Suppression of heparan sulfation resensitizes YAP1-driven BRAF mutant melanoma to MAPK pathway inhibitors
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PROVIDER: PRJNA797810 | ENA |
REPOSITORIES: ENA
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Project description:Preclinical and clinical data implicate the transcriptional co-activator YAP1 in resistance to multiple targeted therapies, including BRAF and MEK inhibitors. However, tumor subtypes driven by YAP1 activity and associated vulnerabilities are poorly defined. Here, we show particularly high YAP1 activity in the MITFlow/AXLhigh subset of melanoma cell lines and patient tumors characterized by resistance to MAPK pathway inhibition and broad receptor tyrosine kinase activity. To uncover genetic dependencies of melanoma cells with high YAP1 activity, we used a genome-wide CRISPR/Cas9 functional screen and identified SLC35B2, the 3′-phosphoadenosine-5′-phosphosulfate transporter of the Golgi apparatus, as an essential gene for YAP1-mediated drug resistance. SLC35B2 expression correlates with tumor progression, and its loss decreases heparan sulfate expression, reduces receptor tyrosine kinase activity, and sensitizes resistant melanoma cells to BRAF inhibition in vitro and in vivo. Thus, SLC35B2 is a target in YAP1-driven BRAF mutant melanoma for overcoming drug resistance to MAPK pathway inhibitors.
2022-08-15 | GSE193775 | GEO
Project description:Embryonic stem (ES) cells continuously decide whether to maintain pluripotency or differentiate. While exogenous LIF and BMP4 perpetuate a pluripotent state, less is known about factors initiating differentiation. We show that heparan sulfate (HS) proteoglycans are critical co-receptors for signals inducing ES cell differentiation. Genetic targeting of NDST1 and 2, two enzymes required for N-sulfation of proteoglycans, blocked differentiation. This phenotype was rescued by HS presented in trans or by soluble heparin. NaClO3-, which reduces sulfation of proteoglycans, potently blocked differentiation of wild type cells. Mechanistically, N-sulfation was identified to be critical for functional autocrine FGF4 signalling. Micro array analysis identified the pluripotency maintaining transcription factors Nanog, KLF2/4/8, Tbx3 and Tcf3 to be negatively regulated, whereas markers of differentiation such as Gbx2, Dnmt3b, FGF5 and Brachyury were induced by sulfation-dependent-FGFR signalling. We show that several of these genes are heterogeneously expressed in ES cells and targeting of heparan sulfation or FGFR-signalling facilitated a homogenous Nanog/KLF4/Tbx3 positive ES cell state. This finding suggests that the recently discovered heterogeneous state of ES cells is regulated by HS-dependent FGFR signalling. Similarly, culturing blastocysts with NaClO3- eliminated GATA6 positive primitive endoderm progenitors generating a homogenous Nanog positive inner cell mass. Functionally, reduction of sulfation robustly improved de novo ES cell derivation efficiency. We conclude that N-sulfated HS is required for FGF4 signalling to maintain ES cells primed for differentiation in a heterogeneous state. Inhibiting this pathway facilitates a more naïve ground state. Four groups with three biological replicates and a technical duplicate in each
2010-04-09 | E-GEOD-15974 | biostudies-arrayexpress
Project description:Embryonic stem (ES) cells continuously decide whether to maintain pluripotency or differentiate. While exogenous LIF and BMP4 perpetuate a pluripotent state, less is known about factors initiating differentiation. We show that heparan sulfate (HS) proteoglycans are critical co-receptors for signals inducing ES cell differentiation. Genetic targeting of NDST1 and 2, two enzymes required for N-sulfation of proteoglycans, blocked differentiation. This phenotype was rescued by HS presented in trans or by soluble heparin. NaClO3-, which reduces sulfation of proteoglycans, potently blocked differentiation of wild type cells. Mechanistically, N-sulfation was identified to be critical for functional autocrine FGF4 signalling. Micro array analysis identified the pluripotency maintaining transcription factors Nanog, KLF2/4/8, Tbx3 and Tcf3 to be negatively regulated, whereas markers of differentiation such as Gbx2, Dnmt3b, FGF5 and Brachyury were induced by sulfation-dependent-FGFR signalling. We show that several of these genes are heterogeneously expressed in ES cells and targeting of heparan sulfation or FGFR-signalling facilitated a homogenous Nanog/KLF4/Tbx3 positive ES cell state. This finding suggests that the recently discovered heterogeneous state of ES cells is regulated by HS-dependent FGFR signalling. Similarly, culturing blastocysts with NaClO3- eliminated GATA6 positive primitive endoderm progenitors generating a homogenous Nanog positive inner cell mass. Functionally, reduction of sulfation robustly improved de novo ES cell derivation efficiency. We conclude that N-sulfated HS is required for FGF4 signalling to maintain ES cells primed for differentiation in a heterogeneous state. Inhibiting this pathway facilitates a more naïve ground state.
2009-11-13 | GSE15974 | GEO
Project description:Accumulating evidence identifies non-genetic mechanisms substantially contributing to drug resistance in cancer patients. Preclinical and clinical data implicate the transcriptional co-activators YAP1 and its paralog TAZ in resistance to multiple targeted therapies, highlighting the strong need for therapeutic strategies overcoming YAP1/TAZ-mediated resistance across tumor entities. Here, we show particularly high YAP1/TAZ activity in MITFlow/AXLhigh melanomas characterized by resistance to MAPK pathway inhibition and broad receptor tyrosine kinase activity. To uncover genetic dependencies of melanoma cells with high YAP1/TAZ activity, we used a genome-wide CRISPR/Cas9 functional screen and identified SLC35B2, the 3'-phosphoadenosine-5'-phosphosulfate transporter of the Golgi apparatus, as an essential gene for YAP1/TAZ-driven drug resistance. SLC35B2 expression correlates with tumor progression, and its loss decreases heparan sulfate expression, reduces receptor tyrosine kinase activity, and sensitizes resistant melanoma cells to BRAF inhibition in vitro and in vivo. Thus, targeting heparan sulfation via SLC35B2 represents a novel approach for breaking receptor tyrosine kinase-mediated resistance to MAPK pathway inhibitors.
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Project description:Heparan sulfate (HS) is a linear polysaccharide that plays a key role in cellular signaling networks. HS functions are regulated by its 6-O-sulfation, which is catalyzed by HS 6-O-sulfotransferases (HS6STs). Although mutations in HS6ST2 cause intellectual disability in human patients, the role and molecular mechanisms of HS6ST2 in the adult mammalian brain remain unknown. Here we found that the brain specifically expresses the long isoform of Hs6st2, which encodes a protein that retains the sulfotransferase domain and acquires a novel sub-structure. To determine the role of Hs6st2 in the brain, we carried out a series of behavioral and molecular assessments on the Hs6st2 knockout mice. We found that Hs6st2 knockout mice exhibit high body weight, hyperactivity, and memory-related deficits. To determine the molecular mechanisms underlying these deficits, we carried out strong anion exchange-high performance liquid chromatography and RNA sequencing. We found that knockout of Hs6st2 decreases HS 6-O-sulfation levels in the brain and impairs transcriptome in the hippocampus. We also found that the transcriptome changes are enriched in genes involved in ribosome and protein translation pathways, which are likely due to the downregulation of the fibroblast growth factor signaling. Together, our study demonstrates the role and molecular mechanisms of Hs6st2 in the adult mammalian brain, which provides new insights into the role of HS in brain health and disease.
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Project description:MAPK pathway-driven tumorigenesis, often induced by BRAFV600E, relies on epithelial dedifferentiation. However, how lineage differentiation events are reprogrammed remains unexplored. Here, we demonstrate that proteostatic reactivation of developmental factor, TBX3, accounts for BRAF/MAPK-mediated dedifferentiation and tumorigenesis. During embryonic development, BRAF/MAPK upregulates USP15 to stabilize TBX3, which orchestrates organogenesis by restraining differentiation. The USP15-TBX3 axis is reactivated during tumorigenesis, and Usp15 knockout prohibits BRAFV600E-driven tumor development in a Tbx3-dependent manner. Deleting Tbx3 or Usp15 leads to tumor redifferentiation, which parallels their overdifferentiation tendency during development, exemplified by disrupted thyroid folliculogenesis and elevated differentiation factors such as Tpo, Nis, Tg. The clinical relevance is highlighted in that both USP15 and TBX3 highly correlates with BRAFV600E signature and poor tumor prognosis. Thus, USP15 stabilized TBX3 represents a critical proteostatic mechanism downstream of BRAF/MAPK-directed developmental homeostasis and pathological transformation, supporting that tumorigenesis largely relies on epithelial dedifferentiation achieved via embryonic regulatory program reinitiation.
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Project description:MAPK pathway-driven tumorigenesis, often induced by BRAFV600E, relies on epithelial dedifferentiation. However, how lineage differentiation events are reprogrammed remains unexplored. Here, we demonstrate that proteostatic reactivation of developmental factor, TBX3, accounts for BRAF/MAPK-mediated dedifferentiation and tumorigenesis. During embryonic development, BRAF/MAPK upregulates USP15 to stabilize TBX3, which orchestrates organogenesis by restraining differentiation. The USP15-TBX3 axis is reactivated during tumorigenesis, and Usp15 knockout prohibits BRAFV600E-driven tumor development in a Tbx3-dependent manner. Deleting Tbx3 or Usp15 leads to tumor redifferentiation, which parallels their overdifferentiation tendency during development, exemplified by disrupted thyroid folliculogenesis and elevated differentiation factors such as Tpo, Nis, Tg. The clinical relevance is highlighted in that both USP15 and TBX3 highly correlates with BRAFV600E signature and poor tumor prognosis. Thus, USP15 stabilized TBX3 represents a critical proteostatic mechanism downstream of BRAF/MAPK-directed developmental homeostasis and pathological transformation, supporting that tumorigenesis largely relies on epithelial dedifferentiation achieved via embryonic regulatory program reinitiation.
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Project description:One third of BRAF-mutant metastatic melanoma patients treated with combined BRAF and MEK inhibition progress within six months. Treatment options for these patients remain limited. Here we analyse twenty BRAFV600 mutant melanoma metastases derived from 10 patients treated with the combination of debrafenib and trametinib for resistance mechanisms and genetic correlates of response. Resistance mechanisms are identified in 9/11 progressing tumors and MAPK reactivation occurred in 9/10 tumors, commonly via BRAF amplification and mutations activating NRAS and MEK2. Our data confirming that MEK2C125S, but not the synonymous MEK1C121S protein confers resistance to combination therapy, highlight the functional differences between these kinases and the preponderance of MEK2 mutations in combination therapy-resistant melanomas. Exome sequencing did not identify additional progression-specific resistance candidates. Nevertheless, most melanomas carried additional oncogenic mutations at baseline (e.g. RCA1 and AKT3) that activate the MAPK and P13K pathways and are thus predicted to diminish response to MAPK inhibitors. Total RNA obtained from fresh frozen melanoma tumors treated with a combination of dabrafenib and trametinib
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Project description:The eIF4F translation initiation complex plays a critical role in melanoma resistance to clinical BRAF and MEK inhibitors. In this study, we uncover a novel function of eIF4F in the negative regulation of the RAS/RAF/MEK/ERK mitogen-activated protein kinase (MAPK) signaling pathway. We demonstrate that eIF4F is essential for maintaining optimal ERK signaling intensity in treatment-naïve melanoma cells harboring BRAF or NRAS mutations. Specifically, the dual-specificity phosphatase DUSP6/MKP3, which acts as a negative feedback regulator of ERK activity, requires continuous production in an eIF4F-dependent manner to limit excessive ERK signaling driven by oncogenic RAF/RAS mutations. Treatment with small molecule eIF4F inhibitors disrupts the negative feedback control of MAPK signaling, leading to ERK hyperactivation and EGR1 overexpression in melanoma cells in vitro and in vivo. Furthermore, our quantitative analyses reveal a high spare signaling capacity in the ERK pathway, suggesting that eIF4F-dependent feedback keeps the majority of ERK molecules inactive under normal conditions. Overall, our findings highlight the crucial role of eIF4F in regulating ERK signaling flux and suggest that pharmacological eIF4F inhibitors can disrupt the negative feedback control of MAPK activity in melanomas with BRAF and NRAS activating mutations.
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Project description:Heparan (HS) proteoglycans (HSPGs) are common on the cell surface and mediate many physiological processes. Binding of HSPG ligands is determined by the sulfation code on the heparan sulfate chain and the HS chain can be N-/2-O/6-O- or 3-O-sulfated, generating a heterogenous sulfation pattern. 3-O sulfated HS (3S-HS) have been reported to play a role in several pathological processes such as the coagulation system, viral pathogenesis, or in the binding and internalization of tau in Alzheimer’s disease. Few 3S-HS-specific interactors are known and the role of 3S-HS in health and disease is limited, especially in the central nervous system. Using human CSF as a surrogate for the extracellular compartment of the CNS, we determined the interactome of synthetic heparan sulfate oligosaccharides with defined sulfation patterns. These AE-MS studies significantly expand the proteins that can interact with HS and for which 3O sulfation is required. LRP1 was found as a novel 3S-HS interactor, requiring GlcA-GlcNS6S3S for binding, similar to ATIII. Both interactions were validated via Western blot. Our dataset brings forward new HS and 3S-HS ligands which can be pertinent to unravel molecular mechanisms dependent on 3S-HS in (patho)physiological conditions.
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