ASS1 Overexpression:A Hallmark of Sonic Hedgehog Hepatocellular Adenomas; Recommendations for Clinical Practice

Until recently, 10% of hepatocellular adenomas (HCAs) remained unclassified (UHCA). Among the UHCAs, the sonic hedgehog HCA (shHCA) was defined by focal deletions that fuse the promoter of Inhibin beta E chain with GLI1. Prostaglandin D2 synthase was proposed as immunomarker. In parallel, our previous work using proteomic analysis showed that most UHCAs constitute a homogeneous subtype associated with overexpression of argininosuccinate synthase (ASS1). To clarify the use of ASS1 in the HCA classification and avoid misinterpretations of the immunohistochemical staining, the aims of this work were to study (1) the link between shHCA and ASS1 overexpression and (2) the clinical relevance of ASS1 overexpression for diagnosis. Molecular, proteomic, and immunohistochemical analyses were performed in UHCA cases of the Bordeaux series. The clinico-pathological features, including ASS1 immunohistochemical labeling, were analyzed on a large international series of 67 cases. ASS1 overexpression and the shHCA subgroup were superimposed in 15 cases studied by molecular analysis, establishing ASS1 overexpression as a hallmark of shHCA. Moreover, the ASS1 immunomarker was better than prostaglandin D2 synthase and only found positive in 7 of 22 shHCAs. Of the 67 UHCA cases, 58 (85.3%) overexpressed ASS1, four cases were ASS1 negative, and in five cases ASS1 was noncontributory. Proteomic analysis performed in the case of doubtful interpretation of ASS1 overexpression, especially on biopsies, can be a support to interpret such cases. ASS1 overexpression is a specific hallmark of shHCA known to be at high risk of bleeding. Therefore, ASS1 is an additional tool for HCA classification and clinical diagnosis

Involvement of Discoidin domain receptors 1 and 2 in resistance to the targeted therapy during melanoma

La combinaison de deux traitements, un anti-BRAF et un anti-MEK est actuellement utilisée en première ligne de traitement dans la prise en charge des patients ayant un mélanome métastatique porteur de la mutation somatique BRAF V600E. Cependant, le problème majeur dans le mélanome est l'acquisition d'une résistance cellulaire chez 80% des patients, qui est associée à une augmentation de la formation de métastases, notamment due à l'hyper-activation de la voie des MAP kinases. Or, les récepteurs à domaine discoïdine DDR1 et DDR2 sont capables d’activer cette voie de signalisation. Les DDRs sont surexprimés dans de nombreux cancers où ils sont associés à des phénomènes de résistance et de récidives. Notre projet a donc pour but d’analyser l’implication des DDRs dans la résistance des cellules tumorales de mélanome à la thérapie ciblée. En premier lieu, nous avons déterminé que les DDRs sont surexprimés dans les cellules résistantes au Vemurafenib par rapport aux cellules sensibles. L’hypothèse posée est que les lignées cellulaires résistantes, malgré la bithérapie, sont capables de suractiver la voie des MAP kinases par l'induction des DDRs. De plus, nous avons démontré que la diminution de l’expression des DDRs par des inhibiteurs des DDRs, comme le Dasatinib ou le CR-13542, induit une diminution de la prolifération tumorale due à une baisse du niveau d’activité de la voie MAP kinase. Enfin, nous avons confirmé ces résultats in vivo, dans un modèle murin de xénogreffe. Par conséquent, nous avons identifié les DDRs comme étant de nouvelles cibles thérapeutiques chez les patients résistants atteints de mélanome métastatique. De ce fait, nous proposons que le Dasatinib (possédant déjà une autorisation de mise sur le marché) puisse être utilisé en deuxième intention, après un traitement à la bithérapie ciblée, chez les patients résistants surexprimant les DDRs.The combination of two treatments, an anti-BRAF plus an anti-MEK is currently used in first line in patient management presenting metastatic melanomas and harboring the BRAF V600E somatic mutation. However, the main issue during targeted therapy is the acquisition of cellular resistance in 80% of the patients, which is associated with an increase of metastasis formation, notably due to the hyperactivation of MAP kinase pathway. Different receptors are known to activate this signaling pathway and previous reports have indicated that Discoidin Domain Receptors (DDRs) 1 and 2 can activate MAP kinase pathway. Then, in order to study the role of DDRs in melanoma cells resistance to the targeted therapy, we firstly determined, that DDRs are overexpressed in Vemurafenib resistant cells compared to sensitive ones. We hypothesized that resistant cell lines, despite the bi-therapy, are able to over-activate MAP kinase pathway through DDRs activation. We also reported that DDRs depletion or inactivation by DDRs inhibitors such as Dasatinib or CR-13542 reduced tumor cell proliferation, due to a decrease of MAP kinase pathway activity in resistant cells. We finally confirmed those results in vivo, in a xenograft mouse model. As a result, we characterized DDRs as new therapeutic targets in resistant patient with metastatic melanoma. Therefore, we propose that Dasatinib, an FDA approved drug, could be a second treatment after the targeted bi-therapy in resistant patients overexpressing DDRs

Implication des récepteurs à domaine discoïdine dans la résistance à la thérapie ciblée au cours du mélanome

The combination of two treatments, an anti-BRAF plus an anti-MEK is currently used in first line in patient management presenting metastatic melanomas and harboring the BRAF V600E somatic mutation. However, the main issue during targeted therapy is the acquisition of cellular resistance in 80% of the patients, which is associated with an increase of metastasis formation, notably due to the hyperactivation of MAP kinase pathway. Different receptors are known to activate this signaling pathway and previous reports have indicated that Discoidin Domain Receptors (DDRs) 1 and 2 can activate MAP kinase pathway. Then, in order to study the role of DDRs in melanoma cells resistance to the targeted therapy, we firstly determined, that DDRs are overexpressed in Vemurafenib resistant cells compared to sensitive ones. We hypothesized that resistant cell lines, despite the bi-therapy, are able to over-activate MAP kinase pathway through DDRs activation. We also reported that DDRs depletion or inactivation by DDRs inhibitors such as Dasatinib or CR-13542 reduced tumor cell proliferation, due to a decrease of MAP kinase pathway activity in resistant cells. We finally confirmed those results in vivo, in a xenograft mouse model. As a result, we characterized DDRs as new therapeutic targets in resistant patient with metastatic melanoma. Therefore, we propose that Dasatinib, an FDA approved drug, could be a second treatment after the targeted bi-therapy in resistant patients overexpressing DDRs.La combinaison de deux traitements, un anti-BRAF et un anti-MEK est actuellement utilisée en première ligne de traitement dans la prise en charge des patients ayant un mélanome métastatique porteur de la mutation somatique BRAF V600E. Cependant, le problème majeur dans le mélanome est l'acquisition d'une résistance cellulaire chez 80% des patients, qui est associée à une augmentation de la formation de métastases, notamment due à l'hyper-activation de la voie des MAP kinases. Or, les récepteurs à domaine discoïdine DDR1 et DDR2 sont capables d’activer cette voie de signalisation. Les DDRs sont surexprimés dans de nombreux cancers où ils sont associés à des phénomènes de résistance et de récidives. Notre projet a donc pour but d’analyser l’implication des DDRs dans la résistance des cellules tumorales de mélanome à la thérapie ciblée. En premier lieu, nous avons déterminé que les DDRs sont surexprimés dans les cellules résistantes au Vemurafenib par rapport aux cellules sensibles. L’hypothèse posée est que les lignées cellulaires résistantes, malgré la bithérapie, sont capables de suractiver la voie des MAP kinases par l'induction des DDRs. De plus, nous avons démontré que la diminution de l’expression des DDRs par des inhibiteurs des DDRs, comme le Dasatinib ou le CR-13542, induit une diminution de la prolifération tumorale due à une baisse du niveau d’activité de la voie MAP kinase. Enfin, nous avons confirmé ces résultats in vivo, dans un modèle murin de xénogreffe. Par conséquent, nous avons identifié les DDRs comme étant de nouvelles cibles thérapeutiques chez les patients résistants atteints de mélanome métastatique. De ce fait, nous proposons que le Dasatinib (possédant déjà une autorisation de mise sur le marché) puisse être utilisé en deuxième intention, après un traitement à la bithérapie ciblée, chez les patients résistants surexprimant les DDRs

Implication des récepteurs à domaine discoïdine dans la résistance à la thérapie ciblée au cours du mélanome

The combination of two treatments, an anti-BRAF plus an anti-MEK is currently used in first line in patient management presenting metastatic melanomas and harboring the BRAF V600E somatic mutation. However, the main issue during targeted therapy is the acquisition of cellular resistance in 80% of the patients, which is associated with an increase of metastasis formation, notably due to the hyperactivation of MAP kinase pathway. Different receptors are known to activate this signaling pathway and previous reports have indicated that Discoidin Domain Receptors (DDRs) 1 and 2 can activate MAP kinase pathway. Then, in order to study the role of DDRs in melanoma cells resistance to the targeted therapy, we firstly determined, that DDRs are overexpressed in Vemurafenib resistant cells compared to sensitive ones. We hypothesized that resistant cell lines, despite the bi-therapy, are able to over-activate MAP kinase pathway through DDRs activation. We also reported that DDRs depletion or inactivation by DDRs inhibitors such as Dasatinib or CR-13542 reduced tumor cell proliferation, due to a decrease of MAP kinase pathway activity in resistant cells. We finally confirmed those results in vivo, in a xenograft mouse model. As a result, we characterized DDRs as new therapeutic targets in resistant patient with metastatic melanoma. Therefore, we propose that Dasatinib, an FDA approved drug, could be a second treatment after the targeted bi-therapy in resistant patients overexpressing DDRs.La combinaison de deux traitements, un anti-BRAF et un anti-MEK est actuellement utilisée en première ligne de traitement dans la prise en charge des patients ayant un mélanome métastatique porteur de la mutation somatique BRAF V600E. Cependant, le problème majeur dans le mélanome est l'acquisition d'une résistance cellulaire chez 80% des patients, qui est associée à une augmentation de la formation de métastases, notamment due à l'hyper-activation de la voie des MAP kinases. Or, les récepteurs à domaine discoïdine DDR1 et DDR2 sont capables d’activer cette voie de signalisation. Les DDRs sont surexprimés dans de nombreux cancers où ils sont associés à des phénomènes de résistance et de récidives. Notre projet a donc pour but d’analyser l’implication des DDRs dans la résistance des cellules tumorales de mélanome à la thérapie ciblée. En premier lieu, nous avons déterminé que les DDRs sont surexprimés dans les cellules résistantes au Vemurafenib par rapport aux cellules sensibles. L’hypothèse posée est que les lignées cellulaires résistantes, malgré la bithérapie, sont capables de suractiver la voie des MAP kinases par l'induction des DDRs. De plus, nous avons démontré que la diminution de l’expression des DDRs par des inhibiteurs des DDRs, comme le Dasatinib ou le CR-13542, induit une diminution de la prolifération tumorale due à une baisse du niveau d’activité de la voie MAP kinase. Enfin, nous avons confirmé ces résultats in vivo, dans un modèle murin de xénogreffe. Par conséquent, nous avons identifié les DDRs comme étant de nouvelles cibles thérapeutiques chez les patients résistants atteints de mélanome métastatique. De ce fait, nous proposons que le Dasatinib (possédant déjà une autorisation de mise sur le marché) puisse être utilisé en deuxième intention, après un traitement à la bithérapie ciblée, chez les patients résistants surexprimant les DDRs

Histidine Phosphorylation: Protein Kinases and Phosphatases

Phosphohistidine (pHis) is a reversible protein post-translational modification (PTM) that is currently poorly understood. The P-N bond in pHis is heat and acid-sensitive, making it more challenging to study than the canonical phosphoamino acids pSer, pThr, and pTyr. As advancements in the development of tools to study pHis have been made, the roles of pHis in cells are slowly being revealed. To date, a handful of enzymes responsible for controlling this modification have been identified, including the histidine kinases NME1 and NME2, as well as the phosphohistidine phosphatases PHPT1, LHPP, and PGAM5. These tools have also identified the substrates of these enzymes, granting new insights into previously unknown regulatory mechanisms. Here, we discuss the cellular function of pHis and how it is regulated on known pHis-containing proteins, as well as cellular mechanisms that regulate the activity of the pHis kinases and phosphatases themselves. We further discuss the role of the pHis kinases and phosphatases as potential tumor promoters or suppressors. Finally, we give an overview of various tools and methods currently used to study pHis biology. Given their breadth of functions, unraveling the role of pHis in mammalian systems promises radical new insights into existing and unexplored areas of cell biology

DDR1 and DDR2 physical interaction leads to signaling interconnection but with possible distinct functions

<p>Discoidin domain receptors 1 and 2 (DDR1 and DDR2) are members of the tyrosine kinase receptors activated after binding with collagen. DDRs are implicated in numerous physiological and pathological functions such as proliferation, adhesion and migration. Little is known about the expression of the two receptors in normal and cancer cells and most of studies focus only on one receptor. Western blot analysis of DDR1 and DDR2 expression in different tumor cell lines shows an absence of high co-expression of the two receptors suggesting a deleterious effect of their presence at high amount. To study the consequences of high DDR1 and DDR2 co-expression in cells, we over-express the two receptors in HEK 293T cells and compare biological effects to HEK cells over-expressing DDR1 or DDR2. To distinguish between the intracellular dependent and independent activities of the two receptors we over-express an intracellular truncated dominant-negative DDR1 or DDR2 protein (DDR1DN and DDR2DN). No major differences of Erk or Jak2 activation are found after collagen I stimulation, nevertheless Erk activation is higher in cells co-expressing DDR1 and DDR2. DDR1 increases cell proliferation but co-expression of DDR1 and DDR2 is inhibitory. DDR1 but not DDR2 is implicated in cell adhesion to a collagen I matrix. DDR1, and DDR1 and DDR2 co-expression inhibit cell migration. Moreover a DDR1/DDR2 physical interaction is found by co-immunoprecipitation assays. Taken together, our results show a deleterious effect of high co-expression of DDR1 and DDR2 and a physical interaction between the two receptors.</p

Discoidin Domain Receptor 2 orchestrates melanoma resistance combining phenotype switching and proliferation

International audienceCombined therapy with anti-BRAF plus anti-MEK is currently used as first-line treatment of patients with metastatic melanomas harboring the somatic BRAF V600E mutation. However, the main issue with targeted therapy is the acquisition of tumor cell resistance. In a majority of resistant melanoma cells, the resistant process consists in epithelial-to-mesenchymal transition (EMT). This process called phenotype switching makes melanoma cells more invasive. Its signature is characterized by MITF low, AXL high, and actin cytoskeleton reorganization through RhoA activation. In parallel of this phenotype switching phase, the resistant cells exhibit an anarchic cell proliferation due to hyper-activation of the MAP kinase pathway. We show that a majority of human melanoma overexpress discoidin domain receptor 2 (DDR2) after treatment. The same result was found in resistant cell lines presenting phenotype switching compared to the corresponding sensitive cell lines. We demonstrate that DDR2 inhibition induces a decrease in AXL expression and reduces stress fiber formation in resistant melanoma cell lines. In this phenotype switching context, we report that DDR2 control cell and tumor proliferation through the MAP kinase pathway in resistant cells in vitro and in vivo. Therefore, inhibition of DDR2 could be a new and promising strategy for countering this resistance mechanism

ASS1 Overexpression: A Hallmark of Sonic Hedgehog Hepatocellular Adenomas; Recommendations for Clinical Practice

Until recently, 10% of hepatocellular adenomas (HCAs) remained unclassified (UHCA). Among the UHCAs, the sonic hedgehog HCA (shHCA) was defined by focal deletions that fuse the promoter of Inhibin beta E chain with GLI1. Prostaglandin D2 synthase was proposed as immunomarker. In parallel, our previous work using proteomic analysis showed that most UHCAs constitute a homogeneous subtype associated with overexpression of argininosuccinate synthase (ASS1). To clarify the use of ASS1 in the HCA classification and avoid misinterpretations of the immunohistochemical staining, the aims of this work were to study (1) the link between shHCA and ASS1 overexpression and (2) the clinical relevance of ASS1 overexpression for diagnosis. Molecular, proteomic, and immunohistochemical analyses were performed in UHCA cases of the Bordeaux series. The clinico-pathological features, including ASS1 immunohistochemical labeling, were analyzed on a large international series of 67 cases. ASS1 overexpression and the shHCA subgroup were superimposed in 15 cases studied by molecular analysis, establishing ASS1 overexpression as a hallmark of shHCA. Moreover, the ASS1 immunomarker was better than prostaglandin D2 synthase and only found positive in 7 of 22 shHCAs. Of the 67 UHCA cases, 58 (85.3%) overexpressed ASS1, four cases were ASS1 negative, and in five cases ASS1 was noncontributory. Proteomic analysis performed in the case of doubtful interpretation of ASS1 overexpression, especially on biopsies, can be a support to interpret such cases. ASS1 overexpression is a specific hallmark of shHCA known to be at high risk of bleeding. Therefore, ASS1 is an additional tool for HCA classification and clinical diagnosis

Large-scale genomic analyses link reproductive aging to hypothalamic signaling, breast cancer susceptibility, and BRCA1-mediated DNA repair [editorial comment]

ABSTRACT: Menopause timing has a major impact on infertility and risk of disease. Younger age at natural (nonsurgical) menopause (ANM) is associated with a higher risk of osteoporosis, cardiovascular disease, and type 2 diabetes and a lower risk of breast cancer. Late menopause is associated with a higher risk of breast cancer. It is well known that the age at which women go through menopause is partly determined by genes, but the underlying mechanisms are poorly understood. Genome-wide association studies have identified 18 common genetic variants associated with ANM. These variants explain less than 5% of the variation in ANM compared with the 21% explained by all common variants on genome-wide association study arrays. This genome-wide association study was the collaborative effort of researchers from 177 institutions worldwide. The study was designed to investigate genetic variants associated with timing of menopause among a population of approximately 70,000 women of European ancestry. A dual strategy was used to identify both common and, for the first time, low-frequency coding variants associated with ANM. The causal relationship between ANM and breast cancer was investigated using a Mendelian randomization approach. Combined analysis identified 1208 single-nucleotide polymorphisms (SNPs) of a total of approximately 2.6 million that reached the genome-wide significance threshold for association with ANM. Forty-four regions with common variants were identified; among these 44 loci were 2 rare low-frequency missense alleles of large effect. A majority of ANM SNPs were enriched in DNA damage response (DDR) genes, including the first common coding variant in BRCA1 associated with any complex trait. Mendelian randomization analyses supported a causal relationship between delayed ANM and breast cancer risk; there was approximately 6% increase in risk per year; P = 3 × 10-14); increased risk with delayed menopause appeared to be mediated primarily by prolonged sex hormone exposure in a woman’s lifetime, not DDR mechanisms. This is the first study to confirm the link between early and late menopause and breast cancer risk using genetic information. Age at natural menopause genetic variants influence breast cancer risk primarily through variation in menopause timing. Although carrying higher numbers of ANM-increasing variants and enrichment in DDR genes are associated with a modest increase in breast cancer risk, the major mechanism for increased risk appears to be prolonged estrogen and/or progesterone exposure due to delayed menopause

Large-scale genomic analyses link reproductive aging to hypothalamic signaling, breast cancer susceptibility and BRCA1-mediated DNA repair

Copyright © 2015, Rights Managed by Nature Publishing GroupThis is the author's version of an article subsequently published in definitive form at: Nature Genetics (2015) doi:10.1038/ng.3412See supplementary documents for full affiliations and acknowledgmentsMenopause timing has a substantial impact on infertility and risk of disease, including breast cancer, but the underlying mechanisms are poorly understood. We report a dual strategy in ∼70,000 women to identify common and low-frequency protein-coding variation associated with age at natural menopause (ANM). We identified 44 regions with common variants, including two regions harboring additional rare missense alleles of large effect. We found enrichment of signals in or near genes involved in delayed puberty, highlighting the first molecular links between the onset and end of reproductive lifespan. Pathway analyses identified major association with DNA damage response (DDR) genes, including the first common coding variant in BRCA1 associated with any complex trait. Mendelian randomization analyses supported a causal effect of later ANM on breast cancer risk (∼6% increase in risk per year; P = 3 × 10(-14)), likely mediated by prolonged sex hormone exposure rather than DDR mechanisms