Abstract
Abstract Introduction: ATP-dependent chromatin remodelers are frequently mutated in cancers. Similar to the better studied SWI/SNF remodelers, the sequencing of cancer genomes has uncovered frequent mutations in genes encoding the Nucleosome remodeling and histone deacetylase (NuRD) subunits. Upon closer inspection, NuRD complex is highly amplified in breast cancer, deleted in prostate cancer, yet mutated in lung cancer. These observations suggest that (in)activation of NuRD might contribute to oncogenesis in a cell-type specific manner. Prompted by these findings, and to gain insights into the functions of the NuRD complex, we first need to understand the composition of this complex(es). Material & Methods: We carried out Immunoprecipitation (IP) with antibodies raised against NuRD members DOC1 and CHD4, followed by mass spectrometry (MS) with HeLa nuclear extracts. This was followed by ‘reverse’ IP-MS i.e. using antibodies raised against these novel NuRD-associated factors (AFs) on HeLa nuclear extracts and data mining for the NuRD-AFs (cBioPortal). Re-expression and knockdowns of DOC1, CHD4 and NuRD-AFs were executed in selected breast, prostate and lung carcinoma cell lines. High resolution MNase nucleosomal mapping followed by qPCR was performed at specific target loci. Results & Discussions: Proteomics data suggest that ZFHX3 (cancer determinant), ZBTB2 (developmental regulator) and SMAD4 (BMP/TGF-beta signalling pathway) as NuRD-AFs. Interestingly, DOC1 IP reveals interaction only with SMAD4 while CHD4 immunoprecipitation uncovered interaction only with ZFHX3. Besides, ZBTB2 associated with both DOC1 and CHD4-NuRD. It is worth noting that these novel NuRD-AFs were found to be frequently altered in specific cancers e.g. prostate, non-small cell lung and breast carcinomas. Re-expression and knockdowns of NuRD-AFs affected epithelial-mesenchymal transitions (EMT) and chromatin dynamics during cancer progression. Conclusion: Remodeling of chromatin is an essential step towards gene expression, therefore in order to study the critical role of NuRD-AFs during carcinogenesis, a higher resolution picture of the dynamic changes in chromatin and nucleosomal structure is pertinent. These mapping experiments revealed nucleosome occupancy as well as (in)accessibility of chromatin during carcinogenesis, in particular at specific target loci. Chromatin dynamics uncovered in specific carcinoma cell lines thereby generating a comprehensive picture of the various chromatin states during carcinogenesis and expanding our understanding of chromatin function. The impact will be protein/gene expression as well as chromatin (in)accessibility and structure could be used in (early) diagnostics and prediction of carcinogenesis or biomarker discovery, in combination with already available diagnostics/biomarkers; towards a more targeted and personalised therapy for cancer patients. Note: This abstract was not presented at the meeting. Citation Format: Adone Mohd-Sarip, Diana Zatreanu, Jeroen Demmers. The mutually exclusive and diverse NuRD chromatin remodeling complex in cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5229.
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