Radiofrequency hyperthermia enhances the antitumor efficacy of oncolytic peptide LTX-315 in liver cancer cells by activating of cGAS-STING pathway

Purpose This study evaluated whether radiofrequency hyperthermia (RFH) could enhance the effects of LTX-315, an oncolytic peptide, for hepatic cancer.Methods In vitro experiments using rat hepatocellular carcinoma (HCC) cells and in vivo experiments with HCC rat models were conducted. Treatments included (1) phosphate buffered saline, (2) RFH at 42 °C for 30 min, (3) LTX-315 alone, and (4) a combination of RFH with LTX-315. Cell viability and apoptosis were measured using MTS assay, flow cytometry, and fluorescence microscopy. Tumor growth was monitored for two weeks using ultrasound and optical imaging. The western blotting, enzyme-linked immunoassay, real-time polymerase chain reaction, were performed to detect the activation of cGAS-STING pathway. The immunohistochemistry, enzyme-linked immunoassay, real-time polymerase chain reaction, and flow cytometry analysis were performed to evaluate changes of immune cells in tumors, and changes of cytokines in plasma and tumors after the treatment.Results The combination treatment (RFH + LTX-315) resulted in the highest level of apoptosis and the lowest cell viability, along with the smallest tumor volume and strongest reduction in bioluminescence signal compared to other groups (p < 0.001). LTX-315 activated the cGAS-STING pathway, with RFH further enhancing this activation. After combination therapy, significant increases in CD8+ T cells, CD8+/IFN-γ+ T cells, CD8+/TNF-α+ T cells, and natural killer cells, along with a decrease in Tregs, were observed in tumors (p < 0.001).Conclusion RFH significantly enhanced the effects of LTX-315 on orthotopic HCC by activating the cGAS-STING pathway.