Étude des mécanismes de résistance aux inhibiteurs de PARP dans le cancer de la prostate

Le cancer de la prostate (CP) est le cancer le plus diagnostiqué chez les hommes en Amérique du Nord. Même si les méthodes de détection et les traitements s’améliorent au fil des années, le phénomène de résistance reste encore un problème majeur pour les thérapies utilisées de nos jours. En effet, une majorité des patients vont développer une résistance à l’hormonothérapie et seront alors traités avec une variété d’agents de type hormonal et avec de la chimiothérapie. Malheureusement, ces derniers, individuellement, rallongent la durée de vie des patients que de quelques mois seulement. De ce fait, de nouvelles thérapies, comme les inhibiteurs de PARP (PARPi ; olaparib, niraparib, talazoparib et rucaparib), sont à l’heure actuelle en essais cliniques. Ces composés ciblent la réparation de l’ADN dans le but d’induire une mort cellulaire lorsque des mutations au niveau de cette voie sont présentes. Il est bien connu dans le cancer de l’ovaire et du sein que plusieurs formes de résistances peuvent se mettre en place au cours du temps. Cette résistance aux PARPi dans le CP est encore trop peu étudiée et comprise. Ce projet de thèse s’est ainsi intéressé à la résistance innée mais aussi acquise à l’olaparib dans le CP. Nous avons démontré dans notre première étude que les cellules du CP sont plus résistantes à l’olaparib quand leur niveau basal d’autophagie est plus élevé. Cette résistance médiée par l’autophagie est due, en partie, par la régulation de la localisation nucléaire de la protéine sequestrosome 1 (SQSTM1/p62), capable de dégrader la filamine A (FLNA), essentielle dans le recrutement de Rad51 lors de la recombinaison homologue (HR). Notre étude suggère donc une prise en compte de l’autophagie avant le traitement à l’olaparib pour y déterminer l’efficacité de ce PARPi. Dans notre deuxième étude, nous avons développé des lignées du CP résistantes à l’olaparib pour y déterminer les voies moléculaires les plus affectées par cette transformation et pouvant réguler la résistance acquise. Nous avons mis en évidence que certaines voies, comme les mécanismes de réparation de l’ADN et l’autophagie, pouvaient jouer un rôle essentiel dans la mise en place de résistance acquise à l’olaparib. Cibler certains membres de ces voies comme BRCC3, ATG2B ou ROCK2, pourrait permettre d’inverser la résistance et ainsi permettre d’augmenter l’efficacité de l’olaparib sur le long terme. Ces travaux permettent ainsi de mieux caractériser le phénomène de résistance aux PARPi dans le CP en donnant de nouvelles cibles pour anticiper son apparition et l’inverser. Ils ont aussi permis d’illustrer l’importance du mécanisme d’autophagie dans la réponse aux PARPi dans le CP.Prostate cancer (CP) is the most diagnosed cancer in North America. Even if detection and treatments have improved over the years, the phenomenon of resistance remains a major problem for the therapies used today. Indeed, most patients will develop resistance to hormone therapy and will subsequently be treated with a variety of hormonally based agents and chemotherapeutic agents. Unfortunately, these agents extend survival by only a few months each. As a result, new therapies, such as PARP inhibitors (PARPi; olaparib, niraparib, talazoparib and rucaparib), are currently in clinical trials. These compounds target DNA repair with the aim of inducing cell death when mutations in this pathway are present. It is well known in ovarian and breast cancer that several forms of resistance will develop over time. Unfortunately, this resistance to PARPi in CP is not well studied and therefore understood. This thesis project focused on innate but also acquired resistance to olaparib in CP. We demonstrated in our first study that CP cells are more resistant to olaparib when their basal level of autophagy is higher. This resistance mediated by autophagy is due, in part, by the regulation of the nuclear localization of the protein sequestrosome 1 (SQSTM1/p62), which degrades filamin A (FLNA), essential in the recruitment of Rad51 during the homologous recombination (HR). Our study therefore suggests the importance of considering autophagy before olaparib treatment to predict the effectiveness of a PARPi. In our second study, we developed CP lines resistant to olaparib to determine the molecular pathways most affected by this transformation and able to contribute to resistance. We have shown that different pathways, such as DNA repair mechanisms and autophagy, could play an essential role in the establishment of acquired resistance to olaparib. Targeting members of these pathways, such as BRCC3, ATG2B or ROCK2, may reverse resistance and thus increase the efficacy of olaparib. This work thus makes it possible to better characterize the phenomenon of resistance to PARPi in CP by identifying new targets to counter its appearance. Together these results support the importance of autophagy and DNA repair in the response to PARPi in PC

Head-up displays in action video games: the effects of physical and semantic characteristics on player performance and experience

International audienceThis study aimed to investigate how different characteristics of head-up displays (HUDs) can impact the performance and subjective experience of players in action video games. HUDs are a very common way to display contextual information. However, very few studies have empirically investigated the influence of HUD design on player performance and experience from a human information processing perspective. Four experiments were conducted in which players of different levels of expertise played commercial action video games. The physical characteristics of HUD, i.e. the physical appearance of the information on screen such as size and color (Experiments 1-2), and the semantic characteristics, i.e. the composition (nature and content) of the information (Experiments 3-4), were manipulated. Player performance and subjective experience were systematically assessed. The results showed that players’ performance and experience were impacted when the semantic characteristics of the HUD elements were manipulated and when their nature was relevant to the main task players have to perform within the game. The performance of more experienced players was particularly affected in this case. In contrast, the results did not show that altering physical or semantic characteristics that were less relevant to the game main task would affect players’ performance and subjective experience

A Keratin 7 and E-Cadherin Signature Is Highly Predictive of Tubo-Ovarian High-Grade Serous Carcinoma Prognosis

During tubo-ovarian high-grade serous carcinoma (HGSC) progression, tumoral cells undergo phenotypic changes in their epithelial marker profiles, which are essential for dissemination processes. Here, we set out to determine whether standard epithelial markers can predict HGSC patient prognosis. Levels of E-CADH, KRT7, KRT18, KRT19 were quantified in 18 HGSC cell lines by Western blot and in a Discovery cohort tissue microarray (TMA) (n = 101 patients) using immunofluorescence. E-CADH and KRT7 levels were subsequently analyzed in the TMA of the Canadian Ovarian Experimental Unified Resource cohort (COEUR, n = 1158 patients) and in public datasets. Epithelial marker expression was highly variable in HGSC cell lines and tissues. In the Discovery cohort, high levels of KRT7 and KRT19 were associated with an unfavorable prognosis, whereas high E-CADH expression indicated a better outcome. Expression of KRT7 and E-CADH gave a robust combination to predict overall survival (OS, p = 0.004) and progression free survival (PFS, p = 5.5 × 10−4) by Kaplan–Meier analysis. In the COEUR cohort, the E-CADH-KRT7 signature was a strong independent prognostic biomarker (OS, HR = 1.6, p = 2.9 × 10−4; PFS, HR = 1.3, p = 0.008) and predicted a poor patient response to chemotherapy (p = 1.3 × 10−4). Our results identify a combination of two epithelial markers as highly significant indicators of HGSC patient prognosis and treatment response

SI TRACEABLE HIGH PRECISION SPECTROSCOPY OF OZONE USING A QUANTUM CASCADE LASER AT 9.5 MICROMETER

International audienceFor subDoppler ozone spectroscopy, we have implemented a QCL laser stabilisation scheme based on an optical frequency comb (OFC) referenced to the international system of units (SI) via an optical fiber which links to the REFIMEVE network [6]. To compare the QCL at 31 THz to a reference laser frequency comb at 193 THz (SI traceable), a sum frequency generation (SFG) scheme between the QCL and an OFC at 162 THz in an oriented patterned GaAs crystal is implemented

SI TRACEABLE HIGH PRECISION SPECTROSCOPY OF OZONE USING A QUANTUM CASCADE LASER AT 9.5 MICROMETER

International audienceFor subDoppler ozone spectroscopy, we have implemented a QCL laser stabilisation scheme based on an optical frequency comb (OFC) referenced to the international system of units (SI) via an optical fiber which links to the REFIMEVE network [6]. To compare the QCL at 31 THz to a reference laser frequency comb at 193 THz (SI traceable), a sum frequency generation (SFG) scheme between the QCL and an OFC at 162 THz in an oriented patterned GaAs crystal is implemented

Immunogenicity of Non-Mutated Ovarian Cancer-Specific Antigens

Epithelial ovarian cancer (EOC) has not significantly benefited from advances in immunotherapy, mainly because of the lack of well-defined actionable antigen targets. Using proteogenomic analyses of primary EOC tumors, we previously identified 91 aberrantly expressed tumor-specific antigens (TSAs) originating from unmutated genomic sequences. Most of these TSAs derive from non-exonic regions, and their expression results from cancer-specific epigenetic changes. The present study aimed to evaluate the immunogenicity of 48 TSAs selected according to two criteria: presentation by highly prevalent HLA allotypes and expression in a significant fraction of EOC tumors. Using targeted mass spectrometry analyses, we found that pulsing with synthetic TSA peptides leads to a high-level presentation on dendritic cells. TSA abundance correlated with the predicted binding affinity to the HLA allotype. We stimulated naïve CD8 T cells from healthy blood donors with TSA-pulsed dendritic cells and assessed their expansion with two assays: MHC-peptide tetramer staining and TCR Vβ CDR3 sequencing. We report that these TSAs can expand sizeable populations of CD8 T cells and, therefore, represent attractive targets for EOC immunotherapy

Si Traceable High Precision Spectroscopy Of Ozone Using A Quantum Cascade Laser At 9.5 Micrometer

International audienceFor subDoppler ozone spectroscopy, we have implemented a QCL laser stabilisation scheme based on an optical frequency comb (OFC) referenced to the international system of units (SI) via an optical fiber which links to the REFIMEVE network [6]. To compare the QCL at 31 THz to a reference laser frequency comb at 193 THz (SI traceable), a sum frequency generation (SFG) scheme between the QCL and an OFC at 162 THz in an oriented patterned GaAs crystal is implemented