miR-142-3p Suppresses the Proliferation of Nasopharyngeal Carcinoma Cells and Stem Cells by Targeting CD133

Abstract

Objective: To investigate whether miR-142-3p can suppress the proliferation and invasion abilities of nasopharyngeal carcinoma cells by targeting CD133, in order to reveal the molecular mechanism that miR-142-3p functions as a tumor suppressor in nasopharyngeal carcinoma.

Methods: This study was conducted between July 2015 and September 2016. CD133 mRNA 3′-UTR-luciferase vector was constructed and dual-luciferase reporter gene assay was employed to examine the effect of miR-142-3p on luciferase activity of CD133 mRNA 3′-UTR. Nasopharyngeal carcinoma CNE2 cells were transfected with negative contrast control agent 40 μmol/L, CD133 siRNA 40 μmol/L, and miR-142-3p mimics 40 μmol/L, respectively. Western blotting was performed to detect the expressions of CD133 protein. CNE2 cells in logarithmic growth phase were divided into 4 groups, negative control group (transient transfection of negative contrast control agent 40 μmol/L), positive control group (transient transfection of CD133 siRNA 40 μmol/L), miR-142-3p group (transient transfection of miR-142-3p mimics 40 μmol/L), and combined group ( transient transfection of miR-142-3p mimics 40 μmol/L and pcDNA3.1 (+)-CD133 0.8 μg). MTS assay and Transwell migration assay were used to detect the proliferation and invasion abilities of CNE2 cells, respectively. Tumorsphere formation assay was employed to detect the sphere-forming ability of CNE2 stem cells.

Results:

Results of luciferase assay with single-photon detector showed that, the luciferase activity of pCD133-Wt cells with transfection of miR-142-3p was much lower than that of those without ((0.535±0.035) vs. (0.924±0.107), t=7.924, P=0.022). Western blotting identified that, the expression of CD133 differed significantly between negative control group, positive control group, and miR-142-3p group (F=12.44, P＜0.05), concretely, the negative control group had higher expression of CD133 than both positive control group, and miR-142-3p group (all P＜0.05); obvious differences in the number of CNE2 cells were found among the 4 groups (F=16.78, P＜0.05), specifically, negative control group had more CNE2 cells than positive control group, and miR-142-3p group (all P＜0.05). Transwell migration assay revealed that, the number of CNE2 cells passing through the matrigel differed significantly among the 4 groups (F=13.19, P＜0.05); negative control group had more CNE2 cells passing through the matrigel than positive control group and miR-142-3p group (all P＜0.05). Tumorsphere formation assay demonstrated the number of sphere-forming CNE2 stem cells were more in negative control group than those in miR-142-3p group (t=14.92, P＜0.05).

Conclusion: miR-142-3p suppresses cell proliferation and invasion, and sphere-formation of stem cells by targeting CD133 in nasopharyngeal carcinoma.