MicroRNA-597 inhibits NSCLC progression through negatively regulating CDK2 expression

D.-J. Yu, Y.-H. Li, M. Zhong

Department of Respiration, China Japan Union Hospital of Jilin University, Changchun, China. zhongmingyn@163.com

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• Oncology

OBJECTIVE: Previous studies have shown that microRNA-597 serves as a tumor suppressor gene. However, the role of microRNA-597 in non-small cell lung cancer (NSCLC) has not been fully elucidated. Therefore, the aim of this study was to investigate the expression of microRNA-597 in NSCLC, and to further explore the possible underlying mechanism.
PATIENTS AND METHODS: Real-time quantitative polymerase chain reaction (qPCR) was performed to examine microRNA-597 level in tumor tissues and para-cancerous normal tissues collected from 50 patients with NSCLC. The interplay between microRNA-597 expression and clinical indicators, as well as prognosis of NSCLC patients, was analyzed. Meanwhile, qPCR was used to verify microRNA-59 level in NSCLC cell lines. Subsequently, microRNA-597 overexpression and knockdown models were constructed using lentivirus in NSCLC cell lines (including H1299 and PC-9). The impacts of microRNA-597 on the biological functions of NSCLC cells were evaluated using cell counting kit-8 (CCK-8), colony formation, and 5-Ethynyl-2’-deoxyuridine (EdU) assay, respectively. Finally, luciferase reporter gene assay and recovery experiment were performed to investigate the underlying molecular mechanism.
RESULTS: QPCR results indicated that microRNA-597 level in NSCLC tissues was remarkably lower than that of adjacent normal tissues, and the difference was statistically significant (p<0.05). Compared with patients with high expression of microRNA-597, patients with low expression of microRNA-597 exhibited significantly higher incidence of pathological stage and lower overall survival rate (p<0.05). Similarly, compared with NC group, the proliferation ability of NSCLC cells was remarkably weakened in microRNA-597 overexpression group (p<0.05). However, the opposite results were observed in microRNA-597 inhibitor group (p<0.05). CDK2 expression was found remarkably elevated in NSCLC cell lines as well as in tissue samples CDK2 expression. Meanwhile, CDK2 expression was negatively correlated with microRNA-597 expression. Luciferase reporter gene assay demonstrated that overexpression of CDK2 could significantly attenuate the luciferase activity of wild-type microRNA-597 vector without attenuating that of mutant vector CDK2 expression. This further suggested that microRNA-597 could target bind to CDK2. Furthermore, cell recovery experiment revealed that CDK2 could reverse the impact of microRNA-597 on the malignant progression of NSCLC.
CONCLUSIONS: MicroRNA-597 expression was significantly down-regulated in NSCLC tissues, as well as cell lines. Meanwhile, microRNA-597 expression was associated with the pathological staging and poor prognosis of patients with NSCLC. In addition, microRNA-597 might suppress the malignant progression of NSCLC through the regulation of CDK2.

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