Antitumoral and Antiproliferative Potential of Synthetic Derivatives of Scorpion Peptide IsCT1 in an Oral Cavity Squamous Carcinoma Model

The oral cavity is a frequent site for head and neck cancers, which rank as the sixth most common cancer globally, with a 5-year survival rate slightly over 50%. Current treatments are limited, and resistance to therapy remains a significant clinical obstacle. IsCT1, a membrane-active peptide derived from the venom of the scorpion , has shown antitumor effects in various cancer cell lines, including breast cancer and chronic myeloid leukemia. However, its hemolytic action limits its potential therapeutic use. This study aims to assess the antitumor and antiproliferative activities of synthetic peptides derived from IsCT1 (IsCT-P, AC-AFPK-IsCT1, AFPK-IsCT1, AC-KKK-IsCT1, and KKK-IsCT1) in the context of oral squamous cell carcinoma. We evaluated the cytotoxic effects of these peptides on tongue squamous cell carcinoma cells and normal cells, as well as their impact on cell cycle phases, the expression of proliferation markers, modulators of cell death pathways, and mitochondrial potential. Our results indicate that the IsCT1 derivatives IsCT-P and AC-AFPK-IsCT1 possess cytotoxic properties towards squamous cell carcinoma cells, reducing mitochondrial membrane potential and the proliferative index. The treatment of cancer cells with AC-AFPK-IsCT1 led to a positive modulation of pro-apoptotic markers p53 and caspases 3 and 8, a decrease in PCNA and Cyclin D1 expression, and cell cycle arrest in the S phase. Notably, contrary to the parental IsCT1 peptide, AC-AFPK-IsCT1 did not exhibit hemolytic activity or cytotoxicity towards normal cells. Therefore, AC-AFPK-IsCT1 might be a viable therapeutic option for head and neck cancer treatment.