High expression of IRE1 in lung adenocarcinoma is associated with a lower rate of recurrence.

Objective: Recent reports have shown that endoplasmic reticulum stress is associated with cancer. However, the impacts of endoplasmic reticulum stress on the prognosis of lung cancer are unknown. Therefore, in this study, we sought to reveal the relationship between the expression of endoplasmic reticulum stress-related genes (endoplasmic reticulum oxidoreductase 1L, protein kinase RNA-like endoplasmic reticulum kinase, activating transcription factor 6 and inositol-requiring kinase 1) and the outcome of lung adenocarcinoma.

Methods: One hundred and twenty-six patients with surgically resected lung adenocarcinomas were subjected to an endoplasmic reticulum stress-related mRNA expression analysis using quantitative RT-PCR. The following parameters were analyzed for all the study patients: age, sex, disease stage, smoking status, lymph node invasion (ly), vascular invasion (v) and EGFR mutation status. We assigned patients to either a high-expression group or a low-expression group according to the expression levels of endoplasmic reticulum stress-related genes.

Results: High expressions of endoplasmic reticulum stress-related genes were observed in patients with lower stages of lung adenocarcinoma and minimal vascular invasion. A Kaplan-Meier analysis showed significant differences in recurrence-free survival and overall survival between high-expression group and low-expression group. High inositol-requiring kinase 1 expression was an independent predictor of recurrence-free survival among patients with lung adenocarcinoma (hazard ratio, 0.396; 95% confidence interval, 0.188-0.834; P = 0.015).

Conclusions: Inositol-requiring kinase 1 may be a useful biomarker to predict recurrence in surgically resected lung adenocarcinoma patients.