Blocking Exosomal miR-19b-3p from Renal Cell Carcinoma Cells Enhances Sunitinib Mediated Anti-Tumor Activity via Promoting TGFBR2/KLF10 Expression
Abstract Background Multiple studies have found that microRNAs contribute to the malignant progression and chemoresistance of renal cell carcinoma (RCC). This study intends to probe the effect of miR-19b-3p shuttled by exosomes derived from RCC cells on RCC development and its resistance to Sunitinib. Methods Sunitinib-resistant cell lines (OSRC-2R and Caki-1R) were constructed from OSRC-2 and Caki-1 RCC cells. Exosomes in the RCC cell supernatant were isolated, and the miR-19b-3p profile in cells and exosomes was measured by reverse transcription-polymerase chain reaction (RT-PCR). Subsequently, the TGFβR2/SMAD2/3 pathway was activated by TGFβ, and the KLF10 overexpression and miR-19b-3p overexpression/knockdown models were constructed. The cell counting kit-8 (CCK-8) assay, colony formation assay and flow cytometry were implemented to verify RCC cell proliferation, Sunitinib chemosensitivity, and apoptosis. The expression of apoptosis-related proteins and the TGFβR2-SMAD2/3-KLF10 pathway was monitored by Western blot. MiR-19b-3p was overexpressed in sunitinib-resistant RCC cell lines (OSRC-2R and Caki-1R) and their exosomes (vs. normal OSRC-2 and Caki-1 cell lines). Results In-vitro experiments showed that knocking down cellular and exosomal miR-19b-3p levels reduced the proliferation and colony-forming ability of OSRC-2 and Caki-1 cells and strengthened their apoptosis and sensitivity to Sunitinib. Bioinformatics analysis illustrated that miR-19b-3p targeted TGFβR2 and inhibited TGFβR2/SMAD2/3. Activation of the TGFβR2-SMAD2/3 pathway via TGFβ dampened ORSC-2 and Caki-1 cell proliferation, induced apoptosis, and enhanced their chemosensitivity to Sunitinib. Conclusion Moreover, TGFβ heightened KLF10 expression, and overexpressing KLF10 attenuated miR-19b-3p-mediated carcinogenic effects and resistance to Sunitinib by increasing SMAD2/3 phosphorylation. RCC cell-derived exosomal miR-19b-3p enhances RCC progression and Sunitinib chemoresistance by inactivating TGFβR2-SMAD2/3-KLF10.