RUSC1‐AS1 promotes the malignant progression of breast cancer depending on the regulation of the miR‐326/XRCC5 pathway

BACKGROUND: Many long noncoding RNAs (lncRNAs) are the key regulators for cancer progression, including breast cancer (BC). RUSC1 antisense 1 (RUSC1‐AS1) has been found to be highly expressed in BC, but its role and potential molecular mechanism in BC remain to be further elucidated. METHODS: Quantitative reverse transcription‐polymerase chain reaction (RT‐PCR) was utilized to measure RUSC1‐AS1, microRNA (miR)‐326 and X‐ray repair cross‐complementing group 5 (XRCC5) expression. Cell proliferation, metastasis, cell cycle, apoptosis and angiogenesis were determined by cell counting kit‐8, colony formation, transwell, flow cytometry and tube formation assays. Protein expression was detected by western blot analysis. The targeted relationship between miR‐326 and RUSC1‐AS1 or XRCC5 was validated using dual‐luciferase reporter assay and RIP assay. Xenograft models were constructed to uncover the effect of RUSC1‐AS1 on BC tumorigenesis. RESULTS: RUSC1‐AS1 was upregulated in BC, and its downregulation suppressed BC proliferation, metastasis, cell cycle, angiogenesis, and tumor growth. MiR‐326 was confirmed to be sponged by RUSC1‐AS1, and its inhibitor reversed the regulation of RUSC1‐AS1 silencing on BC progression. XRCC5 could be targeted by miR‐326. Overexpression of XRCC5 reversed the inhibitory impacts of miR‐326 on BC progression. CONCLUSION: RUSC1‐AS1 could serve as a sponge of miR‐326 to promote BC progression by targeting XRCC5, suggesting that RUSC1‐AS1 might be a target for BC treatment.