To investigate the expression of heterogeneous nuclear ribonucleoprotein C(HNRNPC) and discuss its clinical significance in lung adenocarcinoma(LUAD).

The Cancer Genome Atlas (TCGA) and Clinical Proteomic Tumor Analysis Consortium (CPTAC) public databases were used to collect clinicopathological data and HNRNPC mRNA expression data from 535 patients with LUAD, as well as protein expression data from 111 patients with LUAD. The Genotype-tissue expression (GETx) database was used to obtain HNRNPC mRNA expression data from 288 healthy lung tissues. Based on the median value of HNRNPC mRNA level as the boundary value, LUAD patients were divided into high expression group and low expression group. By the R programming language, the difference of mRNA and protein levels of HNRNPC in LUAD and normal lung tissues were compared, and the link between HNRNPC mRNA expression and clinicopathological characteristics and patient prognosis was investigated. Receiver operating characteristic (ROC) curve was used to analyze the diagnostic value of HNRNPC expression in lung adenocarcinoma. Gene set enrichment analysis (GSEA) was used to look into the relevant signaling pathways regulated by HNRNPC.

The expression of HNRNPC mRNA in LUAD was significantly higher than that in normal lung tissues (all P<0.01). The protein expression level of HNRNPC in LUAD was also significantly up-regulated (P<0.05). Univariate analysis showed that the expression of HNRNPC mRNA was correlated with smoking history, clinical stage, T stage and distant metastasis(all P<0.05). Log-rank test showed that the median survival time of patients with LUAD in the HNRNPC high expression group (42.3 months) was significantly lower than that in the low expression group (59.9 months) (P<0.01). The multivariate Cox regression analysis revealed that lymph node metastasis and the high expression of HNRNPC mRNA were independent prognostic factors of LUAD. ROC curve analysis showed that HNRNPC mRNA expression level could predict the diagnosis of LUAD (AUC=0.843, 95%CI=0.817-0.869). GSEA showed that Rho GTPases pathway, TP53 signaling pathway, DNA repair, cell cycle and M phase regulation were significantly enriched in HNRNPC highly expressed phenotype.

The expression level of HNRNPC in LUAD is significantly higher than that in normal lung tissue, and high HNRNPC expression group indicates poor prognosis in patients with LUAD. HNRNPC maybe a novel potential biomarker for the diagnosis and prognosis of patients with LUAD.