The prognostic value of NRF2 in breast cancer patients: a systematic review with meta-analysis.

PURPOSE: Nuclear factor E2-related factor 2 (NRF2) is a transcription factor that plays a major role in the regulation of intracellular antioxidant response. The effect of NRF2 overexpression in many malignancies is still unclear and recent meta-analysis correlated NRF2 overexpression with poor prognosis in a variety of human cancers. However, the effect of NRF2 overexpression in breast cancer is still unclear. Thus, the main goal of this work was to clarify the role of NRF2 expression in survival and relapse of breast cancer patients by performing a systematic review according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) statement, followed by a meta-analysis. METHODS: The electronic search was conducted in PubMed, Scopus, SciELO, Web of Science and Embase between November of 2017 and September of 2018. To be included, studies should evaluate NRF2 expression in breast cancer tissue, through immunohistochemistry and/or mRNA and had to report one or more of the following outcomes: overall survival (OS), disease-free survival (DFS), mean survival and median survival. RESULTS: For the meta-analysis, seven studies were included and NRF2 expression was correlated with OS and DFS. It was observed that compared to patients with low NRF2 expression, patients with NRF2 overexpression had poorer OS with a hazard ratio of 1.82 (95% CI 1.32-2.50; p value < 0.0001), and poorer DFS, with a hazard ratio of 1.79 (95% CI 1.07-3.01; p value = 0.03). CONCLUSIONS: These results suggest that tumours that overexpress NRF2 have a worse clinical outcome. Thus, NRF2 expression could be a marker for the prognostic of breast cancer patients and, in the future, it would be pertinent to focus on improving treatment efficacy for patients with NRF2 overexpression.

Prognosis of hormone-dependent breast cancer seems to be influenced by KEAP1, NRF2 and GSTM1 genetic polymorphisms.

Influence of Glutathione S-transferase Mu1 (GSTM1) has long been studied in breast cancer and GSTM1 null genotype was correlated with breast cancer risk. Nuclear factor-erythroid 2-related factor-2 (NRF2) is a transcription factor that forms a complex with Kelch-like ECH-associated protein-1 (KEAP1). Recent studies have demonstrated that expression of these proteins is deregulated in several malignancies. Thus, in the present study we aim to distinguish GSTM1 heterozygous from wild type genotype in breast cancer patients and evaluate the presence and clinical significance of NRF2 and KEAP1 polymorphisms, alone or in association, with breast cancer prognosis, in cases confirmed to have GSTM1-present genotype. Study population consisted in 52 patients with breast cancer. Genomic DNA was extracted, GSTM1 was genotyped through multiplex PCR and gene dose was evaluated through real-time PCR. All cases were sequenced, through Sanger sequencing, for specific regions of NRF2 and KEAP1. Genotyping and clinicopathological data were correlated and statistical analysis was performed. GSTM1 wild type was identified in 1 case and 26 cases were identified as heterozygous, these data were correlated with Human Epidermal growth factor Receptor 2 (HER2) status (p value = 0.017). We also verified that most cancers diagnosed at younger ages had the presence of KEAP1 and/or NRF2 polymorphisms. The association of GSTM1 heterozygous genotype with rs1048290 and rs35652124 seems to be associated with HER2+ (p < 0.05). Our results suggest that GSTM1 * 1/0 genotype and the cumulative presence of at least one allele mutated in KEAP1 and/or NRF2 polymorphisms might be associated with worse prognosis for breast cancer patients.