Project description:Secondary mutation of KIT/PDGFRA is the main reason that contributes to the multi-drug resistance phenotype of advanced GIST in the clinical setting. SHP2 is a specific signal transducer of KIT. Therefore, the combination of approved KIT/PDGFRA kinase inhibitors and SHP2 inhibitors is a promising treatment strategy for advanced GIST patients. Here, we treated GIST cells with the SHP2 inhibitor SHP099 and sequenced the total mRNA to analyze the effect of SHP2 inhibition on GIST cells.
Project description:To identify mRNA profiles in GIST and CAFs, we performed RNA sequencing analysis (RNA-seq) using GIST cell lines, GIST-T1 and GIST882, and CAFs.
Project description:Background: Advanced gastrointestinal stromal tumor (GIST) is characterized by genomic perturbations of key cell cycle regulators. Oncogenic activation of CDK4/6 results in RB1 inactivation and cell cycle progression. Given that single-agent CDK4/6 inhibitor therapy failed to show clinical activity in advanced GIST, we evaluated strategies for maximizing response to therapeutic CDK4/6 inhibition. Methods: Targeted next-generation sequencing and multiplexed protein imaging were used to detect cell cycle regulator aberrations in GIST clinical samples. The impact of inhibitors of CDK2, CDK4, and CDK2/4/6 was determined through cell proliferation and protein detection assays. CDK-inhibitor resistance mechanisms were characterized in GIST cell lines after long-term exposure. Results: We identify recurrent genomic aberrations in cell cycle regulators causing co-activation of the CDK2 and CDK4/6 pathways in clinical GIST samples. Therapeutic co-targeting of CDK2 and CDK4/6 is synergistic in GIST cell lines with intact RB1, through inhibition of RB1 hyperphosphorylation and cell proliferation. Moreover, RB1 inactivation and a novel oncogenic cyclin D1 resulting from an intragenic rearrangement (CCND1::chr11.g:70025223) are mechanisms of acquired CDK inhibitor resistance in GIST. Conclusions: These studies establish the biologic rationale for CDK2 and CDK4/6 co-inhibition as therapeutic strategy in patients with advanced GIST, including metastatic GIST progressing on tyrosine kinase inhibitors.
Project description:Next Generation Sequencing was applied to investigate the effects of PI3K inhibition and/or SHP2 inhibition on the mouse mammary carcinoma 4T1.
Project description:Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive sarcomas and the primary cause of mortality in patients with neurofibromatosis type 1 (NF1). These malignancies develop within pre-existing benign lesions called plexiform neurofibromas (PNs). PNs are solely driven by biallelic NF1 loss eliciting RAS pathway activation and respond favorably to MEK inhibitor therapy. MPNSTs harbor additional mutations and respond poorly to MEK inhibition. Our analysis of genetically engineered and orthotopic patient-derived xenograft MPNST tumor models indicates that MEK inhibition has poor anti-tumor efficacy. By contrast, upstream inhibition of RAS through the protein-tyrosine phosphatase SHP2 reduced downstream signaling and suppressed NF1 MPNST growth, although resistance eventually emerged. To investigate possible mechanisms of acquired resistance, kinomic analyses of resistant tumors was performed, and data analysis identified enrichment of activated autophagy pathway protein kinases. Combining SHP2 inhibition with hydroxychloroquine resulted in durable responses in NF1 MPNSTs in both genetic and orthotopic xenograft mouse models. Our studies could be rapidly translated into a clinical trial to evaluate SHP2 inhibition in conjunction with hydroxychloroquine as a novel treatment approach for NF1 MPNSTs.
Project description:KRAS is the most frequently mutated oncogene in human cancer, and KRAS inhibition has been a longtime goal. Recently, inhibitors (G12C-Is) that bind KRAS-G12C-GDP and react with Cys-12 were developed. Using new affinity reagents to monitor KRAS-G12C activation and inhibitor engagement, we found that SHP2 inhibitors (SHP2-Is) increased KRAS-GDP occupancy, enhancing G12C-I efficacy. SHP2-Is abrogated feedback signaling by multiple RTKs and adaptive resistance to G12C-Is in vitro, in xenografts, and in syngeneic KRAS-G12C-mutant pancreatic ductal adenocarcinoma (PDAC) and non-small cell lung cancer (NSCLC) models. The combination of SHP2-I and G12C-I evoked favorable changes in the immune microenvironment, decreasing myeloid suppressor cells, increasing CD8+ T cells, and sensitizing tumors to PD-1 blockade. Experiments using an inhibitor-resistant SHP2 mutant showed that SHP2 inhibition in PDAC cells is required for tumor regression and remodeling of the immune microenvironment, but SHP2-Is also had direct effects on angiogenesis. Our results demonstrate that SHP2-I/G12C-I combinations confer a substantial survival benefit in PDAC and NSCLC and identify additional potential combination strategies. G12C-Is show significant, but limited, efficacy as single agents, in part because of “adaptive resistance”. We find that combining G12C-Is with SHP2-Is abrogates adaptive resistance and results in favorable changes in the immune microenvironment that potentiate PD-1 blockade in KRAS-mutant malignancies. SHP2-Is also can have direct, context-dependent, effects on tumor vasculature.
Project description:Activating mutations in either KIT or PDGFRA are present in approximately 90% of gastrointestinal stromal tumors (GISTs). Although treatment with the KIT and PDGFR inhibitor imatinib can control advanced disease in about 80% of GIST patients, the beneficial effect is not durable. Here, we report that ligands from the FGF family reduced the effectiveness of imatinib in GIST cells, and FGF2 and FGFR1 are highly expressed in all primary GIST samples examined. The combination of KIT and FGFR inhibition showed increased growth inhibition in imatinib-sensitive GIST cell lines in the presence or absence of added FGF2 in vitro, and delayed tumor regrowth in vivo. In addition, inhibition of mitogen-activated protein kinase (MAPK) signaling by imatinib was not sustained in GIST cells. An extracellular signal-regulated kinase (ERK) rebound occurred through activation of FGF signaling, and was repressed by FGFR1 inhibition. Downregultation of Sprouty proteins played a role in the imatinib-induced feedback activation of FGF signaling in GIST cells. We used micorarrays to quantify the gene expression levels in GIST cell lines. Four GIST cell lines were split and cultured overnight. Cells were harvested for RNA extraction and hybridization on Affymetrix U133plus2 microarrays.
Project description:Activating mutations in either KIT or PDGFRA are present in approximately 90% of gastrointestinal stromal tumors (GISTs). Although treatment with the KIT and PDGFR inhibitor imatinib can control advanced disease in about 80% of GIST patients, the beneficial effect is not durable. Here, we report that ligands from the FGF family reduced the effectiveness of imatinib in GIST cells, and FGF2 and FGFR1 are highly expressed in all primary GIST samples examined. The combination of KIT and FGFR inhibition showed increased growth inhibition in imatinib-sensitive GIST cell lines in the presence or absence of added FGF2 in vitro, and delayed tumor regrowth in vivo. In addition, inhibition of mitogen-activated protein kinase (MAPK) signaling by imatinib was not sustained in GIST cells. An extracellular signal-regulated kinase (ERK) rebound occurred through activation of FGF signaling, and was repressed by FGFR1 inhibition. Downregultation of Sprouty proteins played a role in the imatinib-induced feedback activation of FGF signaling in GIST cells. We used micorarrays to quantify the gene expression levels in GIST cell lines.