707 research outputs found

    Etude de l'effet sur la P glycoprotéine (ABCB1) de deux médicaments dirigés contre le récepteur de facteur de croissance épithélial (EGFR), le cétuximab et le lapatinib et conséquence sur la pharmacocinétique et l'efficacité anti tumorale de médicaments substrats de ABCB1

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    La P-glycoprotĂ©ine (P-gp) est une protĂ©ine transmembranaire de la famille des ATP binding cassette transporteurs. Elle est impliquĂ©e dans l efflux du milieu intracellulaire vers le milieu extracellulaire d une grande variĂ©tĂ© de mĂ©dicaments anticancĂ©reux. Elle peut ĂȘtre responsable de la diminution de la biodisponibilitĂ© orale et de la concentration intra-tumorale des mĂ©dicaments qui en sont substrats. Elle peut notamment ĂȘtre surexprimĂ©e par les cellules cancĂ©reuses des adĂ©nocarcinomes du colon naĂŻfs de tout traitement, suggĂ©rant une rĂ©sistance naturelle de cette tumeur et Ă©galement aprĂšs une chimiothĂ©rapie. Notre premier travail in vivo a documentĂ© le caractĂšre substrat de la P-gp de l evĂ©rolimus, inhibiteur de mTOR indiquĂ© dans divers cancers (rein, tumeurs neuroendocrines d oringine pancrĂ©atique et sein), jusqu Ă  maintenant uniquement Ă©tudiĂ© dans des modĂšles in vitro. Une augmentation significative de l AUC de l evĂ©rolimus administrĂ© par voie orale est observĂ©e chez des souris mdr1a-/b- comparĂ©es Ă  des souris mdr1a+/1b+. Une amĂ©lioration significative de la biodisponibilitĂ© orale de l evĂ©rolimus est aussi notĂ©e chez des souris prĂ©traitĂ©es par le lapatinib (TyverbÂź), inhibiteur des tyrosines kinases (EGFR et HER2) indiquĂ© dans le cancer du sein, par rapport aux souris ayant reçu l evĂ©rolimus seul. Ce rĂ©sultat est accompagnĂ© d une inhibition de l expression de la P-gp intestinale par le lapatinib mesurĂ©e par la technique de Western Blot. Enfin, une Ă©tude prĂ©clinique menĂ©e chez des souris porteuses d une xĂ©nogreffe colorectale mutĂ©e KRAS montre une activitĂ© anti-tumorale certaine des deux mĂ©dicaments utilisĂ©s seuls et en schĂ©ma sĂ©quentiel. Notre seconde Ă©tude a montrĂ© pour la premiĂšre fois que le cĂ©tuximab (ErbituxÂź), anticorps anti-EGFR, inhibe la fonctionnalitĂ© de la P-gp dans deux lignĂ©es cellulaires surexprimant la P-gp (les cellules IGROV-1 et les HEK P-gp) indĂ©pendamment de leur statut EGFR et entraĂźne chez des souris porteuses d une xĂ©nogreffe colorectale une augmentation significative de la biodisponibilitĂ© orale et de la concentration intra-tumorale du SN-38, mĂ©tabolite actif de l irinotĂ©can (CamptoÂź) administrĂ© par voie orale. Le cĂ©tuximab Ă©tant prescrit en association avec l irinotĂ©can chez des patients atteints d un cancer colorectal mĂ©tastasĂ©, initialement rĂ©fractaire Ă  l irinotĂ©can, ces rĂ©sultats pourraient en partie expliquer la rĂ©version de la rĂ©sistance Ă  l irinotĂ©can par le cĂ©tuximab par une inhibition de l efflux de la P-gp. GrĂące Ă  l Ă©tude de deux associations de mĂ©dicaments lapatinib-evĂ©rolimus et cĂ©tuximab-irinotĂ©can , nous avons dĂ©montrĂ© l intĂ©rĂȘt de l Ă©tude de l inhibition de la P-gp avec les traitements les plus rĂ©cents, notamment son rĂŽle dans l amĂ©lioration de la biodisponibilitĂ© orale de chimiothĂ©rapies utilisĂ©es par voie orale.P-glycoprotein (P-gp) is a membrane transporter and belongs to the ATP-binding cassette (ABC) transporter super family. P-gp decreases oral bioavailability of substrate drugs and can cause multidrug resistance in tumor cells by decreasing intracellular drug levels. P-gp is overexpressed in colorectal carcinoma naturally resistant to chemotherapy. The aim of our first study was to document the in vivo transport of everolimus (AfinitorÂź), a mTOR inhibitor, by P-gp. A signi cant increase of everolimus oral bioavaibility was observed in mdr1a-/1b- mice compared to the wild type. In addition, a signi cant increase of everolimus oral bioavaibility was showed in mice that received a lapatinib pre-treatment (a dual EGFR/HER2 tyrosine kinase inhibitor) compared to mice that received everolimus alone. These results were accompanied by a signi cant decrease of P-gp expression in duodenum segment in lapatinib pre-treated group as compared to control group. Finally, each drug given alone or in association showed a major antitumor activity in a xenograft model of human colorectal carcinoma with KRAS mutation. Our second study showed for the first time that cetuximab (ErbituxÂź), a monoclonal antibody directed towards EGFR, inhibits P-gp functionality in two cell lines overexpressing P-gp (IGROV-1 and HEK P-gp cells) independently of EGFR status and leads to significant increases of oral bioavailability and intratumoral concentration of SN-38, the active metabolite of irinotecan (CamptoÂź) in mice bearing colorectal carcinoma xenograft. Cetuximab is used in combination with irinotecan in patients with metastatic colorectal cancer, initially refractory to irinotecan, our results may partly explain the reversion of resistance to irinotecan by inhibiting P-gp efflux by cetuximab. In conclusion, our results showed the interest to study the effect of recent anticancerous drugs on P-gp, including their ability to improve oral bioavailability of oral chemotherapy used.PARIS11-SCD-Bib. Ă©lectronique (914719901) / SudocSudocFranceF

    New insights into the clinical and molecular spectrum of the novel CYFIP2-related neurodevelopmental disorder and impairment of the WRC-mediated actin dynamics

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    PURPOSE A few de novo missense variants in the cytoplasmic FMRP-interacting protein 2 (CYFIP2) gene have recently been described as a novel cause of severe intellectual disability, seizures, and hypotonia in 18 individuals, with p.Arg87 substitutions in the majority. METHODS We assembled data from 19 newly identified and all 18 previously published individuals with CYFIP2 variants. By structural modeling and investigation of WAVE-regulatory complex (WRC)-mediated actin polymerization in six patient fibroblast lines we assessed the impact of CYFIP2 variants on the WRC. RESULTS Sixteen of 19 individuals harbor two previously described and 11 novel (likely) disease-associated missense variants. We report p.Asp724 as second mutational hotspot (4/19 cases). Genotype-phenotype correlation confirms a consistently severe phenotype in p.Arg87 patients but a more variable phenotype in p.Asp724 and other substitutions. Three individuals with milder phenotypes carry putative loss-of-function variants, which remain of unclear pathogenicity. Structural modeling predicted missense variants to disturb interactions within the WRC or impair CYFIP2 stability. Consistent with its role in WRC-mediated actin polymerization we substantiate aberrant regulation of the actin cytoskeleton in patient fibroblasts. CONCLUSION Our study expands the clinical and molecular spectrum of CYFIP2-related neurodevelopmental disorder and provides evidence for aberrant WRC-mediated actin dynamics as contributing cellular pathomechanism

    Selective Axonal Expression of the Kv1 Channel Complex in Pre-myelinated GABAergic Hippocampal Neurons.

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    In myelinated fibers, the voltage-gated sodium channels Nav1 are concentrated at the nodal gap to ensure the saltatory propagation of action potentials. The voltage-gated potassium channels Kv1 are segregated at the juxtaparanodes under the compact myelin sheath and may stabilize axonal conduction. It has been recently reported that hippocampal GABAergic neurons display high density of Nav1 channels remarkably in clusters along the axon before myelination (Freeman et al., 2015). In inhibitory neurons, the Nav1 channels are trapped by the ankyrinG scaffold at the axon initial segment (AIS) as observed in pyramidal and granule neurons, but are also forming "pre-nodes," which may accelerate conduction velocity in pre-myelinated axons. However, the distribution of the Kv1 channels along the pre-myelinated inhibitory axons is still unknown. In the present study, we show that two subtypes of hippocampal GABAergic neurons, namely the somatostatin and parvalbumin positive cells, display a selective high expression of Kv1 channels at the AIS and all along the unmyelinated axons. These inhibitory axons are also highly enriched in molecules belonging to the juxtaparanodal Kv1 complex, including the cell adhesion molecules (CAMs) TAG-1, Caspr2, and ADAM22 and the scaffolding protein 4.1B. Here, taking advantage of hippocampal cultures from 4.1B and TAG-1 knock-out mice, we observed that 4.1B is required for the proper positioning of Caspr2 and TAG-1 along the distal axon, and that TAG-1 deficiency induces alterations in the axonal distribution of Caspr2. However, the axonal expression of Kv1 channels and clustering of ankyrinG were not modified. In conclusion, this study allowed the analysis of the hierarchy between channels, CAMs and scaffolding proteins for their expression along hippocampal inhibitory axons before myelination. The early steps of channel compartmentalization preceding myelination may be crucial for stabilizing nerve impulses switching from a continuous to saltatory conduction during network development

    Clinical and genetic characterization of individuals with predicted deleterious PHIP variants

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    Heterozygous deleterious variants in PHIP have been associated with behavioral problems, intellectual disability/developmental delay, obesity/overweight, and dysmorphic features (BIDOD syndrome). We report an additional 10 individuals with pleckstrin homology domain-interacting protein (PHIP)-predicted deleterious variants (four frameshift, three missense, two nonsense, and one splice site; six of which are confirmed de novo). The mutation spectrum is diverse, and there is no clustering of mutations across the protein. The clinical phenotype of these individuals is consistent with previous reports and includes behavioral problems, intellectual disability, developmental delay, hypotonia, and dysmorphic features. The additional individuals we report have a lower frequency of obesity than previous reports and a higher frequency of gastrointestinal problems, social deficits, and behavioral challenges. Characterizing additional individuals with diverse mutations longitudinally will provide better natural history data to assist with medical management and educational and behavioral support

    Towards a Swiss health study with human biomonitoring: Learnings from the pilot phase about participation and design.

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    BACKGROUND A large-scale national cohort aiming at investigating the health status and determinants in the general population is essential for high-quality public health research and regulatory decision-making. We present the protocol and first results of the pilot phase to a Swiss national cohort aiming at establishing the study procedures, evaluating feasibility, and assessing participation and willingness to participate. METHODS The pilot phase 2020/21 included 3 components recruited via different channels: a population-based cross-sectional study targeting the adult population (20-69 years) of the Vaud and Bern cantons via personal invitation, a sub-study on selenium in a convenience sample of vegans and vegetarians via non-personal invitation in vegan/vegetarian networks, and a self-selected sample via news promotion (restricted protocol). Along with a participatory approach and participation, we tested the study procedures including online questionnaires, onsite health examination, food intake, physical activity assessments and biosample collection following high-quality standards. RESULTS The population-based study and the selenium sub-study had 638 (participation rate: 14%) and 109 participants, respectively, both with an over-representation of women. Of altogether 1349 recruited participants over 90% expressed interest in participating to a national health study, over 75% to contribute to medicine progress and help improving others' health, whereas about one third expressed concerns over data protection and data misuse. CONCLUSIONS Publicly accessible high-quality public health data and human biomonitoring samples were collected. There is high interest of the general population in taking part in a national cohort on health. Challenges reside in achieving a higher participation rate and external validity. For project management clear governance is key

    New Insights Into the Clinical and Molecular Spectrum of the Novel CYFIP2-Related Neurodevelopmental Disorder and Impairment of the WRC-Mediated Actin Dynamics

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    Purpose: A few de novo missense variants in the cytoplasmic FMRP-interacting protein 2 (CYFIP2) gene have recently been described as a novel cause of severe intellectual disability, seizures, and hypotonia in 18 individuals, with p.Arg87 substitutions in the majority. Methods: We assembled data from 19 newly identified and all 18 previously published individuals with CYFIP2 variants. By structural modeling and investigation of WAVE-regulatory complex (WRC)-mediated actin polymerization in six patient fibroblast lines we assessed the impact of CYFIP2 variants on the WRC. Results: Sixteen of 19 individuals harbor two previously described and 11 novel (likely) disease-associated missense variants. We report p.Asp724 as second mutational hotspot (4/19 cases). Genotype–phenotype correlation confirms a consistently severe phenotype in p.Arg87 patients but a more variable phenotype in p.Asp724 and other substitutions. Three individuals with milder phenotypes carry putative loss-of-function variants, which remain of unclear pathogenicity. Structural modeling predicted missense variants to disturb interactions within the WRC or impair CYFIP2 stability. Consistent with its role in WRC-mediated actin polymerization we substantiate aberrant regulation of the actin cytoskeleton in patient fibroblasts. Conclusion: Our study expands the clinical and molecular spectrum of CYFIP2-related neurodevelopmental disorder and provides evidence for aberrant WRC-mediated actin dynamics as contributing cellular pathomechanism

    A standard of care for individuals with PIK3CA ‐related disorders: an international expert consensus statement

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    Growth promoting variants in PIK3CA cause a spectrum of developmental disorders, depending on the developmental timing of the mutation and tissues involved. These phenotypically heterogeneous entities have been grouped as PIK3CA-Related Overgrowth Spectrum disorders (PROS). Deep sequencing technologies have facilitated detection of low-level mosaic, often necessitating testing of tissues other than blood. Since clinical management practices vary considerably among healthcare professionals and services across different countries, a consensus on management guidelines is needed. Clinical heterogeneity within this spectrum leads to challenges in establishing management recommendations, which must be based on patient-specific considerations. Moreover, as most of these conditions are rare, affected families may lack access to the medical expertise that is needed to help address the multi-system and often complex medical issues seen with PROS. In March 2019, macrocephaly-capillary malformation (M-CM) patient organizations hosted an expert meeting in Manchester, United Kingdom, to help address these challenges with regards to M-CM syndrome. We have expanded the scope of this project to cover PROS and developed this consensus statement on the preferred approach for managing affected individuals based on our current knowledge

    Baraitser-Winter cerebrofrontofacial syndrome: Delineation of the spectrum in 42 cases

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    Baraitser-Winter, Fryns-Aftimos and cerebrofrontofacial syndrome types 1 and 3 have recently been associated with heterozygous gain-of-function mutations in one of the two ubiquitous cytoplasmic actin-encoding genes ACTB and ACTG1 that encode ÎČ- and Îł-actins. We present detailed phenotypic descriptions and neuroimaging on 36 patients analyzed by our group and six cases from the literature with a molecularly proven actinopathy (9 ACTG1 and 33 ACTB). The major clinical anomalies are striking dysmorphic facial features with hypertelorism, broad nose with large tip and prominent root, congenital non-myopathic ptosis, ridged metopic suture and arched eyebrows. Iris or retinal coloboma is present in many cases, as is sensorineural deafness. Cleft lip and palate, hallux duplex, congenital heart defects and renal tract anomalies are seen in some cases. Microcephaly may develop with time. Nearly all patients with ACTG1 mutations, and around 60% of those with ACTB mutations have some degree of pachygyria with anteroposterior severity gradient, rarely lissencephaly or neuronal heterotopia. Reduction of shoulder girdle muscle bulk and progressive joint stiffness is common. Early muscular involvement, occasionally with congenital arthrogryposis, may be present. Progressive, severe dystonia was seen in one family. Intellectual disability and epilepsy are variable in severity and largely correlate with CNS anomalies. One patient developed acute lymphocytic leukemia, and another a cutaneous lymphoma, indicating that actinopathies may be cancer-predisposing disorders. Considering the multifaceted role of actins in cell physiology, we hypothesize that some clinical manifestations may be partially mutation specific. Baraitser-Winter cerebrofrontofacial syndrome is our suggested designation for this clinical entity
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