INOSITOL HEXAPHOSPHATE AND INOSITOL INHIBIT DMBA-INDUCED RAT MAMMARY-CANCER

Because inositol hexaphosphate (InsP(6)) and inositol (Ins), contained in plants and most mammalian cells, have been demonstrated to have an ti-cancer and anti-cell proliferative action in several experimental m odels of carcinogenesis we have examined the effect of InsP(6) +/- Ins on DMBA-induced rat mammary tumor model, Starting two weeks prior to induction with DMBA, the drinking water of female Sprague-Dawley rats was supplemented with either: 15 mM InsP(6), 15 mM Ins, or 15 mM InsP( 6) + 15 mM Ins; a control group received no inositol compounds, Animal s (49-day-old) were given a single intragastric dose of DMBA (5 mg/rat ) in 1 ml of corn oil administered by oral intubation. After 45 weeks of treatment, the animals in all the three treatment regimens showed a significant reduction (P < 0.05) in tumor incidence, Tumor number, mu ltiplicity and tumor burden were also significantly (P < 0.05) reduced by InsP(6) +/- Ins, When all the parameters were taken into considera tion, the best results were obtained by the combination treatment of I nsP(6) + Ins, Four additional groups not receiving DMBA, but drinking tap water, InsP(6), Ins, or InsP(6) + Ins of the same molarity as expe rimental groups were observed for the duration of the study to monitor for any toxicity following this long-term treatment; no significant t oxicity as evaluated by body weight gain, serum and bone mineral level s was detected. We demonstrate that InsP(6) + Ins reproducibly inhibit s experimental mammary carcinoma, therefore having great potential as a chemopreventive and adjuvant therapeutic agent for this disease as w ell.