Anti-proliferative and Anti-migratory Activities of Diphyllin on Human Colorectal Cancer Cells

Background: Colorectal cancer (CRC) is the third leading cause of death, probably because of its invasive and metastatic potential. Agents that can mitigate the growth and prevent migration may benefit CRC. Diphyllin and its analogues belong to glycosylated compounds previously reported for their in vitro cytotoxicity against many viruses, candida, and human malignant cells. This study aims to evaluate the anti-proliferative and antimigratory activities of diphyllin on human CRC cells. Methods: The MTT assay was performed to determine the 50% inhibitory concentrations (IC50) in HT-29, SW-480, and HCT-15 CRC cells. The acridine orange and ethidium bromide (AO/EB) dual staining was used to ascertain the type of cell death. HT-29 cells were subjected to short-term 5-fluorouracil+oxaliplatin (5-FU+Ox) to eliminate the most sensitive cells. The remaining surviving cells were further treated with diphyllin alone or combined with 5-FU. The combination effect of diphyllin with 5-FU in 5-FU+Ox surviving HT-29 cells was determined by flow cytometry-based Annexin V apoptosis assay. The wound-healing assay was used to detect the anti-migratory activity of diphyllin on 5-FU+Ox surviving HT-29 CRC cells. Results: The IC50 values of diphyllin were found to be 2.9±0.38, 1.3±0.28, and 3.9±0.65 µg/mL against HT-29, SW-480, and HCT-15, respectively. Microscopic examination manifested apoptotic changes like chromatin condensation, nuclear fragmentation, and formation of apoptotic bodies in diphyllin treated CRC cells. Flow cytometry analysis revealed that diphyllin enhances the apoptosis in 5-FU+Ox surviving HT-29 cells. Wound-healing assay displayed the inhibitory activity of diphyllin in 5-FU+Ox surviving HT-29 cells. Conclusion: Diphyllin shows anti-proliferative activity by inducing apoptosis in HT-29, SW-480, HCT-15 cells and 5-FU+Ox surviving HT-29 cells and impairs their migration.