Abstract PO-150: Comparison of RUNX1, RUNX2, RUNX3 and CBFβ gene expression in breast tumors Indicate ethnic differences and similarities by receptor status
Authors: Okoli Uzoamaka A. 
Published: January 2022

Abstract
The RUNX family of transcription factors RUNX1, RUNX2 and RUNX3 encode nuclear proteins with a Runt DNA-binding domain that functions in a complex with their obligate partner core-binding factor CBFβ to regulate gene expression. RUNX genes are known for paradoxical roles, with oncogenic as well as tumor suppressor functions, dependent on context. Interestingly, RUNX2 has been shown to play a potentially important functional role in Triple-Negative Breast Cancer (TNBC), and RUNX1 expression associates with poor prognosis in TNBC in a cohort of women of European descent. Women of African descent experience more aggressive TNBC with higher mortality rates than their women of European ancestry counterparts. TNBC is the most difficult breast cancer subtype to treat globally and has a poor prognosis and low survival which remains an important clinical challenge. There is a paucity of genomics studies interrogating TNBC of diverse populations. Hence, RNAseq datasets of 782 breast cancer patients were leveraged from a web-based platform -CbioPortal and published literature. 685 patients were queried for the RUNX1, RUNX2, RUNX3, and CBFβ genes, and an additional 97 patient data were harnessed from research publications. The cohort includes 595 (70%) patients of European ancestry (EA), 90 (11%) of African descent (AD), both from The Cancer Genome Atlas (TCGA), and 97 (13%) patients indigenous African from Nigeria (IAN). The queried genes were compared for race/ethnic disparity by estrogen receptor status (er). Mutual exclusivity was analyzed and P-values were determined by Fisher's extract test with the null hypothesis that a pair of genes alteration frequency of occurrence is proportional to uncorrelated occurrence in each gene. The queried genes enrichment in TP53, PIK3CA, CDH1, MAP3K1, and GATA3 between patients of European ancestry and African descent were analyzed and the Kaplan-Meier plots with P-value from the Long rank test were determined. The queried genes were altered in 69 patients (12%) of EA and 9 patients of AD due to unavailability of data on RUNX2 and RUNX 3 in IAN only RUNX1 and CBfβ was altered in 4 (4%) patients of 97 patients. Ethnic disparities and similarities were indicated in the queried altered genes in RUNX1 and RUNX 2 and showed similar expression in ER-negative correlating with the TNBC poor prognosis however RUNX3 genes were silenced in that of AD and was expressed in EA. They were differences in mutual exclusivity and co-occurrence but were not statistically significant, this may be due to the small data size. Interestingly, there was statistically significant equal gene enrichment of RUNX1 and CBfβ in CDH1mutations of both EA and AD. Larger cohorts in particular the AD cohort is needed, to further elucidate some of these borderline findings. In conclusion, our findings are insightful towards deciphering the characteristic aggressive nature of TNBC in ethnic disparity.
Citation Format: Uzoamaka A. Okoli. Comparison of RUNX1, RUNX2, RUNX3 and CBFβ gene expression in breast tumors Indicate ethnic differences and similarities by receptor status [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PO-150.