Search

Women of African ancestry suffer higher rates of breast cancer mortality compared with all other groups in the United States. Though the precise reasons for these disparities remain unclear, many recent studies have implicated a role for differences in tumor biology. Using an epitope-validated antibody against the endoplasmic reticulum-associated E3 ligase, gp78, we show that elevated levels of gp78 in patient breast cancer cells predict poor survival. Moreover, high levels of gp78 are associated with poor outcomes in both ER+ and ER- tumors, and breast cancers expressing elevated amounts of gp78 protein are enriched in gene expression pathways that influence cell cycle, metabolism, receptor-mediated signaling, and cell stress response pathways. In multivariate analysis adjusted for subtype and grade, gp78 protein is an independent predictor of poor outcomes in women of African ancestry. Furthermore, gene expression signatures, derived from patients stratified by gp78 protein expression, are strong predictors of recurrence and pathological complete response in retrospective clinical trial data and share many common features with gene sets previously identified to be overrepresented in breast cancers based on race. These findings implicate a prominent role for gp78 in tumor progression and offer insights into our understanding of racial differences in breast cancer outcomes.

The use of digital pathology for the histomorphologic profiling of pathological specimens is expanding the precision and specificity of quantitative tissue analysis at an unprecedented scale; thus, enabling the discovery of new and functionally relevant histological features of both predictive and prognostic significance. In this study, we apply quantitative automated image processing and computational methods to profile the subcellular distribution of the multi-functional transcriptional regulator, Kaiso (ZBTB33), in the tumors of a large racially diverse breast cancer cohort from a designated health disparities region in the United States. Multiplex multivariate analysis of the association of Kaiso’s subcellular distribution with other breast cancer biomarkers reveals novel functional and predictive linkages between Kaiso and the autophagy-related proteins, LC3A/B, that are associated with features of the tumor immune microenvironment, survival, and race. These findings identify effective modalities of Kaiso biomarker assessment and uncover unanticipated insights into Kaiso’s role in breast cancer progression., Through automated image analysis, Singhal et al quantify nuclear versus cytoplasmic distribution of the Kaiso transcription factor in breast cancer patient tissue. They find that Kaiso distribution correlates with breast cancer subtype and overall survival, and discover a link between cytoplasmic Kaiso and autophagy marker LC3.

The C-terminal binding protein (CtBP) is an NADH-dependent dimeric family of nuclear proteins that scaffold interactions between transcriptional regulators and chromatin-modifying complexes. Its association with poor survival in several cancers implicates CtBP as a promising target for pharmacological intervention. We employed computer-assisted drug design to search for CtBP inhibitors, using quantitative structure-activity relationship (QSAR) modeling and docking. Functional screening of these drugs identified 4 compounds with low toxicity and high water solubility. Micro molar concentrations of these CtBP inhibitors produces significant de-repression of epigenetically silenced pro-epithelial genes, preferentially in the triple-negative breast cancer cell line MDA-MB-231. This epigenetic reprogramming occurs through eviction of CtBP from gene promoters; disrupted recruitment of chromatin-modifying protein complexes containing LSD1, and HDAC1; and re-wiring of activating histone marks at targeted genes. In functional assays, CtBP inhibition disrupts CtBP dimerization, decreases cell migration, abolishes cellular invasion, and improves DNA repair. Combinatorial use of CtBP inhibitors with the LSD1 inhibitor pargyline has synergistic influence. Finally, integrated correlation of gene expression in breast cancer patients with nuclear levels of CtBP1 and LSD1, reveals new potential therapeutic vulnerabilities. These findings implicate a broad role for this class of compounds in strategies for epigenetically targeted therapeutic intervention. Fil: Byun, Jung S.. Public Health Service. National Institute Of Health; Estados Unidos Fil: Park, Samson. Public Health Service. National Institute Of Health; Estados Unidos Fil: Yi, Dae Ik. Public Health Service. National Institute Of Health; Estados Unidos Fil: Shin, Jee Hye. Public Health Service. National Institute Of Health; Estados Unidos Fil: Hernandez, Sara Gil. Public Health Service. National Institute Of Health; Estados Unidos Fil: Hewitt, Stephen M.. Public Health Service. National Institute Of Health; Estados Unidos Fil: Nicklaus, Marc C.. Public Health Service. National Institute Of Health; Estados Unidos Fil: Peach, Megan L.. Leidos Biomedical Research ; Estados Unidos Fil: Guasch, Laura. Public Health Service. National Institute Of Health; Estados Unidos Fil: Tang, Binwu. Public Health Service. National Institute Of Health; Estados Unidos Fil: Wakefield, Lalage M.. Public Health Service. National Institute Of Health; Estados Unidos Fil: Yan, Tingfen. Public Health Service. National Institute Of Health; Estados Unidos Fil: Caban, Ambar. Public Health Service. National Institute Of Health; Estados Unidos Fil: Jones, Alana. Public Health Service. National Institute Of Health; Estados Unidos Fil: Kabbout, Mohamed. Public Health Service. National Institute Of Health; Estados Unidos Fil: Vohra, Nasreen. East Carolina University; Estados Unidos Fil: Nápoles, Anna María. Public Health Service. National Institute Of Health; Estados Unidos Fil: Singhal, Sandeep. Columbia University; Estados Unidos Fil: Yancey, Ryan. Columbia University; Estados Unidos Fil: de Siervi, Adriana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Gardner, Kevin. Public Health Service. National Institute Of Health; Estados Unidos. Columbia University; Estados Unidos

Purpose: Women of African ancestry in the United States are more likely to die from breast cancer than their European counterparts. While prior studies suggest differences in the frequency of hormone receptor-negative disease as an underlying cause, recent studies report higher race-based mortality rates in patients with hormone receptor-positive, luminal breast cancer. Here we explore biologic factors that may underly this disparity by comparing racial differences in the level, functional activity, and prognostic significance of 3 master transcriptional regulators of mammary luminal differentiation. Patients and Methods: Medical records and tissues from 555 patients (293 European and 262 African ancestry) diagnosed with Stage 0 to IV breast cancer, from 2001 to 2010 at a major medical center in East North Carolina, were analyzed for the expression of functional biomarkers of luminal differentiation including estrogen receptor (ESR1), and pioneer transcription factors FOXA1 and GATA3. Differential comparison of protein expression was integrated with network-level gene expression analysis (22% of cohort) to define predictive correlations with race and survival. Results: Univariate and multivariate odds ratios combined with area under the curve receiver operator characteristics show significant differences in predictive activity of these functional biomarkers based on race and survival—ESR1 (EA OR= 0.47, p = 5e-04; AA OR= 0.77, p = 0.22), FOXA1 (EA OR= 0.38, p= 1.4e-04; AA OR = 0.53, p = 1.3e-02), and GATA3 (EA OR= 0.36, p= 3.7e-06, AA OR= 0.57, p= 0.51)—and uncover genes in the downstream regulons of these biomarkers that strongly correlate either with genetic ancestry or overall survival. Conclusion: Transcriptional regulatory networks linked to mammary luminal differentiation reveal race-specific differences in master regulatory activity that may underlie tumor characteristics contributing to racial disparities in outcome. These biomarkers and their downstream regulons represent important targets to explore intrinsic mechanisms that drive breast cancer survival disparities. Citation Format: Jung S. Byun, Sandeep K. Singhal, Sam Park, Dae Ik Yi, Tingfen Yan, Ambar Caban, Alana Jones, Partha Mukhopadhyay, Sara Gil Hernandez, Stephen Hewitt, Lisa A. Newman, Melissa Davis, Jorge Sepulveda, Adrianna De Siervi, Anna Napoles, Nasreen Vohra, Kevin Gardner. Racial differences in the associations between luminal master regulator transcription factor expression and breast cancer survival [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr C033.