Project description:Hepatocellular carcinoma is generally refractory to clinical treatment. Here, we report that inactivation of the MYC oncogene is sufficient to induce sustained regression of invasive liver cancers. MYC inactivation resulted en masse in tumour cells differentiating into hepatocytes and biliary cells forming bile duct structures, and this was associated with rapid loss of expression of the tumour marker alpha-fetoprotein, the increase in expression of liver cell markers cytokeratin 8 and carcinoembryonic antigen, and in some cells the liver stem cell marker cytokeratin 19. Using in vivo bioluminescence imaging we found that many of these tumour cells remained dormant as long as MYC remain inactivated; however, MYC reactivation immediately restored their neoplastic features. Using array comparative genomic hybridization we confirmed that these dormant liver cells and the restored tumour retained the identical molecular signature and hence were clonally derived from the tumour cells. Our results show how oncogene inactivation may reverse tumorigenesis in the most clinically difficult cancers. Oncogene inactivation uncovers the pluripotent capacity of tumours to differentiate into normal cellular lineages and tissue structures, while retaining their latent potential to become cancerous, and hence existing in a state of tumour dormancy.
Project description:Hepatocellular carcinoma is generally refractory to clinical treatment. Here, we report that inactivation of the MYC oncogene is sufficient to induce sustained regression of invasive liver cancers. MYC inactivation resulted en masse in tumour cells differentiating into hepatocytes and biliary cells forming bile duct structures, and this was associated with rapid loss of expression of the tumour marker alpha-fetoprotein, the increase in expression of liver cell markers cytokeratin 8 and carcinoembryonic antigen, and in some cells the liver stem cell marker cytokeratin 19. Using in vivo bioluminescence imaging we found that many of these tumour cells remained dormant as long as MYC remain inactivated; however, MYC reactivation immediately restored their neoplastic features. Using array comparative genomic hybridization we confirmed that these dormant liver cells and the restored tumour retained the identical molecular signature and hence were clonally derived from the tumour cells. Our results show how oncogene inactivation may reverse tumorigenesis in the most clinically difficult cancers. Oncogene inactivation uncovers the pluripotent capacity of tumours to differentiate into normal cellular lineages and tissue structures, while retaining their latent potential to become cancerous, and hence existing in a state of tumour dormancy. Set of arrays organized by shared biological context, such as organism, tumors types, processes, etc. Using regression correlation
Project description:Hepatocellular carcinoma is generally refractory to clinical treatment. Here, we report that inactivation of the MYC oncogene is sufficient to induce sustained regression of invasive liver cancers. MYC inactivation resulted en masse in tumour cells differentiating into hepatocytes and biliary cells forming bile duct structures, and this was associated with rapid loss of expression of the tumour marker alpha-fetoprotein, the increase in expression of liver cell markers cytokeratin 8 and carcinoembryonic antigen, and in some cells the liver stem cell marker cytokeratin 19. Using in vivo bioluminescence imaging we found that many of these tumour cells remained dormant as long as MYC remain inactivated; however, MYC reactivation immediately restored their neoplastic features. Using array comparative genomic hybridization we confirmed that these dormant liver cells and the restored tumour retained the identical molecular signature and hence were clonally derived from the tumour cells. Our results show how oncogene inactivation may reverse tumorigenesis in the most clinically difficult cancers. Oncogene inactivation uncovers the pluripotent capacity of tumours to differentiate into normal cellular lineages and tissue structures, while retaining their latent potential to become cancerous, and hence existing in a state of tumour dormancy. Set of arrays organized by shared biological context, such as organism, tumors types, processes, etc. Keywords: Logical Set
Project description:Systemic metabolic alterations associated with increased consumption of saturated fat and obesity are linked with increased risk of prostate cancer progression and mortality, but the molecular underpinnings of this association are poorly understood. Here, we demonstrate in a murine prostate cancer model, that high-fat diet (HFD) enhances the MYC transcriptional program through metabolic alterations that favour histone H4K20 hypomethylation at the promoter regions of MYC regulated genes, leading to increased cellular proliferation and tumour burden. Saturated fat intake (SFI) is also associated with an enhanced MYC transcriptional signature in prostate cancer patients. The SFI-induced MYC signature independently predicts prostate cancer progression and death. Finally, switching from a high-fat to a low-fat diet, attenuates the MYC transcriptional program in mice. Our findings suggest that in primary prostate cancer, dietary SFI contributes to tumour progression by mimicking MYC over expression, setting the stage for therapeutic approaches involving changes to the diet.
Project description:To identify proteomic signatures associated with hepatocellular carcinoma driven by MYC overexpression, proteomics was performed on the LAP-tTA/tetO-MYC mouse conditional liver cancer model. Upon MYC activation, mice form liver cancer. Differential proteomics was performed in "MYC on" (MYC-HCC) mouse liver tumors versus mouse control normal liver tissue (where MYC was not overexpressed to drive tumorigenesis -- "MYC off").
Project description:MYC deregulation is common in human cancer and has a role in sustaining the aggressive cancer stem cell populations. MYC mediates a broad transcriptional response controlling normal biological programs but its activity is not clearly understood. We address MYC function in cancer stem cells through the inducible expression of Omomyc – a MYC derived polypeptide interfering with MYC activity – taking as model the most lethal brain tumour, glioblastoma. Omomyc bridles the key cancer stem-like cell features and affects tumour microenvironment, inhibiting angiogenesis. This occurs because Omomyc interferes with proper Myc localisation and binds to DNA, with a preference for sites previously occupied by MYC. This is accompanied by (leads to) selective repression of master transcription factors for glioblastoma stem-like cell identity like POU3F2, SOX2, and OLIG2, upregulation of effectors of tumour suppression and differentiation such as PTEN, ID4, MIAT, and modulation of the expression of microRNAs that target molecules implicated in glioblastoma growth and invasion like EGFR and ZEB1. Data support a novel view of MYC as a network stabiliser that strengthens the regulatory nodes of the gene expression programs controlling cell phenotype and highlight Omomyc as model molecule for targeting cancer stem cells.
Project description:Chavez2009 - a core regulatory network of OCT4 in human embryonic stem cells
A core OCT4-regulated network has been identified as a test case, to analyase stem cell characteristics and cellular differentiation.
This model is described in the article:
In silico identification of a core regulatory network of OCT4 in human embryonic stem cells using an integrated approach.
Chavez L, Bais AS, Vingron M, Lehrach H, Adjaye J, Herwig R
BMC Genomics, 2009, 10:314
Abstract:
BACKGROUND: The transcription factor OCT4 is highly expressed in pluripotent embryonic stem cells which are derived from the inner cell mass of mammalian blastocysts. Pluripotency and self renewal are controlled by a transcription regulatory network governed by the transcription factors OCT4, SOX2 and NANOG. Recent studies on reprogramming somatic cells to induced pluripotent stem cells highlight OCT4 as a key regulator of pluripotency.
RESULTS: We have carried out an integrated analysis of high-throughput data (ChIP-on-chip and RNAi experiments along with promoter sequence analysis of putative target genes) and identified a core OCT4 regulatory network in human embryonic stem cells consisting of 33 target genes. Enrichment analysis with these target genes revealed that this integrative analysis increases the functional information content by factors of 1.3 - 4.7 compared to the individual studies. In order to identify potential regulatory co-factors of OCT4, we performed a de novo motif analysis. In addition to known validated OCT4 motifs we obtained binding sites similar to motifs recognized by further regulators of pluripotency and development; e.g. the heterodimer of the transcription factors C-MYC and MAX, a prerequisite for C-MYC transcriptional activity that leads to cell growth and proliferation.
CONCLUSION: Our analysis shows how heterogeneous functional information can be integrated in order to reconstruct gene regulatory networks. As a test case we identified a core OCT4-regulated network that is important for the analysis of stem cell characteristics and cellular differentiation. Functional information is largely enriched using different experimental results. The de novo motif discovery identified well-known regulators closely connected to the OCT4 network as well as potential new regulators of pluripotency and differentiation. These results provide the basis for further targeted functional studies.
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Project description:The paper describes a spatio-temporal mathematical model, in the form of a moving boundary problem, to explain cancer dormancy is developed. Created by COPASI 4.24 (Build 197)
Abstract:
A spatio-temporal mathematical model, in the form of a moving boundary problem, to explain cancer dormancy is developed. Analysis of the model is carried out for both temporal and spatio-temporal cases. Stability analysis and numerical simulations of the temporal model replicate experimental observations of immune-induced tumour dormancy. Travelling wave solutions of the spatio-temporal model are determined using the hyperbolic tangent method and minimum wave speeds of invasion are calculated. Travelling wave analysis depicts that cell invasion dynamics are mainly driven by their motion and growth rates. A stability analysis of the spatio-temporal model shows a possibility of dynamical stabilization of the tumour-free steady state. Simulation results reveal that the tumour swells to a dormant level.
Project description:Patients diagnosed with hormone dependent breast cancer (HDBC) receive five or more years of adjuvant endocrine therapies (ETs). Adjuvant ETs delay relapse by targeting clinically undetectable micro-metastatic deposits, yet up to 50% of patients receiving ET relapse at a constant rate over the course of decades after surgery. The mechanisms driving these clinical dynamics are largely unknown but likely involve dormancy. We developed two approaches to study the fate of dormant cells in long-term experiments. Firstly, we profiled samples from late relapse (10-35 yrs.) and patients treated with 16-44 months of neoadjuvant ETs until progression to dissect the contribution of genetic and transcriptional changes to tumour awakening. Next, we developed a first of its kind in vitro evolutionary study to systematically record adaptive strategies of individual lineages in unperturbed parallel experiments through several months. Collectively our data demonstrate that ETs induce a heritable cell state transition into dormancy via epigenetic reprogramming. Single lineages with divergent phenotypes awaken unpredictably via epigenetic erosion. Targeting the dormant epigenome shows promising activity against adapting cancer cells. Overall, this study uncovers the contribution of epigenetic adaptation to the evolution of resistance to ETs with profound implications for breast cancer.
Project description:Patients diagnosed with hormone dependent breast cancer (HDBC) receive five or more years of adjuvant endocrine therapies (ETs). Adjuvant ETs delay relapse by targeting clinically undetectable micro-metastatic deposits, yet up to 50% of patients receiving ET relapse at a constant rate over the course of decades after surgery. The mechanisms driving these clinical dynamics are largely unknown but likely involve dormancy. We developed two approaches to study the fate of dormant cells in long-term experiments. Firstly, we profiled samples from late relapse (10-35 yrs.) and patients treated with 16-44 months of neoadjuvant ETs until progression to dissect the contribution of genetic and transcriptional changes to tumour awakening. Next, we developed a first of its kind in vitro evolutionary study to systematically record adaptive strategies of individual lineages in unperturbed parallel experiments through several months. Collectively our data demonstrate that ETs induce a heritable cell state transition into dormancy via epigenetic reprogramming. Single lineages with divergent phenotypes awaken unpredictably via epigenetic erosion. Targeting the dormant epigenome shows promising activity against adapting cancer cells. Overall, this study uncovers the contribution of epigenetic adaptation to the evolution of resistance to ETs with profound implications for breast cancer.