Effect of extracellular ATP on the growth of hormone-refractory prostate cancer in vivo

To investigate whether the antineoplastic action of ATP on hormone-refractory prostate carcinoma (HRPC) cells in vitro also occurs in vivo, by examining the effect of ATP in vivo on tumours resulting from implanted HRPC cells in mice. HRPC tumour cells DU145 and PC-3 were implanted into male nude athymic mice. The effect of daily intraperitoneal (i.p.) injections of ATP (25 mm) on the growth of freshly implanted and established HRPC tumours was assessed. Histological examination using light and electron microscopy was used to confirm retention of the original ultrastructure of the implanted tumours. Daily i.p. injections of ATP significantly reduced the growth of freshly implanted DU145 tumour by 57.8% (P = 0.003), and reduced the rate of growth of established DU145 tumour by 69.0% (P = 0.006). ATP also significantly reduced the growth of freshly implanted PC-3 tumour by 68.9% (P < 0.001). ATP treatment had no adverse effects on the host mice. Our results show, for the first time, that ATP effectively reduces the growth of advanced HRPC tumours in vivo. This may represent a step in establishing ATP as an effective agent for HRPC treatment.