Project description:The Notch signaling pathway regulates fate decision, proliferation and differentiation of intestinal epithelial cells. However, the role of Notch signaling in colorectal cancer progression is largely unknown. Here we show that Notch signaling suppresses the progression of colorectal tumorigenesis, even though it augments tumor initiation. In contrast to adenomas of Apcmin mice, Notch-inactivated Apcmin adenomas showed more malignant characteristics, such as submucosal invasion and loss of glandular pattern. Conversely, Notch-activated Apcmin adenomas showed a reversion from high-grade to low-grade features, such as the restoration of adherent junctions. Expression profiling revealed that Notch signaling promotes the differentiation of tumor cells with down regulation of Wnt/beta-catenin target genes and inhibition of epithelial-mesenchymal transition. Comparison of mouse and human expression profiles also suggests the common role of Notch in inhibition of tumor progression. Interestingly, Notch signaling suppressed the expression of beta-catenin responsive genes through chromatin modification of Tcf4/beta-catenin binding sides. Our results suggest that Notch signaling has dual roles in colorectal tumorigenesis: promoting adenoma initiation, while inhibiting tumor progression to colorectal cancer. mRNAs from normal (WT, Notch-activated and Notch-inactivated) and tumor (WT, Notch-activated and Notch-inactivated) tissues were profiled.
Project description:The Wnt-signalling pathway is one of the core de-regulated pathways in chronic lymphocytic leukemia (CLL), activated in a subset of patients by somatic coding mutations. Here we describe an alternative mechanism of Wnt-activation in malignant B cells, mediated by Notch2 activity in mesenchymal stromal cells (MSC) in the tumor microenvironment. We identified that tumor cells specifically induce and activate Notch2 in MSCs. Notch2 orchestrates the expression of target genes essential for the activation of canonical Wnt-signaling in CLL cells. Mechanistically, stromal Notch2 mediates the stabilization of â-catenin by inhibiting the activation of Gsk3-â in malignant B cells. Pharmacological inhibition of the Wnt-pathway mitigates microenvironment-mediated survival of malignant B cells in vitro. Similarly, inhibition of Notch-signaling impaired survival of CLL cells and disease engraftment in a PDX mouse model. Notch2 activation in the tumour microenvironment is a pre-requisite for the GSK3-â dependent activation of the canonical Wnt-signaling in tumor cells.
Project description:Current therapies for metastasized kidney cancer in humans include treatments with multi-tyrosine kinase inhibitors, monoclonal antibodies against VEGF or inhibitors of mTOR. While many tumors initially respond to these treatments, nearly all resume their progression within two years. Here we characterize CXCR4+MET+CD44+ cancer stem cells in clear cell renal cancer (ccRCC), whose presence represents a major subgroup of the disease that correlates with the aggressiveness of the tumors and poor patient outcomes. Transcriptional profiling revealed that WNT and NOTCH signaling are activated in ccRCC cancer stem cells.
Project description:In triple negative breast cancer (TNBC), aberrant activation of Notch signaling plays an important role for the maintenance of cancer stem cell (CSC) stemness. Targeting CSCs via inhibition of Notch signaling can be a potential therapeutic option for this incurable disease. We previously used genome mining strategy to discover a new indolocarbazole alkaloid loonamycin A (Loo A). In this study, we demonstrate that Loo A has stronger cytotoxicity toward TNBC cells than its structural analog rebeccamycin. Apart from inhibition of TNBC cell proliferation and migration, Loo A reduced CD44high/CD24low/- sub-population, mammosphere formation, as well as the expression of stemness-associated genes. Co-administration of Loo A enhanced antitumor effects of paclitaxel by inducing apoptosis. RNA sequencing result showed that Loo A treatment caused the inhibition of Notch signaling, accompanied by the decreased expression of Notch1 and its targeted genes in TNBC cells. These results reveal a novel bioactivity of indolocarbazole-type alkaloids and provide promising Notch-inhibiting small molecular candidates for TNBC therapy.
Project description:The unfolded protein response (UPR) maintains endoplasmic reticulum (ER) homeostasis by sensing protein-folding stress and orchestrating cellular adaptation via the ER-transmembrane proteins IRE1, PERK and ATF6. Malignant cells can co-opt UPR signaling by IRE1 and PERK to sustain tumor growth; however, the importance of ATF6 in cancer remains poorly deciphered. We observed elevated ATF6 transcriptional activity in several cancers including colorectal carcinoma (CRC). Genetic silencing or small molecule inhibition of ATF6 blocked cell cycle progression and reduced viability of several human CRC cell lines in vitro and disrupted tumor progression in vivo. Unexpectedly, ATF6 interference also disabled Myc and Wnt signaling and reduced stemness. ATF6 inhibition attenuated growth of organoids derived from malignant but not normal human intestinal tissue, reducing Wnt-pathway activity and driving cellular differentiation. Wnt-surrogate agonism rescued the growth inhibitory phenotype of ATF6 interference. Our findings identify ATF6 as an unexpected facilitator of oncogenic Wnt signaling in CRC.
Project description:Schimke immuno-osseous dysplasia (SIOD) is a multisystemic disorder caused by biallelic mutations in SWI/SNF-related matrix associated actin-dependent regulator of chromatin, subfamily A-like protein 1 (SMARCAL1). Changes in gene expression appear to underlie the immunodeficiency and arteriosclerosis of SIOD; therefore, we hypothesized that SMARCAL1 deficiency alters renal gene expression to cause the focal segmental glomerulosclerosis (FSGS) of SIOD. We tested this hypothesis by transcriptome analysis and quantitative reverse transcription PCR (qRT-PCR) of an SIOD patient kidney, a genetic screen and immunofluorescence. These showed increased expression of genes in the Wnt and Notch signaling pathways in an SIOD patient kidney, interaction of Marcal1 with genes encoding components of the Wnt and Notch signaling pathways, and increased levels of unphosphorylated b-catenin and Notch1 intracellular domain (NICD) in the glomeruli of SIOD patient kidneys. Given that increased Wnt and Notch activity are established causes of FSGS, we hypothesize that SMARCAL1 deficiency increases the activity of one or both of these pathways to cause the renal disease of most SIOD patients.
Project description:The crosstalk and balance regulation of Wnt-Notch have been known to be essential for cell fate decision and tissue regeneration, while how the balance is maintained and how the Wnt-Notch pathways are connected with the cell cycle regulation are still not clear. In the mouse model with accelerated aging phenotypes due to the loss of cell cycle inhibitor p21 function in Werner syndrome background, we observed the imbalance of Wnt-Notch signaling, along with the fast turnover of intestinal epithelia, which might cause the abnormal mobilization of stem cells, exhaust the stem cell reservoir, and result in the accelerated aging phenotypes. We revealed that the loss of p21 caused the shift of DREAM/Rb complex to MMB/E2F1 complex and the fast turnover of intestinal epithelia. Importantly, we identified the E2F1 as the transcriptional regulator for Notch1, which connected the p21-DREAM/MMB/Rb-E2F1 pathway with Wnt-Notch pathway. The overexpression of p21 rescued the imbalance of Wnt-Notch pathway. Our data identify p21 as an important factor in maintaining sequential mobilization, proliferation, and homeostasis of intestinal stem cells.