Significance of lncRNA MALAT1 expression in peripheral blood in the short-term efficacy of radiotherapy for esophageal squamous cancer and its molecular mechanism
Abstract：Radiotherapy is the main treatment for many advanced esophageal squamous cell carcinoma (ESCC) patients. Recent studies demonstrated that patients with high level of long non-coding RNA (lncRNA) MALAT1 in tumor had poor prognosis. Thus, our study aims to investigate the significance of blood-derived MALAT1 in short-term efficacy of radiotherapy in ESCC and its underlying mechanism. LncRNA MALAT1 expression levels in plasma and serum from 47 ESCC patients were detected by quantitative RT-PCR. ESCC cell line EC9706 was transfected with siRNA to modulate MALAT1 expression. The effect of MALAT1 on cell growth, apoptosis, and radioresistance was studied in vitro. The results showed that there was a linear correlation between both plasma and serum MALAT1 level. MALAT1 level in plasma was associated with TNM stage (P=0.04), differentiation degree (P=0.004), and poor radiotherapy efficacy (P<0.001). Reducing MALAT1 in EC7906 cells inhibited cell growth, promoted apoptosis, alleviated radioresistance, and enhanced caspase-3 activity. The mechanism could be possibly associated with the negative regulation of miR-145 expression by MALAT1. In conclusion, MALAT1 could be used as a potential prognostic marker of ESCC. Reducing MALAT1 was beneficial for enhancing cell radiosensitivity and apoptosis.
Keywords: esophageal squamous cancer, MALAT1, prognosis, redioresistance, miR-145