Project description:The ts-p53 E285K protein is a rare p53 mutant with temperature-sensitive (ts) loss of function characteristics. In cancer cells, which express ts-p53 E285K intrinsically, endogenous wild type p53 activity is reconstituted by appropriate cultivation temperature (permissive condition). At non-appropriate cultivation temperature (restrictive condition) this p53 mutant is inactive. The present study took advantage of this mechanism and employed IPH-926 lobular breast cancer cells and BT-474 ductal breast cancer cells, which both harbor endogenous ts-p53 E285K, for the transcriptional profiling of p53-responsive genes. This new approach eliminated the need for genetic modification or cytotoxic stimulation to achive a p53 response in the cells being investigated . Three subseqent passages of IPH-926 lobular breast cancer cells (harboring ts-p53 E285K) were seeded into two parallel culture dishes each and were allowed to adopt to restrictive and permissive condition for 24 h before analysis on Affymetrix U133 Plus 2.0 microarrays. Subsequently, this experiment was repeated with BT-474 ductal breast cancer cells (also harboring ts-p53 E285K). To gate out non-specific temperature effects, the same experiment was also performed with MCF-7 breast cancer cells (harboring wt p53). Probe sets differentially expressed at restrictive versus permissive condition in MCF-7 were considered as non-specifically regulated. These probe sets were excluded from the final statistical analysis of IPH-926 and BT-474 expression data. response to restored p53 activity
Project description:The ts-p53 E285K protein is a rare p53 mutant with temperature-sensitive (ts) loss of function characteristics. In cancer cells, which express ts-p53 E285K intriniscally, endogenous wild type p53 activity is reconstituted by appropriate cultivation temperature (permissive condition). At non-appropriate cultivation temperature (restrictive condition) this p53 mutant is inactive. The present study took advantage of this mechanism and employed IPH-926 lobular breast cancer cells and BT-474 ductal breast cancer cells, which both harbor endogenous ts-p53 E285K, for the transcriptional profiling of p53-responsive genes. This new approach eliminated the need for genetic modification or cytotoxic stimulation to achive a p53 response in the cells being investigated .
Project description:Analysis of miRNA expression in human breast cancer samples with Agilent's miRNA arrays. These samples are part of a study where we have investigated the mammalian cell proliferation control network consisting of transcription regulators, E2F and p53, their targets, and a family of 14 microRNAs. We observed that indicative of their significance, expression of these microRNAs is down-regulated in senescent cells and in breast cancers harboring wild-type p53. These microRNAs are repressed by p53 in an E2F1-mediated manner. Abstract of paper: Normal cell growth is governed by a complicated biological system, featuring multiple levels of control, often deregulated in cancers. The role of microRNAs in the control of gene expression is now increasingly appreciated, yet their involvement in controlling cell proliferation is still not well understood. Here we investigated the mammalian cell proliferation control network consisting of transcription regulators, E2F and p53, their targets, and a family of 14 microRNAs. Indicative of their significance, expression of these microRNAs is down-regulated in senescent cells and in breast cancers harboring wild-type p53. These microRNAs are repressed by p53 in an E2F1-mediated manner. Furthermore, we show that these microRNAs silence anti-proliferative genes, which themselves are E2F1 targets. Thus, microRNAs and transcriptional regulators appear to cooperate in the framework of a multi-gene transcriptional and post-transcriptional feed-forward loop. Finally, we show that, similarly to p53 inactivation, overexpression of representative microRNAs promotes proliferation and delays senescence, manifesting the detrimental phenotypic consequence of perturbations in this circuit. Together these findings position microRNAs as novel key players in the mammalian cellular proliferation network. Keywords: Breast Cancer, miRNA, p53. 18 Primary human breast cancer samples analyzed for their miRNA expression. From two to four replicates were performed for each sample. Quality check (QC) were performed with Feature Extraction 9.1.3.44 and arrays not passing QC were excluded
Project description:TP53 is one of the most frequently mutated gene in breast cancer. While p53 mutations often lead to loss of wild-type p53 activity, they can have a wide variety of gain-of-function (GOF) consequences. The impact of these GOF mutations in p53 on the anti-tumor immune response in breast cancer remains elusive. To address this, we have generated mouse mammary tumor models based on orthotopic injection of isogenic cell lines harboring the p53 mutations that most frequently occur in human breast cancer. By comparing the tumor immune landscape of these models and human breast tumors, we have uncovered that specific p53 point mutants consistently induce an immunologically ‘hot’ tumor phenotype, characterized by high infiltration of cytotoxic T cells, while other p53 mutations induce a non-T cell inflamed (‘cold’) microenvironment. In accordance with these high T cell levels, the hotp53 mutant tumors respond better to anti-PD-1immune checkpoint blockade than cold p53 mutant tumors. By comparing the different p53 mutants in terms of proteome profile, chromatin bindingproperties and protein complex formation, we have uncovered that T cell-enriched p53 mutants activate autophagy. Disruption of autophagy in an immunologically hot p53 mutant tumor abrogated the response to anti-PD-1 therapy. This work demonstrates that not all p53 mutations shape the immune microenvironment of mammary tumors in a similar fashion, and that response to immune checkpoint blockade depends on specific mutations in p53. This argues that screening for specific p53 aberrations in breast cancer may help guide immunotherapeutic strategies.
Project description:Mutations in the TP53 gene are the most common genetic alterations in breast cancer. To investigate at a single cell level what is the gene expression network that is regulated by mutant p53 at a non-tumoral stage, we employed a pre-neoplastic mouse model harboring the germline hotspot missense mutation R172H. We thus performed scRNAseq of cells derived from the normal mammary glands of mice harboring wt or mutant p53.
Project description:Analysis of miRNA expression in human breast cancer samples with Agilent's miRNA arrays. These samples are part of a study where we have investigated the mammalian cell proliferation control network consisting of transcription regulators, E2F and p53, their targets, and a family of 14 microRNAs. We observed that indicative of their significance, expression of these microRNAs is down-regulated in senescent cells and in breast cancers harboring wild-type p53. These microRNAs are repressed by p53 in an E2F1-mediated manner. Abstract of paper: Normal cell growth is governed by a complicated biological system, featuring multiple levels of control, often deregulated in cancers. The role of microRNAs in the control of gene expression is now increasingly appreciated, yet their involvement in controlling cell proliferation is still not well understood. Here we investigated the mammalian cell proliferation control network consisting of transcription regulators, E2F and p53, their targets, and a family of 14 microRNAs. Indicative of their significance, expression of these microRNAs is down-regulated in senescent cells and in breast cancers harboring wild-type p53. These microRNAs are repressed by p53 in an E2F1-mediated manner. Furthermore, we show that these microRNAs silence anti-proliferative genes, which themselves are E2F1 targets. Thus, microRNAs and transcriptional regulators appear to cooperate in the framework of a multi-gene transcriptional and post-transcriptional feed-forward loop. Finally, we show that, similarly to p53 inactivation, overexpression of representative microRNAs promotes proliferation and delays senescence, manifesting the detrimental phenotypic consequence of perturbations in this circuit. Together these findings position microRNAs as novel key players in the mammalian cellular proliferation network. Keywords: Breast Cancer, miRNA, p53.
Project description:MicroRNAs (miRNAs) are small, non-coding, endogenous RNAs involved in many human diseases including breast cancer. miRNA expression profiling of human breast cancers has identified miRNAs related to the clinical diversity of the disease and potentially provides novel diagnostic and prognostic tools for breast cancer therapy. In order to further understand the roles of miRNAs in association with oncogenic drivers and in specifying sub-types of breast cancer, we performed miRNAexpression profiling on mammary tumors from eight well-characterized genetically -engineered Mouse (GEM) models of human breast cancer including MMTV–H-Ras, -Her2/neu, -c-Myc, -PymT, –Wnt1 and C3(1)/SV40 T/t-antigen transgenic mice, BRCA1fl/fl;p53+/-;MMTV-cre and the p53fl/fl ;MMTV-cre transplant model. miRNA expression data for 41 mouse primary mammary tumors and 5 mouse normal mammary glands
Project description:Epithelial stem cells self-renew while maintaining multipotency, but the dependence of stem cell properties on maintenance of the epithelial phenotype is unclear. We previously showed that trophoblast stem (TS) cells lacking the protein kinase MAP3K4 maintain properties of both stemness and epithelial-mesenchymal transition (EMT). Here, we show that MAP3K4 controls the activity of the histone acetyltransferase CBP, and that acetylation of histone H2B by CBP is specifically required to maintain the epithelial phenotype. Combined loss of MAP3K4/CBP activity represses expression of epithelial genes and causes TS cells to undergo EMT while maintaining their self-renewal and multipotency properties. The expression profile of MAP3K4 deficient TS cells defines an H2B acetylation regulated gene signature that closely overlaps with that of human breast cancer cells. Taken together, our data define an epigenetic switch that maintains the epithelial phenotype in TS cells and reveal previously unrecognized genes potentially contributing to breast cancer. Three separate trophoblast stem (TS) cell conditions were compared to define the gene expression changes that occur with the induction of epithelial-mesenchymal transition (EMT) in TS cells. These conditions were TS cells differentiated for 4 days (T^Diff), TS cells differentiated for 4-days and isolated following invasion through Matrigel (T^Inv), and TS cells with an inactive MAP3K4 (TS^KI4). All conditions were normalized to wild-type control TS cells (TS^WT). T^Diff and T^Inv were analyzed in triplicate. TS^KI4 was analyzed in duplicate in two independent biological replicates.