ABSTRACT
BACKGROUND: Cancer stem cells (CSCs) are different from regular cancer cells because of their self-renewal feature and differentiation potential, which establishes the backbone of the vital role of CSCs in the progress and drug resistance of hepatocellular carcinoma (HCC). The objective of this study was to evaluate the effects of blood exosome-derived miRNA-30d-5p on the stemness and gemcitabine resistance of HCC cells and the underlying mechanisms. METHODS: The expression data of HCC-related miRNAs and mRNAs were downloaded from TCGA database and analyzed for differences. Employing the databases of starBase, TargetScan, miRDB, and mirDIP, we conducted target gene prediction upstream of mRNA. The expression of miRNA-30d-5p and SOCS3 mRNA was assayed by qRT-PCR, and the binding between them was validated by dual luciferase assay. CCK-8 was employed to evaluate cell viability and the IC50 value of gemcitabine. Cells were subjected to a sphere-forming assay to assess their ability to form spheres. Western blot was applied to evaluate the levels of cell surface marker proteins (Nanog, CD133, and Oct4) and exosome markers (CD9, CD81, and FLOT1). RESULTS: Bioinformatics analysis found that SOCS3 expression was down-regulated in HCC. qRT-PCR showed that SOCS3 expression was notably lower in HCC cell lines than in normal liver cell WRL68. At the cellular functional level, SOCS3 overexpression inhibited the viability, sphere-forming ability, stemness, and gemcitabine resistance of HCC cells. Bioinformatics analysis demonstrated that miRNA-30d-5p was the upstream regulator of SOCS3 and highly expressed in HCC tissues and cells. Dual luciferase assay demonstrated that miRNA-30d-5p could bind SOCS3. Rescue experiments showed that upregulating SOCS3 could reverse the effects of miRNA-30d-5p overexpression on the viability, sphere-forming ability, and gemcitabine sensitivity of HCC cells. CONCLUSIONS: Blood exosome-derived miRNA-30d-5p promoted the stemness and gemcitabine resistance of HCC cells by repressing SOCS3 expression. Hence, the miRNA-30d-5p/SOCS3 axis might be a therapeutic target for chemotherapy resistance and a feasible marker for the prognosis of HCC patients.
