Punicalagin is cytotoxic to human colon cancer cells by modulating cell proliferation, apoptosis, and invasion

Purpose: The purpose of this study was to explore the anticancer effect of punicalagin, an abundant bioactive tannin compound isolated from Punica granatum L., on three colon cancer cell lines, namely, HCT 116, HT-29, and LoVo. Research Design: Normal and colon cancer cells were treated with different concentrations of punicalagin for different periods. Data Collection and Analysis: Cell viability was measured with a CCK-8 assay. Programmed cell death and invasion were analyzed using an annexin V and cell death kit and a cell invasion analysis kit. The expression of active caspase-3, MMP-2, MMP-9, Snail, and Slug were measured by Western blot. Results: The results of the cell viability analysis showed that punicalagin was cytotoxic to colon cancer cells, but it was not to normal cells in a dose- and time-dependent manner. Additionally, punicalagin induced apoptosis in colon cancer cells (shown by the cumulative percentage of colorectal cancer cells in early and late apoptosis). It was found that caspase-3 activity increased following punicalagin treatment. Western blot results also showed that punicalagin increased the expression of activated caspase-3. In contrast, punicalagin inhibited the invasion of colon cancer cells. Further, treatment of colon cancer cells with punicalagin suppressed the expression of MMP-2, MMP-9, Snail, and Slug. Conclusions: These results showed that the activation of caspase-3 and the inhibition of MMP-2, MMP-9, Snail and Slug were involved in the effects of punicalagin on colon cancer cells.