Project description:Global Transcriptional analysis of BRG1 in lung cancer cells Comparative transcriptional profile comparing the expression in lung cancer cells before and after restoring the wild type BRG1 or mutant BRG1 expression controlled by the Tet-ON system (doxycycline depending expression)
Project description:Global Transcriptional analysis of BRG1 in lung cancer cells Comparative transcriptional profile comparing the expression in lung cancer cells before and after restoring the wild type BRG1 or mutant BRG1 expression controlled by the Tet-ON system (doxycycline depending expression)
Project description:Gupta M, Concepcion CP, Fahey CG, Keshishian H, Bhutkar A, Brainson CF, Sanchez-Rivera FJ, Pessina P, Kim JY, Simoneau A, Paschini M, Beytagh MC, Stanclift C, Schenone M, Mani DR, Li C, Oh A, Li F, Hu H, Karatza A, Bronson RT, Shaw AT, Hata AN, Wong K, Zou L, Carr SA, Jacks T, Kim CF. Cancer Res 2020.
Inactivation of SMARCA4/BRG1, the core ATPase subunit of mammalian SWI/SNF
complexes, occurs at very high frequencies in non-small cell lung cancers. There are no
targeted therapies for this subset of lung cancers, nor is it known how mutations in BRG1
contribute to lung cancer progression. Using a combination of gain- and loss-of-function
approaches, we demonstrate that deletion of BRG1 in lung cancer leads to activation of
replication stress responses. Single-molecule assessment of replication fork dynamics in
BRG1-deficient cells revealed increased origin firing, mediated through pre-licensing protein
CDC6. Quantitative mass spectrometry and co-immunoprecipitation assays showed that
BRG1-containing SWI/SNF complexes interact with RPA complexes. Lastly, we show that
BRG1-deficient lung cancers are sensitive to the pharmacological inhibition of ATR. These
findings provide novel mechanistic insight into BRG1-mutant lung cancers and suggest that
their ATR dependency can be leveraged therapeutically, and potentially expanded to BRG1-
mutant cancers in other tissues.
Project description:The SWI/SNF complex remodels chromatin in an ATP-dependent manner through the ATPase subunits BRG1 and BRM. Chromatin remodeling alters nucleosome structure to change gene expression, however aberrant remodeling and gene expression can result in cancer. The function and localization on chromatin of the SWI/SNF complex depends on the protein makeup of the complex. Here we report the protein-protein interactions of wild-type BRG1 or mutant BRG1 in which the HSA domain has been deleted (BRG1-HSA). We demonstrate the interaction of BRG1 with most SWI/SNF complex members and a failure of a number of these members to interact with BRG1-HSA. These results demonstrate that the HSA domain of BRG1 is a critical interaction platform for the correct formation of SWI/SNF remodeling complexes.
Project description:The transcription factors Smad2 and Smad3 mediate a large set of genes responses induced by the cytokine TGFβ, but the extent to which their function depends on chromatin remodeling remains to be defined. We observed interactions between these two Smads and BRG1, BAF250b, BAF170 and BAF155, which are core components of the SWI/SNF chromatin-remodeling complex. Smad2 and Smad3 have a similar affinity for these components in vitro, and their interactions are primarily mediated by BRG1. In vivo, however, BRG1 predominantly interacts with Smad3, and this interaction is enhanced by TGFβ stimulation. Our results suggest that BRG1 is incorporated into transcriptional complexes that are formed by activated Smads in the nucleus, on target promoters. Using BRG1-deficient cell systems(H522 lung cancer cells), we defined the BRG1 dependence of the TGFβ transcriptional program genome-wide. Most TGFβ gene responses in human epithelial cells are dependent on BRG1 function. Remarkably, BRG1 is not required for the TGFβ-mediated induction of SMAD7 and SNON, which encode key mediators of negative feedback in this pathway. Our results provide a genome-wide scope of the participation of BRG1 in TGFβ action and suggest a widespread yet differential involvement of BRG1 SWI/SNF remodeler in the transcriptional response of many genes to this cytokine. Keywords: comparative genomic hybridization
Project description:Mammalian SWI/SNF-related complexes have been implicated in cancer based on some of the subunits physically interacting with RB and other proteins involved in carcinogenesis. Additionally, several subunits are mutated or not expressed in tumor-derived cell lines. Strong evidence for a role in tumorigenesis in vivo, however, has been limited to SNF5 mutations that result primarily in malignant rhabdoid tumors (MRTs) in humans and MRTs as well as other sarcomas in mice. We previously generated a null mutation of the Brg1 catalytic subunit in the mouse and reported that homozygotes die during embryogenesis. Here, we demonstrate that Brg1 heterozygotes are susceptible to mammary tumors that are fundamentally different than Snf5 tumors. First, mammary tumors are carcinomas not sarcomas. Second, Brg1+/- tumors arise because of haploinsufficiency rather than loss of heterozygosity (LOH). Third, Brg1+/- tumors exhibit genomic instability but not polyploidy based on array CGH results. We monitored Brg1+/-, Brm-/- double-mutant mice but did not observe any tumors resembling those from Snf5 mutants, indicating that the Brg1+/- and Snf5+/- tumor phenotypes do not differ simply because Brg1 has a closely related paralog whereas Snf5 does not. These findings demonstrate that BRG1 and SNF5 are not functionally equivalent but protect against cancer in different ways. We also demonstrate that Brg1+/- mammary tumors have relatively heterogeneous gene expression profiles with similarities and differences compared to other mouse models of breast cancer. The Brg1+/- expression profiles are not particularly similar to mammary tumors from Wap-T121 transgenic line where RB is perturbed. We were also unable to detect a genetic interaction between the Brg1+/- and Rb+/- tumor phenotypes. These latter findings do not support a BRG1-RB interaction in vivo. Experiment Overall Design: 14 microarrays consisting of 12 unique Brg1+/- murine mammary Experiment Overall Design: tumors
Project description:To development our gene expression approach , we have employed whole genome microarray expression profiling as a discovery platform to identify genes potentialy regulated by the treatment with glucocorticoids (GC) and retinoic acid (RA) alone and combined with AZA/SAHA and the relationship of these features with the status of BRG1 and MYC in lung cancer cell lines. MYC amplified cell lines and BRG1 mutant cell lines were treated with glucocorticoids (GC) and retinoic acid (RA) alone and combined with AZA/SAHA and their expression was then measured
Project description:Comprehensive characterization of the DNA methylome regulated by the treatment with glucocorticoids (GC) and retinoic acid (RA) alone and combined with AZA/SAHA and the relationship of these features with the status of BRG1 and MYC in lung cancer cell lines. MYC amplified cell lines and BRG1 mutant cell lines were treated with glucocorticoids (GC) and retinoic acid (RA) alone and combined with AZA/SAHA and their methylation was then measured
Project description:Lung cancer is the leading cause of cancer-related mortality. The two main lung cancer types are small cell lung cancer (SCLC) and non-SCLC (NSCLC), where NSCLC comprises about 80-85% of all lung cancer. Despite the introduction of improved treatments, the overall survival rate of lung cancer patients remains low. Further elucidation of the regulatory network perturbations between cancer-related genes and proteins is one promising route to alter this mortality trend. The deregulation of the DNA replication, cell cycle, proliferation and migration are the common factors that are involved in cancer development and progression, and therefore logical targets for analysis. Minichromosome maintenance 2(MCM2) is a DNA replication licensing factor, which belongs to the heterohexameric MCM2-7 complex. MCM2 has been proposed as an excellent proliferation marker in many types of cancer. Our study will establish a global functional distribution of identified proteins in silenced-MCM2 in H1299 NSCLC by the means of iTRAQ. Understanding the molecular basis of MCM2 in lung cancer cells enables us to discover alternative target for lung cancer therapy.
Project description:Zygotic gene expression programs control cell differentiation in vertebrate development. In Xenopus, these programs are initiated by local induction of regulatory genes through maternal signaling activities in the wake of zygotic genome activation (ZGA) at the midblastula transition (MBT). These programs lay down the vertebrate body plan through gastrulation and neurulation, and are accompanied by massive changes in chromatin structure, which increasingly constrain cellular plasticity. Here we report on developmental functions for Brahma related gene 1 (BRG1), a key component of embryonic SWI/SNF chromatin remodeling complexes. Carefully controlled, global BRG1 protein depletion in X. tropicalis and X. laevis leads to embryonic lethality from gastrulation on, similar to BRG1-/- mice. Transcriptome analysis at late blastula, before development becomes arrested, indicates predominantly a role for BRG1 in transcriptional activation of a limited set of genes involved in pattern specification processes and nervous system development. Mosaic analysis by targeted microinjection defines BRG1 as an essential amplifier of gene expression in dorsal (BCNE and Nieuwkoop centers) and ventral (BMP/Vent) signaling centers. By tissue transplantation, we define BRG1-dependent activation of chordin (chrd) transcription in the prospective neural plate (BCNE region) as an essential step in head formation. BRG1-sensitive genes are typically characterized by a robust burst of transcription at MBT. These results define a systemic function for BRG1-containing SWI/SNF chromatin remodelers as a transcriptional amplifier of the gene network that initiates embryonic patterning.