• Qiao-Li Jiang, Shu-Jiong Feng, Zhu-Ying Yang, Qi Xu, and Shuang-Zhu Wang.
• Department of Gastroenterology, Tongde Hospital of Zhejiang Province, Hangzhou, Zhejiang 310012, China.
• Chin. Med. J. 2020 Aug 5; 133 (15): 1774-1785.

BackgroundNon-coding RNAs have attracted considerable attention for their vital role in cancer. The purpose of this study was to determine the effects of non-coding RNAs on hepatocellular carcinoma (HCC) and reveal their regulatory mechanism in the pathophysiological process.MethodsWe measured the expression of mucin 1 (MUC1) and miR-485-5p in tissues from 15 HCC patients and in liver cancer cell lines by quantitative real-time polymerase chain reaction and Western blot, screened for aberrantly expressed microRNAs (miRNAs) by miRNA microarrays. Bioinformatics tools were used to find the miRNA and circular RNA that regulated MUC1, which were validated by RNA immunoprecipitation assay and luciferase reporter assay. Cell counting kit-8, Transwell assays, and flow cytometry were used to conduct functional experiments. Proteins were examined by western blot and immunohistochemical staining assays. Significant differences between groups were estimated using the one-way analysis of variance. A P < 0.05 was considered statistically significant.ResultsMUC1 was overexpressed in HCC tissues compared with that in paratumor tissues (normal vs. tumor, 1.007 ± 0.215 vs. 75.213 ± 18.403, t = 18.401, P < 0.001) while miR-485-5p was down-regulated (normal vs. tumor, 4.894 ± 0.684 vs. 1.586 ± 0.398, t = 16.191, P < 0.001). Inhibition of miR-485-5p promoted cell proliferation (73.33% ± 5.13% vs. 41.33% ± 3.51%, t = 8.913, P < 0.001), migration (102 ± 8 cells vs. 46 ± 8 cells, t = 8.681, P < 0.001), invasion (59 ± 7 cells vs. 28 ± 2 cells, t = 8.034, P < 0.01), and suppressed apoptosis (22.64% ± 6.97% vs. 36.33% ± 3.96%, t = 2.958, P < 0.05) of HepG2 cells with which MUC1 is knocked down. Mechanically, miR-485-5p binds to MUC1, while circHECTD1 binds to miR-485-5p, resulting in the indirect up-regulation of the MUC1 level.ConclusionsOur findings reveal that circHECTD1 facilitates HCC progression by sponging miR-485-5p to up-regulate MUC1.

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