Renal cancer stem cell-derived sEVs impair renal function by inducing renal cell ERS and apoptosis in mice

BACKGROUND: Cancer stem cells (CSCs) have been confirmed to participate in tumorigenesis, development, and metastasis, and to affect the local environment in normal tissues. Extracellular vesicles derived from CSCs (CSC-EVs) affect the local environment, contributing to tumor metastasis. However, the effect of small extracellular vesicles (sEVs) from renal CSCs (RCSCs) on renal function has not been studied. This study aimed to establish the impact of RCSC-sEVs on the renal function. METHODS: RCSC-sEVs were isolated from cell lines and locally injected into C57 mouse kidneys to observe the effect of RCSC-sEVs on the renal function. 24-hour urinary protein and serum creatinine were examined for renal function evaluation. Periodic Acid-Schiff (PAS) and immunochemistry (IHC) staining were applied for investigations of the pathological changes. Western blot (WB), flow cytometry (FCM), real-time quantitative polymerase chain reaction (RT-qPCR), and TUNEL were employed to assess cell apoptosis and endoplasmic reticulum stress (ERS). RESULTS: We found that RCSC-sEVs induced apoptosis and ERS in the mouse kidneys and eventually led to a decrease in the renal function. In vivo, RCSC-sEVs, applied by local injection, induced a continual increase in the 24-hour urinary protein and serum creatinine. In vitro, RCSC-sEVs induced HK2 cell ERS and apoptosis, which was caused by miR-142-3p and was confirmed by antagomir treatment. Further research showed that the miR-142-3p carried by RCSC-sEVs regulated ERp44, thus activating the PERK-CHOP pathway, which induced ERS and led to cell apoptosis. CONCLUSIONS: Renal function impairment during tumor development is induced not only by tumor invasion but also by RCSC-sEVs-induced renal cell apoptosis. As a natural vector of miR-142-3p, RCSC-sEVs return to the kidney cells and interfered with the expression of ERp44, inducing ERS and ultimately leading to apoptosis of normal renal cells and renal function impairment.