Expression of Adenosine Receptor Subclasses in Malignant and Adjacent Normal Human Prostate Tissues

Abstract

BACKGROUNDAdenosine, a purine nucleoside plays important roles in the pathogenesis of cancer initiation and promotion via interaction with four adenosine receptors. In the present study we examined the differential expression pattern of adenosine receptors in the malignant and adjacent normal human prostate tissues. METHODSProstate cancer tissue samples and adjacent normal tissues were obtained from 20 patients undergoing radical prostatectomy and histopathological diagnosis was confirmed for each sample. Total RNA was extracted and reverse transcribed into cDNA and the mRNA expression levels of adenosine receptors were investigated by Taq-man real-time RT-PCR experiment. Quantitative protein analysis was done by Western blotting experiment. Moreover, the mRNA and protein expression levels of adenosine receptors were measured after androgen treatment. RESULTTaq-man real-time RT-PCR measurements show different expression levels of adenosine receptor transcripts. A(2B) adenosine receptor was predominantly expressed in tumor tissues (2.4-fold) followed by significantly expression of A(3) (1.6-fold) and A(2A) adenosine receptors (1.5-fold) compared to adjacent normal tissues. The presence of adenosine receptors at protein levels in prostate cancer tissues compared with normal tissues was shown the following rank order: A(2B)>A(3)>A(2A)>A(1). Androgen receptor regulates adenosine receptors mRNA and protein expression in AR-positive LNCaP cells, which was not seen in AR-negative PC-3 cells. CONCLUSIONThese results indicated for the first time, the differential mRNA expression profile and protein levels of adenosine receptors in the human prostate cancer. Interestingly, the A(2B) adenosine receptor followed by A(3) is highly expressed in prostate tumor samples in comparison with the adjacent normal tissues. The findings support the possible key role of A(2B) adenosine receptor in promoting cancer cell growth and suggest that A(2B) may be a novel target for prostate cancer treatment. Prostate 75:735-747, 2015. (c) 2015 Wiley Periodicals, Inc.