ABSTRACT
Hypoxia, a strong and selective pressure, has been involved in invasion, metastasis, and angiogenesis of tumor cells. Our study performed the transcriptome profiles of 666 non-small-cell lung cancer (NSCLC) patients. Various bioinformatic approaches were combined to evaluate the immune cell infiltration in the high hypoxia risk patients. In addition, in vitro experiments were performed to assess the effects of tumor-associated neutrophils (TANs) on NSCLC cells proliferation, migration and invasion and to reveal the underlying mechanisms. We divided NSCLC into two groups (Cluster1/2) based on the expression profiles of hypoxia-associated genes. Compared with the Cluster1 subgroup, the Cluster2 had a worse prognosis. Significant enrichment analysis revealed that PI3K/AKT/mTOR signaling pathway and TANs were highly related to hypoxia microenvironment. Eleven hypoxia-related genes (FBP1, NDST2, ADM, LDHA, DDIT4, EXT1, BCAN, IGFBP1, PDGFB, AKAP12, and CDKN3) were scored by LASSO COX regression to yield risk scores, and we revealed a significant difference in overall survival (OS) between the low- and high-risk groups. Mechanistically, CXCL6 in hypoxic cancer cells promoted the migration of TANs in vitro, and in turn promote NSCLC cells proliferation, migration and invasion. In summary, this study revealed a 11-hypoxia gene signature that predicted OS of NSCLC patients, and improved our understanding of the role of TANs in hypoxia microenvironment.
Subject(s)
Biomarkers, Tumor/metabolism , Carcinoma, Non-Small-Cell Lung/pathology , Gene Expression Regulation, Neoplastic , Hypoxia/physiopathology , Lung Neoplasms/pathology , Neutrophils/immunology , Tumor Microenvironment , Apoptosis , Biomarkers, Tumor/genetics , Carcinoma, Non-Small-Cell Lung/genetics , Carcinoma, Non-Small-Cell Lung/immunology , Carcinoma, Non-Small-Cell Lung/metabolism , Cell Movement , Cell Proliferation , Humans , Lung Neoplasms/genetics , Lung Neoplasms/immunology , Lung Neoplasms/metabolism , Signal Transduction , Tumor Cells, CulturedABSTRACT
The current therapeutic strategies for non-small cell lung cancer (NSCLC) are limited and unsatisfactory. MicroRNAs (miRNAs) participate in tumor angiogenesis in NSCLC. The aim of this study was to investigate the role of miR-20a-5p (miR-20a) in human NSCLC metastasis. In the current study, bioinformatics analysis and RT-PCR were performed to examine the expression level of miR-20a in tissues of NSCLC patients and NSCLC cell lines, respectively. Western blot was performed to test the protein levels. Cell proliferation, migration and angiogenesis capacity were tested by 5-ethynyl-29-deoxyuridine (EdU) assay, transwell assay and tube formation assay, respectively. Dual-luciferase reporter assay (DLR) was used to confirm the interaction between miR-20a and paired ribonucleotide reductase regulatory subunit M2 (RRM2). We found that the expression of RRM2 was upregulated, while the expression of miR-20a was downregulated in cancer tissues compared with adjacent tissues in NSCLC patients. We also detected the expression level of RRM2 and miR-20a in NSCLC cell lines, showing A549 cell line exhibited the lowest expression level of miR-20a and highest expression level of RRM2. Overexpressed miR-20a not only dramatically suppressed NSCLC cells proliferation, endothelial cells migration and tube formation in vitro, but also inhibited tumor growth and angiogenesis in vivo. It was demonstrated that miR-20a suppressed NSCLC growth by inhibiting RRM2-mediated PI3K/Akt signaling pathway. These findings indicate that the novel identified miR-20a could function as a tumor suppressor in NSCLC through modulating the RRM2-mediated PI3K/Akt axis, and it could be a valid molecular target for NSCLC treatment.
