Recent evidence suggests that constitutive activation of NF?B is associated with more aggressive estrogen receptor (ER) positive tumors, the development of tamoxifen resistance, and progression to estrogen-independent growth. To date, the major mode of crosstalk between ER and NF?B that has been described is mutual transrepression, where ER antagonizes NF?B activity and NF?B antagonizes ER activity, but whether transrepression contributes to breast tumor progression is not known. Our preliminary data suggest that it is the rapid, robust and synergistic up-regulation of multiple genes by ER and NF?B acting in a synergistic rather than an antagonistic manner that may be the major mechanism of crosstalk between these two factors in breast cancer cells. Furthermore, our findings suggest that ER and NF?B interaction may play an essential role in breast cancer cell survival. Our overall objective is to understand the functional and mechanistic significance of synergistic gene regulation by ER and NF?B in breast cancer. Our hypothesis is that activation of NF?B in ER+ breast tumors leads to synergistic up-regulation of pro-survival and drug resistance genes, which contribute to breast tumor progression. To explore this hypothesis, we propose to examine the effect of NF?B activation and inhibition on ER+ breast cancer cell survival and tumor growth in response to therapeutic drugs (Aim 1). In these studies, we will focus our attention on the role of one synergistically regulated, cell survival gene in cancer cell drug response and its expression in human ER positive breast tumors. To investigate the mechanism by which ER and NF?B synergistically regulate gene transcription, we will first examine whether a unique combination of response elements in the 5'flanking region of synergistically regulated genes contributes to synergy through cooperative ER and NF?B DNA binding and enhanced RNA Pol II recruitment and activation (Aim 2). In addition, we will focus on how the gene specific recruitment of SRC/p160 coactivators, and other known histone acetyltransferases, contributes to synergistic gene transcription through enhanced histone acetylation (Aim 3). Our transcriptional studies will be coupled with survival assays to determine if the same underlying mechanisms are essential for both. Taken together these studies are designed to provide insight into the molecular mechanisms of synergistic crosstalk between ER and NF?B and the importance of this crosstalk in the progression of hormone-dependent breast cancer.
We have identified a number of genes synergistically up-regulated by estrogen and proinflammatory cytokines in breast cancer cells in an ER and NF?B dependent manner. Many of these genes have the potential to enhance tumor progression, through a variety of mechanisms including increased cell survival and the development of resistance to drugs. Our objective, which forms the basis of this proposal, is to understand the functional and mechanistic significance of synergistic gene regulation by ER and NF?B in breast cancer, with the hope that this novel mechanism of gene regulation may be exploited to improve breast tumor responsiveness to current endocrine and chemotherapeutic drugs.
|Srinivasan, Sathish; Nwachukwu, Jerome C; Bruno, Nelson E et al. (2017) Full antagonism of the estrogen receptor without a prototypical ligand side chain. Nat Chem Biol 13:111-118|
|Kastrati, Irida; Siklos, Marton I; Calderon-Gierszal, Esther L et al. (2016) Dimethyl Fumarate Inhibits the Nuclear Factor ?B Pathway in Breast Cancer Cells by Covalent Modification of p65 Protein. J Biol Chem 291:3639-47|
|Emmadi, Rajyasree; Canestrari, Emanuele; Arbieva, Zarema H et al. (2015) Correlative Analysis of miRNA Expression and Oncotype Dx Recurrence Score in Estrogen Receptor Positive Breast Carcinomas. PLoS One 10:e0145346|
|Frasor, Jonna; El-Shennawy, Lamiaa; Stender, Joshua D et al. (2015) NF?B affects estrogen receptor expression and activity in breast cancer through multiple mechanisms. Mol Cell Endocrinol 418 Pt 3:235-9|
|Kastrati, I; Canestrari, E; Frasor, J (2015) PHLDA1 expression is controlled by an estrogen receptor-NF?B-miR-181 regulatory loop and is essential for formation of ER+ mammospheres. Oncogene 34:2309-16|
|Kastrati, Irida; Litosh, Vladislav A; Zhao, Shuangping et al. (2015) A novel aspirin prodrug inhibits NF?B activity and breast cancer stem cell properties. BMC Cancer 15:845|
|Pradhan, Madhumita; Baumgarten, Sarah C; Bembinster, Leslie A et al. (2012) CBP mediates NF-?B-dependent histone acetylation and estrogen receptor recruitment to an estrogen response element in the BIRC3 promoter. Mol Cell Biol 32:569-75|
|Baumgarten, Sarah C; Frasor, Jonna (2012) Minireview: Inflammation: an instigator of more aggressive estrogen receptor (ER) positive breast cancers. Mol Endocrinol 26:360-71|
|Shehu, Aurora; Albarracin, Constance; Devi, Y Sangeeta et al. (2011) The stimulation of HSD17B7 expression by estradiol provides a powerful feed-forward mechanism for estradiol biosynthesis in breast cancer cells. Mol Endocrinol 25:754-66|
|Locklear, Tracie D; Huang, Yue; Frasor, Jonna et al. (2010) Estrogenic and progestagenic effects of extracts of Justicia pectoralis Jacq., an herbal medicine from Costa Rica used for the treatment of menopause and PMS. Maturitas 66:315-22|
Showing the most recent 10 out of 13 publications