Extracellular vesicle-mediated transfer of long non-coding RNA ROR modulates chemosensitivity in human hepatocellular cancer

摘要

Hepatocellular cancers (HCC) are highly resistant to chemotherapy. TGF@b has been associated with chemoresistance in some human cancers but the mechanisms involved are unknown. We explored how TGF@b might contribute to altered responses to therapy by assessing the involvement and mechanistic contribution of extracellular vesicle long non-coding RNA (lncRNA) in mediating TGF@b-dependent chemoresistance. TGF@b reduced the sensitivity of HCC cells to sorafenib or doxorubicin and altered the release of both extracellular vesicles and of selected lncRNA within these vesicles. Amongst these, lincRNA-ROR (linc-ROR), a stress-responsive lncRNA was highly expressed in HCC cells and enriched within extracellular vesicles derived from tumor cells. Incubation with HCC-derived extracellular vesicles increased linc-ROR expression and reduced chemotherapy-induced cell death in recipient cells. Sorafenib increased linc-ROR expression in both tumor cells and extracellular vesicles, whereas siRNA to linc-ROR increased chemotherapy-induced apoptosis and cytotoxicity. Tumor-initiating cells that express CD133 have an increased resistance to therapy. TGF@b increased expression of CD133+ cells and colony growth in limiting dilution assays, both of which were attenuated by linc-ROR knockdown. These data provide mechanistic insights into primary chemoresistance in HCC by showing that: (a) TGF@b selectively enriches linc-RoR within extracellular vesicles, which has a potential role in intercellular signaling in response to TGF@b; (b) expression and enrichment of linc-ROR during chemotherapeutic stress plays a functional role in chemoresistance; and (c) the effects of TGF@b on chemoresistance in HCC may involve linc-RoR-dependent effects on tumor-initiating cells. These findings implicate extracellular vesicle lncRNA as mediators of the chemotherapeutic response, and support targeting linc-ROR to enhance chemosensitivity in HCC.