IP6 in Cancer Therapy: Past, Present and Future

Inositol hexaphosphate (IP6) and its derivatives are naturally occurring, most abundant polyphosphorylated carbohydrates in organisms as diverse as yeast, endo-parasites, mammals and plants. IP6 represents a major metabolic pool in cellular phosphate pathways involved in vital functions such as signal transduction, regulation of cell proliferation and differentiation, RNA export, DNA repair, energy transduction and ATP regeneration. IP6 has been recognized as a natural antioxidant and agent preventing calcification and kidney stone formation, normalizing cholesterol concentrations, and reducing pathological platelet activity. The most striking effect of IP6 has been documented in cancer prevention by controlling tumor growth, progression and metastasis. Its anti-cancer actions involve boosting immunity, antioxidant properties, reducing cell proliferation and inducing differentiation of malignant cells. This is brought about via lower-phosphate inositol phosphates (IP1- 5) and probably by the highly phosphorylated derivatives (PP-IP4 and PP-IP5); however the selectivity of its metabolite(s) in anti-cancer activity has not been adequately investigated. Preliminary in vitro studies show that IP6 synergistically acts with conventional anti-cancer drugs like tamoxifen overcoming its resistance thus enhancing the anticancer effect of conventional chemotherapy. In this review we present anti-cancer abilities of IP6 and its metabolites and discuss their future use as potential drug(s) for cancer prevention and therapy.