Project description:Acute Myeloid Leukemia (AML) is the most common and aggressive form of acute leukemia, with a 5-year survival rate of just 24%. Over a third of all AML patients harbor activating mutations in kinases, such as the receptor tyrosine kinases FLT3 and KIT. FLT3 and KIT mutations are associated with poor clinical outcomes and lower remission rates in response to standard-of-care chemotherapy. We have recently identified that the core kinase of the non-homologous end joining DNA repair pathway, DNA-PK, is activated downstream of FLT3; and targeting DNA-PK sensitized FLT3-mutant AML cells to standard-of-care therapies. Herein, we investigated DNA-PK as a possible therapeutic vulnerability in KIT mutant AML, using isogenic FDC-P1 myeloid progenitor cell lines transduced with an empty vector or oncogenic mutant KIT (V560G, D816V). Targeted quantitative phosphoproteomic profiling identified phosphorylation of DNA-PK at threonine 2599 in KIT mutant cells, indicative of DNA-PK activation. Accordingly, proliferation assays revealed that KIT mutant FDC-P1 cells were more sensitive to the DNA-PK inhibitors M3814 or NU7441, compared to empty vector controls. DNA-PK inhibition combined with inhibition of KIT signaling via using the kinase inhibitors dasatinib or ibrutinib, or the protein phosphatase 2A activators FTY720 or AAL(S), led to synergistic cell death. Discovery phosphoproteomic analysis of KIT-D816V cells revealed that dasatinib single-agent treatment inhibited ERK1 activity, and M3814 single-agent treatment inhibited Akt/mTOR activity. The combination of dasatinib and M3814 treatment inhibited both ERK/MAPK and Akt/mTOR activity, and induced synergistic inhibition of phosphorylation of transcription regulators including MYC and MYB. This study provides insight into the oncogenic pathways regulated by DNA-PK beyond its canonical role in DNA repair, and demonstrates that DNA-PK is a promising novel therapeutic target for KIT mutant cancers.
Project description:<p>Metabolic lesions with pleiotropic effects on epigenetic regulation and other cellular processes are widely implicated in cancer, yet their oncogenic mechanisms remain poorly understood. Succinate dehydrogenase (SDH) deficiency causes a subset of gastrointestinal stromal tumors (GISTs) with DNA hyper-methylation. Here we associate this hyper-methylation with changes in chromosome topology that activate oncogenic programs. To investigate epigenetic alterations in this disease, we systematically mapped DNA methylation, CTCF insulators, enhancers and chromosome topology in KIT-mutant, PDGFRA-mutant and SDH-deficient GISTs. Although these respective subtypes share similar enhancer landscapes, we identified hundreds of putative insulators where DNA methylation replaced CTCF binding in SDH-deficient GISTs. We focused on disrupted insulators that partitions super-enhancers from FGF3, FGF4 and the KIT oncogene. Recurrent loss of this insulator alters locus topology in SDH-deficient GISTs, allowing aberrant physical interaction between enhancers and oncogenes. CRISPR-mediated excision of the corresponding CTCF motif in an SDH-intact model disrupted the boundary and up-regulated FGFs and KIT expression. Our findings reveal how a metabolic lesion destabilizes chromatin structure to facilitate the initiation and selection of epigenetic alterations that drive oncogenic programs in the absence of canonical mutations.</p>
Project description:Purpose: Management of gastrointestinal stromal tumor (GIST) has been revolutionized by the identification of activating mutations in KIT and PDGFRA and the clinical application of receptor tyrosine kinase (RTK) inhibitors in the advanced disease setting. Stratification of GIST into molecularly defined subsets provides insight into clinical behavior and response to approved targeted therapies. Although these RTK inhibitors are effective in the majority of GIST, resistance to these agents remains a significant clinical obstacle. Development of effective treatment strategies for refractory GIST requires identification of novel targets to provide additional therapeutic options. Global kinome profiling has the potential to identify critical signaling networks and reveal protein kinases that are essential in GIST. Experimental Design: Using Multiplexed Inhibitor Beads and Mass Spectrometry paired with a super-SILAC kinome standard, we explored the majority of the kinome in GIST specimens from three GIST subtypes (KIT-mutant, PDGFRA-mutant and succinate dehydrogenase-deficient GIST) to identify novel kinase targets. In vitro and in vivo studies were performed to evaluate the utility of targeting the identified kinases in GIST. Results: Kinome profiling revealed distinct signatures in three GIST subtypes. PDGFRA-mutant GIST had elevated tumor associated macrophage (TAM) kinases and immunohistochemical analysis confirmed increased TAMs present in these tumors. Kinome profiling with loss-of-function assays revealed a significant role for G2-M tyrosine kinase, Wee1, in GIST survival. In vitro and in vivo studies revealed significant efficacy of MK-1775 (Wee1 inhibitor) in combination with avapritinib in both KIT and PDGFRA-mutant GIST cell lines, as well as notable efficacy of MK-1775 as a single agent in the PDGFRA-mutant line. Conclusions: These studies provide strong preclinical justification for the use of MK-1775 in GIST.
Project description:mRNA expression profiling of pancreatic cancer, comparing adjacent normal tissue, patient tumour and first generation patient derived xenograft tumours Fresh tumour samples for human pancreatic adenocarcinoma patients were implanted in SCID mice. 70% of these pancreatic ductal adenocarcinoma patients grew as PDX tumours, confirmed by histopathology. Frozen samples from F1 PDX tumours could be later successful passaged in SCID mice to F2 PDX tumours. The human origin of the PDX was confirmed using human specific antibodies; however, the stromal component was replaced by murine cells. Cell lines were successfully developed from three PDX tumours. RNA was extracted from 8 PDX tumours and where possible, corresponding primary tumour and adjacent normal tissues. mRNA profiles of tumour vs F1 PDX and normal vs tumour were compared by Affymetric microarray analysis
Project description:mRNA expression profiling of pancreatic cancer, comparing adjacent normal tissue, patient tumour and first generation patient derived xenograft tumours Fresh tumour samples for human pancreatic adenocarcinoma patients were implanted in SCID mice. 70% of these pancreatic ductal adenocarcinoma patients grew as PDX tumours, confirmed by histopathology. Frozen samples from F1 PDX tumours could be later successful passaged in SCID mice to F2 PDX tumours. The human origin of the PDX was confirmed using human specific antibodies; however, the stromal component was replaced by murine cells. Cell lines were successfully developed from three PDX tumours. RNA was extracted from 8 PDX tumours and where possible, corresponding primary tumour and adjacent normal tissues. mRNA profiles of tumour vs F1 PDX and normal vs tumour were compared by Affymetric microarray analysis
Project description:The stromal microenvironment plays key roles in prostate development and cancer. Cancer associated fibroblasts (CAFs) and other stromal cells stimulate tumourigenesis via several mechanisms including the expression of pro-tumourigenic factors. Mesenchyme (embryonic stroma) controls prostate organogenesis, and in some circumstances can re-differentiate prostate tumours. Epithelia are regulated by powerful paracrine signalling from the stroma in both development and disease, and identification of these stromal signals is important. We have applied next-generation Tag profiling to fetal human prostate, normal human prostate fibroblasts (NPFs) and CAFs to identify molecules expressed in prostatic stroma
Project description:The stromal microenvironment plays key roles in prostate development and cancer. Cancer associated fibroblasts (CAFs) and other stromal cells stimulate tumourigenesis via several mechanisms including the expression of pro-tumourigenic factors. Mesenchyme (embryonic stroma) controls prostate organogenesis, and in some circumstances can re-differentiate prostate tumours. Epithelia are regulated by powerful paracrine signalling from the stroma in both development and disease, and identification of these stromal signals is important. We have applied next-generation Tag profiling to fetal human prostate, normal human prostate fibroblasts (NPFs) and CAFs to identify molecules expressed in prostatic stroma Each sample was used for Tag library construction, by Solexa Inc