Immunocytochemical and pharmacological characterisation of P2-purinoceptor-mediated cell growth and death in PC-3 hormone refractory prostate cancer cells

Background: Extracellular nucleotides (e.g. adenosine 5'-triphosphate, ATP) influence biological processes via purinergic receptors. We characterised the P2-purinoreceptors in human hormone refractory prostate cancer (HRPC) cells (PC-3 cells). Results: 1. Immunofluorescent staining demonstrated P2X(3), P2X(4), P2X(5), P2X(7) and P2Y(2) receptors. 2. ATP inhibited cell growth by up to 91% over 72h. Pharmacological characterisation indicated a P2X-putinoreceptor-mediated response. 3. Comparable maximum growth inhibition was seen after either a single addition of 1mM or daily addition of 100mM ATP. ATP concentrations ([ATP]) returned to baseline levels within 24h if the initial [ATP] was less than or equal to100 muM, while [ATP] remained high for 72h if a single concentration of 1 mM was used. 4. ATP 1 mM significantly (p<0.001) increased the proportion of cells undergoing apoptosis from 0.27% (+/- 0.04%) to 5.28% (+/- 0.77%). Conclusion: Threshold concentrations of ATP inhibited HRPC cell growth in vitro via the activation of P2X-purinoreceptors. The role of nucleotides in the treatment of HRPC requires further investigation.