miR-21-5p is a Biomarker for Predicting Prognosis of Lung Adenocarcinoma by Regulating PIK3R1 Expression

BACKGROUND: Lung cancer (LUCA) is one of the most prevalent human malignancies, and the leading cause of cancer-related deaths worldwide. Previous reports have shown that miR-21-5p plays a vital role in development of various tumors. Here, we explored the relationship between miR-21-5p/PIK3R1 axis and prognosis of patients with lung adenocarcinoma (LUAD). METHODS: MiRNAseq data, deposited in The Cancer Genome Atlas (TCGA) database, was downloaded and used to determine patterns of miR-21-5p expression in both LUAD and normal lung tissues. Statistical analyses and data visualization were performed using dbDEMC v3.0 platform, starBase v3.0 database and packages implemented in R software. Next, we employed TargetScan Human, miRDB and DIANA Tools databases to predict miR-21-5p target genes, then analyzed their expression patterns as well as prognostic value in LUAD. FINDINGS: Most human cancers overexpressed miR-21-5p. Specifically, miR-21-5p was significantly upregulated in LUAD tissues relative to normal lung tissues (P < 0.001), and this high expression was significantly correlated with poor patient prognosis (hazard ratio [HR]=1.45, P = 0.014). PIK3R1 was predicted as a miR-21-5p target gene, and both were negatively correlated (r=−0.218, P < 0.01). Notably, PIK3R1 was significantly downregulated in LUAD, relative to normal lung tissues (P < 0.01), with its overexpression significantly associated with poor prognosis of LUAD patients (HR = 0.62, P = 0.0014). CONCLUSION: miR-21-5p is a potential prognostic biomarker for LUAD patients. Moreover, it might be playing a role in LUAD progression by regulating PIK3R1 expression.