Oncogenic BRAF, unrestrained by TGFβ-receptor signalling, drives right-sided colonic tumorigenesis.
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ABSTRACT:
SUBMITTER: Leach JDG
PROVIDER: S-EPMC8187652 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The BRAF kinase is mutated, typically Val 600→Glu (V600E), to induce an active oncogenic state in a large fraction of melanomas, thyroid cancers, hairy cell leukaemias and, to a smaller extent, a wide spectrum of other cancers. BRAF(V600E) phosphorylates and activates the MEK1 and MEK2 kinases, which in turn phosphorylate and activate the ERK1 and ERK2 kinases, stimulating the mitogen-activated protein kinase (MAPK) pathway to promote cancer. Targeting MEK1/2 is proving to be an important therapeutic strategy, given that a MEK1/2 inhibitor provides a survival advantage in metastatic melanoma, an effect that is increased when administered together with a BRAF(V600E) inhibitor. We previously found that copper (Cu) influx enhances MEK1 phosphorylation of ERK1/2 through a Cu-MEK1 interaction. Here we show decreasing the levels of CTR1 (Cu transporter 1), or mutations in MEK1 that disrupt Cu binding, decreased BRAF(V600E)-driven signalling and tumorigenesis in mice and human cell settings. Conversely, a MEK1-MEK5 chimaera that phosphorylated ERK1/2 independently of Cu or an active ERK2 restored the tumour growth of murine cells lacking Ctr1. Cu chelators used in the treatment of Wilson disease decreased tumour growth of human or murine cells transformed by BRAF(V600E) or engineered to be resistant to BRAF inhibition. Taken together, these results suggest that Cu-chelation therapy could be repurposed to treat cancers containing the BRAF(V600E) mutation.
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Project description:Diverticulosis results from complex interactions related to aging, environmental factors and genetic predisposition. Despite epidemiologic evidence of genetic risk factors, there has been no attempt to identify genes that confer susceptibility to colonic diverticulosis. We performed the first genome-wide association study (GWAS) on susceptibility to diverticulosis in a Korean population. A GWAS was carried out in 7,948 healthy individuals: 893 patients and 1,075 controls comprised the test set, and 346 patients and 305 controls comprised the replication set. Diverticulosis was diagnosed by colonoscopy during comprehensive medical check-ups, and single-nucleotide polymorphisms (SNPs) related to diverticulosis were detected with the Affymetrix Axiom KORV1.1-96 Array. In all, 9 SNPs were identified in three SNP aggregates in the test set (P < 10-3, within 200 kb) after adjusting for sex. All the SNPs were replicated in the replication set (P < 0.05). Three SNPs were near the WNT4 gene, four near the RHOU gene, and two in the OAS1/3 genes. The top SNP associated with right-sided colonic diverticulosis was rs22538787, located near the WNT4 gene [combined set, P-value = 3.128 × 10-6, odds ratio = 1.415 (95% confidence interval: 1.223-1.637)]. These 9 novel SNP alleles associated with the WNT4, RHOU, and OAS1/3 genes are possibly involved in the underlying genetic susceptibility to right-sided diverticulosis. Our results provide basic knowledge about the development of diverticulosis in an Asian population.
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Project description:Background & aimsEpigenetic processes regulating gene expression contribute markedly to epithelial cell plasticity in colorectal carcinogenesis. The lysine methyltransferase SUV420H2 comprises an important regulator of epithelial plasticity and is primarily responsible for trimethylation of H4K20 (H4K20me3). Loss of H4K20me3 has been suggested as a hallmark of human cancer due to its interaction with DNMT1. However, the role of Suv4-20h2 in colorectal cancer is unknown.MethodsWe examined the alterations in histone modifications in patient-derived colorectal cancer organoids. Patient-derived colorectal cancer organoids and mouse intestinal organoids were genetically manipulated for functional studies in patient-derived xenograft and orthotopic transplantation. Gene expression profiling, micrococcal nuclease assay, and chromatin immunoprecipitation were performed to understand epigenetic regulation of chromatin states and gene expression in patient-derived and mouse intestinal organoids.ResultsWe found that reduced H4K20me3 levels occurred predominantly in right-sided patient-derived colorectal cancer organoids, which were associated with increased chromatin accessibility. Re-compaction of chromatin by methylstat, a histone demethylase inhibitor, resulted in reduced growth selectively in subcutaneously grown tumors derived from right-sided cancers. Using mouse intestinal organoids, we confirmed that Suv4-20h2-mediated H4K20me3 is required for maintaining heterochromatin compaction and to prevent R-loop formation. Cross-species comparison of Suv4-20h2-depleted murine organoids with right-sided colorectal cancer organoids revealed a large overlap of gene signatures involved in chromatin silencing, DNA methylation, and stemness/Wnt signaling.ConclusionsLoss of Suv4-20h2-mediated H4K20me3 drives right-sided colorectal tumorigenesis through an epigenetically controlled mechanism of chromatin compaction. Our findings unravel a conceptually novel approach for subtype-specific therapy of this aggressive form of colorectal cancer.
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Project description:Cutaneous squamous cell carcinoma (cSCC) is the second most common skin cancer characterized by increased mortality. Here, we show for the first time that anaplastic lymphoma kinase (ALK), a receptor tyrosine kinase of the insulin receptor superfamily, plays a pivotal role in the pathogenesis of cSCC. Our data demonstrate that the overexpression of the constitutively active, mutated ALK, ALKF1174L , is sufficient to initiate the development of cSCC and is 100% penetrant. Moreover, we show that cSCC development upon ALKF1174L overexpression is independent of the cell-of-origin. Molecularly, our data demonstrate that ALKF1174L cooperates with oncogenic KrasG12D and loss of p53, well-established events in the biology of cSCC. This cooperation results in a more aggressive cSCC type associated with a higher grade histological morphology. Finally, we demonstrate that Stat3 is a key downstream effector of ALKF1174L and likely plays a role in ALKF1174L -driven cSCC tumorigenesis. In sum, these findings reveal that ALK can exert its tumorigenic potential via cooperation with multiple pathways crucial in the pathogenesis of cSCC. Finally, we show that human cSCCs contain mutations in the ALK gene. Taken together, our data identify ALK as a new key player in the pathogenesis of cSCC, and this knowledge suggests that oncogenic ALK signaling can be a target for future clinical trials.
| S-EPMC7184028 | biostudies-literature
Project description:BackgroundGiven the differences in embryonic origin, vascular and nervous supplies, microbiotic burden, and main physiological functions of left and right colons, tumor location is increasingly suggested to dictate tumor behavior affecting pathology, progression and prognosis. Right-sided colon cancers arise in the cecum, ascending colon, hepatic flexure and/or transverse colon, while left-sided colon cancers arise in the splenic flexure, descending, and/or sigmoid colon. In contrast to prior reports, we attempt to delineate programs of tumorigenesis independently for each side.MethodsFour hundred and eleven samples were extracted from The Cancer Genome Atlas-COAD cohort, based on a conservative sample inclusion criterion. Each side was independently analyzed with respect to their respective normal tissue, at the level of transcription, post-transcription, miRNA control and methylation in both a stage specific and stage-agnostic manner.ResultsOur results indicate a suppression of enzymes involved in various stages of carcinogen breakdown including CYP2C8, CYP4F12, GSTA1, and UGT1A within right colon tumors. This implies its reduced capacity to detoxify carcinogens, contributing to a genotoxic tumor environment, and subsequently a more aggressive phenotype. Additionally, we highlight a crucial nexus between calcium homeostasis (sensing, mobilization and absorption) and immune/GPCR signaling within left-sided tumors, possibly contributing to its reduced proliferative and metastatic potential. Interestingly, two genes SLC6A4 and HOXB13 show opposing regulatory trends within right and left tumors. Post-transcriptional regulation mediated by both RNA-binding proteins (e.g. NKRF (in left) and MSI2 (in right)) and miRNAs (e.g. miR-29a (in left); miR-155, miR181-d, miR-576 and miR23a (in right)) appear to exhibit side-specificity in control of their target transcripts and is pronounced in right colon tumors. Additionally, methylation results depict location-specific differences, with increased hypomethylation in open seas within left tumors, and increased hypermethylation of CpG islands within right tumors.ConclusionsDifferences in molecular mechanisms captured here highlight distinctions in tumorigenesis and progression between left and right colon tumors, which will serve as the basis for future studies, influencing the efficacies of existing and future diagnostic, prognostic and therapeutic interventions.
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Project description:To compare protein expression levels, gene mutation and survival among Right-Sided Colon Cancer (RSCC), Left-Sided Colon Cancer (LSCC) and rectal cancer patients, 57 cases of RSCC, 87 LSCC and 145 rectal cancer patients were included retrospectively. Our results demonstrated significant differences existed among RSCC, LSCC and rectal cancer regarding tumor diameter, differentiation, invasion depth and TNM stage. No significant difference was identified in expression levels of MLH1, MSH2, MSH6, PMS2, β-Tubulin III, P53, Ki67 and TOPIIα, and gene mutation of KRAS and BRAF among three groups. Progression Free Survival (PFS) of RSCC was significantly lower than that of LRCC and rectal cancer. In univariate analyses, RSCC, preoperative chemoradiotherapy, poor differentiation, advanced TNM stage, elevated serum CEA and CA19-9 level, tumor deposit, perineural and vascular invasion were found to be predictive factors of shorter PFS. In multivariate analyses, only differentiation and TNM stages were found to be independent predictors of PFS. In conclusion, compared with LSCC and rectal cancer, RSCC has larger tumor size, poor differentiation, advanced TNM stage and shorter survival. The shorter survival in RSCC might be attributed to the advanced tumor stage caused by its inherent position feature of proximal colon rather than genetic difference.
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Project description:Most animals show external bilateral symmetry, which hinders the observation of multiple internal left-right (L/R) asymmetries that are fundamental to organ packaging and function. In vertebrates, left identity is mediated by the left-specific Nodal-Pitx2 axis that is repressed on the right-hand side by the epithelial-mesenchymal transition (EMT) inducer Snail1 (refs 3, 4). Despite some existing evidence, it remains unclear whether an equivalent instructive pathway provides right-hand-specific information to the embryo. Here we show that, in zebrafish, BMP mediates the L/R asymmetric activation of another EMT inducer, Prrx1a, in the lateral plate mesoderm with higher levels on the right. Prrx1a drives L/R differential cell movements towards the midline, leading to a leftward displacement of the cardiac posterior pole through an actomyosin-dependent mechanism. Downregulation of Prrx1a prevents heart looping and leads to mesocardia. Two parallel and mutually repressed pathways, respectively driven by Nodal and BMP on the left and right lateral plate mesoderm, converge on the asymmetric activation of the transcription factors Pitx2 and Prrx1, which integrate left and right information to govern heart morphogenesis. This mechanism is conserved in the chicken embryo, and in the mouse SNAIL1 acts in a similar manner to Prrx1a in zebrafish and PRRX1 in the chick. Thus, a differential L/R EMT produces asymmetric cell movements and forces, more prominent from the right, that drive heart laterality in vertebrates.
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Project description:This SuperSeries is composed of the SubSeries listed below.
2022-11-09 | GSE217267 | GEO