Carboxypeptidase E mRNA: Overexpression predicts recurrence and death in lung adenocarcinoma cancer patients

BACKGROUND: Effective biomarkers for prediction of recurrence of lung adenocarcinoma cancer (LADC) patients are needed to determine treatment strategies post-surgery to improve outcome. OBJECTIVE: This study evaluates the efficacy of carboxypeptidase E (CPE) mRNA including its splice isoforms, CPE-δN, as a biomarker for predicting recurrence in adenocarcinoma patients. METHODS: RNA was extracted from resected tumors from 86 patients with different stages of non-small cell LADC. cDNA was synthesized and qRT-PCR carried out to determine the copy numbers of CPE/CPE-δN mRNA. Patients were followed for 7 years post-tumor resection to determine recurrence and death. RESULTS: ROC curve analysis showed the overall AUC for CPE/CPE-δN copy number was 0.563 in predicting recurrence and 0.562 in predicting death. Kaplan-Meier survival analysis showed statistical difference (p= 0.018), indicating that patients with high CPE/CPE-δN copy numbers had a shorter time of disease-free survival and also shorter time to death (p= 0.035). Subgroup analyses showed that association of disease-free survival time with CPE/CPE-δN copy number was stronger among stage I and II LADC patients (p= 0.047). CONCLUSIONS: CPE/CPE-δN mRNA is a potentially useful biomarker for predicting recurrence and death in LADC patients, especially in identifying patients at high risk of recurrence at early stages I and II.