Immunotherapeutic strategies are recognized as promising treatment methods for colorectal cancer (CRC). αβT cell-mediated cytotoxicity is tolerated by cancer cells with low MHC class I expression; therefore, γδT cell-based cancer immunotherapy has generated increasing interest as a potential treatment option. To enhance the potency of γδT cell-based immunotherapy, the key factors involved in the regulation of γδT cells in CRC need to be identified along with devising ways to overcome potential hurdles. In this study, we observed that leukemia inhibitory factor (LIF), the serum level of which was highly increased in those with solid tumors, could specifically attenuate the cytotoxic function of peripheral γδT cells in patients with CRC. We observed that in patients with CRC, the expression levels of perforin and granzyme were significantly decreased in the recombinant human LIF (rhLIF)-treated peripheral γδT cells, whereas that of the LIF receptor (LIFR) was higher. The regulation of the cytotoxic function of the γδT cells by rhLIF was effected mainly through the STAT3 signaling pathway, which caused an increase in the expression levels of interleukin (IL)-17, COX-2, and prostaglandin E2 (PGE2). Our results revealed that rhLIF could impair the function of γδT cells in CRC patients by reducing the cytotoxic function and increasing the expression of tumor-promoting molecules, such as IL-17, COX-2, and PGE2.
Keywords: Colorectal cancer; STAT3; granzyme; leukemia inhibitory factor; perforin; γδT cells.