Project description:Deregulation of RNA polymerase II (RNAPII) by oncoproteins, such as transcription factor Myc, interferes with DNA replication and is a major source of DNA damage and genomic instability. Ubiquitination is a key pathway controlling RNAPII activity via modification of RNAPII subunits or associated regulatory proteins. We uncover a mechanism for genome maintenance by ubiquitin ligase Trim33 and transcription factor E2f4. We show that Trim33 promotes E2f4 protein turnover, restricting interactions of E2f4 with chromatin and with the Recql DNA helicase. Replicative stress blunts Trim33-dependent regulation, which stimulates E2f4 and Recql recruitment to chromatin and facilitates recovery of DNA replication. Deletion of Trim33 triggers chronic recruitment of Recql to chromatin and accelerates DNA replication under stress, accompanied by compromised DDR signaling and DNA repair. Depletion of Trim33 in Myc-overexpressing cells leads to accumulation of replication-associated DNA damage and delays Myc-driven tumorigenesis. We propose that the Trim33-E2f4-Recql axis provides a mechanism to control DNA replication at transcriptionally active chromatin to maintain genome integrity.
Project description:Breast cancer is a highly heterogeneous disease that is categorized into distinct tumor subtypes based on specific molecular attributes, which ultimately influence therapeutic options. Unlike ER+ and/or HER2+ cancers that are subject to specific targeted therapies, triple negative breast cancers (TNBCs) do not express these receptors, which leaves patients with limited treatment options. Thus, significant focus has been placed on identifying molecular attributes of basal-like disease that could be used to develop and/or direct novel treatment regimens. Activation of MYC signaling and inactivation of the RB-pathway are frequent events in many types of human cancers. These pathways influence many biological processes, such as cell proliferation, that contribute to the aggressiveness and therapeutic response of tumors. The current study examines the interaction of the MYC and RB pathways in mammary epithelial cell tumorigenesis. Mouse mammary epithelial cells were isolated and sub-cultured. Adenoviral expression of Cre-recombinase was used to delete the RB and/or p53 genes, and retrovirus was used to achieve MYC overexpression (OE). Proliferating cells were harvested for each condition, and RNA was isolated for analyses.
Project description:Transgenic expression in mice of two synergistically acting SV40 early region encoded proteins, large (LT) and small (sT) tumor antigens, in the mammary epithelium recapitulates loss of p53 and Rb function and deregulation of PP2A-controlled mitogenic pathways in human breast cancer. In primiparous mice, WAP-promoter driven expression of SV40 proteins induces well and poorly differentiated mammary adenocarcinomas. We performed a correlative aCGH and gene expression analysis of 25 monofocal tumors, representing four histopathological grades, to explore the molecular traits of SV40-induced mammary tumors and to emphasize the relevance of this tumor model for human breast tumorigenesis. CGH analysis of 15 mammary carcinoma samples of the NP8 WAP-SV40 mouse line.
Project description:Cell cycle deregulation leads to abnormal proliferation and cell death in a context-specific manner. Cell cycle progression driven via Rb pathway forces neurons to undergo S-phase, resulting in cell death associated with the progression of neuronal degeneration. Nevertheless, some Rb- and Rb family (Rb, p107, and p130)-deficient differentiating neurons can proliferate and form tumors. Here, we found that differentiating cerebral cortical excitatory neurons underwent S-phase progression but not cell division after acute Rb family inactivation in differentiating neurons. However, the differentiating neurons underwent cell division and form tumors when Rb family members were inactivated in cortical progenitors. Differentiating neurons generated from Rb -/-; p107 -/-; p130 -/- (Rb-TKO) progenitors, but not acutely inactivated Rb-TKO differentiating neurons, activated DNA double-strand break (DSB) repair pathway without increasing the tri-methylation of histone H4 at lysine 20 (H4K20M3), which is known to protect from DNA damage. The activation of DSB repair pathway was essential for the cell division of Rb-TKO differentiating neurons. These results suggest that newly-born cortical neurons from progenitors epigenetically become protected from DNA damage and cell division in a Rb family-dependent manner. 3 samples of pCAG-control, pCAG-RbTKO, pMAP2-control, and pMAP2-RbTKO cells
Project description:Transgenic expression in mice of two synergistically acting SV40 early region encoded proteins, large (LT) and small (sT) tumor antigens, in the mammary epithelium recapitulates loss of p53 and Rb function and deregulation of PP2A-controlled mitogenic pathways in human breast cancer. In primiparous mice, WAP-promoter driven expression of SV40 proteins induces well and poorly differentiated mammary adenocarcinomas. We performed a correlative aCGH and gene expression analysis of 25 monofocal tumors, representing four histopathological grades, to explore the molecular traits of SV40-induced mammary tumors and to emphasize the relevance of this tumor model for human breast tumorigenesis. Gene expression analysis of 6 involuted normal mammary gland 30 days post weaning in WAP-SV40 T1 and BALB/c samples.
Project description:Transgenic expression in mice of two synergistically acting SV40 early region encoded proteins, large (LT) and small (sT) tumor antigens, in the mammary epithelium recapitulates loss of p53 and Rb function and deregulation of PP2A-controlled mitogenic pathways in human breast cancer. In primiparous mice, WAP-promoter driven expression of SV40 proteins induces well and poorly differentiated mammary adenocarcinomas. We performed a correlative aCGH and gene expression analysis of 25 monofocal tumors, representing four histopathological grades, to explore the molecular traits of SV40-induced mammary tumors and to emphasize the relevance of this tumor model for human breast tumorigenesis. Gene expression analysis of 25 mammary carcinoma samples of two different WAP-SV40 mouse lines, T1 and NP8. Three involuted mammary gland tissues were included in the study as reference samples.
Project description:Transgenic expression in mice of two synergistically acting SV40 early region encoded proteins, large (LT) and small (sT) tumor antigens, in the mammary epithelium recapitulates loss of p53 and Rb function and deregulation of PP2A-controlled mitogenic pathways in human breast cancer. In primiparous mice, WAP-promoter driven expression of SV40 proteins induces well and poorly differentiated mammary adenocarcinomas. We performed a correlative aCGH and gene expression analysis of 25 monofocal tumors, representing four histopathological grades, to explore the molecular traits of SV40-induced mammary tumors and to emphasize the relevance of this tumor model for human breast tumorigenesis.
Project description:Transgenic expression in mice of two synergistically acting SV40 early region encoded proteins, large (LT) and small (sT) tumor antigens, in the mammary epithelium recapitulates loss of p53 and Rb function and deregulation of PP2A-controlled mitogenic pathways in human breast cancer. In primiparous mice, WAP-promoter driven expression of SV40 proteins induces well and poorly differentiated mammary adenocarcinomas. We performed a correlative aCGH and gene expression analysis of 25 monofocal tumors, representing four histopathological grades, to explore the molecular traits of SV40-induced mammary tumors and to emphasize the relevance of this tumor model for human breast tumorigenesis.
Project description:Transgenic expression in mice of two synergistically acting SV40 early region encoded proteins, large (LT) and small (sT) tumor antigens, in the mammary epithelium recapitulates loss of p53 and Rb function and deregulation of PP2A-controlled mitogenic pathways in human breast cancer. In primiparous mice, WAP-promoter driven expression of SV40 proteins induces well and poorly differentiated mammary adenocarcinomas. We performed a correlative aCGH and gene expression analysis of 25 monofocal tumors, representing four histopathological grades, to explore the molecular traits of SV40-induced mammary tumors and to emphasize the relevance of this tumor model for human breast tumorigenesis.
Project description:Deregulation of RNA polymerase II (RNAPII) by oncoproteins, such as transcription factor Myc, interferes with DNA replication and is a major source of DNA damage and genomic instability. Ubiquitination is a key pathway controlling RNAPII activity via modification of RNAPII subunits or associated regulatory proteins. We uncover a mechanism for genome maintenance by ubiquitin ligase Trim33 and transcription factor E2f4. We show that Trim33 promotes E2f4 protein turnover, restricting interactions of E2f4 with chromatin and with the Recql DNA helicase. Replicative stress blunts Trim33-dependent regulation, which stimulates Recql recruitment to chromatin and facilitates recovery of DNA synthesis. Deletion of Trim33 triggers chronic recruitment of Recql and accelerates DNA replication under stress, accompanied by compromised DDR signaling and DNA repair. Depletion of Trim33 in Myc-overexpressing cells leads to accumulation of replication-associated DNA damage and delays Myc-driven tumorigenesis. We propose that the Trim33-E2f4-Recql axis provides a mechanism to control DNA replication at transcriptionally active chromatin to maintain genome integrity.