MicroRNA-145 suppresses esophageal squamous cell carcinoma by targeting phospholipase C epsilon 1

Abstract

Objective To investigate the mechanism of microRNA (miRNA, miR)-145 in modulating the capacity of proliferation and invasion in esophageal squamous cell carcinoma (ESCC). Methods Real-time quantitative reverse transcriptase-polymerase chain reaction (RT-qPCR) was used to detect the expression of miR-145 and phospholipase C epsilon 1 (PLCE1) mRNA. PLCE1 protein level was evaluated by Western blotting. The potential target gene of miR-145 was predicted by targetscan software. Luciferase reporter gene assay was used to validate the predicted miR-145 binding site in PLCE1 3’untranslated region (3’UTR). Proliferation and invasion capacity were assessed by MTT and wound healing assay separately. Results The relative expression of miR-145 in four types of ESCC cells were 0.63±0.06, 0.72±0.05, 0.55±0.05 and 0.79±0.04 separately, which were obviously lower than in normal esophageal epithilum (P=0.000, P=0.001, P=0.000, P=0.003). While, relative expression of miR-145 in ESCC tissues was 0.68±0.03, which was 31.9% lower than in normal esophageal tissue (P=0.000). An inverse correlation between miR-145 expression and tumor invasion depth and TNM stage were observed (χ2=8.380, P=0.039; χ2=6.810, P=0.033). Luciferase reporter gene assay proved that PLCE1 was a direct target of miR-145. PLCE1 was overexpressed and inversely correlated with miR-145 expression in ESCC (r=-0.828, P=0.002). The relative expression of PLCE1 in four types of ESCC cells were 1.69±0.04, 1.46±0.06, 1.31±0.06 and 1.60±0.08, which were obviously higher than in normal esophageal epithilum (P=0.000, P=0.000, P=0.004, P=0.001). And relative PLCE1 expression was 1.85±0.04 in ESCC tissues, which was 1.85 times higher than in normal esophageal tissue (P=0.000). In addition, overexpression of miR-145 suppressed Eca109 cells proliferation (P=0.006) and decreased invasion capacity by 22.1% (P=0.013). Whereas, overexpression of PLCE1 induced proliferation (P=0.003) and elevated invasion capacity by 24.9% (P=0.029). Enforced expression of miR-145 could partially reversed the promoting effect of PLCE1 (P=0.003). Conclusion MiR-145 suppresses proliferation and invasion of ESCC by targeting PLCE1. Key words: MicroRNA-145; Phospholipase C epsilon 1; Esophageal neoplasms; Proliferation; Invasion