Abstract

Drug repurposing, which is defined as the process of searching for new uses for existing FDA-approved drugs outside the scope of their original medical indication, has been gaining popularity in recent years. Several success stories of drug repurposing brought global attention to the already existing drug space for potential off-target effects that may be beneficial to certain diseases such as cancer. Nowadays, antibiotics have been widely recognized in the treatment of cancers. In the current study, we performed a cytotoxicity screening of 12 commercial antibiotics available in the Egyptian market on human colorectal cancer cell line (HCT-116) and also on normal human retinal pigment epithelial cells (RPE-1) for their potential activity as anticancer drugs in 2D model using MTT assay at concentration of (100 μM). Screening results showed that Vibramycin is a highly promising drug against HCT-116 cell line. Further studies on Vibramycin on 2-d and 3-d cultures were done. Ultrastructural examination of HCT-116 cells revealed that the effect of Vibramycin (100 µM) on the spheroid model was inducing apoptosis and spacing the cells from each other. In conclusion, the antibiotic Vibramycin has ‘a second life' as an anticancer drug for colorectal cancer.