Potential for the blood- biomarker cell free UPK2 RNA to detect recurrence during monitoring after surgical resection of adenocarcinoma of the lung

Abstract Background: Lung cancer is one of the most common malignant tumors in the world. Non-small-cell lung cancer (NSCLC) accounting for top of all diagnosed lung cancers. Lung adenocarcinoma(LUAD) is the most common subtype in NSCLC. This study attempts to identify and validate biomarkers that can be used to monitor recurrence after LUAD surgery. Methods: In this research, we downloaded lung adenocarcinoma data from the TCGA database and selected postoperative recurrence samples, and then performed WGCNA analysis to find key co-expression gene modules. Enrichment analysis of key gene modules was also performed using the DAVID database. Finally, we performed a survival analysis of the most interesting biomarker UPK2 obtained from the TCGA analysis in the Oncomine database and evaluated its impact on prognosis. We collected 132 blood samples from patients with early-stage lung adenocarcinoma who were tested the expression level of free mRNA in the plasma.Results: The results revealed that UPK2, KLHDC3, GALR2 and TYRP1 occupied a central position in the co-expression network which were also significantly correlated with the survival of patients. The expression level of free UPK2 in the plasma relative to GADPH in non-relapsed patients was 0.1623, and in relapsed patients, it was 0.2763. ROC was used to evaluate the effectiveness of free UPK2 mRNA in the blood for monitoring postoperative recurrence, with an AUC of 0.767 and a 95% confidence interval of 0.675-0.858. At the same time, patients with high expression of free UPK2 mRNA had significantly poorer survival than those with low expression of UPK2. Conclusions: The expression level of free UPK2 mRNA in plasma has the potential as an indicator of postoperative recurrence in patients with early LUAD. This may have guiding significance for the subsequent clinical treatment of patients.