The NRF2 transcriptional target NQO1 has low mRNA levels in TP53-mutated endometrial carcinomas

NRF2 is a major transcription factor regulating the expression of antioxidative/detoxifying enzymes, involved in oncogenic processes and drug resistance. We aimed to identify molecular alterations associated with NRF2 activation in endometrial carcinoma (EC).

Ninety patients treated (2012-2017) for localized/locally advanced EC were included in this study. Formalin-fixed paraffin-embedded tissue samples were processed for immunohistochemical (NRF2 and Mismatch Repair proteins) analyses. Next generation sequencing (NGS) of a panel of genes including POLE, TP53, NFE2L2, KEAP1 and CUL3 was performed using Ampliseq panels on Ion Torrent PGM (ThermoFisher). NRF2 activity was assessed by NQO1, GCLC, and AKR1C3 mRNA expressions, using TaqMan assays and quantitative RT-PCR.

Tumors were classified as POLE exonuclease domain mutated (N = 3, 3%), MMR-deficient (MSI-like) (N = 28, 31%), TP53 mutated (Copy-number high-like) (N = 22, 24%), and other tumors (Copy-number low-like) (N = 32, 36%). NRF2 nuclear immunostaining did not correlate with NRF2 target genes expression. The 3 tumors with highest NRF2 target genes expression harbored oncogenic KEAP1 or NFE2L2 mutations. Low NQO1 mRNA and protein levels were observed in the TP53 mutated subgroup compared to others tumors (p < .05) and in silico analyses of The Cancer Genome Atlas data further indicated that NQO1 mRNA levels were lower in serous compared to endometrioid copy-number high EC.

In contrast with previous reports based on immunohistochemistry, our study indicates that NRF2 activation is a rare event in EC, associated with NFE2L2 or KEAP1 mutations. The subset of aggressive EC with low NQO1 mRNA level might represent a specific subgroup, which could be sensitive to combination therapies targeting oxidative stress.