Cancer Genet. 2020 Aug 21;248-249:1-10. doi: 10.1016/j.cancergen.2020.08.006. Online ahead of print.
We hypothesise that the NRF2 transcription factor would act a biomarker of poor prognosis in colorectal cancer. We derived and validated an mRNA based metagene signature of NRF2 signalling and validated it in 1360 patients from 4 different datasets as an independent biomarker of poor prognosis. This is a novel insight into the molecular signalling of colorectal cancer.
BACKGROUND: NRF2 over activity confers poor prognosis in some cancers but its prognostic role in colorectal cancer (CRC) is unknown. As a transcription factor, we hypothesise a signature of NRF2 regulated genes could act as a prognostic biomarker in CRC and reveal novel biological insights.
METHODS: Using known NRF2 regulated genes, differentially expressed in CRC, we defined a signature of NRF2 pathway activity using principal component analysis and Cox proportional hazard models and tested it in four independent mRNA datasets, profiled on three different mRNA platforms.
RESULTS: 36 genes comprised the final NRF2 signature. 1360 patients were included in the validation. High NRF2 was associated with worse disease free survival (DFS) and/or overall survival (OS) in all datasets: (GSE14333 HR=1.55, 95% C.I 1.2-2.004, p = 0.0008; GSE39582 HR=1.24, 95% C.I 1.086-1.416, p = 0.001; GSE87211 HR=1.431, 95% C.I 1.06-1.93, p = 0.056; MRC FOCUS trial HR=1.14, 95% C.I 1.04-1.26, p = 0.008). In multivariate analyses, NRF2 remained significant when adjusted for stage and adjuvant chemotherapy in stage I-III disease, and BRAF V600E mutation and sidedness in stage IV disease. NRF2 activity was particularly enriched in Consensus Molecular Subtype (CMS) 4.
CONCLUSION: For the first time, NRF2 is shown to be a consistent, robust prognostic biomarker across all stages of colorectal cancer with additional clinical value to current known prognostic biomarkers. High NRF2 signalling in CMS 4 further refines the molecular taxonomy of CRC, a new biological insight, suggesting avenues of further study.