Phytate hydrolysate induces circumferential F-actin ring formation at cell-cell contacts by a Rho-associated kinase-dependent mechanism in colorectal cancer HT-29 cells

Phytate (inositol hexa-phosphate or IP6) possessing anticancer activity is hydrolyzed by phytase in intestinal microbes and the metabolites are distributed throughout the colon. Cellular circumferential F-actin rings, which are involved in cell polarity and structure, are lost early during tumorigenesis. We investigated F-actin ring formation by the phytate hydrolysate in colorectal cancer HT-29 cells to explore the novel mechanisms underlying the phytate-mediated anticancer function. The phytate hydrolysate, but not inositol or phytate, induced F-actin ring formation with a peak at 10 min in the cells and was associated with phosphorylation of myosin regulatory light chain. F-actin ring formation and myosin regulatory light chain phosphorylation by the phytate hydrolysate were suppressed by inhibitors of Rho-associated kinase (ROCK), Janus kinase (JAK), c-Jun N-terminal kinase (JNK), and protein kinase C delta (PKC delta). Activation of ROCK and JAK, but not JNK or PKC delta, was observed at 10 min and/or earlier after stimulation with the phytate hydrolysate. Altogether, the phytate hydrolysate induces circumferential F-actin ring formation through a ROCK-dependent myosin II activation in the HT-29 cells, which requires JAK activation and basal activities of JNK and PKC. Hydrolysis products of phytate in the intestine may contribute to anticancer function of phytate.