Microbiota-Mediated Modulation of Chemotherapeutic Drug Efficacy in Colorectal Cancer: An In-Depth Analysis of Six Key Drugs.

Colorectal cancer (CRC) remains a major health burden, and emerging evidence suggests that gut microbiota may influence therapeutic responses. This study explores the interaction between Escherichia coli and non-CRC-specific anticancer drugs cyclophosphamide, Cytalon, Nitrol, etoposide, gemcitabine, and methotrexate through bacterial modification. Following bacterial incubation, drugs were tested in vitro using MTT and Alamar Blue assays, revealing significantly enhanced cytotoxicity against CRC cells (HCT116) while preserving variability in normal fibroblasts (L929). Mechanistic studies, including ROS production, mitochondrial membrane potential loss, cell cycle arrest, NF-κB translocation, and TNF-α activation confirmed the cell death induction. NMR analysis and 3D spheroid disruption demonstrated structural drug alterations postincubation in one of the best-responding drugs. These findings highlight microbial drug transformation as a promising avenue for enhancing chemotherapeutic selectivity and efficacy in colorectal cancer treatment.