Abstract
Long non-coding RNAs (lncRNAs) have a considerable regulatory influence on multiple biological processes. Nevertheless, the role of TMEM220-AS1 in hepatocellular carcinoma (HCC) remains unclear. We used The Cancer Genome Atlas (TCGA) database to analyze the differentially expressed lncRNAs. qRT-PCR was used to verify the results for a large population. The in vitro effects of TMEM220-AS1 on HCC cells were determined using Cell Counting Kit-8 (CCK-8), 5-ethynyl-2’-deoxyuridine (EdU), flow cytometry, and Transwell assays in HCC cells. We used qRT-PCR and western blotting to identify the epithelial-mesenchymal transition (EMT). Moreover, we performed bioinformatics analysis, western blotting, dual luciferase reporter gene assay, RNA pull-down, and RNA binding protein immunoprecipitation (RIP) to investigate the underlying molecular mechanisms of TMEM220-AS1 function. Finally, the function of TMEM220-AS1 was verified in vivo. The results showed that TMEM220-AS1 was expressed at considerably low levels in HCC. It was demonstrated that malignant phenotypes and EMT of HCC cells were promoted by the knock down of TMEM220-AS1 both in vivo and in vitro. TMEM220-AS1, which was detected primarily in the cytoplasm, functioned as an miRNA sponge to bind miR-484 and promote the level of membrane-associated guanylate kinase, WW, and PDZ domain containing 1 (MAGI1), thereby curbing the malignant phenotypes of HCC cells. In conclusion, low levels of TMEM220-AS1 promote proliferation and metastasis through the miR-484/MAGI1 axis in HCC.
Highlights
As the sixth most frequently occurring cancer worldwide, liver cancer is the third leading cause of cancer-related deaths, globally (Nakagawa et al, 2019; Anwanwan et al, 2020; Rahmani et al, 2020)
Through analysis of the The Cancer Genome Atlas (TCGA) database, we found that TMEM220-AS1 was remarkably lower in hepatocellular carcinoma (HCC) tissues than that in normal tissues (Figure 1A)
We detected the mRNA level of TMEM220-AS1 in six cell lines, including one normal cell line (LO2) and five HCC cell lines (HB611, HHCC, H97, HuH-7, and Li-7)
Summary
As the sixth most frequently occurring cancer worldwide, liver cancer is the third leading cause of cancer-related deaths, globally (Nakagawa et al, 2019; Anwanwan et al, 2020; Rahmani et al, 2020). Among all primary liver cancers, hepatocellular carcinoma (HCC) is the most frequent, accounting for 80–90% of all cases (Ringelhan et al, 2017). The number of patients diagnosed with HCC is almost 800,000 worldwide, with approximately 750,000 causalities (Ryerson et al, 2016; Momin et al, 2017). Chronic hepatitis B and C viral infections are the most common risk factors and are responsible for approximately 75% of HCCs, leading to a twenty-fold increase in the development of HCCs (Ryerson et al, 2016). The molecular mechanisms involved in the pathogenesis of HCC are still under intense investigation
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