Screening of a Novel Upregulated lncRNA, A2M‐AS1, That Promotes Invasion and Migration and Signifies Poor Prognosis in Breast Cancer

Understanding of prognostic factors and therapeutic targets for breast cancer is imperative for guidance of patient care. We studied 1203 tumour samples from the Gene Expression Omnibus (GEO) to evaluate potential genes related to breast cancer. R software was used to analyse differentially expressed long noncoding RNAs (lncRNAs) in the RNA microarray expression profiles GSE45827 and GSE65216 and to identify a series of differentially expressed lncRNAs associated with human breast cancer. Of these lncRNAs, A2M‐AS1, a lncRNA that has not been previously reported, was significantly upregulated in human breast cancer tissues compared with adjacent nontumour tissues. Importantly, A2M‐AS1 upregulation was significantly associated with ER‐negative, HER2‐positive, and basal‐like breast cancer and with poor recurrence‐free survival and metastasis‐free survival in breast cancer patients. After validating these results in 96 collected human breast cancer tissues and 64 paired adjacent noncancerous tissues, we further investigated the roles of A2M‐AS1 in human ER‐negative and basal‐like breast cancer cells. The results revealed that A2M‐AS1 significantly promotes human breast cancer cell proliferation, invasion, and migration. Additionally, bioinformatics analysis of genes coexpressed with A2M‐AS1 in the context of human breast cancer combined with qRT‐PCR and Western blot assays revealed that A2M‐AS1 exerts regulatory effects on downstream factors in the cell adhesion molecule pathway, including CD2 and SELL. These results imply that A2M‐AS1 might be a promising candidate prognostic factor and therapeutic target for breast cancer.