Project description:Increasing evidence suggests that cancer arises from cells that are capable of initiating and sustaining neoplastic tissue growth, termed cancer stem cells (CSCs). Of central scientific and clinical relevance, cells with CSC properties are enriched for chemo- and radiation resistance and therefore may represent a population of cells that must be therapeutically targeted to prevent cancer recurrence/relapse 1. Human CSCs were first isolated in neoplastic hematopoietic tissue that manifests leukemias such as adult acute myeloid leukemia (AML) 2. AML stem cells represent a benchmark model of human CSC biology, ultimately motivating foundational studies leading to the identification of CSCs from solid tumours such as breast and colon 3. Independent of tissue type, a consistent feature of CSCs is their uncontrolled self-renewal capacity and differentiation blockade that have been commonly related to aberrant activation of pro-oncogenic events such as dysregulation of CBP/p300 transcriptional regulation involving β-catenin 4. However, the transcriptional networks involving CBP/p300/β-catenin complex have been shown to be equally critical to maintain normal stem cell (SCs) self-renewal for tissue homeostasis and regeneration 5. Here, we identify Sam68 as a distinct target that affords the ability to uniquely regulate CBP mediated transcription in human CSCs. Using a small molecule that targets Sam68, we reveal that shifting its affinity for CBP disrupts CBP/β-catenin complexes, leading to immediate changes in histone H3 (K14 and K18) acetylation. Chemical targeting of Sam68 induced global changes in transcriptional programs of patient AML cells involving apoptosis and differentiation and was able to uniquely reduce neoplastic self-renewal of human CSCs in an in vivo model of patient specific acute myeloid leukemia (AML). Our study establishes an approach whereby the CBP/β-catenin transcriptome can be uniquely targeted via Sam68 based vulnerability of CSCs that impacts neoplastic differentiation and self-renewal.
Project description:Our data show that E-7386 which has been reported to be a “first-in-class orally active CBP/beta-catenin modulator” anticancer agent, unfortunately by multiple criteria does not appear to be a bona fide CBP/β-catenin selective
Project description:Although ERBB2 amplification and overexpression is correlated with poor outcome in breast cancer, the molecular mechanisms underlying the aggressive nature of these tumors has not been fully elucidated. To investigate this further, we have used a transgenic mouse model of ErbB2-driven tumor progression (ErbB2KI model) that recapitulates clinically relevant events, including selective amplification of the core erbB2 amplicon. By comparing the transcriptional profiles of ErbB2KI mammary tumors and human ERBB2-positive breast cancers, we demonstrate that ErbB2KI tumors possess molecular features of the basal subtype of ERBB2-positive human breast cancer, including activation of canonical β-catenin signaling. Inhibition of β-catenin-dependent signaling in ErbB2KI-derived tumor cells using RNA interference impaired tumor initiation and metastasis. Furthermore, treatment of ErbB2KI or human ERBB2-overexpressing tumor cells with a selective β-catenin/CBP inhibitor significantly decreased proliferation and ErbB2 expression. Collectively, our data indicate that ERBB2-mediated breast cancer progression requires β-catenin signaling and can be therapeutically targeted by selective β-catenin/CBP inhibitors. Common reference design. 9 samples (including 2 normal tissue, 2 NIC tumors, and 5 KI tumor tissue samples) replicated twice as dye swaps, generating a total of 18 arrays.
Project description:Although ERBB2 amplification and overexpression is correlated with poor outcome in breast cancer, the molecular mechanisms underlying the aggressive nature of these tumors has not been fully elucidated. To investigate this further, we have used a transgenic mouse model of ErbB2-driven tumor progression (ErbB2KI model) that recapitulates clinically relevant events, including selective amplification of the core erbB2 amplicon. By comparing the transcriptional profiles of ErbB2KI mammary tumors and human ERBB2-positive breast cancers, we demonstrate that ErbB2KI tumors possess molecular features of the basal subtype of ERBB2-positive human breast cancer, including activation of canonical β-catenin signaling. Inhibition of β-catenin-dependent signaling in ErbB2KI-derived tumor cells using RNA interference impaired tumor initiation and metastasis. Furthermore, treatment of ErbB2KI or human ERBB2-overexpressing tumor cells with a selective β-catenin/CBP inhibitor significantly decreased proliferation and ErbB2 expression. Collectively, our data indicate that ERBB2-mediated breast cancer progression requires β-catenin signaling and can be therapeutically targeted by selective β-catenin/CBP inhibitors.
Project description:Wnt/β-catenin is involved in every aspect of embryonic development and in the pathogenesis of many human diseases, and is also implicated in organ fibrosis. However, the role of β-catenin-mediated signaling on liver fibrosis remains unclear. To explore this issue, the effects of PRI-724, a selective inhibitor of the cAMP-response element-binding protein-binding protein (CBP)/β-catenin interaction, on liver fibrosis were examined using carbon tetrachloride (CCl4)- or bile duct ligation (BDL)-induced mouse liver fibrosis models. Following repetitive CCl4 administrations, the nuclear translocation of β-catenin was observed only in the non-parenchymal cells in the liver. PRI-724 treatment reduced the fibrosis induced by CCl4 or BDL, accompanied by the suppression of S100A4 expression, a CBP/β-catenin transcript. C-82, an active form of PRI-724, inhibited the activation of isolated primary mouse quiescent hepatic stellate cells (HSCs) and promoted cell death in culture-activated HSCs. During the fibrosis resolution period, an increase in F4/80+ CD11b+ and Ly6Clow CD11b+ macrophages was induced by CCl4 and was sustained for two weeks thereafter, even after having stopped CCl4 treatment. PRI-724 accelerated the resolution of CCl4-induced liver fibrosis, and this was accompanied by increased matrix metalloproteinase (MMP)-9, MMP-2, and MMP-8 expression in intrahepatic leukocytes. These results suggest that the inhibition of CBP/β-catenin suppresses liver fibrosis through the inhibition of HSCs activation, the induction of activated HSC death, and the production of MMPs from macrophages. Thus, targeting the CBP/β-catenin interaction may become a new therapeutic strategy in treating liver fibrosis. We used microarrays to detail the global change of gene expression by PRI-724 (C-82)-treatment in culture-activated murine hepatic stellate cells.
Project description:Androgen receptor (AR) is the major therapeutic target in aggressive prostate cancer. However, targeting AR alone can result in drug resistance and disease recurrence. Therefore, simultaneous targeting of multiple pathways could in principle be an effective new approach to treating prostate cancer. Here we provide proof-of-concept that a small molecule inhibitor of nuclear β-catenin activity (called C3) can inhibit both the AR and β-catenin signaling pathways that are often misregulated in prostate cancer. Treatment with C3 ablated prostate cancer cell growth by disruption of both β-catenin/TCF and β-catenin/AR protein interaction, reflecting the fact that TCF and AR have overlapping binding sites on β-catenin. Given that AR interacts with, and is transcriptionally regulated by β-catenin, C3 treatment also resulted in decreased occupancy of β-catenin on the AR promoter and diminished AR and AR/β-catenin target gene expression. Interestingly, C3 treatment resulted in decreased AR binding to target genes accompanied by decreased recruitment of an AR and β-catenin cofactor, CARM1, providing new insight into the unrecognized function of β-catenin in prostate cancer. Importantly, C3 inhibited tumor growth in an in vivo xenograft model, and blocked renewal of bicalutamide-resistant sphere forming cells, indicating the therapeutic potential of this approach. Compare and contrast the expression profile of prostate cancer cells treated with a Wnt inhibitor (C3) with respect to β-catenin and AR knockdown (all samples in duplicates).
Project description:Exploiting an Asp-Glu “switch” in glycogen synthase kinase 3 to design paralog selective inhibitors for use in acute myeloid leukemia: Genome-wide transcriptional profiles for the GSK3α selective inhibitor BRD0507 and for the GSK3α/β dual inhibitor BRD0320 Glycogen synthase kinase 3 (GSK3), a key regulatory kinase in the WNT pathway, remains a therapeutic target of interest in many diseases. While dual GSK3α/β inhibitors have entered clinical trials, none has successfully translated to clinical application. Mechanism-based toxicities, driven in part by the inhibition of both GSK3 paralogs and subsequent β-catenin stabilization, are a concern in the translation of this target class to cancer therapy, particularly for the treatment of acute myeloid leukemia (AML). Knockdown of GSK3α or GSK3β individually does not increase β-catenin in certain cellular subtypes and offers a conceptual resolution to targeting GSK3: paralog-selective inhibition. However, only inadequate chemical tools exist. The design of selective ATP competitive inhibitors poses a drug discovery challenge due to the high homology (95% identity, 100% similarity) in their ATP binding domains. Taking advantage of an Asp133®Glu196 “switch” in their hinge binding domains, we present a rational design strategy towards the discovery of a paralog selective set of GSK3 inhibitors. These first-in-class GSK3α and GSK3β selective inhibitors provided insights into GSK3 targeting in AML where GSK3α has been identified as a therapeutic target using genetic approaches. Our GSK3α selective compound (BRD0705) inhibits kinase function and does not stabilize β-catenin, mitigating potential neoplastic concerns. BRD0705 induces myeloid differentiation and impairs colony formation in AML cells while no effect is observed on normal hematopoietic cells. Moreover, BRD0705 impairs leukemia initiation and prolongs survival in AML mouse models. These studies validate feasibility of paralog selective GSK3α inhibition offering a promising therapeutic approach in AML.
Project description:Exploiting an Asp-Glu “switch” in glycogen synthase kinase 3 to design paralog selective inhibitors for use in acute myeloid leukemia: Genome-wide transcriptional profile for the GSK3β selective inhibitor BRD3731. Glycogen synthase kinase 3 (GSK3), a key regulatory kinase in the WNT pathway, remains a therapeutic target of interest in many diseases. While dual GSK3α/β inhibitors have entered clinical trials, none has successfully translated to clinical application. Mechanism-based toxicities, driven in part by the inhibition of both GSK3 paralogs and subsequent β-catenin stabilization, are a concern in the translation of this target class to cancer therapy, particularly for the treatment of acute myeloid leukemia (AML). Knockdown of GSK3α or GSK3β individually does not increase β-catenin in certain cellular subtypes and offers a conceptual resolution to targeting GSK3: paralog-selective inhibition. However, only inadequate chemical tools exist. The design of selective ATP competitive inhibitors poses a drug discovery challenge due to the high homology (95% identity, 100% similarity) in their ATP binding domains. Taking advantage of an Asp133®Glu196 “switch” in their hinge binding domains, we present a rational design strategy towards the discovery of a paralog selective set of GSK3 inhibitors. These first-in-class GSK3α and GSK3β selective inhibitors provided insights into GSK3 targeting in AML where GSK3α has been identified as a therapeutic target using genetic approaches. Our GSK3α selective compound (BRD0705) inhibits kinase function and does not stabilize β-catenin, mitigating potential neoplastic concerns. BRD0705 induces myeloid differentiation and impairs colony formation in AML cells while no effect is observed on normal hematopoietic cells. Moreover, BRD0705 impairs leukemia initiation and prolongs survival in AML mouse models. These studies validate feasibility of paralog selective GSK3α inhibition offering a promising therapeutic approach in AML.
Project description:Head and neck squamous cell carcinoma (HNSCC) presents primarily as oral squamous cell carcinoma (OSCC), an aggressive malignancy characterized by heterogeneity, locoregional metastases and resistance to existing treatments. Although a number of molecular alterations associated with OSCC have been identified, they have had limited impact on clinical management. A frequent feature of OSCC is the inappropriate activation of nuclear β-catenin. Here, we provide a comprehensive characterization of the effects of blocking the interaction between nuclear β-catenin and the cAMP-responsive element binding (CREB)-binding protein (CBP) using the small molecule inhibitor ICG-001. We demonstrate that ICG-001 inhibits cell proliferation and aggressive OSCC cell phenotypes in cellular, zebrafish and murine models, and that its inhibition-associated transcriptional signature tracks with advanced tumor grade and poor survival in human patients. Our results suggest that targeting the β-catenin/CBP interaction in the nucleus represents a new and effective therapy for OSCC.