肿瘤来源的外泌体 circFARSA 通过 PTEN/PI3K/AKT 通路介导 M2 巨噬细胞极化，促进非小细胞肺癌转移。

Tumor-derived exosomal circFARSA mediates M2 macrophage polarization via the PTEN/PI3K/AKT pathway to promote non-small cell lung cancer metastasis.

机构信息

Department of Thoracic Surgery, The First Affiliated Hospital of Soochow University, Medical College of Soochow University, Suzhou, Jiangsu, China.

Department of Pharmacology, Soochow University, Suzhou, 215000, China.

出版信息

Cancer Treat Res Commun. 2021;28:100412. doi: 10.1016/j.ctarc.2021.100412. Epub 2021 Jun 5.

DOI:10.1016/j.ctarc.2021.100412

PMID:34119765

Abstract

BACKGROUND

Exosomes in the tumor microenvironment (TME) facilitate tumor progression by enabling inter-cellular communication. Tumor cell-derived exosomes can polarize tumor-associated macrophages (TAMs) to an immunosuppressive M2 phenotype. The aim of this study was to determine the role of exosomal circFARSA in non-small cell lung cancer (NSCLC) and elucidate the underlying mechanisms.

METHODS

In situ circFARSA expression in NSCLC tissues was analyzed using qRT-PCR. The in vitro migration of NSCLC cells was evaluated using a transwell assay or through indirect co-culture with M2 macrophages, as appropriate. Immunoprecipitation (IP), western blotting, RNA binding protein immunoprecipitation (RIP), and RNA pull down assays were conducted for mechanistic studies.

RESULTS

CircFARSA was significantly upregulated in NSCLC tissues, and the ectopic overexpression of circFARSA enhanced NSCLC cell metastasis. Furthermore, NSCLC cell-derived exosomal circFARSA polarized the macrophages to a M2 phenotype. The NSCLC cells co-cultured with macrophages transfected with circFARSA or pre-treated with exosomal circFARSA showed enhanced EMT and metastasis. Mechanistically, exosomal circFARSA induced M2 polarization via PTEN ubiquitination and degradation, which further activated the PI3K/AKT signaling pathway. In addition, eIF4A3 promoted circRNA biogenesis and cyclization by binding to its flanking sequences.

CONCLUSION

Exosomal circFARSA plays a crucial role in cross-talk between macrophages and NSCLC cells through the PTEN/PI3K/AKT signaling pathway, and is a promising diagnostic/prognostic biomarker for NSCLC.

摘要

背景

肿瘤微环境（TME）中的外泌体通过实现细胞间通讯促进肿瘤进展。肿瘤细胞衍生的外泌体可以将肿瘤相关巨噬细胞（TAMs）极化为免疫抑制的 M2 表型。本研究旨在确定外泌体 circFARSA 在非小细胞肺癌（NSCLC）中的作用，并阐明其潜在机制。

方法

使用 qRT-PCR 分析 NSCLC 组织中 circFARSA 的原位表达。通过 Transwell 测定或与 M2 巨噬细胞间接共培养，适当评估 NSCLC 细胞的体外迁移。进行免疫沉淀（IP）、Western blot、RNA 结合蛋白免疫沉淀（RIP）和 RNA 下拉测定以进行机制研究。

结果

circFARSA 在 NSCLC 组织中显著上调，外源性过表达 circFARSA 增强了 NSCLC 细胞转移。此外，NSCLC 细胞衍生的外泌体 circFARSA 将巨噬细胞极化为 M2 表型。与转染了 circFARSA 的巨噬细胞共培养或用外泌体 circFARSA 预处理的 NSCLC 细胞表现出增强的 EMT 和转移。机制上，外泌体 circFARSA 通过 PTEN 泛素化和降解诱导 M2 极化，从而进一步激活 PI3K/AKT 信号通路。此外，eIF4A3 通过结合其侧翼序列促进 circRNA 的生物发生和环化。