Combination of Nisin and Glabridin Enhanced Apoptosis in Colorectal Cancer Cells

Nisin is an antimicrobial peptide (AMP) that is used as an approved food preservative. This peptide also acts as an anti-cancer agent inducing apoptosis in various cancer cell lines, such as colorectal cancer cells. Glabridin (GLA) with anti-cancer properties is a type of isoflavonoid extracted from Glycyrrhiza glabra. Several studies have demonstrated Glabridin's anti-cancer properties affect the apoptotic pathway. In combination, this study evaluated Glabridin and Nisin's effects on colorectal cancer cells. HCT116 and HT-29 cell lines were exposed to different concentrations of Glabridin and Nisin. MTT assays evaluated cytotoxicity and IC50. Apoptosis induction was assessed by Bax and Bcl-2 gene expression. Also, Annexin-PI flow cytometry and western blot were used to study the induction of apoptosis. Our findings showed that these compounds at IC50 concentration (Nisin at 491.4, 363.2 IU/ml and Glabridin at 35.9, 29.6 µM) inhibited the proliferation of HCT116 and HT-29 cell lines. Bax and Bcl-2 gene expressions were significantly altered in favor of apoptosis induction in the combined group more than in the single-agent groups (* p < 0.05). Annexin-PI evaluation showed a significant increase in early apoptosis in the drug-combination group (* p < 0.05). Furthermore, western blot results exhibited increased cleaved caspase-3 in the drug-combination group. The combination of Glabridin and Nisin may inhibit colorectal cancer by decreasing the Bcl-2/Bax ratio and raising the active substance of caspase-3. Therefore, we propose a new treatment strategy for colorectal cancer, combining the two compounds with negligible side effects and the induction of apoptotic pathways.