Cartographie du phosphoprotéome régulé par les isoformes du PI3K de classe I dans le cancer du pancréas

L'adénocarcinome pancréatique est un des cancers les plus létaux, avec une survie à 5 ans après diagnostic de seulement 5%. L'absence de traitement curatif et les nombreux échecs des thérapies ciblées mettent en avant l'urgence d'identifier une stratégie thérapeutique efficace. L'atteinte de cet objectif doit passer par l'identification de biomarqueurs diagnostic et pronostic, l'identification de nouvelles cibles thérapeutiques et la connaissance des mécanismes de résistance induits par les thérapies ciblées. La voie PI3K/Akt/mTOR, une des voies les plus altérées dans les cancers, est suractivée dans les cancers du pancréas et corrélée à un mauvais pronostic. Chez les Vertébrés, la famille des phosphoinositide-3-kinases (PI3K) de classe I est constituée des isoformes p110a, p110ß, p110d et p110?. Bien qu'elles réalisent toutes la même réaction biochimique (phosphorylation du PIP2 en PIP3, second messager lipidique), chaque isoforme de PI3K possède des rôles physiologiques spécifiques. Les inhibiteurs globaux de PI3Ks actuellement testés en phase I/II dans les cancers solides avancés présentent un bénéfice thérapeutique limité à des doses maximales tolérées. Les inhibiteurs des isoformes de PI3K sont actuellement les agents les plus prometteurs car ils offrent les avantages d'être, à de faibles doses, plus efficaces, plus puissants dans l'inhibition d'une PI3K et donc moins toxiques que les inhibiteurs pan-PI3K. Les objectifs de cette thèse sont de déterminer les rôles isoforme-spécifiques des PI3K et l'intérêt thérapeutique de cibler une ou plusieurs isoformes dans la pancréatite et l'adénocarcinome pancréatique, par l'identification de voies isoforme-spécifiques et l'étude des réponses adaptatives induites par le ciblage d'une ou de toutes les isoformes de PI3K. Dans un premier temps, mon travail a permis de mettre en évidence, valider et compléter des résultats obtenus dans l'équipe, visant à démontrer l'importance de la signalisation PI3K/Akt dans ces deux processus physiopathologiques : la pancréatite chronique et l'initiation de la carcinogenèse pancréatique. Plus précisément, l'hyperactivation de la voie PI3K/Akt observée dans des échantillons humains et murins atteints de pancréatique chronique est corrélée avec l'enrichissement d'une signature transcriptomique d'activation de l'isoforme p110a. Par ailleurs, l'inactivation génétique et pharmacologique de p110a lors d'une inflammation chronique pancréatique ou en présence de Kras oncogénique empêche l'apparition de métaplasies acino-canalaires, structures associées à l'initiation de la carcinogenèse pancréatique. L'élaboration d'un protocole de transdifférenciation acino-canalaire in vitro m'a permis de valider que seule l'isoforme p110a est nécessaire à cette étape d'initiation de la carcinogenèse pancréatique en régulant les petites GTPases Rho, essentielles au remodelage du cytosquelette d'actine. Dans un deuxième temps, grâce à une analyse quantitative du phosphoprotéome d'une lignée cancéreuse pancréatique traitée ou non à différents temps par un inhibiteur pan- ou isoforme-sélectif, j'ai démontré pour la première fois l'existence de cibles, de réseaux de signalisation et de réponses adaptatives régulés par chaque isoforme de PI3K. Pour conclure, l'ensemble des résultats démontrent le rationnel de l'utilisation combinatoire d'inhibiteurs isoforme-spécifiques de PI3K chez les patients atteints de cancer du pancréas pour une meilleure réponse clinique.Pancreatic ductal adenocarcinoma is one of the most lethal cancers, with a 5 year-survival rate below 5%. Lack of curative treatment and failure of targeted therapies urge the need to identify novel efficient therapeutic strategy. Achievement of this goal will be obtained through the identification of diagnosis and prognosis biomarkers, identification of novel therapeutic targets and the knowledge of resistance mechanisms induced by these targeted therapies. PI3K/Akt/mTOR signalling, one of the most altered in cancers, is overactivated in pancreatic cancer and correlated with poor prognosis. In the Vertebrates, the family of class I phosphoinoitide-3-kinase (PI3K) includes four isoforms: p110a, p110ß, p110d and p110?. Although they all perform the same biochemical reaction (phosphorylation of PIP2 in PIP3, a membrane lipid messenger), each isoform were demonstrated to have specific physiological roles. Global PI3K inhibitors are currently being tested in phase I/II clinical trials in advanced solid cancers, but show at maximal doses tolerated a limited therapeutic benefit. Isoform-selective PI3K inhibitors are currently the most promising agents because, at low doses, they are more efficient to inhibit one PI3K isoform, and thus, less toxic than pan-PI3K inhibitors. The objectives of this thesis are to determine isoform-specific PI3K roles and the therapeutic interest to target one or more isoforms in pancreatitis and PDAC, by the identification of isoform-specific pathways and the study of adaptive responses induced by targeting of one or all isoforms of PI3K. In a first part, my work has highlighted, validated and completed results obtained in the team, to demonstrate the significance of PI3K/Akt signalling in two physiological processes: chronic pancreatitis and initiation of pancreatic carcinogenesis. Precisely, the overactivation of PI3K/Akt pathway measured on human and murine chronic pancreatitis samples is correlated with a specific p110a activation gene expression signature. Moreover, genetic and pharmacologic inactivation of p110a during pancreatic chronic inflammation or cancerogenesis (by oncogenic Kras) prevents the formation of acino-ductal metaplasia, structures at the origin of pancreatic carcinogenesis initiation. Development of in vitro acino-ductal transdifferentiation protocol allowed me to demonstrate that only p110a is necessary at this initial step of pancreatic carcinogenesis by the regulation of Rho small GTPases, further regulating actin remodelling. In the second part, by a phosphoproteomic-based approach, I quantified PI3K downstream phosphorylation-regulated targets in a pancreatic cancer cell line treated or not by a pan- or selective PI3K inhibitor at different times. I demonstrated for the first time existence of targets, signalling pathways and adaptive responses regulated by each PI3K isoform. To conclude, all these results demonstrate the rational of combinatorial use of isoform-specific PI3K inhibitors in patients with pancreatic cancer for better clinical response

Facial asymmetry and genetic ancestry in Latin American admixed populations

Fluctuating and directional asymmetry are aspects of morphological variation widely used to infer environmental and genetic factors affecting facial phenotypes. However, the genetic basis and environmental determinants of both asymmetry types is far from being completely known. The analysis of facial asymmetries in admixed individuais can be of help to characterize the impact of a genome's heterozygosity on the deveiopmental basis of both fl.uctuating and directional asymmetries. Here we characterize the association between genetic ancestry and individual asymmetry on a sample of Latin-American admixed populations. To do so, three-dimensional (3D) facial shape attributes were explored on a sample of 4,104 volunteers aged between 18 and 85 years. Individual ancestry and heterozygosity was estimated using more than 730,000 genome-wide markers. Multivariate techniques applied to geometric morphometric data were used to evaluate the magnitude and significance of directional and ftuctuating asymmetry (FA), as well as correiations and multipie regressions aimed to estimate the relationship between facial FA scores and heterozygosity and a set of covariates. Resuits indicate that directional and FA are both signi:ficant, the former being the strongest expression of asymmetry in this sample. In addition, our analyses suggest that there are some specific patterns of facial asymmetries characterizing the different ancestry groups. Finally, we find that more heterozygous individuais exhibit lower leveis of asymmetry. Our results highlight the importance of including ancestry-admixture estimators, especially when the analyses are aimed to compare leveis of asymmetries on groups differing on socioeconomic leveis, as a proxy to estimate developmental noise

Convergence of patient- and physician-reported outcomes in the French National Registry of Facioscapulohumeral Dystrophy

International audienceFacioscapulohumeral muscular dystrophy (FSHD) is among the most prevalent muscular dystrophies and currently has no treatment. Clinical and genetic heterogeneity are the main challenges to a full comprehension of the physiopathological mechanism. Improving our knowledge of FSHD is crucial to the development of future therapeutic trials and standards of care. National FSHD registries have been set up to this end. The French National Registry of FSHD combines a clinical evaluation form (CEF) and a self-report questionnaire (SRQ), filled out by a physician with expertise in neuromuscular dystrophies and by the patient, respectively. Aside from favoring recruitment, our strategy was devised to improve data quality. Indeed, the pairwise comparison of data from 281 patients for 39 items allowed for evaluating data accuracy. Kappa or intra-class coefficient (ICC) values were calculated to determine the correlation between answers provided in both the CEF and SRQ. Results Patients and physicians agreed on a majority of questions common to the SRQ and CEF (24 out of 39). Demographic, diagnosis- and care-related questions were generally answered consistently by the patient and the medical practitioner (kappa or ICC values of most items in these groups were greater than 0.8). Muscle function-related items, i.e. FSHD-specific signs, showed an overall medium to poor correlation between data provided in the two forms; the distribution of agreements in this section was markedly spread out and ranged from poor to good. In particular, there was very little agreement regarding the assessment of facial motricity and the presence of a winged scapula. However, patients and physicians agreed very well on the Vignos and Brooke scores. The report of symptoms not specific to FSHD showed general poor consistency. Conclusions Patient and physician answers are largely concordant when addressing quantitative and objective items. Consequently, we updated collection forms by relying more on patient-reported data where appropriate. We hope the revised forms will reduce data collection time while ensuring the same quality standard. With the advent of artificial intelligence and automated decision-making, high-quality and reliable data are critical to develop top-performing algorithms to improve diagnosis, care, and evaluate the efficiency of upcoming treatments