Knockdown of Long Noncoding RNA HOXA-AS2 Suppresses Chemoresistance of Acute Myeloid Leukemia via the miR-520c-3p/S100A4 Axis
Cellular Physiology and Biochemistry
Background/Aims: Among different molecular candidates, there is growing data to support that long noncoding RNAs (lncRNAs) play a significant role in acute myeloid leukemia (AML). HOXA-AS2 is significantly overexpressed in a variety of tumors and associated with anti-cancer drug resistance, however, little is known regarding the expression and function of HOXA-AS2 in the chemoresistance of AML. In this study, we aimed to determine the role and molecular mechanism of HOXA-AS2 in adriamycin-based
... in adriamycin-based chemotherapy resistance in AML cells. Methods: Quantitative real-time PCR was used to detect HOXA-AS2 expression in the BM samples and ADR cell lines, U/A and T/A cells. Furthermore, the effects of HOXA-AS2 silencing on cell proliferation and apoptosis were assessed in vitro by CCK8 and flow cytometry, and on tumor growth in vivo. Furthermore, bioinformatics online programs predicted and luciferase reporter assay were used to validate the association of HOXA-AS2 and miR-520c-3p in AML. Results: In this study, we showed that HOXA-AS2 is significantly upregulated in BM samples from AML patients after treatment with adriamycin-based chemotherapy and in U/A and T/A cells. Knockdown of HOXA-AS2 inhibited ADR cell proliferation in vitro and in vivo and promoted apoptosis. Bioinformatics online programs predicted that HOXA-AS2 sponge miR-520c-3p at 3'-UTR with complementary binding sites, which was validated using luciferase reporter assay and anti-Ago2 RIP assay. HOXA-AS2 could negatively regulate the expression of miR-520c-3p in ADR cells. S100A4 was predicted as a downstream target of miR-520c-3p, which was confirmed by luciferase reporter assay. Conclusion: Our results suggest that HOXA-AS2 plays Fig. 4 . A: HOXA-AS2 and miR-520c-3p simultaneously existed in the production precipitated by anti-AGO2; B: The wild-type or mutant miR-520c-3p-binding sites in HOXA-AS2 were inserted into pMIR-report luciferase vector. Luciferase activity was detected in cells co-transfected with miR-520c-3p or negative control (miRcontrol) and reporter plasmids containing WT-HOXA-AS2 (wild type) or MUT-HOXA-AS2 (mutant type). The normalized luciferase activity in the miR-control group was used as the relative luciferase activity; C: silencing of HOXA-AS2 increased the expression level of miR-520c-3p in U/A and T/A cells; D: Luciferase reporter assay demonstrated miR-520c-3p mimics significantly decreased the luciferase activity of S100A4wt in HEK293T cells; E: silencing of HOXA-AS2 decreased the expression level of S100A4 in U/A and T/A cells; F: overexpression of miR-520c-3p decreased the expression level of S100A4 in U/A and T/A cells.