Notch Inhibits Expression of the Kruppel-Like Factor 4 Tumor Suppressor in the Intestinal Epithelium

Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322, USA.
Molecular Cancer Research (Impact Factor: 4.38). 12/2008; 6(12):1920-7. DOI: 10.1158/1541-7786.MCR-08-0224
Source: PubMed


The zinc finger-containing transcription factor, Krüppel-like factor 4 (KLF4), inhibits cell proliferation. An in vivo tumor-suppressive role for KLF4 is shown by the recent finding that Klf4 haploinsufficiency in Apc(Min/+) mice promotes intestinal tumorigenesis. Studies also show that KLF4 is required for the terminal differentiation of goblet cells in the mouse intestine. The Notch signaling pathway suppresses goblet cell formation and is up-regulated in intestinal tumors. Here, we investigated the relationship between Notch signaling and KLF4 expression in intestinal epithelial cells. The rate of proliferation of HT29 human colon cancer cells was reduced when treated with the gamma-secretase inhibitor dibenzazepine to inhibit Notch signaling or small interfering RNA directed against Notch. KLF4 levels were increased in dibenzazepine-treated or Notch small interfering RNA-treated cells. Conversely, overexpression of Notch in HT29 cells reduced KLF4 levels, suppressed KLF4 promoter activity, and increased proliferation rate. Treatment of Apc(Min/+) mice with dibenzazepine resulted in a 50% reduction in the number of intestinal adenomas compared with the vehicle-treated group (P < 0.001). Both the normal-appearing intestinal mucosa and adenomas obtained from dibenzazepine-treated Apc(Min/+) mice had increased goblet cell numbers and Klf4 staining accompanied by reduced cyclin D1 and Ki-67 staining when compared with those from vehicle-treated mice. Results of these studies indicate that Notch signaling suppresses KLF4 expression in intestinal tumors and colorectal cancer cells. Inhibition of Notch signaling increases KLF4 expression and goblet cell differentiation and reduces proliferation and tumor formation. KLF4 is therefore a potential mediator for the antitumor effect of Notch inhibitors such as dibenzazepine.

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    • "The authors demonstrated that induction of wild-type APC causes a reduction on IFTIM3 genes within 24 hours. In another study, Ghaleb et al. demonstrated that IFITM3 transcription is dependent on activation of Wnt/β-catenin signaling, in intestinal epithelium [37]. This study appears to be in concordance with our results. "
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    ABSTRACT: Cancer cells frequently adopt cellular and molecular alterations and acquire resistance to cytostatic drugs. Chemotherapy with oxaliplatin is among the leading treatments for colorectal cancer with a response rate of 50%, inducing intrastrand cross-links on the DNA. Despite of this drug's efficiency, resistance develops in nearly all metastatic patients. Chemoresistance being of crucial importance for the drug's clinical efficiency this study aimed to contribute to the identification and description of some cellular and molecular alterations induced by prolonged oxaliplatin therapy. Resistance to oxaliplatin was induced in Colo320 (Colo320R) and HT-29 (HT-29R) colorectal adenocarcinoma cell lines by exposing the cells to increasing concentrations of the drug. Alterations in morphology, cytotoxicity, DNA cross-links formation and gene expression profiles were assessed in the parental and resistant variants with microscopy, MTT, alkaline comet and pangenomic microarray assays, respectively. Morphology analysis revealed epithelial-to-mesenchymal transition in the resistant vs parental cells suggesting alterations of the cells' adhesion complexes, through which they acquire increased invasiveness and adherence. Cytotoxicity measurements demonstrated resistance to oxaliplatin in both cell lines; Colo320 being more sensitive than HT-29 to this drug (P < 0.001). The treatment with oxaliplatin caused major DNA cross-links in both parental cell lines; in Colo320R small amounts of DNA cross-links were still detectable, while in HT-29R not. We identified 441 differentially expressed genes in Colo320R and 613 in HT-29R as compared to their parental counterparts (at least 1.5 -fold up- or down- regulation, p < 0.05). More disrupted functions and pathways were detected in HT-29R cell line than in Colo320R, involving genes responsible for apoptosis inhibition, cellular proliferation and epithelial-to-mesenchymal transition. Several upstream regulators were detected as activated in HT-29R cell line, but not in Colo320R. Our findings revealed a more resistant phenotype in HT-29R as compared to Colo320R and different cellular and molecular chemoresistance patterns induced by prolonged treatment with oxaliplatin in cell lines with identical origins (colorectal adenocarcinomas).
    Full-text · Article · Jul 2013 · BMC Genomics
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    • "However, alternative mechanisms for KLF4 transcriptional inactivation may occur in other KLF4 deficient cancers that don’t exhibit genetic loss and promoter methylation. In colon cancers, KLF4 could be down-regulated by caudal type homeobox 2 (CDX2) [42], notch signaling [43], transcription factor 4 (TCF4) [44] or sex determining region Y-box 9 (Sox9) [44]. Furthermore, KLF4 could also be regulated post-transcriptionally by microRNA targeting, as found in human esophageal cancer cell lines [36]. "
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    Full-text · Article · Aug 2012 · PLoS ONE
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    • "Activation of Notch signaling is essential for the development of adenomas in ApcMin ⁄ + mice [42]. Hes1 is reported to suppress the expression of Kru¨ppel-like factor 4, a transcriptional repressor [45]. KLF4, the zinc finger-containing transcription factor, is highly expressed in terminally differentiated epithelial cells of the intestine [46], whose overexpression can inhibit colon cancer cell proliferation [47]. "
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    Full-text · Article · Aug 2012 · Journal of Molecular Signaling
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