INOSITOL HEXAPHOSPHATE INHIBITS GROWTH AND INDUCES DIFFERENTIATION OF PC-3 HUMAN PROSTATE-CANCER CELLS

We investigated the effects of inositol hexaphosphate (InsP(6)) on growth inhibition and differentiation of human prostate cancer cells PC-3 in vitro, A significant dose- and time-dependent growth inhibition was observed as tested by the MTT-incorporation assay (P < 0.05 at 1 mM InsP(6) after 24 h treatment, P < 0.01 at 0.1 mM after 3 days), DNA synthesis as determined by [H-3]thymidine incorporation assay was also suppressed by InsP(6) in a dose-dependent manner, occurring as early as 3 h after treatment and continuing up to 48 h (P < 0.01 at 1 mM InsP(6)), A 9- to 10-fold increase (P < 0.01) in expression of HLA class I molecule associated with tumor immunosurveillance and cell differentiation was induced by InsP(6). The marker for prostatic cell differentiation, prostate acid phosphatase, was significantly (P < 0.05) increased after 48 h treatment at 0.5-5 mM InsP(6), Since InsP(6) strongly inhibits growth and induces differentiation in human prostate cancer cells in vitro, in vivo studies using a tumor xenograft model and a prostate carcinogenesis model are warranted to validate the efficacy of InsP(6) in the treatment and prevention of prostate cancer.