Abstract
The present study aimed to investigate microRNA (miRNA)-27a-3p expression in the pulmonary macrophages and peripheral blood of patients with early non-small cell lung carcinoma (NSCLC) and its regulatory effect on the infiltration of pulmonary macrophages into cancer tissues and invasion of NSCLC cells. Blood specimens were withdrawn from 36 patients with NSCLC and 29 healthy subjects. NSCLC tissues and cancer-adjacent tissues were both obtained from patients with NSCLC; furthermore, certain tissue samples were used to extract macrophages. The levels of miRNA-27a-3p and C-X-C motif ligand chemokine 2 (CXCL2) mRNA were detected by reverse transcription-quantitative PCR and the levels of CXCL2 protein were measured by ELISA and western blot analysis. A dual-luciferase reporter assay was performed to determine the interactions between miRNA and mRNA. An MTT assay was employed to examine the viability of transfected cells and macrophages and a Transwell assay was performed to assess chemotaxis. The differential expression of miRNA-27a-3p in NSCLC tissues, pulmonary macrophages and peripheral blood indicated that miRNA-27a-3p exerted different roles in these specimens. CXCL2 was upregulated in NSCLC tissues at both transcriptional and translational levels. In addition, the untranslated region of CXCL2 was confirmed to be directly targeted by miRNA-27a-3p prior to its transcriptional activation. Furthermore, miRNA-27a-3p regulated CXCL2 expression, thereby affecting the proliferation of human pulmonary macrophages. The present study highlights that miRNA-27a-3p expression in the pulmonary macrophages and peripheral blood of patients with NSCLC is downregulated, while its target gene CXCL2 is upregulated. miRNA-27a-3p may regulate the viability and chemotaxis of macrophages in tumor tissues of patients with NSCLC through CXCL2 and is expected to become a genetic marker of this disease.