Macrophage-derived exosomal miR-342-3p promotes the progression of renal cell carcinoma through the NEDD4L/CEP55 axis

Due to its difficulty in early diagnosis and lack of sensitivity to chemotherapy and radiotherapy, renal cell carcinoma (RCC) remains to be a frequent cause of cancer-related death. Here, we probed into new targets for its early diagnosis and treatment for RCC. microRNA (miRNA) data of M2-EVs and RCC were searched on the Gene Expression Omnibus database, followed by the prediction of the potential downstream target. Expression of target genes was measured via RT-qPCR and Western blot, respectively. M2 macrophage was obtained via flow cytometry with M2-EVs extracted. The binding ability of miR-342-3p to NEDD4L and to CEP55 ubiquitination was studied with their roles in the physical abilities of RCC cells assayed. Subcutaneous tumor-bearing mouse models and lung metastasis models were prepared to observe in vivo role of target genes. M2-EVs induced RCC growth and metastasis. miR-342-3p showed high expression in both M2-EVs and RCC cells. M2-EVs carrying miR-342-3p promoted RCC cell abilities to proliferate, invade and migrate. In RCC cells, M2-EV-derived miR-342-3p could specifically bind to NEDD4L and consequently elevate CEP55 protein expression via suppressing NEDD4L, thereby exerting tumor-promoting effects. CEP55 could be degraded by ubiquitination under the function of NEDD4L, and miR-342-3p delivered by M2-EVs facilitated the RCC occurrence and development by activating the PI3K/AKT/mTOR signaling pathway. In conclusion, M2-EVs promote RCC growth and metastasis by delivering miR-342-3p to suppress NEDD4L and subsequently inhibit CEP55 ubiquitination and degradation via activation of the PI3K/AKT/mTOR signaling pathway, strongly driving the proliferative, migratory and invasive of RCC cells.