1720P - Downregulation of BRCA1 protein in clear cell renal cellular carcinoma.

Date 11 September 2017
Event ESMO 2017 Congress
Session Poster display session
Topics Renal Cell Cancer
Genitourinary Cancers
Translational Research
Presenter Elzbieta Sarnowska
Citation Annals of Oncology (2017) 28 (suppl_5): v595-v604. 10.1093/annonc/mdx391
Authors E. Sarnowska1, N. Rusetska1, M. Szymanski2, I. Jancewicz1, M. Chmielarczyk1, R. Konopinski1, M. Leszczynski1, A. Chrzan3, M. Ligaj3, A. Maassen4, T. Sarnowski5, J. Siedlecki1
  • 1Department Of Molecular And Translational Oncology, Maria Sklodowska-Curie Cancer Center, 02-781 - Warsaw/PL
  • 2Department Of Urology, Maria Skłodowska-Curie Cancer Center, 02-781 - Warsaw/PL
  • 3Department Of Pathology, Maria Skłodowska-Curie Cancer Center, 02-781 - Warsaw/PL
  • 4Department Of Protein Biosynthesis, Institute of Biochemistry and Biophysics, 02-106106 - Warsaw/PL
  • 5Protein Biosyntesis, Instytut of Biochemy and Biophysic, 02-106 - Warsaw/PL

Abstract

Background

Around 75% of renal cancer in adult kidney is clear cell renal cellular carcinoma (ccRCC). This type of cancer is characterized by lipids overacumulation and mutations in VHL (around 90% cases), BAP1 and PBRM1 genes as well as stabilization of HIF1α transcription factor. Additionally, metabolic switch to aerobic glycolysis and aberration in TCA cycle was observed in ccRCC independently on the stage of the disease. Moreover, the mTOR pathway hyperactivation and downregulation of AMPK pathway featured the ccRCC. This type of cancer is highly resistant to classical chemotherapy. BRCA1 is tumor suppressor gene, mutation in this gene is associated with breast and ovarian cancer. BRCA1 is a protein involved in DNA repair and apoptosis also interacts with BRG1 – core subunit of SWI/SNF chromatin remodeling complex. BRCA1 is transcribed from bidirectional promoter together with NBR2 – lncRNA. Interestingly, NBR2 interacts with AMPK and is downregulated in ccRCC. CTCF is a protein which binds Topologicaly Associated Domains, and CTCF binding site was found in BRCA1/NBR2 promoter region.

Methods

Immunohistochemistry (IHC) on paraffin embedded clinical samples for BRCA1 and BRG1 core subunit of SWI/SNF complex, comparative transcriptomic study, co-immunoprecipitation (Co-IP) and chromatin immunoprecipitation (ChIP) method were used in this work.

Results

In this study we found downregulation of BRCA1 and BRG1 proteins in ccRCC patient samples independently on stage of the disease. Interestingly, downregulation of BRG1 was more severe in samples with strong lymphocyte infiltration. By contrast, downregulation at the transcript level was observed for BRG1 encoding gene but not for BRCA1. BRG1 and CTCF co-precipitated from cancer cells, indicating the existence of co-interaction between CTCF, BRG1 and BRCA1 proteins. Additionally, overexpression of BRG1 caused increased expression of CTCF in human cells. We also found that BRG1 targets both CTCF and BRCA1 genes.

Conclusions

BRCA1, BRG1 and CTCF module is dysregulated in ccRCC cells independently on Fuhrman grade and stage of the disease. This missregulation can have a brought spectrum of changes including 3D chromatin structure, transcription, epigenetic and others.

Clinical trial identification

Legal entity responsible for the study

Elzbieta Sarnowska

Funding

This work was supported by grant from National Science Center No UMO–2013/11/B/NZ2/00132

Disclosure

All authors have declared no conflicts of interest.