Receptor Tyrosine Kinase AXL Regulates c-Myc to Participate in Immune Escape of Endometrial Cancer Cells

Abstract

Background: There is currently no standard follow-up treatment method for metastatic endometrial carcinoma (EC). Exploring the molecular mechanisms of EC is of great significance for the prevention and treatment of EC. This research aimed to study the impact of the receptor tyrosine kinase (AXL) on the surface of EC cells and the crucial mechanism of AXL in tumor immune escape. Methods: Western blot and flow cytometry were used to detect programmed death ligand 1 (PD-L1) and programmed cell death protein 1 (PD-1) protein in EC cell line. The AXL level was determined using quantitative real-time polymerase chain reaction (qRT-PCR). AXL plasmid and AXL shRNA were transfected into EC cells. The killing outcome of activated peripheral blood mononuclear cells (PBMC) on EC cells was detected by the lactate dehydrogenase (LDH) method. Enzyme linked immunosorbent assay (ELISA) was used for Interferon γ (IFN-γ), Granzyme B (GZMB), Perforin, and cluster of differentiation 107a (CD107a) detection in the supernatant. Furthermore, Western blot was employed to detect PD-L1 in EC cell lines treated with the c-Myc inhibitor (JQ1) for 24 h. The survival rate of tumor cells killed by PBMC was observed using crystal violet staining. Results: EC cell lines RL-952, KLE, and HEC-1B exhibited varying levels of PD-1 and PD-L1 content. RL-952 cells showed relatively high levels, while HEC-1B cells displayed low levels. AXL was found to confer resistance to lymphocyte killing and enhance PD-L1 levels in EC cells. At the cytotoxic molecules level, AXL promoted the deactivation of CD8⁺ T (Cytotoxic T lymphocytes) cells, whereas JQ1 was observed to reverse this effect. A preliminary mechanism study indicated that AXL enhanced PD-L1 levels via the c-Myc pathway in EC cells. Treatment of EC with JQ1 resulted in a decrease in cellular-myelocytomatosis viral oncogene (c-Myc) and PD-L1 levels, potentially reversing the tumor immune escape induced by AXL. Conclusions: AXL can increase the levels of PD-L1 and reinforce the immune evasion of EC cells by activating c-Myc.