocarcinoma cells was extracted and AT1 receptors were detected by real-time RT PCR. B – Representative Western blot with anti-AT1 receptor antibody. a – non-treated PC-3 cells, b – PC-3 cells exposed to angiotensin II (10 µM), c – PC-3 cells exposed to candesartan (10 µM), d – PC-3 cells pre-treated with candesartan and exposed to angiotensin II. C, D – The effect of Ang II and CV on cell proliferation and viability. Columns, mean of three different experiments; *p < 0.05). Control – non-treated cells, Ang II – the cells exposed to angiotensin II, CV – the cells exposed to candesartan, Ang II/CV – cells pre-treated with candesartan and exposed to angiotensin II

Figure 2

Effect of Ang II and CV on Cav-1 expression in prostate cancer cells. A – Total RNA from prostate adenocarcinoma cells was extracted and Cav-1 was detected by real-time RT PCR. B – Representative Western blot with anti-Cav-1 antibody. a – non-treated PC-3 cells, b – PC-3 cells exposed to angiotensin II (10 µM), c – PC-3 cells exposed to candesartan (10 µM), d – PC-3 cells pretreated with candesartan and exposed to angiotensin II. C – Relative protein levels are shown in the diagram. Columns, mean of three different experiments; *p < 0.05). Control – non-treated cells, Ang II – the cells exposed to angiotensin II, CV – the cells exposed to candesartan, Ang II/CV – cells pretreated with candesartan and exposed to angiotensin II