Whole genome sequencing of AVM endothelial and non-endothelial cell fractions
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ABSTRACT:
PROVIDER: EGAS00001006719 | EGA |
REPOSITORIES: EGA
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Project description:We previously identified somatic activating KRAS mutations in a majority of human arteriovenous malformations (AVMs), using whole exome sequencing. We have now performed targeted sequencing on AVMS, investigating genes in the RAS-MAPK pathway, angiogenesis and brain vascular disorders among others.
| EGAS00001006729 | EGA
Project description:Rationale – We previously identified somatic activating mutations in the KRAS gene in the endothelium of the majority of human sporadic brain arteriovenous malformations (bAVMs); a disorder characterized by direct connections between arteries and veins. However, whether this genetic abnormality alone is sufficient for lesion formation, as well as how active KRAS signaling contributes to AVM formation, remains unknown. Objective – To establish the first in vivo models of somatic KRAS gain of function in the endothelium in both mice and zebrafish in order to directly observe the phenotypic consequences of constitutive KRAS activity at a cellular level in vivo, and to test potential therapeutic interventions for AVMs. Methods and Results – Using both postnatal and adult mice, as well as embryonic zebrafish, we demonstrate that endothelial-specific gain of function mutations in Kras (G12D or G12V) are sufficient to induce bAVMs. Active KRAS signaling leads to altered endothelial cell morphogenesis and increased cell size, ectopic sprouting, expanded vessel lumen diameter, and direct connections between arteries and veins. Furthermore, we show that these lesions are not associated with altered endothelial growth dynamics or a lack of proper arteriovenous identity, but instead appear to feature exuberant angiogenic signaling. Finally, we demonstrate that KRAS-dependent AVMs in zebrafish are refractory to inhibition of the downstream effector PI3K, but instead require active MEK signaling. Conclusions – We demonstrate that active KRAS expression in the endothelium is sufficient for bAVM formation, even in the setting of uninjured adult vasculature. Furthermore, the finding that KRAS-dependent lesions are reversible in zebrafish suggests that MEK inhibition may represent a promising therapeutic treatment for AVM patients.
2020-07-01 | GSE150426 | GEO
Project description:Sturge-Weber syndrome (SWS) is a sporadic, congenital, neuro-cutaneous disorder characterized by a mosaic, capillary malformation. SWS and isolated capillary malformations are caused by a somatic activating mutation in GNAQ encoding the G protein subunit alpha-q protein. The missense mutation R183Q is the sole GNAQ mutation identified thus far in affected tissues of 90% of SWS patients. In this study, we sequenced skin biopsies of affected capillary malformations from 9 patients. We identified the R183Q mutation in nearly all samples, but one sample exhibited a Q209R mutation. This new mutation occurs at the same residue as the constitutively-activating Q209L mutation, commonly seen in tumors. However, Q209R is a rare variant in this gene. To compare the effect of the Q209R mutation on downstream signaling, we performed reporter assays with a GNAQ-responsive reporter co-transfected with either GNAQ WT, R183Q, Q209L, Q209R, or C9X (representing a null allele). Q209L showed the highest reporter activation, with R183Q and Q209R showing significantly lower activation. To determine whether these mutations had similar or different downstream consequences we performed RNAseq analysis in microvascular endothelial cells (HMEC-1) electroporated with the same GNAQ variants. The R183 and Q209 missense variants caused extensive dysregulation of a broad range of transcripts compared to the WT or null allele, confirming that these are all activating mutations. However, the missense variants exhibited very few differentially expressed genes (DEGs) when compared to each other. These data suggest that these activating GNAQ mutations differ in magnitude of activation but have similar downstream effects.
2022-07-28 | GSE199978 | GEO
Project description:Complex lymphatic anomalies (CLAs) are sporadically occurring diseases caused by the maldevelopment of lymphatic vessels. We and others recently reported that somatic activating mutations in KRAS can cause CLAs. However, the mechanisms by which activating KRAS mutations cause CLAs are poorly understood. Here we show that KRASG12D expression in lymphatic endothelial cells (LECs) during embryonic development impairs the formation of lymphovenous valves and causes the enlargement of lymphatic vessels. We demonstrate that KRASG12D expression in primary human LECs induces cell spindling, proliferation, and migration. It also increases AKT and ERK1/2 phosphorylation and decreases the expression of genes that regulate lymphatic vessel maturation. We show that MEK1/2 inhibition with the FDA-approved drug trametinib suppresses KRASG12D-induced morphological changes, proliferation, and migration. Trametinib also decreases ERK1/2 phosphorylation and increases the expression of genes that regulate the maturation of lymphatic vessels. We also show that trametinib and Cre-mediated expression of a dominant-negative form of MEK1 (Map2k1K97M) suppresses KRASG12D-induced lymphatic vessel hyperplasia in embryos. Last, we demonstrate that conditional knockout of wild-type Kras in LECs does not affect the formation or function of lymphatic vessels. Together, our data indicate that KRAS/MAPK signaling must be tightly regulated during embryonic development for the proper development of lymphatic vessels and further support the testing of MEK1/2 inhibitors for treating CLAs.
2023-09-25 | GSE239737 | GEO
Project description:KRAS is a proto-oncogene encoding a small GTPase. Mutations contribute up to 30% of human solid tumours including lung adenocarcinoma, pancreatic and colorectal carcinomas. Most KRAS activating mutations interfere with GTP hydrolysis, essential for its role as a molecular switch, leading to alterations in their molecular environment and oncogenic signalling. Here, APEX-2 proximity labelling was used to profile the molecular environment of wild type and G12D, G13D and Q61H activating mutants of KRAS under both, starvation and stimulation conditions. We demonstrate by quantitative proteomics the presence of known interactors of KRAS including a-RAF and LZTR1, which varied in abundance with wildtype and KRAS mutants. Notably, the KRAS mutations G12D, G13D and Q61H abrogate association with LZTR1. Wildtype KRAS and LZTR1, as part of the CUL3 ubiquitin E3 ligase complex, affect each other’s protein stability.
2024-03-06 | PXD029725 | Pride
Project description:Background: The Ras pathway genes KRAS, BRAF or ERBBs have somatic mutations in ~60% of human colorectal carcinomas. At present, it is unknown whether the remaining cases lack mutations activating the Ras pathway, or whether they have acquired mutations in genes hitherto not known to belong to the pathway. Methods: To address the second possibility, and extend the compendium of Ras pathway genes, we used genome-wide transposon mutagenesis of two human colorectal cancer cell systems deprived of their activating KRAS or BRAF allele to identify genes enabling growth in low glucose, a Ras pathway phenotype, when targeted. Results: Of the 163 recurrently targeted genes in the two different genetic backgrounds, one third were known cancer genes and one-fifth had links to the EGFR/Ras/MAPK pathway. When compared to cancer genome sequencing datasets, 9 genes also mutated in human colorectal cancers were identified. Among these, stable knock-down of FOXO3, NCOA3, and TCF7L2 restored growth in low glucose but reduced MEK/MAPK phosphorylation, reduced anchorage-independent growth, and modulated expressions of GLUT1 and Ras pathway related proteins. Knock-down of NCOA3 and FOXO3 significantly decreased the sensitivity to cetuximab of KRAS mutant but not wild-type cells. Conclusions: This work establishes a proof-of-concept that human cell based genome-wide forward genetic screens can assign genes to pathways with clinical importance in human colorectal cancer.
2018-02-20 | PXD008382 | Pride
Project description:Mutant KRAS is the most common oncogenic driver of epithelial cancers. Nevertheless, the molecular changes induced by KRAS activation in primary epithelial cells remain unknown. Here, we determined transcriptional changes at single-cell resolution after KRAS activation in distal lung epithelial cell populations. We observed that activating somatic KRAS mutations had the most pronounced effect on alveolar type 2 (AT2) cells, one type of distal lung epithelial progenitor cells, whereas other distal lung epithelial cell types were similar to their wildtype KRAS counterparts. We found that tumor-associated AT2 cells highly expressed EPCAM and SFTPB, but had a significant reduction of STFPC and STFPD expression compared to their normal lung-associated counterparts.
2020-08-13 | GSE149655 | GEO
Project description:RAS-MAPK activating mutations in NRAS, KRAS and PTPN11 were present in 24/55 (44%) cases in our series of diangosis and relapsed ALL. To evaluate the specific role of RAS-MAPK activating mutations in chemotherapy resistance in ALL we used primary isogenic leukemia cells expressing either Kras wild type or a mutant oncogenic form of Kras (Kras G12D) Mechanistically, functional dissection of Kras wild type and mutant Kras (Kras G12D) isogenic ALL cells demonstrated induction of methotrexate resistance, but also improved response to vincristine, in mutant Kras-expressing ALL cells. These results pave the road for the development of tailored personalized therapies for the treatment of relapsed ALL
2018-11-01 | GSE75090 | GEO
Project description:Purpose: The uncommonness of gallbladder cancer in the developed world has contributed to the generally poor understanding of the disease. The development of new and effective treatment has been and continues to be a major public health imperative. Methods: We report mutational and copy number analysis of 44 predominantly early-staged gallbladder tumors and 5-gallbladder cancer cell lines by a combination of directed and whole exome sequencing at an average coverage of 100X and above. Using gallbladder cancer cell lines and xenograft mouse models we performed phospho-proteome array profiling, followed by an in-depth functional characterization. Results: We describe recurrent activating ERBB2 somatic mutation in 6 of 44 gallbladder primary tumors with an overall mutation frequency of 13%, along with KRAS activating mutations in 3 of 44 samples. Consistent with whole exome findings, a phospho-proteomic array profile of 49-tyrosine kinase revealed constitutive phosphorylation of ERBB2 and EGFR that were found to heterodimerize. We demonstrate that treatment with ERBB2-specific, EGFR-specific shRNA or with covalent EGFR family inhibitor BIBW-2992 inhibits transformation, survival, migration, invasion, and tumor forming characteristics of gallbladder cancer cells harboring wild type or KRAS (G13D) but not KRAS (G12V) mutation. Furthermore, we show in vivo reduction in tumor size is paralleled by a reduction in the amounts of phospho-ERK in KRAS (G13D) but not in KRAS (G12V) xenografts, validating the in vitro findings Conclusion: Findings from this study implicate ERBB2 as an important therapeutic target in early stage gallbladder cancer. We also present the first evidence that the presence of KRAS (G12V), but not KRAS (G13D) mutation, may preclude gallbladder cancer patients to respond to anti-EGFR treatment, similar to the clinical algorithm commonly practiced to opt for anti-EGFR treatment in colorectal cancer.
2018-12-29 | E-MTAB-6619 | biostudies-arrayexpress