Project description:To understand molecular mechanisms driving HB pathogenesis, we hypothesize that pathologic activation of Enhancer of Zeste Homolog 2 contributes to hepatoblastoma propagation. Here we demonstrate that EZH2 promotes proliferation in HB cell lines through interaction with β-catenin, the most frequently mutated gene in HB. We demonstrate that canonical and noncanonical EZH2 signaling occur in HB tumor cells, likely driven by aberrant EZH2 expression. We use comparison groups of liver cancer, hepatocytes, and dermal fibroblasts to establish the hepatoblastoma identity of our patient-derived cell lines.
Project description:Overexpression of EZH2 in estrogen receptor negative (ER-) breast cancer promotes metastasis. EZH2 has been mainly studied as the catalytic component of the Polycomb Repressive Complex 2 (PRC2) that mediates gene repression by trimethylating histone H3 at lysine 27 (H3K27me3). However, how EZH2 drives metastasis despite the low H3K27me3 levels observed in ER- breast cancer is unknown. We have shown that in human invasive carcinomas and distant metastases, cytoplasmic EZH2 phosphorylated at T367 is significantly associated with ER- disease and low H3K27me3 levels. Here, we explore the interactome of EZH2 and of a phosphodeficient mutant EZH2_T367A. We identified novel interactors of EZH2, and identified interactions that are dependent on the phosphorylation and cellular localization of EZH2 that may play a role in EZH2 dependent metastatic progression.
Project description:The mechanisms underlying hepatoblastoma are not well defined. To address this, we generated transcriptomic profiles of normal, background, and hepatoblastoma liver samples from patients aged 0.01 months to 6 years, using RNA-sequencing. Hepatoblasoma was histologically confirmed. Here we focus on the elevation of stem cell markers and the loss of tumor suppressor proteins leading to the development of hepatoblastoma in very young children.
Project description:Hepatoblastoma (HB) is the most common primary liver malignancy of childhood. However, molecular investigations of the disease are limited and effective treatment options are lacking. The use of patient derived xenografts (PDX) to study biology and treatment strategies of HB has proven to be a useful tool. There is currently a knowledge gap in the investigation of key driver cells of HB in PDX models. Key driving pathways of HB tumor including WNT, AP-1, Hedgehog, Notch and MAPK pathways and genes such as GPC3, DLK1 and HMGA2 have been identified in primary HB tumor and PDX as integral players in HB tumor growth. Cell clusters have been defined with distinct roles in tumor development. Cell populations with initiating, angiogenic (endothelial), maintenance, and progression signatures have been identified in one HB patient tumor and corresponding PDX tumor. Critical pathways combined with identification of distinct cell populations within HB tumor will allow for investigation of novel treatment strategies in vitro and in vivo.
Project description:Hepatoblastoma (HB) is the most common primary liver malignancy of childhood. However, molecular investigations of the disease are limited and effective treatment options are lacking. The use of patient derived xenografts (PDX) to study biology and treatment strategies of HB has proven to be a useful tool. There is currently a knowledge gap in the investigation of key driver cells of HB in PDX models. Key driving pathways of HB tumor including WNT, AP-1, Hedgehog, Notch and MAPK pathways and genes such as GPC3, DLK1 and HMGA2 have been identified in primary HB tumor and PDX as integral players in HB tumor growth. Cell clusters have been defined with distinct roles in tumor development. Cell populations with initiating, angiogenic (endothelial), maintenance, and progression signatures have been identified in one HB patient tumor and corresponding PDX tumor. Critical pathways combined with identification of distinct cell populations within HB tumor will allow for investigation of novel treatment strategies in vitro and in vivo.
Project description:Unveiling the molecular mechanisms of tissue remodelling following injury is imperative to elucidate its regenerative capacity and aberrant repair in disease. Using different omics approaches, we identified enhancer of zester homolog 2 (EZH2) as a key regulator that initiates a fibrotic cascade in injured lung epithelium. Epithelial-injury-driven enrichment of nuclear transforming growth factor-b-activated kinase 1 (TAK1) mediates EZH2 phosphorylation to facilitate the release of EZH2 from polycomb repressive complex 2 (PRC2). This process leads to the establishment of a fibrotic transcriptional complex of EZH2, RNA-polymerase II (POL2) and nuclear actin, which orchestrates aberrant epithelial lung repair programs. The liberation of EZH2 from PRC2 is accompanied by an EZH2-EZH1 switch to preserve silencing at non-target genes. Loss of epithelial TAK1, EZH2 or blocking nuclear actin influx attenuates the fibrotic cascade and restores respiratory homeostasis. Accordingly, EZH2 inhibition significantly improves outcomes in a pulmonary fibrosis mouse model. Our results reveal an important non-canonical function of EZH2, paving the way for new therapeutic interventions in fibrotic lung diseases.
Project description:Increased activity of the epigenetic modifier EZH2 has been associated with different cancers. However, evidence for a functional role of EZH2 in tumourigenesis in vivo remains poor, in particular in metastasising solid cancers. Here we reveal central roles of EZH2 in promoting growth and metastasis of cutaneous melanoma. In a melanoma mouse model, conditional Ezh2 ablation as much as treatment with the preclinical Ezh2 inhibitor GSK503 stabilises the disease through inhibition of growth and virtually abolishes metastases formation without affecting normal melanocyte biology. Comparably, in human melanoma cells, EZH2 inactivation impairs proliferation and invasiveness, accompanied by re-expression of tumour suppressors connected to increased patient survival. These EZH2 target genes suppress melanoma growth and prevent EMT / metastasis in vivo revealing the dual function of EZH2 in promoting tumour progression. Thus, EZH2-mediated epigenetic repression is highly relevant especially during advanced melanomagenesis, which makes EZH2 a promising target for novel melanoma therapies.
Project description:Hepatoblastoma remains one of the most difficult childhood tumors to treat and is alarmingly understudied. Over half of patients initially present with locally advanced or metastatic disease and the prognosis for this cohort remains dismal. In addition, many of these children have disease that is resistant to standard therapies and will require novel and targeted therapies to effectively treat or manage their disease. We previously demonstrated that Proviral Insertion site in Maloney murine leukemia virus (PIM) kinases, specifically PIM3, are overexpressed in human hepatoblastoma cells and function to promote tumorigenesis. We aimed to use CRISPR/Cas9 gene editing technology with dual gRNAs to introduce large inactivating deletions in the PIM3 gene and achieve stable PIM3 knockout (KO) in the human hepatoblastoma cell line, HuH6. PIM3 KO of hepatoblastoma cells led to significantly decreased proliferation, viability, and motility, inhibited cell-cycle progression, decreased tumor growth in a xenograft murine model, and increased animal survival. Analysis of RNA sequencing data revealed that PIM3 KO downregulated expression of pro-migratory and pro-invasive genes and upregulated expression of genes involved in apoptosis and differentiation. Furthermore, PIM3 KO decreased hepatoblastoma cancer cell stemness as evidenced by decreased tumorsphere formation, decreased mRNA abundance of stemness markers, and decreased cell surface expression of CD133, a marker of hepatoblastoma stem cell-like cancer cells. Reintroduction of PIM3 into PIM3 KO cells rescued the malignant phenotype. These findings emphasize the role of PIM3 in promoting hepatoblastoma tumorigenesis and provide evidence that targeting PIM3 may offer a novel therapeutic approach for children with hepatoblastoma.