A novel mechanism by which ACTA2-AS1 promotes cervical cancer progression: acting as a ceRNA of miR-143-3p to regulate SMAD3 expression.

ABSTRACT

BACKGROUND: Long non-coding RNAs (LncRNAs) have been increasingly confirmed to be abnormally expressed in human cancer and closely related to tumorigenesis. LncRNA ACTA2-AS1 is abnormally expressed in multiple tumors and participates in their development. However, whether ACTA2-AS1 plays a role in the development of cervical cancer (CC) and the exact mechanism of its role has not been elucidated. METHODS: Quantitative real-time PCR (qRT-PCR) was conducted to detect the expression level of messenger RNA of ACTA2-AS1, miR-143-3p and SMAD3 in tumor tissues and cells. Additionally, SMAD3 protein expression by western blots in cells. Small interference RNA against ACTA2-AS1 or SMAD3 and miR-143-3p mimic/inhibitor was designed and transfected into CC cell lines to investigate their correlations and potential impacts on cell function. Cell Counting Kit-8 (CCK-8) assay, colony formation, cell cycle assay, transwell assay and flow cytometry analysis were performed to detect the specific effects on cell line proliferation, metastasis and apoptosis. RESULTS: ACTA2-AS1 was significantly increased in CC tissues and cells and miR-143-3p was down-regulated. Clinically, the higher expression of ACTA2-AS1 was significantly correlated with higher FIGO stage. Loss-of-function assay revealed that silencing of ACTA2-AS1 inhibited cell proliferation, colony formation, migration and promoted apoptosis in CC. Additionally, Pearson correlation analysis showed that the expression of ACTA2-AS1 and miR-143-3p were negatively correlated. Dual-luciferase reporter assay and further mechanistic experiments confirmed that ACTA2-AS1 could sponge and regulate the expression of miR-143-3p. Furthermore, SMAD3 was the target gene of miR-143-3p and ACTA2-AS1 could upregulate SMAD3 through acting as a competitive endogenous RNA (ceRNA) of miR-143-3p. Finally, rescue assay demonstrated that the ACTA2-AS1/miR-143-3p/SMAD3 axis played an important role in the proliferation, migration and apoptosis of CC cells. CONCLUSIONS: In summary, our study revealed that ACTA2-AS1 upregulates SMAD3 by competitively binding miR-143-3p, thereby accelerating CC progression. The ACTA2-AS1/miR-143-3p/SMAD3 axis can play a crucial role in cervical carcinogenesis, providing new clues for the early diagnosis and treatment of CC.