Expression of A1 and A3 adenosine receptors in human breast tumors.

BACKGROUND Adenosine receptors (A1, A2A, A2B, A3) play an important role in the regulation of growth, proliferation and death of cancer and normal cells. We recently showed the expression profile of A2A and A2B receptors in normal and tumor breast tissues. In the present study, we used semiquantitative RT-PCR to measure the A1 and A3 gene expression levels in normal and tumor breast tissues. METHODS Breast tumors (n = 18) and non-neoplastic mammary tissues (n = 10) were collected and histologically confirmed to be neoplastic or non-neoplastic, respectively. Total RNA was extracted and reverse transcribed into cDNA, and PCR was performed under optimized condition for each receptor subtype. Amplification of beta-actin mRNA served as control for RT-PCR. The PCR products were separated on 1.7% agarose gels. The intensity of the bands was quantitated with ImageJ software after normalization against beta-actin expression. RESULTS All breast tumor and normal tissue specimens expressed A1 and A3 adenosine receptor transcripts. However, we observed that the expression level of the A3 receptor in tumor tissues was 1.27-fold that of normal tissues, whereas there was no significant difference between the expression levels of A1 in normal and tumor tissues. CONCLUSIONS Interestingly, the results of the present study indicate that breast tumors exhibit a higher level of A3 transcripts (than normal tissues) and support the possible key role of A3 adenosine receptor in tumor development. However, further studies based on real-time quantitative RT-PCR are needed to identify the exact gene expression levels.