Exosome-transferred long non-coding RNA ASMTL-AS1 contributes to malignant phenotypes in residual hepatocellular carcinoma after insufficient radiofrequency ablation.

OBJECTIVES: Long non-coding RNAs (lncRNAs) are emerging RNA regulators in cancer progression, including in hepatocellular carcinoma (HCC). Recently, insufficient radiofrequency ablation (RFA) has been reported to lead to recurrence and metastasis of residual HCC tumours. Herein, we aimed to the role of ASMTL-AS1 in residual HCC after insufficient RFA. MATERIALS AND METHODS: In vitro insufficient RFA model was simulated in Huh7 cells and subsequently named Huh7-H cells. In vitro and in vivo assays were conducted to investigate ASMTL-AS1 function in HCC. RESULTS: LncRNA ASMTL-AS1 low expressed in normal human liver was found to be highly expressed in HCC tissues and further increased in tumours after insufficient RFA. ASMTL-AS1 expression was related to stage, metastasis and prognosis in HCC. Huh7-H possessed higher ASMTL-AS1 level and more aggressive than Huh7 cells. ASMTL-AS1 contributed to the malignancy of HCC cells both in vitro and in vivo. Mechanistically, ASMTL-AS1 was trans-activated by MYC and promoted NLK expression to activate YAP signalling via sequestering miR-342-3p in HCC. Interestingly, ASMTL-AS1 could be wrapped by exosomes and then convey malignancy through NLK/YAP axis between cells even in residual HCC after insufficient RFA. CONCLUSIONS: Exosomal ASMTL-AS1 aggravates the malignancy in residual HCC after insufficient RFA via miR-342-3p/NLK/YAP signalling, opening a new road for the treatment of HCC and the prevention of recurrence or metastasis of residual HCC after insufficient RFA.