Growth Inhibition by Caffeic Acid, One of the Phenolic Constituents of Honey, in HCT 15 Colon Cancer Cells

Previous work from our laboratory showed that the mechanism of crude-honey induced apoptosis in colon cancer cells. Since phenolic constituents of honey were attributed to its apoptosis-inducing ability, we studied caffeic acid, one of the phenolic constituents of honey, induced effect on colon cancer cells. Antiproliferative effect of caffeic acid was estimated using 3-(4,5dimethylthiazol- 2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. MTT assay signified the antiproliferative nature of caffeic acid against the HCT 15 colon cancer cells. A time-dependent inhibition of colony formation was evident with caffeic acid treatment. Cell-cycle analysis of caffeic acid-(CA-) treated cells indicated increasing accumulation of cells at sub-G(1) phase. Photomicrograph images of treated cells showed membrane blebbing and cell shrinkage. Yo-pro-1 staining of caffeic-acid-treated cells confirmed apoptosis in dose-and time-dependent manner. Increasing ROS generation and reduction in the mitochondrial membrane potential were also accompanied in the caffeic acid-induced apoptosis. This work will promote caffeic acid as a likely candidate in the chemoprevention of colon cancer.