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OR07-2 Endocrine Response And Resistance Is Driven By Novel Transcriptional Co-Regulator Activity In Invasive Lobular Carcinoma Of The Breast

Invasive lobular carcinoma of the breast (ILC) affects ∼40,000 US women annually and is a top ten most diagnosed cancer in women. ∼95% of ILC express estrogen receptor alpha (ER), but ILC is associated with poor long-term outcomes and anti-estrogen resistance, suggesting ER function is distinct in I...

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Autores principales: Costello, James, Danis, Etienne, Goodspeed, Andrew, Mohammed, Hisham, Sottnik, Joseph, Sikora, Matthew
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Oxford University Press 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9706628/
http://dx.doi.org/10.1210/jendso/bvac150.1489
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author Costello, James
Danis, Etienne
Goodspeed, Andrew
Mohammed, Hisham
Sottnik, Joseph
Sikora, Matthew
author_facet Costello, James
Danis, Etienne
Goodspeed, Andrew
Mohammed, Hisham
Sottnik, Joseph
Sikora, Matthew
author_sort Costello, James
collection PubMed
description Invasive lobular carcinoma of the breast (ILC) affects ∼40,000 US women annually and is a top ten most diagnosed cancer in women. ∼95% of ILC express estrogen receptor alpha (ER), but ILC is associated with poor long-term outcomes and anti-estrogen resistance, suggesting ER function is distinct in ILC cells. We reported that MDC1 (mediator of DNA damage checkpoint 1) is an ILC-specific ER co-regulator required for ER-driven proliferation, and that MDC1 knockdown dysregulates the ER transcriptome in ILC. Mechanisms of MDC1 co-regulator activity are unknown, but must be defined to understand endocrine response and resistance in ILC. To understand MDC1 co-regulator functions, we profiled ER/MDC1 genomic binding (ie. "cistrome") using CUT&RUN in ER+ ILC cell line MDA MB 134VI (MM134). We identified ∼2500 binding sites each for ER and MDC1, but only ∼8% of sites were bound by both factors. However, using BETA to integrate cistrome and transcriptome data predicted that both ER and MDC1 activate estrogen-regulated genes with over half of direct ER target genes also direct MDC1 targets (p=9.8×10-375). Among shared ER: MDC1 direct target genes (n=760), 58% had MDC1 binding in the promoter region with ER bound at nearby enhancers, while only 15% were linked to shared ER: MDC1 binding sites, suggesting MDC1 primarily facilitates promoter access for ER-bound enhancers. Further, MDC1 knockdown reduced ER binding at enhancer sites at ER: MDC1 target genes, implicating MDC1 in regulating chromatin access. Importantly, MDC1 does not have known enzymatic activity to directly regulate chromatin structure. We profiled MDC1-interacting proteins in ILC cells by RIME (Rapid immunoprecipitation mass spectrometry of endogenous proteins), and determined whether knockdown of putative ER: MDC1 partners disrupted ER function. This identified the SWI/SNF complex protein BRG1 (SMARCA4) as a critical ER: MDC1 partner. BRG1 was required for ILC cell growth, and BRG1 knockdown specifically suppressed ER regulation of MDC1-dependent ER target genes. Taken together, our data suggest that in ILC cells, MDC1 facilitates ER access to and activity at target gene promoters. The BRG1 SWI/SNF complex is a putative ER: MDC1 partner and mediator of MDC1 co-regulator functions. Ongoing research is focused on understanding how MDC1 regulates ILC-specific ER activity by licensing access to ILC-specific target genes, and the role of the SWI/SNF complex in mediating genomic ER: MDC1 activity. Presentation: Saturday, June 11, 2022 11:45 a.m. - 12:00 p.m.
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spelling pubmed-97066282022-11-30 OR07-2 Endocrine Response And Resistance Is Driven By Novel Transcriptional Co-Regulator Activity In Invasive Lobular Carcinoma Of The Breast Costello, James Danis, Etienne Goodspeed, Andrew Mohammed, Hisham Sottnik, Joseph Sikora, Matthew J Endocr Soc Steroid Hormones and Receptors Invasive lobular carcinoma of the breast (ILC) affects ∼40,000 US women annually and is a top ten most diagnosed cancer in women. ∼95% of ILC express estrogen receptor alpha (ER), but ILC is associated with poor long-term outcomes and anti-estrogen resistance, suggesting ER function is distinct in ILC cells. We reported that MDC1 (mediator of DNA damage checkpoint 1) is an ILC-specific ER co-regulator required for ER-driven proliferation, and that MDC1 knockdown dysregulates the ER transcriptome in ILC. Mechanisms of MDC1 co-regulator activity are unknown, but must be defined to understand endocrine response and resistance in ILC. To understand MDC1 co-regulator functions, we profiled ER/MDC1 genomic binding (ie. "cistrome") using CUT&RUN in ER+ ILC cell line MDA MB 134VI (MM134). We identified ∼2500 binding sites each for ER and MDC1, but only ∼8% of sites were bound by both factors. However, using BETA to integrate cistrome and transcriptome data predicted that both ER and MDC1 activate estrogen-regulated genes with over half of direct ER target genes also direct MDC1 targets (p=9.8×10-375). Among shared ER: MDC1 direct target genes (n=760), 58% had MDC1 binding in the promoter region with ER bound at nearby enhancers, while only 15% were linked to shared ER: MDC1 binding sites, suggesting MDC1 primarily facilitates promoter access for ER-bound enhancers. Further, MDC1 knockdown reduced ER binding at enhancer sites at ER: MDC1 target genes, implicating MDC1 in regulating chromatin access. Importantly, MDC1 does not have known enzymatic activity to directly regulate chromatin structure. We profiled MDC1-interacting proteins in ILC cells by RIME (Rapid immunoprecipitation mass spectrometry of endogenous proteins), and determined whether knockdown of putative ER: MDC1 partners disrupted ER function. This identified the SWI/SNF complex protein BRG1 (SMARCA4) as a critical ER: MDC1 partner. BRG1 was required for ILC cell growth, and BRG1 knockdown specifically suppressed ER regulation of MDC1-dependent ER target genes. Taken together, our data suggest that in ILC cells, MDC1 facilitates ER access to and activity at target gene promoters. The BRG1 SWI/SNF complex is a putative ER: MDC1 partner and mediator of MDC1 co-regulator functions. Ongoing research is focused on understanding how MDC1 regulates ILC-specific ER activity by licensing access to ILC-specific target genes, and the role of the SWI/SNF complex in mediating genomic ER: MDC1 activity. Presentation: Saturday, June 11, 2022 11:45 a.m. - 12:00 p.m. Oxford University Press 2022-11-01 /pmc/articles/PMC9706628/ http://dx.doi.org/10.1210/jendso/bvac150.1489 Text en © The Author(s) 2022. Published by Oxford University Press on behalf of the Endocrine Society. https://creativecommons.org/licenses/by-nc-nd/4.0/This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs licence (https://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reproduction and distribution of the work, in any medium, provided the original work is not altered or transformed in any way, and that the work is properly cited. For commercial re-use, please contact journals.permissions@oup.com
spellingShingle Steroid Hormones and Receptors
Costello, James
Danis, Etienne
Goodspeed, Andrew
Mohammed, Hisham
Sottnik, Joseph
Sikora, Matthew
OR07-2 Endocrine Response And Resistance Is Driven By Novel Transcriptional Co-Regulator Activity In Invasive Lobular Carcinoma Of The Breast
title OR07-2 Endocrine Response And Resistance Is Driven By Novel Transcriptional Co-Regulator Activity In Invasive Lobular Carcinoma Of The Breast
title_full OR07-2 Endocrine Response And Resistance Is Driven By Novel Transcriptional Co-Regulator Activity In Invasive Lobular Carcinoma Of The Breast
title_fullStr OR07-2 Endocrine Response And Resistance Is Driven By Novel Transcriptional Co-Regulator Activity In Invasive Lobular Carcinoma Of The Breast
title_full_unstemmed OR07-2 Endocrine Response And Resistance Is Driven By Novel Transcriptional Co-Regulator Activity In Invasive Lobular Carcinoma Of The Breast
title_short OR07-2 Endocrine Response And Resistance Is Driven By Novel Transcriptional Co-Regulator Activity In Invasive Lobular Carcinoma Of The Breast
title_sort or07-2 endocrine response and resistance is driven by novel transcriptional co-regulator activity in invasive lobular carcinoma of the breast
topic Steroid Hormones and Receptors
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9706628/
http://dx.doi.org/10.1210/jendso/bvac150.1489
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