Propranolol and Capecitabine Synergy on Inducing Ferroptosis in Human Colorectal Cancer Cells: Potential Implications in Cancer Therapy

Background/Objectives: Colorectal cancer (CRC) is a significant global health issue with rising incidence and mortality rates. In oncology, drug repurposing has emerged as a promising therapeutic strategy in conjunction with conventional treatments. This study aimed to evaluate the potential of repurposing propranolol (PRO), a beta blocker, for the treatment of CRC cell lines (HCT-116 and HT-29), both as a monotherapy and in combination with capecitabine (CAP). Methods: Effects of mono- and combination therapies on viability, combination index, morphology, and cell death induction of CRC cells were assessed. Transcriptome analysis of HT-29 cells was performed using RNA sequencing. Metabolite profiling was conducted, and changes in biochemical parameters were evaluated using flow cytometry and biochemical analyses. Results: The combination index showed that HT-29 cells were the most responsive to the combined treatment, even with PIK3CA, B-RAF (V600E), and TP53 mutations. Moreover, ferroptosis was synergistically activated in the combined group of HT-29 in comparison to control. Furthermore, we observed an increase in OXPHOS metabolites, along with elevated intracellular and mitochondrial ROS, disruption of mitochondrial membrane potential, and greater levels of malondialdehyde (MDA) in the HT-29 combined group, which are the features of ferroptosis. Furthermore, ferroptosis induction was coupled with necroptosis, as indicated by RNA-sequencing data. Combination therapy inhibited cell migration and enhanced the immune response of HT-29 cells. Conclusions: These findings suggest that PRO is promising as a potential adjuvant therapy in combination with CAP for the treatment of CRC. Only HT-29 cells with the B-RAF (V600E) mutation showed promising findings in this study.