Low RYR2 Level Relates to Poor Prognosis of Patients With Lung Adenocarcinoma by Promoting Tumor Cell Proliferation and Inhibiting Immune Cell Infiltration.

Abstract

Ryanodine receptor type 2 (RYR2) is a large calcium channel that has been identified as one of the most frequently mutated genes in lung adenocarcinoma (LUAD). Despite its potential significance, the role of RYR2 in LUAD remains poorly understood. In this study, we obtained transcriptomic data (normal n = 59, tumor n = 541) from TCGA portal and RYR2 protein abundance data from cProSite, which includes 86 normal and 91 tumor samples. Additionally, we assembled a cohort of 38 patients with LUAD and collected paired tumor and adjacent non-tumor control samples. To investigate the functional impact of RYR2, we employed 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometry analysis to assess cell viability and apoptosis, respectively. While mitochondria function was evaluated via measuring oxygen consumption rate. The relationship between RYR2 expression level and immune cell infiltration was analyzed by immunohistochemistry and flow cytometry analysis. Furthermore, RT-qPCR and enzyme-linked immunosorbent assay were used to quantify the expression levels of CCL14 and CXCL12. Our findings demonstrated that both the mRNA and protein levels of RYR2 were significantly downregulated in LUAD samples, and lower RYR2 levels are associated with the poor patient prognosis. Overexpression of RYR2 in A549 and H1299 cells resulted in impaired mitochondrial function, decreased cell viability, and increased apoptosis. Notably, RYR2 levels exhibited a negative correlation with tumor purity, and tumors with lower RYR2 levels showed diminished infiltration of T cells and dendritic cells. Knockdown of RYR2 in LUAD cells inhibited the production of chemokines, particularly CCL14 and CXCL12. In conclusion, our study reveals that RYR2 functions as a tumor suppressor in LUAD by inducing mitochondrial dysfunction and promoting immune cell infiltration.