Expression of NLRC4 is Associated with Apoptosis and Immune Infiltration in Lung Adenocarcinoma Cells

Abstract

Background: Nucleotide-binding domain leucine-rich family caspase-activation and recruitment domain (CARD) domain-containing protein 4 (NLRC4) has been linked to several human diseases. However, its function in lung adenocarcinoma is uncertain. Methods: NLRC4 expression was investigated using The Cancer Genome Atlas (TCGA) and pan-cancer Genotype-Tissue Expression data. The researchers examined the link between NLRC4 expression and patient outcome by using TCGA clinical survival data. NLRC4 enrichment was analyzed using the clusterProfiler R package. The TCGA database was also used to investigate the association between NLRC4 expression and immune cell infiltration. Western blot was used to confirm NLRC4 expression and its effect on apoptosis-related proteins in lung adenocarcinoma. Immunohistochemistry was used to investigate the effect of NLRC4 expression on immune cell infiltration. Results: NLRC4 expression is low in lung adenocarcinoma. Low NLRC4 expression was associated with related genes involved in apoptosis and immune cell activation. Further investigation showed that low NLRC4 expression was associated with high infiltration scores of macrophages, dendritic cells, T cells, B cells, and natural killer (NK) cells. NLRC4 knockdown inhibited apoptosis-related protein production in lung adenocarcinoma cells. The number of peripheral macrophages, dendritic cells, T cells, B cells, and NK cells was significantly reduced in pathological tissues with low NLRC4 expression. Conclusions: Our findings suggest that NLRC4 may be a risk gene for lung adenocarcinoma and affects the infiltration of the tumor immune cells.