Overexpression of long non-coding RNA ZXF2 promotes lung adenocarcinoma progression through c-Myc pathway

Abstract

Objective: To investigate the expression of long non-coding RNA ZXF2 in lung adenocarcinoma tissues and its effect on cell proliferation, migration and invasion. Methods: Forty pairs of cancerous and adjacent non-cancerous lung adenocarcinoma specimens were collected for the studies. Quantitative real-time PCR was used to analyze the expression of ZXF2 in tumor tissues and adjacent normal tissues. The expression of ZXF2 was correlated with patients' clinico-pathological data. Molecular pathway controlled by ZXF2 was explored by using small interfering RNA (siRNA) technology. CCK-8 cell proliferation assay, flow cytometry analysis and transwell assays were used to evaluate cell proliferation, migration and invasion. Results: The expression of ZXF2 was 2 fold or higher in 27 out of 40 (67.5%) cases of lung adenocarcinoma specimens than that in non-cancerous tissues (P<0.05). The relative expression level of ZXF2 was positively correlated with tumor lymph node metastasis (χ 2 =8.485, P<0.05) and poor prognosis of the patients (p=0.0217). In order to explore the molecular mechanisms of ZXF2 mediated tumor progression, ZXF2 expression was inhibited by siRNA in A549 cells, a highly aggressive and metastatic lung adenocarcinoma cell line. We found that siRNA-ZXF2 treatment inhibited cell proliferation (P<0.01) leading to cell cycle arrest (P<0.01). The cell migration and invasion were suppressed by siRNA-ZXF2 treatment (P<0.01). Further biochemical studies revealed that the knockdown of ZXF2 led to down regulation of c-Myc signaling. Conclusion: ZXF2 was overexpressed in lung adenocarcinoma tissues and the high expression of ZXF was closely related to tumor progression through c-Myc related pathway. Given the fact that both ZXF2 and c-Myc are located in the same chromosome 8q24.2 loci, the potential interaction between ZXF2 and c-Myc might be a novel target for treatment of lung adenocarcinoma.