Micro (mi)RNAs have recently been found to play an important role in cancer biology. In order to further understand how miRNAs affect prostate tumour progression, we evaluated miRNA expression in two invasive prostate tumour lines, PC3 and DU145. We then focused our evaluation on a novel miRNA, miR-105, whose levels were significantly decreased in both tumour cell lines as compared to normal prostate epithelial cells. As miR-105 levels were reduced in prostate tumour cell lines, we restored its expression following transfection of cells with mimic constructs to over-express miR-105 in both cell lines, in order to determine its effect on various tumourigenic properties. Over-expression caused decreased tumour cell proliferation, anchorage-independent growth and invasion in vitro and inhibited tumour growth in vivo. We further identified CDK6 as a putative target of miR-105, which likely contributed to its inhibition of tumour cell growth. Our results suggest that miR-105 inhibits tumour cell proliferation and may be an interesting target to regulate tumour growth or potentially used as a biomarker to differentiate between less and more aggressive tumours in patients.

MSc (Microbiology) / Department of Microbiology / Background: Prostate cancer (PCA) is a major health concern in males, particularly those above 40 years old. It is the most common form of cancer in males worldwide, including South Africa. In South Africa, the rate of histologically diagnosed prostate cancer is 40 per 100 000 in whites and 14 per 100 000 in blacks, and 1 in 8 men will develop PCA in their lifetime. Several reports have suggested the association of viruses in the pathogenesis of prostate cancer. Objectives: This study was aimed at identifying Hepatitis B virus (HBV), human papilloma virus (HPV) and human herpes virus type 8 (HHV-8), implicated in other forms of cancer, in a cohort of South African patients with either PCA or benign prostatic hyperplasia (BPH); and to seek possible associations thereof. Methods: The study group comprised 187 male patients recruited from Polokwane Hospital presenting with either PCA (staged by Gleason scores) or BPH. Enzyme-linked immunosorbent assay was used to detect antibodies to HHV-8 and HPV; and to detect hepatitis B surface antigen (HBsAg) in the plasma of the study subjects. Total DNA was extracted from plasma and targeted for the identification of HBV and HHV-8 DNA by nested PCR protocols. The HBV nested PCR protocol amplifies a 336bp fragment of the overlapping surface polymerase gene of HBV. The HHV-8 nested protocol amplifies a 233bp fragment of the ORF 26 gene of HHV-8. Amplified DNA products were purified, sequenced by the Sanger protocol and phylogenetically analysed for viral genotypes. The Chi-square test was used to infer statistically significant differences in the level of detection of viruses and the stage of prostate cancer development. Results: Of the 187 participants, a seroprevalence of 4.8% (9/187, HBsAg), 5.3% (10/187, HPV IgG antibody) and 27% (33/124, HHV-8 IgG antibody) were observed. HBsAg was detected more in individuals with BPH than those without and this was statistically significant at ( 2=6.0, p< 0.05). HHV-8 DNA was detected more in individuals in the 60-79 years age range and this was statistically significant at ( 2=61.1, p< 0.05). Occult HBV infection (that is the presence of HBV DNA in the absence of HBsAg) was detected in 23/178 (12.9%) of patients. Taking into account occult HBV infection, the overall prevalence of HBV was 17.7%. HBV genotype E was more prevalent (86.7%) followed by genotype A (13.3%). HHV-8 genotypes K and R were inferred. Apparently, this is the first report on the identification of HHV-8 genotypes K and R from South Africa. Conclusion: The current study has demonstrated for the first time, the presence of genotypes K and R of HHV-8 in South Africa. This study also suggests that there is a high level of occult genotype E HBV infection. Future studies will explore the virome in prostate cancer biopsies.

Introduction: Prostate-specific membrane antigen (PSMA)-based imaging and theranostics have played an important ole in the diagnosis, staging, and treatment of prostate cancer (PCa). We aimed to evaluate the acceptance and use of PSMA theranostics among German urologists.- Methods: An anonymous online questionnaire was sent via survio.com to the members of the German Society of Urology (DGU). - Results: Seventy-two percent of participants performed PSMA positron emission tomography (PET) imaging regularly in biochemically recurrent PCa. Overall, 61% of participants considered PSMA-radioligand therapy to be very useful or extremely useful. PSMA PET imaging in high-risk PCa is more often considered by urologists working in a university setting than in nonuniversity settings or medical practices (51% vs. 25%, p < 0.001). Most perform PSMA-radioligand therapy as an option after all approved systemic treatments for metastatic metastatic castration-resistant PCa (56%) or after cabazitaxel (14%). A total of 93.9% and 70.3% of respondents consider the lack of reimbursement by health insurance to be the main obstacle to using PSMA PET imaging or radioligand therapy, respectively. - Discussion/Conclusion: PSMA-based maging/theranostics are already widely applied but would find even more widespread use if reimbursement is clearly regulated by health insurance in Germany.

Overexpression of tumor-derived mutant p53 is a common event in tumorigenesis, suggesting an advantageous selective pressure in cancer initiation and progression. Given that p53 is found to be mutated in 50% of all human cancers, restoration of mutant p53 to its wild type biological function has been a widely sought after avenue for cancer therapy. Most research efforts have largely focused on restoration of mutant p53 by artificial means given that p53 has some degree of conformational flexibility allowing for introduction of short peptides and artificial compounds. Recently, theoretical modeling and studies focused on restoration of mutant p53 by physiological means has raised the question of whether there are effective therapies worth exploring that focus on global physiological mechanisms of restoration of p53. Herein, we provide computational analysis of the thermodynamic stabilities of both wild-type and mutant p53 core domains by studying their respective minimum potential energies. Also, it is widely accepted that wild type p53 is modulated by various acetyl transferases as well as deactylases, but whether this mechanism of p53 modulation can be exploited for physiological restoration of mutant p53 remains under intense investigation. Using prostate cancer cell lines representative of varying stages of aggressiveness as a model, we show that ID4 dependent acetylation promotes mutant p53 DNA-binding capabilities to its wild type consensus sequence, thus regulating p53-dependent target genes leading to subsequent cell cycle arrest and apoptosis. Specifically, we identify that ID4 promotes acetylation of K373 and to a lesser extent K320, in turn regulating p53-dependent biological activities. Together, our data provides computational analysis of the core domain of certain mutant forms of p53 and a molecular understanding of ID4 dependent acetylation that suggests a strategy of enhancing p53 acetylation at sites K373 and K320, critical sites of post translational modification of p53, that may serve as a viable mechanism of physiological restoration of mutant p53 to its wild type biological function.

published_or_final_version / abstract / Anatomy / Doctoral / Doctor of Philosophy

No description available.

Le cancer de la prostate (CaP) est le plus diagnostiqué chez les hommes au Canada et représente le troisième cancer le plus meurtrier au sein de cette population. Malgré l’efficacité des traitements de première ligne, de nombreux patients finiront par développer une résistance et, le cas échéant, verront leur CaP progresser vers une forme plus agressive. Plusieurs paramètres, essentiellement cliniques, permettent de prédire la progression du CaP mais leur sensibilité, encore limitée, implique la nécessité de nouveaux biomarqueurs afin de combler cette lacune. Dans cette optique nous nous intéressons au facteur de transcription NF-κB. Des études réalisées au laboratoire et ailleurs, associent RelA(p65) à un potentiel clinique dans le CaP, soulignant ainsi l’importance de la voie classique NF-κB. L’implication de la voie alternative NF-κB dans la progression du CaP a aussi été suggérée dans une de nos études illustrant la corrélation entre la distribution nucléaire de RelB et le score de Gleason. Alors que la voie classique est largement documentée et son implication dans la progression du CaP établie, la voie alternative, elle, reste à explorer. La présente thèse vise à clarifier l’implication de la voie alternative NF-κB dans le CaP et répond à deux objectifs fixés dans ce but. Le premier objectif fut d’évaluer l’impact de l'activation de la voie alternative NF-κB sur la biologie des cellules cancéreuses prostatiques. L’étude de la surexpression de RelB a souligné les effets de la voie alternative NF-κB sur la prolifération et l'autophagie. Étant ainsi impliquée tant dans la croissance tumorale que dans un processus de plus en plus associée à la progression tumorale, quoique potentiellement létal pour les cellules cancéreuses, son impact sur la tumorigénèse du CaP reste encore difficile à définir. Il n'existe, à ce jour, aucune étude permettant de comparer le potentiel clinique des voies classique et alternative NF-κB. Le second objectif de ce projet fut donc l'analyse conjointe de RelA(p65) et RelB au sein de mêmes tissus de patients atteints de CaP afin de déterminer l'importance clinique des deux signalisations NF-κB, l'une par rapport à l'autre. Le marquage immunofluorescent de RelA(p65) et RelB en a permis l'analyse quantitative et objective par un logiciel d'imagerie. Nos travaux ont confirmé le potentiel clinique associé à RelA(p65). La variable RelA(p65)/RelB s’est, elle, avérée moins informative que RelA(p65). Par contre, aucune corrélation entre RelB et les paramètres cliniques inclus dans l'étude n’est ressortie. En définitive, mon projet de thèse aura permis de préciser l'implication de la voie alternative NF-κB sur la biologie du CaP. Son impact sur la croissance des cellules cancéreuses prostatiques ainsi que sur l'autophagie, dénote l’ambivalence de la voie alternative NF-κB face à la tumorigénèse du CaP. L’étude exhaustive de la signalisation NF-κB souligne davantage l'importance de la voie classique dont l’intérêt clinique est principalement associé au statut de RelA(p65). Ainsi, bien que RelB n’affiche aucun potentiel en tant que biomarqueur exploitable en clinique, l’analyse de l’intervention de la voie alternative NF-κB sur la biologie des cellules cancéreuses prostatiques reste d’intérêt pour la compréhension de son rôle exact dans la progression du CaP. / Prostate cancer (PCa) is the most frequently diagnosed cancer and represents the third cause of cancer-death in Canadian men. Despite effective first-line therapies, many patients experience disease recurrence where PCa progresses toward a more aggressive form. Several parameters, largely clinical, have been used to predict the progression of PCa but their accuracy is still limited and implies the need for new biomarkers to fill this gap. Previous research from the laboratory has demonstrated that the transcription factor NF-B, and its nuclear localization, could be such a prognostic biomarker. Studies in our laboratory and elsewhere have correlated RelA(p65) with a clinical progression in PCa, underlining the importance of the classical NF-B pathway. The involvement of the alternative NF-B pathway in the progression of PCa was also suggested in one of our studies showing the correlation between the nuclear distribution of RelB and Gleason score. While the classical pathway is well documented and its involvement in the PCa progression established, the alternative NF-B pathway remains largely unexplored. This thesis describes two research objectives that aims to clarify the involvement of the alternative NF-B pathway in PCa. The first objective assessed the impact of the alternative NF-B pathway activation on the biology of PCa cells. RelB overexpression in 22RV1 PCa cells highlighted an effect of the alternative NF-B pathway on cell proliferation and autophagy. Its dual role in cell growth and a form of cell death requires further study to understand the balance of these in PCa tumorigenesis. To date no study has addressed the comparative prognostic potential of both the classical and alternative NF-B pathways simultaneously. Therefore the second objective of this research project was to analyze both RelA(p65) and RelB at a cellular level in the same tissue of patients with PCa to determine their unique and combined contribution to predicting biochemical recurrence in patients. This analysis was possible through immunofluorescent labeling of RelA (p65) and RelB, and was followed by a quantitative and objective analysis using an appropriate software. Our work confirmed the predictive value of RelA(p65) for biochemical recurrance. Combining RelA(p65) with RelB weakened the association, and RelB on its own was not found to predict biochemical recurrance. Ultimately, the research presented here has clarified the involvement of the alternative NF-B pathway on the biology of PCa. Its impact on the growth of PCa cells as well as autophagy reveals the dual role of the alternative NF-B pathway in PCa tumorigenesis. This exhaustive study of NF-B in PCa tissues further underscores the importance of the classical pathway whose clinical interest is mainly associated with RelA(p65) status. Thus, although RelB shows no potential as a clinically exploitable biomarker, further studies are needed to determine whether RelB contributes, either positively or negatively, and in a temporal fashion, to PCa progression.

Résumé : La protéolyse par les proprotéines convertases (PC) représente une étape cruciale de maturation pour de nombreux peptides et protéines destinés aux voies de sécrétions cellulaires. Parmi ces substrats des PC, de nombreuses molécules participent aux étapes clés de progression tumorale. L’enzyme PACE4, une des PC, est d’ailleurs surexprimée dans le cancer de la prostate et des études antérieures réalisées dans notre laboratoire démontrent que cette protéase occupe un rôle essentiel et non redondant dans la progression du cancer de la prostate. Puisque PACE4 représente une cible thérapeutique potentielle pour le traitement du cancer de la prostate, l’objectif principal des travaux présentés dans cette thèse vise à développer un inhibiteur pharmacologique de PACE4 et d’évaluer son potentiel thérapeutique. Le développement d’inhibiteur spécifique à la PACE4 représente un défi de taille, puisque le site actif des PC démontre un fort niveau d’homologie. Bien que les sous-sites S1 à S4 des PC soient hautement conservés, la littérature suggère qu’il existe des déterminants moléculaires exploitables au sein des sous-sites S5 à S8. Ainsi, ces observations suggèrent qu’une sélectivité d’inhibition pourrait provenir de courts peptides. En analysant les profils d’inhibition obtenus pour divers peptides inhibiteurs des PC, la séquence Ac-LLLLRVKR-NH[indice inférieur 2], nommée Multi-Leu, a été identifiée comme inhibiteur permettant d’obtenir une préférence d’inhibition 20 fois plus importante pour PACE4 que pour Furine. Dans le but d’améliorer les propriétés pharmacocinétiques du composé et permettre son utilisation comme inhibiteur pharmacologique, des études de relation structure-activité ont été conduites. Ces études ont permis de déterminer que le peptide Multi-Leu est sujet à une dégradation par des exopeptidases, et par conséquent l’addition d’acides aminés non naturels aux extrémités N et C-terminales permet d’augmenter la stabilité du composé. Suivant cette étude, la modification amidinobenzylamide (Amba) a été introduite en position P1, permettant d’augmenter la puissance d’inhibition du composé, ainsi qu’un stéréoisomère D-Leucine en position P8. La caractérisation du potentiel inhibiteur du peptide Ac-[DLeu]LLLRVK-Amba démontre l’efficacité du peptide in vivo alors qu’une administration par voie intra veineuse du composé parvient à freiner la progression tumorale dans un modèle de xénogreffes de cancer de la prostate. Dans ce modèle, l’analogue du peptide Multi-Leu parvient à bloquer la néovascularisation tumorale en plus d’induire la quiescence et l’apoptose dans les tumeurs traitées. // Abstract : Numerous secreted peptides or proteins require a proteolytic activation by the proprotein convertases (PC) to fully gain their biologic activities. Among substrates of the PC family, there exist various cancer-related molecules. The enzyme PACE4, one of the seven kexinlike PC has been demonstrated to be overexpressed in prostate cancer and to have a nonredundant role in prostate cancer progression. Since PACE4 is a validated therapeutic target for prostate cancer, the main aim of this thesis was to develop a pharmacologic PACE4 inhibitor and to evaluate its therapeutic potential. The development of PACE4 specific inhibitors represents a challenge since PC share an important homology level within their active site. Whereas S1 to S4 subsites appear to be highly homologous within the PC family, litterature suggests that significant differences exist in subsites S5 and beyond, suggesting that peptide compound could result in specific inhibitors. In this thesis, the Multi-Leu peptide (Ac-LLLLRVKR-NH[subscript 2]) was identified as a selective PACE4 inhibitor, which displays a 20-fold inhibitory preference toward PACE4 over furin. In order to improve Multi-Leu peptide pharmacokinetic profile, structureactivities relationship studies were performed and allowed for the identification of two modifications that increase both inhibitory properties and stability of this molecule. Peptide resulting from introduction of an arginine mimetic residue amidinobenzylamide (Amba) in P1 and a stereoisomer D-Leucine in position P8 displayed an improved pharmacokinetic profile. Futhermore, intravenous administration of the compound Ac-[DLeu]LLLRVKAmba significantly inhibited prostate cancer progression in a LNCaP xenograft model of prostate cancer. This Multi-Leu peptide analog also inhibited tumor neovascularisation along with inducing cell quiescence and apoptosis in tumors of treated animals.

Évaluation et modélisation de la qualité de vie des patients traités pour un cancer de la prostate.Le cancer de la prostate « CaP » est le cancer le plus fréquent en France, chez l'homme avec 72.5000 nouveau cas chaque année. Il y a quelques années la problématique du CaP était d'augmenter le taux de survie, à présent elle se concentre sur l'amélioration de la «QdV» des patients. La plupart des études de QdV de patients atteints de CaP utilisent des questionnaires de QdV qui conduisent à la construction d'échelle de QdV ne donnant pas d'information sur l'utilité individuelle. Il nous parait donc essentiel d'évaluer d'une part la QdV des cas incidents ou avec progression / récidive (tous les types confondus) afin de connaître pour chaque type de prise en charge la QdV et d'estimer d'autre part son utilité par la méthode dite de Standard Gamble. Ces deux aspects de la QdV répondent à une réalité clinique et à un besoin évaluatif et comparatif voire médico-économique (analyse en QALYs ou Espérance de vie ajustée sur la QdV). Nous avons mené une étude de type cohorte-prospective de 305 patients traités pour un CaP dans le département de l'Hérault de du Gard. Le recueil de données était effectué à partir de 7 questionnaires de QDV « standardisés et validés en France » et l'utilité étaient renseignés avant le début du traitement à 2 mois, 6 et 12 mois après le début du traitement. L'étude retrouvait que la QdV des patients était différents selon les modalités thérapeutiques. Les patients dans le groupe « prostatectomie » avaient plus de dysfonctions sexuelles et problèmes d'incontinence urinaire. Les patients dans le groupe « radiothérapie » avaient plus de dysfonctions intestinales et des symptômes liés au traitements hormonaux du CaP. Les symptômes liés aux troubles hormonaux du CaP, les dysfonctions sexuelles, l'insomnie, l'incontinence urinaire, et la somme de co-morbidités sont des facteurs prédictifs significatifs de l'utilité. / Treatments for prostate cancer "PCa" are almost equivalent in terms of survival; however,they can provoke different side effects affecting quality of life "QoL" patients. It is thereforeessential to assess on one hand the QoL of patients newly diagnosed with PCa as wells asthose newly diagnosed with a recurrence of PCa to know the quality of life associated witheach kind of treatment is and on the other hand to evaluate their utility scores by the methodof “ Standard Gamble”. We conducted a prospectively cohort study of 305 patients treated forPCa in the departments of Hérault and Gard. The study found that QoL of patients wasdifferent according to treatment modalities. Patients in the group "prostatectomy" had moresexual dysfunction and urinary incontinence. Patients in the group “radiotherapy" had morebowel dysfunction and symptoms related to hormone treatment. Symptoms related tohormonal disorders of PCa, sexual dysfunction, insomnia, urinary incontinence, and the sumof co-morbidities are significant predictors of utility score.

Capillary electrochromatography (CEC) is a major capillary electrophoresis (CE) mode that have been interfaced to mass spectrometry (MS) for sensitive and selective analysis of chiral compounds. This research expands CEC applications in cancer biomarker and chiral CE analysis. Chapter 1 is a review of liquid chromatography-mass spectrometry (LC/MS), gas chromatography-mass spectrometry (GC/MS), and capillary electrophoresis mass spectrometry (CE/MS) for analysis of metabolites in prostate cancer diagnostics and therapies. In this chapter, a literature survey was performed within the databases PubMed, 4 Caplus/Webline and Web of Sciences. A total 17 studies reporting on various analytical platforms for metabolite identification in prostate cancer research, which often include case-control comparison were identified and reviewed. Chapter 2 described the analysis of metabolite biomarkers in prostate cancer tissues by capillary electrochromatography mass spectrometry. In this chapter, a capillary CEC–MS/MS method was developed for the simultaneous determination and separation of eight proofs of concept (POC) metabolites (betaine, malate, proline, N-acetyl aspartate, N-acetylglucosamine, uracil, xanthine, and alanine) as potential prostate cancer diagnostic markers. A polymeric monolith column with a hydrophilic crosslinker and strong anion-exchange mixed-mode has been fabricated by an in situ copolymerization of vinyl benzyl trimethylammonium chloride, and bisphenol A glycerolate dimethacrylate (BisGMA) in the presence of methanol and dodecyl alcohol as porogens and AIBN as initiator. After CEC separation, samples were analyzed by a triple–quadrupole mass spectrometer operated in positive ion mode. After optimization, the data showed that the CEC-MS/MS method using monolithic column achieved a much better chromatographic selectivity compared to coated columns and increased sensitivity than bare fused silica column The effect of mobile phase pH, ACN percentage and additive were studies. Under the optimum mobile phase conditions, this method was carried out to separate and detect eight metabolites in the biopsy sample. The LOD for the metabolites is between 50nM-100nM. This method has successfully used to examine patients’ prostate cancer with an accuracy of 95%. Chapter 3 demonstrates Insights into Chiral Recognition Mechanisms in CEC using linear salvation energy relationship. By varying the linker (amide and carbamate), head group (alanine, leucine, and valine) and chain length (C8, C10 and C12) of the amino acid bound surfactants; monolithic column was made to ultimately understand the factors governing chiral stationary solid phase. Through the comparison of system parameters, we can see that surfactant head group, linker and chain length affect the separation of achiral and chiral compounds. Also, with the same type surfactant, data was presented to show how the trend of LSER parameters and how it affects separation between in CEC. This study showed the predictive capability of LSER to understand the aforementioned intermolecular processes controlling retention and by doing so, be able to quantitatively predict the experimental conditions to achieve an acceptable chiral separation.