The Nod-like receptor (NLR) family CARD domain containing 5 (NLRC5) has been reported as an activator of human leukocyte antigen (HLA) class I that is responsible for immune activity in cancer treatment. This work focuses on the role of BMI1 proto-oncogene (BMI1) in the NLRC5-HLA class I axis and in immune escape in nonsmall cell lung cancer (NSCLC). First, immunoblot analysis and/or reverse transcription-quantitative polymerase chain reaction were performed, which identified decreased NLRC5 and HLA class I levels in NSCLC tissues and cell lines. NSCLCs were co-cultured with activated CD8 + T cells. Overexpression of NLRC5 in NSCLC cells elevated the expression of HLA class I and increased the activity of T cells and IL-2 production, and it reduced the PD-1/PD-L1 levels. The ubiquitination and immunoprecipitation assays confirmed that BMI1 bound to NLRC5 to induce is ubiquitination and protein degradation. Downregulation of BMI1 in NSCLC cells elevated NLRC5 and HLA class I levels, and consequently promoted T cell activation and decreased PD-1/PD-L1 levels in the co-culture system. However, overexpression of BMI1 in cells led to inverse trends. In summary, this study demonstrates that BMI1 induces ubiquitination and protein degradation of NLRC5 and suppresses HLA class I expression, which potentially helps immune escape in NSCLC.

Background: To assess the efficacy and safety of combination of PD-1 inhibitors, recombinant human endostatin (Rh-endostatin) and chemotherapy as first-line treatment for advanced non-small-cell lung cancer (NSCLC). Methods: A total of 100 patients with advanced NSCLC were retrospectively reviewed and analyzed (58 in the group receiving PD-1 inhibitors plus Rh-endostatin and chemotherapy; 42 in the group receiving Rh-endostatin and chemotherapy). The primary end point was progression-free survival. Results: Patients in the group receiving PD-1 inhibitors plus Rh-endostatin and chemotherapy had significantly improved progression-free survival (10.2 vs 6.5 months; p < 0.001) and objective response rate (67.2 vs 42.9%; p = 0.015), with acceptable toxicity. Conclusion: Our study showed the superiority of combination therapy of PD-1 inhibitors and Rh-endostatin as first-line treatment for advanced NSCLC.