xav939 and Colorectal-Neoplasms

Colorectal Cancer (CRC) is highly heterogeneous for which prognosis is dependent mainly on clinical staging. There is a need to stratify subpopulations of CRC on molecular basis to better predict outcome and therapy response. Truncating mutations in adenomatous polyposis coli (APC) are well-described events in CRC carcinogenesis. Clinical and genotypic characterization of Middle Eastern CRC based on presence and type of APC was determined in 412 CRC tumors using modern next generation sequencing. APC truncating mutations were identified in 58.2% (240/412) of CRCs. Overall, mutation was significant predictor of superior overall survival. Further, the type of APC mutations (short or long) did not have impact on clinical outcome. However, in vitro analysis showed difference between CRC cell lines carrying short truncating APC vs CRC cells that carry long truncating APC mutation in response to 5-flourouracil (5-FU). Importantly, we were able to overcome the resistance to 5-FU seen in CRC cells carrying short APC by tankyrase inhibitor, XAV939, thereby inhibiting Wnt/β-catenin signaling cascade. Overall, our results showed that APC mutation status plays an important role in predicting overall survival in Middle Eastern population. Furthermore, in vitro data showed that selective targeting of APC mutated CRC by tankyrase inhibitor can be an effective strategy to overcome 5-FU resistance in CRC cells.

Topics: Adenomatous Polyposis Coli; Aged; Antimetabolites, Antineoplastic; Cell Line, Tumor; Colorectal Neoplasms; Drug Resistance, Neoplasm; Female; Fluorouracil; Heterocyclic Compounds, 3-Ring; Humans; Male; Middle Aged; Mutation; Saudi Arabia; Survival; Tankyrases; Wnt Signaling Pathway

Recently there has been a growing interest in three-dimensional (3D) cell culture systems for drug discovery and development. These 3D culture systems better represent the in vivo cellular environment compared to two-dimensional (2D) cell culture, thereby providing more physiologically reliable information on drug screening and testing. Here we present the quantitative profiling of a drug-induced proteome in 2D- and 3D-cultured colorectal cancer SW480 cells using 2D nanoflow liquid chromatography-tandem mass spectrometry (2D-nLC-MS/MS) integrated with isobaric tags for relative and absolute quantitation (iTRAQ). We identified a total of 4854 shared proteins between 2D- and 3D-cultured SW480 cells and 136/247 differentially expressed proteins (up/down-regulated in 3D compared to 2D). These up/down-regulated proteins were mainly involved in energy metabolism, cell growth, and cell-cell interactions. We also investigated the XAV939 (tankyrase inhibitor)-induced proteome to reveal factors involved in the 3D culture-selective growth inhibitory effect of XAV939 on SW480 cells. We identified novel XAV939-induced proteins, including gelsolin (a possible tumor suppressor) and lactate dehydrogenase A (a key enzyme of glycolysis), which were differentially expressed between 2D- and 3D-cultured SW480 cells. These results provide a promising informative protein dataset to determine the effect of XAV939 on the expression levels of proteins involved in SW480 cell growth.

Topics: Cell Communication; Cell Culture Techniques; Cell Line, Tumor; Cell Proliferation; Colorectal Neoplasms; Gelsolin; Gene Expression Regulation, Neoplastic; Heterocyclic Compounds, 3-Ring; Humans; L-Lactate Dehydrogenase; Proteome; Proteomics; Spheroids, Cellular

With the goal of modeling human disease of the large intestine, we sought to develop an effective protocol for deriving colonic organoids (COs) from differentiated human embryonic stem cells (hESCs) or induced pluripotent stem cells (iPSCs). Extensive gene and immunohistochemical profiling confirmed that the derived COs represent colon rather than small intestine, containing stem cells, transit-amplifying cells, and the expected spectrum of differentiated cells, including goblet and endocrine cells. We applied this strategy to iPSCs derived from patients with familial adenomatous polyposis (FAP-iPSCs) harboring germline mutations in the WNT-signaling-pathway-regulator gene encoding APC, and we generated COs that exhibit enhanced WNT activity and increased epithelial cell proliferation, which we used as a platform for drug testing. Two potential compounds, XAV939 and rapamycin, decreased proliferation in FAP-COs, but also affected cell proliferation in wild-type COs, which thus limits their therapeutic application. By contrast, we found that geneticin, a ribosome-binding antibiotic with translational 'read-through' activity, efficiently targeted abnormal WNT activity and restored normal proliferation specifically in APC-mutant FAP-COs. These studies provide an efficient strategy for deriving human COs, which can be used in disease modeling and drug discovery for colorectal disease.

Topics: Adenoma; Adenomatous Polyposis Coli; Adenomatous Polyposis Coli Protein; Antibiotics, Antineoplastic; Blotting, Western; Cell Differentiation; Cell Proliferation; Colon; Colorectal Neoplasms; Drug Screening Assays, Antitumor; Enteroendocrine Cells; Flow Cytometry; Fluorescent Antibody Technique; Gene Expression Profiling; Gentamicins; Germ-Line Mutation; Goblet Cells; Heterocyclic Compounds, 3-Ring; Human Embryonic Stem Cells; Humans; Immunohistochemistry; Induced Pluripotent Stem Cells; Microscopy, Confocal; Mutation; Organoids; Real-Time Polymerase Chain Reaction; Sirolimus; Wnt Signaling Pathway

Reprogramming of energy metabolism (aerobic glycolysis) is thought to play an essential role in cancer. Compared to oxidative phosphorylation, aerobic glycolysis consumes more glucose through the upregulation of glucose transporters, notably glucose transporter 1 (GLUT1). Elevated glycolysis occurs in chemoresistant cancer cells, but the detailed mechanism is not well understood. The upregulation of the Ca2+-permeable transient receptor potential channel 5 (TrpC5) activates the Wnt/β-catenin signaling pathway in 5-fluorouracil (5-Fu)-resistant human colorectal cancer (CRC) HCT-8 (HCT-8/5-Fu) cells. In the present study, TrpC5 was overexpressed at the mRNA and protein levels along with GLUT1 in HCT-8/5-Fu cells. Suppression of TrpC5 expression with a TrpC5-specific shRNA reduced the induction of GLUT1 in the HCT-8 cells. The inhibition of the Wnt/β-catenin signaling pathway with XAV939 resulted in a decreased GLUT1 and nuclear c-Myc expression. Further study using clinical specimens validated the positive correlation between TrpC5 and GLUT1 protein levels and showed that a high TrpC5/GLUT1 expression was significantly correlated with chemoresistance. Taken together, we demonstrated the essential role of TrpC5 in GLUT1 induction and revealed that a high TrpC5/GLUT1 expression is associated with chemoresistance in human CRC.

Topics: Aged; Cell Line, Tumor; Colorectal Neoplasms; Drug Resistance, Neoplasm; Female; Fluorouracil; Gene Expression Regulation, Neoplastic; Glucose Transporter Type 1; Heterocyclic Compounds, 3-Ring; Humans; Male; Middle Aged; Treatment Failure; TRPC Cation Channels; Wnt Signaling Pathway

The DNA repair enzyme O6-methylguanine-DNA methyltransferase (MGMT) is commonly overexpressed in cancers and is implicated in the development of chemoresistance. The use of drugs inhibiting MGMT has been hindered by their haematologic toxicity and inefficiency. As a different strategy to inhibit MGMT we investigated cellular regulators of MGMT expression in multiple cancers. Here we show a significant correlation between Wnt signalling and MGMT expression in cancers with different origin and confirm the findings by bioinformatic analysis and immunofluorescence. We demonstrate Wnt-dependent MGMT gene expression and cellular co-localization between active β-catenin and MGMT. Pharmacological or genetic inhibition of Wnt activity downregulates MGMT expression and restores chemosensitivity of DNA-alkylating drugs in mouse models. These findings have potential therapeutic implications for chemoresistant cancers, especially of brain tumours where the use of temozolomide is frequently used in treatment.

Topics: Animals; Antineoplastic Agents; Benzeneacetamides; beta Catenin; Brain Neoplasms; Camptothecin; Celecoxib; Cisplatin; Colorectal Neoplasms; Dacarbazine; DNA Modification Methylases; DNA Repair Enzymes; Doxorubicin; Drug Resistance, Neoplasm; Flow Cytometry; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Glioma; Glucose-6-Phosphate Isomerase; Heterocyclic Compounds, 3-Ring; Humans; Immunoblotting; Immunohistochemistry; Irinotecan; Medulloblastoma; Mice; Neoplasm Transplantation; Neoplasms; Neuroblastoma; Pyrans; Pyrazines; Pyridines; Real-Time Polymerase Chain Reaction; Sulfones; Temozolomide; Triazoles; Tumor Suppressor Proteins; Vincristine; Wnt Proteins; Wnt Signaling Pathway

Activating mutations in the Wnt signaling pathway account for the initiation of greater than 90% of all colorectal cancers and this pathway has been implicated in numerous other diseases. Therefore, identifying small molecule inhibitors of this pathway is of critical importance towards identifying clinically relevant drugs. Numerous screens have been employed to identify therapeutic reagents, but none have made it to advanced clinical trials, suggesting that traditional screening methods are ineffective at identifying clinically relevant targets. Here, we describe a novel in vivo screen to identify small molecule inhibitors of the Wnt pathway. Specifically, treatment of zebrafish embryos with LiCl inhibits GSK3 kinase function, resulting in hyperactivation of the signaling pathway and an eyeless phenotype at 1 day post fertilization. Using the small molecule XAV939, a known inhibitor of Wnt signaling, we rescued the LiCl induced eyeless phenotype, confirming efficacy of the screen. We next tested our assay with 400 known small molecule kinase inhibitors, none of which should inhibit Wnt signaling below the level of GSK3 based on their known targets. Accordingly, none of these small molecules rescued the eyeless phenotype, which demonstrates the stringency of the assay. However, several of these small molecule kinase inhibitors did generate a non-Wnt phenotype in accordance with the kinase they targeted. Therefore, combining the efficacy, sensitivity, and stringency of this preliminary screen, this model will provide an alternative to the traditional in vitro screen, generating potentially clinical relevant drugs in a rapid and cost-effective way.

Topics: Animals; Colorectal Neoplasms; Drug Evaluation, Preclinical; Embryo, Nonmammalian; Embryonic Development; Gene Expression Regulation, Developmental; Glycogen Synthase Kinase 3; Heterocyclic Compounds, 3-Ring; Lithium Chloride; Phenotype; Wnt Signaling Pathway; Zebrafish

Constitutive Wnt signalling is characterized by excessive levels of β-catenin protein and is a frequent occurrence in cancer. APC and Axin are key components of the β-catenin destruction complex that acts to promote β-catenin degradation. The levels of Axin are in turn controlled by tankyrases, members of the PARP-family of poly-ADP-ribosylation enzymes. In colorectal cancer cells, which typically harbor APC mutations, inhibition of tankyrase activity promotes Axin stabilization and attenuates Wnt signalling. Here, we examined the effect of inhibiting tankyrases in breast cancer cells with normal APC. We show that application of the small molecule tankyrase inhibitor, XAV939 or siRNA-mediated abrogation of tankyrase expression increases Axin1 and Axin2 protein levels and attenuates Wnt-induced transcriptional responses in several breast cancer lines. In MDA-MB-231 cells, inhibiton of tankyrase activity also attenuate Wnt3a induced cell migration. Moreover, in both MDA-MB-231 and colorectal cancer cells, XAV939 inhibits cell growth under conditions of serum-deprivation. However, the presence of serum prevents this growth inhibitory effect, although inhibition of Wnt-induced transcriptional and migratory responses was maintained. These results indicate that stabilization of Axin by inhibition of tankyrases alone, may not be an effective means to block tumor cell growth and that combinatorial therapeutic approaches should be considered.

Topics: Animals; Axin Protein; Breast Neoplasms; Cell Line, Tumor; Cell Movement; Colorectal Neoplasms; Culture Media, Conditioned; HEK293 Cells; Heterocyclic Compounds, 3-Ring; Humans; MCF-7 Cells; Mice; RNA Interference; Tankyrases; Wnt Signaling Pathway

The stability of the Wnt pathway transcription factor beta-catenin is tightly regulated by the multi-subunit destruction complex. Deregulated Wnt pathway activity has been implicated in many cancers, making this pathway an attractive target for anticancer therapies. However, the development of targeted Wnt pathway inhibitors has been hampered by the limited number of pathway components that are amenable to small molecule inhibition. Here, we used a chemical genetic screen to identify a small molecule, XAV939, which selectively inhibits beta-catenin-mediated transcription. XAV939 stimulates beta-catenin degradation by stabilizing axin, the concentration-limiting component of the destruction complex. Using a quantitative chemical proteomic approach, we discovered that XAV939 stabilizes axin by inhibiting the poly-ADP-ribosylating enzymes tankyrase 1 and tankyrase 2. Both tankyrase isoforms interact with a highly conserved domain of axin and stimulate its degradation through the ubiquitin-proteasome pathway. Thus, our study provides new mechanistic insights into the regulation of axin protein homeostasis and presents new avenues for targeted Wnt pathway therapies.

Topics: Axin Protein; beta Catenin; Cell Division; Cell Line; Cell Line, Tumor; Colorectal Neoplasms; Heterocyclic Compounds, 3-Ring; Humans; Proteasome Endopeptidase Complex; Protein Binding; Proteomics; Repressor Proteins; Signal Transduction; Tankyrases; Transcription, Genetic; Ubiquitin; Ubiquitination; Wnt Proteins