Upregulated MiRNA-182-5p Expression in Tumor Tissue and Peripheral Blood Samples from Patients with Non-small Cell Lung Cancer is Associated with Downregulated Caspase 2 Expression

Lung cancer has the highest morbidity and mortality rates among all malignant tumors worldwide. Previous studies demonstrated that microRNA (miR)-182-5p may serve different roles in different types of cancer, including renal cell carcinoma and liver cancer. However, the functional role of miR-182-5p in non-small cell lung cancer (NSCLC) remains unknown. In the current study, the expression level of miR-182-5p in tumor tissue and peripheral blood samples obtained from patients with NSCLC was examined. The biological function of miR-182-5p on NSCLC cell proliferation was also investigated. Tissue and adjacent normal tissue samples were collected from 33 patients with NSCLC. In addition, peripheral blood samples were obtained from patients with NSCLC and 26 healthy control patients. The NSCLC cell line H1299 was used for all functional assays. Reverse transcription-quantitative polymerase chain reaction was used to determine the miR-182-5p or Caspase 2 (CASP2) mRNA expression levels in NSCLC tissue and peripheral blood samples, as well as in the NSCLC cell line. Western blotting was used to examine the protein expression level of CASP2 in tissue samples and cells, and ELISA was performed to measure the protein level of CASP2 in peripheral blood samples. MTT assay was performed to examine NSCLC cell proliferation. Flow cytometry was used to detect apoptosis. Dual-luciferase reporter assay was used to examine whether miRN182-5p directly interacts with CASP2. The current study demonstrated that miR-182-5p expression was upregulated in NSCLC tissue and peripheral blood samples from patients with NSCLC, which suggests that miR-182-5p, may serve a functional role in NSCLC. In addition, inhibition of miR-182-5p expression suppressed cell proliferation and enhanced cell apoptosis in NSCLC cells. CASP2 expression was downregulated in NSCLC tissue and peripheral blood samples from patients with NSCLC. The current study demonstrated that miR-182-5p may regulate NSCLC cell proliferation and apoptosis by regulating CASP2 expression as miR-182-5p directly binds with the 3'-untranslated region of CASP2, thereby regulating CASP2 expression.