Many researches indicated that long non-coding RNAs (lncRNAs) were involved in the malignant progression of tumors, including Adrenocortical Carcinoma (ACC). However, as for most lncRNAs, their biological behaviors and molecular mechanism remain unclear in ACC. In the present research, weighted gene co-expression network analysis (WGCNA) was used to identify pathologically relevant gene, including lncRNAs. By comparing their expressions in GSE61359 tumors and normal controls, long intergenic non-protein coding RNA 1234 (LINC01234) was selected to investigate the clinical significance, biological function, and mechanism in ACC. Data mining revealed that LINC01234 expression was significantly up-regulated in ACC patients, and a shorter survival time presents in patients with higher LINC01234 expression compared to that in patients with lower LINC01234 expression. Further, LINC01234 silencing resulted in cells growth arrest in vitro and in vivo. Mechanism studies suggested that LINC01234 silencing induced cell cycle arrest, and bromodomain-containing protein 4 (BRD4) overexpression could restore this phenomenon. Further research showed that LINC01234 could mediate BRD4 expression through competitively sequestering microRNA (miR)-140-3p, as evidenced by the positive correlation of LINC01234 with BRD4 and inverse correlation with miR-140-3p expression. Luciferase activity assay also verified the targeting relationship between LINC01234, BRD4 and miR-140-3p. And up-regulated LINC01234 in ACC cells significantly reversed the degradation of BRD4 by miR-140-3p. Collectively, we deduce that LINC01234 functions as a ceRNA to regulate BRD4 expression by sponging miR-140-3p in ACC progress. Our findings have the potential to provide a new target for the diagnosis and treatment of ACC.
Keywords: ACC; BRD4; LINC01234; cell cycle; miR-140-3p.