TY - JOUR T1 - The role of adenosine A3 receptors in cytotoxicity of the breast cancer cell lines TT - JF - Physiol-Pharmacol JO - Physiol-Pharmacol VL - 7 IS - 2 UR - http://ppj.phypha.ir/article-1-434-en.html Y1 - 2003 SP - 115 EP - 122 KW - Adenosine receptor; A3; Breast cancer; MCF- 7; MDA; MB-468; RT -PCR N2 - The nucleoside adenosine is present within cells and body fluids of all living organisms and its production, both intra- and extracellularly, is tightly coupled to energy consumption resulting in increased level of extracellular adenosine. The physiological effects of adenosine are mediated through four pharmacologically and biochemically distinct adenosine receptors (AR), i.e. A1, A2A, A2B and A3. Al and A3 AR generally couple to Gi proteins, whereas A2A and A2B receptors activate Gs proteins. Although the presence of these receptors has been reported in both normal and cancer cells, no data is available regarding breast cancer. Therefore, this study was aimed to investigate the existence and possible role of A3 AR in ER+ MCF- 7 and ER- MDA-MB468 breast cancer cell lines. The cell lines were cultured in RPMI-1640 medium and incubated with different concentrations of IB-MECA (0.1-100 µM), A3 selective agonist, and MRS-1220 (0.1-10 µM), a highly selective antagonist for different time periods (24 - 72 hr). MTT viability test was used to evaluate the proliferative and cytotoxic response. Then, mRNA was isolated and reverse transeriptase polymerase chain reaction (RT -PCR) was used. The results showed that IB-MECA at concentrations higher than 10 µM results in a significant cell death (p M3 ER -