Repurposing an antimicrobial arginine-rich decapeptide as a novel anticancer agent: Evidence from in vitro and in vivo breast cancer models.

Objectives: . Materials and Methods: Cytotoxicity was assessed in breast (4T1), colon (SW480), and normal fibroblast (NIH3T3) cell lines by MTT assay following 48- and 72-hr treatment (6-400 µg/ml). Membrane integrity was examined in 4T1 cells after 48 hr using lactate dehydrogenase (LDH) release. Flow cytometry was applied to determine apoptosis induction and alterations in cell cycle distribution. Caspase 3/7 activity was also evaluated. Apoptosis-related gene expressions were analyzed using RT-PCR. The antitumor effect of RL10 was assessed in a murine 4T1 model, followed by histopathological analysis using H&E staining. Results: ˂0.01), accompanied by increased apoptotic figures and reduced mitotic counts. Conclusion: These findings provide the first evidence that an arginine-rich short peptide exhibits anticancer activity through apoptosis induction and tumor growth inhibition, underscoring its potential as a candidate for cancer therapy or drug delivery systems.