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

Abstract

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.