Cancer cell-derived exosomal LINC00313 induces M2 macrophage differentiation in non-small cell lung cancer

Abstract

Purpose: Non-small cell lung cancer (NSCLC) is the major subtype of lung cancer, which is the leading cause of cancer death worldwide. Tumor-associated macrophages (TAMs) are one of the main non-tumor cells in the tumor microenvironment. Here, we investigated the effect of cancer cell-derived exosomal LINC00313 on the M2 macrophage differentiation in NSCLC and clarified its underlying mechanism.

Methods: Flow cytometry, Western blotting, ELISA and immunohistochemical staining were performed to identify the macrophage phenotype by detecting the expression of M2 markers. The expression levels of LINC00313 and miR-135a-3p were measured by qRT-PCR, and luciferase reporter assay was used to validate the binding of lncRNA to miRNA, and miRNA to the target gene STAT6. The mouse-xenograft models were established by subcutaneous injection of the NCl-H1299 cells with stable overexpression or knockdown of LINC00313. GW4869 was injected intra-tumorally after tumor implantation.

Results: It was found that the cancer cells promoted M2 macrophage differentiation by secreting exosomes. LINC00313 was overexpressed in H1299-derived exosomes, and its knockdown abolished the effect of H1299-induced M2 macrophage differentiation. LINC00313 sponged miR-135a-3p to increase the STAT6 expression, resulting in the M2 macrophage differentiation. LINC00313 promoted tumor progression and promoted the expression of M2 markers in isolated tumor macrophages. A novel regulatory mechanism of M2 macrophage differentiation in NSCLC was revealed. It was found that cancer cell-derived exosomal LINC00313 promoted M2 macrophage differentiation in NSCLC by up-regulating STAT6 as miR-135a-3p sponge.

Conclusions: This study provides a new mechanism and direction to prevent the M2 macrophage differentiation in NSCLC.

Keywords: Exosome; LncRNA; Macrophage differentiation; Non-small cell lung cancer; microRNA.