CASQ2 alleviates lung cancer by inhibiting M2 tumor‐associated macrophage polarization and JAK/STAT pathway

Lung cancer (LC) is a major inducer of cancer-related death. We aim to reveal the effect of Calsequestrin2 (CASQ2) on macrophage polarization and Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway in LC. Hub genes were determined from protein-protein interaction networks based on GSE21933 and GSE1987 data sets using bioinformatic analysis. Expression of hub genes was verified by real-time quantitative polymerase chain reaction (RT-qPCR). Cell Counting Kit-8, 5-ethynyl-2'-deoxyuridine, wound-healing, colony formation, and transwell assays were performed to assess the impact of CASQ2 on LC cells. A xenograft mouse model was evaluated using hematoxylin-eosin, immunohistochemistry, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining to investigate the effect of CASQ2 on LC. The role of CASQ2 in regulating macrophage polarization and JAK/STAT pathway was evaluated by western blot andRT-qPCR. We screened out 155 common differentially expressed genes in GSE21933 and GSE1987 data sets. Myomesin-2, tyrosine kinase, sex determining region Y-box 2, platelet and endothelial cell adhesion molecule 1, matrix metallopeptidase 9, claudin-5, caveolin-1, CASQ2, recombinant ATPase, Ca++ transporting, cardiac muscle, slow twitch 2 (ATP2A2), and ankyrin repeat domain 1 were identified as the hub genes with high prediction value. CASQ2 was selected as a pivotal regulator of LC. In vitro experiments and xenograft models revealed that CASQ2 overexpression suppressed proliferation, colony formation, migration, invasion of LC cells, and tumor growth in vivo. Additionally, overexpression of CASQ2 promoted the expression of M1 macrophage markers (cluster of differentiation 80 [CD80], interleukin [IL]-12, inducible nitric oxide synthase [iNOS]), while decreasing the expression of M2 macrophage markers (CD163, IL-10, Arg1) in tumor-associated macrophages and xenograft tissues. Finally, we found that overexpression of CASQ2 inhibited JAK/STAT pathway. CASQ2 is a novel biomarker, which can alleviate LC via inhibiting M2 tumor-associated macrophage polarization and JAK/STAT pathway.