Comprehensive characterization of the effects of ellagic acid and urolithins on colorectal cancer and key-associated molecular hallmarks: MicroRNA cell specific induction of CDKN1A (p21) as a common mechanism involved.

SCOPE: Ellagitannins, ellagic acid, and the colonic metabolites urolithins (Uros) exhibit anticancer effects against colon cells, but a comprehensive molecular analysis has not been done. Herein, we used a panel of cell lines to first time evaluate the antiproliferative properties and accompanying molecular responses of two ellagitannin metabolites mixtures mimicking the situation in vivo and of each individual metabolite.

METHODS AND RESULTS: We examined cell growth, cell cycle, apoptosis, and the expression of related genes and microRNAs (miRs) in a panel of nonmalignant and malignant colon cell lines. Regardless of the composition, the mixed metabolites similarly inhibited proliferation, induced cycle arrest, and apoptosis. All the metabolites contributed to these effects, but Uro-A, isourolithin A, Uro-C, and Uro-D were more potent than Uro-B and ellagic acid. Despite molecular differences between the cell lines, we discerned relevant changes in key cancer markers and corroborated the induction of CDKN1A (cyclin-dependent kinase inhibitor 1A gene (p21, Cip1); encoding p21) as a common step underlying the anticancer properties of Uros. Interestingly, cell-unique downregulation of miR-224 or upregulation of miR-215 was found associated with CDKN1A induction.

CONCLUSION: Physiologically relevant mixtures of Uros exert anticancer effects against colon cancer cells via a common CDKN1A upregulatory mechanism. Other associated molecular responses are however heterogeneous and mostly cell-specific.