Inositol hexaphosphate (IP6) inhibits cellular proliferation in melanoma

Inositol Hexaphosphate (IP6) is a naturally occurring polyphosphorylated carbohydrate found in food sources high in fiber content. We have previously reported IP6 to have significant inhibitory effects against pancreatic cancer in vitro. We hypothesized that the IP6 would significantly inhibit cell growth of cutaneous melanoma in vitro.

The melanoma line HTB68 was cultured using standard techniques and treated with IP6 at doses ranging from 0.2 to 1.0 mM/well. Cell viability was measured by MTT at 72 h. VEGF production was measured in the cell supernatants by ELISA. Apoptosis was evaluated by Annexin V-FITC and results calculated using FACS analysis. Statistical analysis was performed by ANOVA.

Significant reductions (P < 0.001) in cellular proliferation were observed with IP6. Overall, IP6 exhibited a mean inhibition of cell growth of 52.1 +/- 11.5% (range, 1.6-83.0%) at 72 h of incubation. VEGF production was significantly reduced (P < 0.001) by the addition of IP6 (7.5 pg/ml) compared to control (40.9 pg/ml). IP6 significantly increased (P = 0.029) late apoptosis from 5.3 to 7.0% gated events. No changes in necrosis or early apoptosis were observed.

Adjuvant treatment of melanoma continues to challenge clinicians and patients. Our findings that IP6 significantly decreased cellular growth, VEGF production and increased late apoptosis in melanoma suggest its potential therapeutic value. Further in vivo studies are planned to evaluate safety and clinical utility of this agent.