Abstract
The KEAP1-NRF2 system induces the expression of antioxidant genes in response to various types of oxidative stress. Some cancer cells activate this system, which increases their malignancy through genetic mutations. We performed a retrospective cohort study using the C-CAT database, which contains the gene-panel sequence data from 60,056 cases of diagnosed solid tumors. We analyzed somatic mutations in NRF2 and KEAP1 genes and their associations with clinical outcomes. Variants in the NRF2 gene were clustered in exon 2, which encodes the DLG and ETGE motifs essential for KEAP1 interaction. The NRF2 variants were frequently observed in esophageal and lung squamous cell carcinoma with frequencies of 35.9% and 19.6%, respectively. Among these mutations, the NRF2 variants in the ETGE motif were indicators of a worse prognosis. KEAP1 variants were found in 2.5% of all cases. The variants were frequent in lung cancer and showed a worse prognosis in lung and other types of adenocarcinomas. We then conducted gene expression analysis using TCGA data. While cancers with DLG and ETGE variants were similar in terms of gene expression profiles, there were significant differences between cancers with KEAP1 and NRF2 variants. Our results indicate that genetic alteration of the KEAP1-NRF2 pathway is a major factor in patient prognosis for each cancer type and its genetic variant. Variants in NRF2 and KEAP1 genes can characterize the biological basis of each cancer type and are involved in carcinogenesis, resistance to therapy, and other biological differences.