[Nrf2 and Keap1 Abnormalities in 104 Lung Adenocarcinoma Cases and Association with Clinicopathologic Features]

There are significantly interindividual variations of the expression level of nuclear factor erythroid-2-related factor 2 (Nrf2) and/or Kelch-like ECH-associated protein 1 (Keap1) in our previous studies. It has been proven that Nrf2 or Keap1 is related to resistance of chemotherapeutic drugs and/or epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs). However, the expression of Nrf2 and Keap1 in lung adenocarcinoma patients with different "driver gene" is not clear. The aim of this study is to investigate the protein expression level of Nrf2 and Keap1 in lung adenocarcinoma and to elucidate the correlation between Nrf2 or Keap1 expression and the status of EGFR gene mutation and to determine the effects of Nrf2 and Keap1 on the patients.

Immunohistochemical analysis of Nrf2 and Keap1 in tumor specimens was performed in a total of 104 lung adenocarcinoma patients with the status of EGFR gene mutations or EGFR wide-type.

The Nrf2 positive rate was 71.2% and Keap1 high expression rate was 34.6% in 104 patients. The Nrf2 positive rate significantly correlated with gender, stage and status of EGFR gene mutation (P<0.05), but not with age, smoking, differentiation and subtype of lung adenocarcinoma (P>0.05). The high expression of Keap1 was not significantly correlated with gender, age, smoking, differentiation, subtype of lung adenocarcinoma and status of EGFR gene mutation (P>0.05). The progression -free survival (PFS) and overall survival (OS) of the patients treated by EGFR-TKIs were significantly correlated with the expression level of Nrf2, but not with Keap1. The PFS and OS of the patients with Nrf2 high expression were significantly shorter than the patients with low/negative expression (P<0.05). Furthermore, Nrf2 high expression was the independent predictive factor for EGFR-TKIs induced PFS and OS (P<0.05).

The Nrf2 positive rate significantly correlated with the status of EGFR gene mutation in lung adenocarcinoma. The Nrf2 high expression significantly correlated with PFS and OS of EGFR-TKIs. Therefore, Nrf2 may be a biomarker for predicting response of EGFR-TKIs and a potential target for overcoming resistance of EGFR-TKIs.