67 research outputs found

    E2F4 Regulatory Program Predicts Patient Survival Prognosis in Breast Cancer

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    Genetic and molecular signatures have been incorporated into cancer prognosis prediction and treatment decisions with good success over the past decade. Clinically, these signatures are usually used in early-stage cancers to evaluate whether they require adjuvant therapy following surgical resection. A molecular signature that is prognostic across more clinical contexts would be a useful addition to current signatures. We defined a signature for the ubiquitous tissue factor, E2F4, based on its shared target genes in multiple tissues. These target genes were identified by chromatin immunoprecipitation sequencing (ChIP-seq) experiments using a probabilistic method. We then computationally calculated the regulatory activity score (RAS) of E2F4 in cancer tissues, and examined how E2F4 RAS correlates with patient survival

    Oncogenic Transformation of Mammary Epithelial Cells by Transforming Growth Factor Beta Independent of Mammary Stem Cell Regulation

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    BackgroundTransforming growth factor beta (TGFβ) is transiently increased in the mammary gland during involution and by radiation. While TGFβ normally has a tumour suppressor role, prolonged exposure to TGFβ can induce an oncogenic epithelial to mesenchymal transition (EMT) program in permissive cells and initiate the generation of cancer stem cells. Our objective is to mimic the transient exposure to TGFβ during involution to determine the persistent effects on premalignant mammary epithelium

    DeltaNp63alpha-Mediated Induction of Epidermal Growth Factor Receptor Promotes Pancreatic Cancer Cell Growth and Chemoresistance

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    Pancreatic ductal adenocarcinoma (PDAC) is highly resistant to current chemotherapy regimens, in part due to alterations in the p53 tumor suppressor pathway. p53 homolog p63 is a transcription factor essential for the development and differentiation of epithelial surfaces. However its function in cancer is controversial and its role in PDAC is not known. We discovered that ΔNp63α was the predominantly expressed p63 variant in pancreatic cancer cell lines. ΔNp63α protein and mRNA levels were high in T3M4, BxPC3 and COLO-357 pancreatic cancer cells and low in ASPC-1 and PANC-1 cells. Overexpression of ΔNp63α in PANC-1 cells and shRNA-mediated knockdown in T3M4 cells indicated that ΔNp63α promoted anchorage-dependent and -independent growth, motility and invasion, and enhanced resistance to cisplatin-induced apoptosis. Epidermal growth factor receptor (EGFR) signaling pathways contribute to the biological aggressiveness of PDAC, and we found that the motogenic effects of ΔNp63α were augmented in presence of EGF. Ectopic expression of ΔNp63α resulted in upregulation of EGFR and β1-integrin in PANC-1 cells. Conversely, ΔNp63α knockdown had an opposite effect in T3M4 cells. ΔNp63α potentiated EGF-mediated activation of ERK, Akt and JNK signaling. Chromatin immunoprecipitation and functional reporter assays demonstrated that ΔNp63α activated EGFR transcription. 14-3-3σ transcription was also positively regulated by ΔNp63α and we have previously shown that 14-3-3σ contributes to chemoresistance in pancreatic cancer cell lines. Conversely, shRNA-mediated knockdown of 14-3-3σ led to abrogation of the ΔNp63α effects on cell proliferation and invasion. Thus, p53 homolog ΔNp63α enhances the oncogenic potential of pancreatic cancer cells through trans-activation of EGFR and 14-3-3σ

    ΔNp63 transcriptionally regulates ATM to control p53 Serine-15 phosphorylation

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    Background: Delta Np63 alpha is an epithelial progenitor cell marker that maintains epidermal stem cell self-renewal capacity. Previous studies revealed that UV-damage induced p53 phosphorylation is confined to Delta Np63 alpha-positive cells in the basal layer of human epithelium. Results: We now report that phosphorylation of the p53 tumour suppressor is positively regulated by Delta Np63 alpha in immortalised human keratinocytes. Delta Np63 alpha depletion by RNAi reduces steady-state ATM mRNA and protein levels, and attenuates p53 Serine-15 phosphorylation. Conversely, ectopic expression of Delta Np63 alpha in p63-null tumour cells stimulates ATM transcription and p53 Serine-15 phosphorylation. We show that ATM is a direct Delta Np63 alpha transcriptional target and that the Delta Np63 alpha response element localizes to the ATM promoter CCAAT sequence. Structure-function analysis revealed that the Delta Np63-specific TA2 transactivation domain mediates ATM transcription in coordination with the DNA binding and SAM domains. Conclusions: Germline p63 point mutations are associated with a range of ectodermal developmental disorders, and targeted p63 deletion in the skin causes premature ageing. The Delta Np63 alpha-ATM-p53 damage-response pathway may therefore function in epithelial development, carcinogenesis and the ageing processes

    Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR Cascade Inhibitors: How Mutations Can Result in Therapy Resistance and How to Overcome Resistance

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    The Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR cascades are often activated by genetic alterations in upstream signaling molecules such as receptor tyrosine kinases (RTK). Integral components of these pathways, Ras, B-Raf, PI3K, and PTEN are also activated/inactivated by mutations. These pathways have profound effects on proliferative, apoptotic and differentiation pathways. Dysregulation of these pathways can contribute to chemotherapeutic drug resistance, proliferation of cancer initiating cells (CICs) and premature aging. This review will evaluate more recently described potential uses of MEK, PI3K, Akt and mTOR inhibitors in the proliferation of malignant cells, suppression of CICs, cellular senescence and prevention of aging. Ras/Raf/MEK/ERK and Ras/PI3K/PTEN/Akt/mTOR pathways play key roles in the regulation of normal and malignant cell growth. Inhibitors targeting these pathways have many potential uses from suppression of cancer, proliferative diseases as well as aging
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