Frequent epigenetics inactivation of KEAP1 gene in non-small cell lung cancer

The KEAP1/Nrf2 pathway is a master regulator of several redox-sensitive genes implicated in resistance of tumor cells against chemotherapeutic drugs. Recent data suggest that epigenetic mechanisms may play a pivotal role in the regulation of KEAP1 expression. We performed a comprehensive genetic and epigenetic analysis of the KEAP1 gene in 47 non-small cell lung cancer tissues and normal specimens. Promoter methylation analysis was performed using a quantitative methylation specific PCR assay in real time. Methylation at the KEAP1 promoter region was detected in 22 out of the 47 NSCLCs (47%) and in none of the normal tissues analyzed. Somatic mutations were detected in 7 out of the 47 tumors (15%) and loss of heterozygosity (LOH) in 10 out of the 47 (21%) of the cases. Overall, we found at least one molecular alteration in 57% of the cases. Approximately one third of the tumors had two alterations and this feature was associated with higher risk of disease progression in univariate COX regression analysis (HR = 3.62; 95% CI 1.24-10.65, p = 0.02). This result was confirmed by Kaplan-Meier analysis, which demonstrated an association between worst outcome and KEAP1 double alterations (p = 0.01, Log rank test). Our results further suggest that deregulation of the NRF2/KEAP1 system could play a pivotal role in the cancerogenesis of NSCLC. In addition identifying patients with KEAP1 genetic and epigenetic abnormalities may contribute to disease progression prediction and response to therapy in lung cancer patients.