Crosstalk of renal cell carcinoma cells and tumor-associated macrophages aggravates tumor progression by modulating muscleblind-like protein 2/B-cell lymphoma 2/beclin 1-mediated autophagy

Background aims: M2-polarized tumor-associated macrophages contribute to the development of multiple human cancers, including renal cell carcinoma (RCC). However, the crosstalk mechanism between M2 macro-phages and RCC remains unclear. Methods: The authors constructed a co-culture system of M2 macrophages differentiated from THP-1 and RCC cells. Microscopic examination and quantitative real-time polymerase chain reaction (qRT-PCR) vali-dated the morphology and types of macrophages. The proliferation, migration and invasion of RCC cells were assessed by Cell Counting Kit 8 (Dojindo Molecular Technologies, Inc, Santa Clara, CA, USA) and Transwell assay (Corning, Corning, NY, USA). Messenger RNA (mRNA) and protein expression of target molecules was detected by qRT-PCR and western blotting. Expression of Ki-67, E-cadherin and N-cadherin was measured by immunofluorescence staining or immunohistochemistry. Molecular interaction was evaluated by RNA pull -down, RNA immunoprecipitation and co-immunoprecipitation. A xenograft model was established to deter-mine tumor growth in vivo.Results: RCC cells triggered the activation of M2 macrophages. Functionally, M2-polarized macrophages facil-itated the growth, migration, invasion and epithelial-mesenchymal transition of RCC cells by suppressing autophagy, whereas rapamycin, an activator of autophagy, significantly counteracted the tumor-promoting effects of M2 macrophages. Mechanistically, M2 macrophage-derived C-C motif chemokine 2 (CCL2) enhanced modulation of muscleblind-like protein 2 (MBNL2) expression. MBNL2 raised the stability of B-cell lymphoma 2 (Bcl-2) by directly binding to Bcl-2 mRNA, which endowed RCC cells with malignant properties via inhibition of beclin 1-dependent autophagy.Conclusions: RCC-induced M2-polarized macrophages secrete CCL2 to promote the growth and metastasis of RCC cells via inhibition of MBNL2/Bcl-2/beclin 1-mediated autophagy, which provide a novel perspective for the development of a therapeutic strategy for-RCC. (c) 2022 International Society for Cell & Gene Therapy. Published by Elsevier Inc. All rights reserved.