La dépendance de la croissance des tumeurs prostatiques vis-à-vis des androgènes est mise à profit pour traiter les cancers diagnostiqués à un stade avancé. Lablation androgénique entraine inévitablement lapparition de cancers résistants à la thérapie antihormonale. Dans ces cancers, la signalisation du récepteur aux androgènes (RA) semble réactivée par différents mécanismes, en dépit de la concentration sérique réduite en androgènes. A coté de la signalisation androgénique, la signalisation induite par les récepteurs de la famille du REGF (encore appelée famille ERBB) est impliquée dans la prolifération, la survie, linvasion et langiogenèse du cancer de la prostate. Ces récepteurs sont aussi capables de se substituer aux androgènes pour activer le RA. Des résultats antérieurs obtenus par dautres équipes ont montré que les androgènes régulaient lexpression du REGF et dERBB2 dans les cellules cancéreuses prostatiques, sans préciser à quel(s) niveau(x) seffectue cette régulation. Le but de ce travail est de déterminer par quels mécanismes les androgènes agissent pour contrôler lexpression des récepteurs ERBB1-3 dans des lignées cancéreuses prostatiques présentant différentes sensibilités aux androgènes, à savoir les cellules LNCaP dont la prolifération est androgéno-dépendante et les cellules 22Rv1 dont la prolifération est androgéno-indépendante. En plus du RA, les cellules 22Rv1 expriment un RA dépourvu du domaine carboxy-terminal contenant le domaine de liaison à lhormone (RAΔCTD) et dont lorigine et la fonction nétaient pas connues. Dans les cellules LNCaP, nous avons montré que le RA activé par la dihydrotestostérone (DHT) stimule le taux des transcrits et des protéines REGF et répriment ceux dERBB2 en agissant à un niveau transcriptionnel. La DHT ninfluence pas les taux dERBB3. Dans les cellules 22Rv1, la DHT ninfluence pas les taux du REGF et dERBB2 ni le taux des transcrits de trois gènes endogènes androgéno-sensibles que nous avons testés. A laide de siRNA dirigés contre la région codant le domaine amino-terminal (NTD) ou carboxy-terminal du RA, nous avons montré que le RAΔCTD résulte de la présence de transcrit différent de celui codant la forme longue. La capacité de ces siRNA à éteindre lexpression de la forme longue, ou de la forme longue et de la forme courte du RA, nous a permis détudier la contribution des deux isoformes à réguler lexpression de gènes et la viabilité des cellules 22Rv1. Nous avons ainsi montré que la présence du RAΔCTD contrôle le taux des protéines REGF et ERBB2 à un niveau post-transcriptionnel. De plus, le RAΔCTD et dans une moindre mesure, le RA contribuent à lexpression des trois gènes androgéno-sensibles endogènes testés et à la viabilité des cellules 22Rv1 cultivées dans un milieu appauvri en stéroïdes. Une inhibition plus importante de la viabilité cellulaire était observée en présence dun inhibiteur tyrosine kinase des récepteurs. En conclusion, notre étude montre que différents mécanismes régulés par les androgènes ou leurs récepteurs contrôlent lexpression du REGF et dERBB2 dans des cellules présentant différentes sensibilités aux androgènes. Nous avons par ailleurs identifié le RAΔCTD comme un régulateur important du phénotype hormono-réfractaire des cellules 22Rv1. Des études complémentaires devront déterminer si la participation du RAΔCTD à la viabilité des cellules 22Rv1 passe par la régulation de lexpression du REGF ou dERBB2. De plus, si lexpression du RAΔCTD venait à se confirmer dans les cancers de la prostate, le développement de nouvelles thérapies ciblant le domaine NTD ou lexpression du RA constituerait une alternative intéressante aux thérapies actuelles dirigées contre le CTD.

Intraprostatic injection of BTX-A has demonstrated clinical improvement in men with bladder out let obstruction. Firstly, we investigated the mechanisms of action of BTX-A on the prostate. Secondly, an animal model for nonbacterial prostatitis in rats was developed using intraprostatic injection of capsaicin, an agent thought to excite c-afferent fibers and cause neurogenic inflammation. The analgesic and anti-inflammatory properties of Botulinum toxin type A (BoNT-A) was tested in this model. (1) Adult male Spragu-Dawley rats were injected with varying doses of BTX-A into the prostate, and the prostates were harvested after 1 or 2 weeks. The effects of BTX-A on prostate histology, and the proliferative and apoptotic indexes were determined using hematoxylin and eosin staining, proliferative cell nuclear antigen staining and TUNEL staining, respectively. Changes in a1A adrenergic receptor and androgen receptor were evaluated by Western blotting. (2) Adult male Spragu-Dawley rats were injected with varying doses of capsaicin into the prostate. The nociceptive effects of capsaicin were evaluated for 30 min by using a behavior approach; the prostate was removed for histology and cyclooxygenase (COX) 2 concentration measurement. Evans blue (50mg/kg) was also injected intravenously to assess for plasma protein extravasation. The other set of animals were injected with up to 20U of BoNT-A into the prostates 1 wk prior to intraprostatic injection of 1000umol/l capsaicin. (1) One week after BTX-A injection generalized prostate atrophy was observed. There was a significant increase in apoptotic cells (12, 16 and 22-fold), and decrease in proliferative cells (38%, 77% and 80%) and a1A adrenergic receptor (13%, 80% and 81%) for 5U, 10U and 20U, respectively. There was no significant change in androgen receptors. The effects were decreased 2 weeks after BTX-A treatment. (2) Capsaicin dose dependently induced modifications in pain behavior closing of the eyes, hypolocomotion, and inflammatory changes: increase of inflammatory cell accumulation, COX2 expression, and plasma extravasation at the acute stage, but completely recovered at 1 wk. BoNT-A pretreatment dose dependently reversed pain behavior and inflammation. BoNT-A 20U significantly decreased inflammatory cell accumulation, COX2 expression, and Evans blue extraction (82.1%, 93.0% and 50.4, respectively), and reduced pain behavior (66.% for eye score and 46.5% for locomotion score). Conclusion (1): BTX-A injection into the prostate alters cellular dynamics by inducing apoptosis, inhibiting proliferation and down-regulating a1A adrenergic receptors. BTX-A may potentially be the drug that has dual actions on the static and dynamic components of benign prostatic hyperplasia. (2): Intraprostatic capsaicin injection induced neurogenic prostatitis and prostatic pain, and may be a useful research model. BoNT-A produced anti-inflammatory and analgesic effects, and support clinical evaluation in prostatitis.

Estrogens maintain the appropriate androgen-estrogen balance for normal regulation of the structure and function of the male reproductive tract, including the prostate gland. This research investigated viability of cells and expression of selected genes in prostate carcinoma cells (PC-3) exposed to bisphenol A (BPA), an estrogen-like substance present in a number of plastic materials. PC-3 cells are able to metabolize BPA at concentrations below 100 µM. BPA exposure at concentrations between 1nM and 100 µM does not increase or significantly reduce cell viability of these cells. Although the genes investigated in this study (GSTP1 and MGMT) did not show a significant change in expression following in vitro exposure to BPA, the positive control ethinyl estradiol (EE2) caused an increase in GSTP1 expression at mRNA level. These results indicate that BPA does not affect the viability of prostate cells, and motivate a need for further research to identify other genes that could be affected by BPA.

Prostate cancer, one of the most common cancers among men, can be relatively harmless or extremely aggressive. The most widely used biomarker for the disease, the PSA test, is not independently diagnostic or prognostic of prostate cancer. One of the main challenges of prostate cancer research is to find reliable and effective prognostic biomarkers that will predict cancer recurrence following surgery, in order to identify clinically significant prostate cancer and improve management of the disease. In recent years, microRNAs (miRNAs) have been identified as master regulators of cellular processes, and dysregulated miRNAs have been associated with cancer development and progression. The intent of my PhD research program was to uncover novel miRNAs that contribute to prostate cancer pathogenesis in order to assess their potential as predictors of clinical progression. By analyzing a large cohort of primary prostate cancer samples, we have discovered that microRNA-221 (miR-221) is associated with metastasis and biochemical recurrence in prostate cancer, and is downregulated in TMPRSS2:ERG fusion gene- positive tumors. In addition, we have determined that microRNA-182 (miR-182) is overexpressed in prostate cancer and is associated with increased metastasis and clinical progression by targeting a tumors suppressor Forkhead box O1 (FOXO1). Overall, this work introduces novel candidate miRNA genes and downstream targets that are aberrantly expressed in more aggressive prostate cancer, and presents a potentially significant role for miRNAs as prognostic biomarkers that are associated with clinical progression, and perhaps aids in defining how miRNAs might one day serve as anti-cancer therapeutic agents.

Selective receptor modulators have been developed for steroid hormone receptors as a new class of mechanism-based drugs for treatment of hormone related diseases. We investigated an alternative mechanism-based strategy for treating various cancers with selective aryl hydrocarbon receptor modulators (SAhRMs), such as diindolylmetane/(DIM), 2,3,7,8-tetrachlorodibenzo-pdioxin/( TCDD), and 6-6-methyl-1,3,8-trichlorodibenzofuran/(MCDF) that exhibit antiproliferative activity in several cancer cell lines. MDA-MB-453 and BT-474 are estrogen receptor/(ER) negative breast cancer cell lines that express a functional aryl hydrocarbon receptor/(AhR) and treatment with SAhRMs significantly inhibited MDA-MB-453/BT-474 cell proliferation but did not significantly affect the percent distribution of cells in G0/G1/S/G2/M phases of cell cycle. TCDD and the SAhRMs had minimal effects on the expression of various cellular kinases. These data coupled with results obtained for other activated kinase pathways demonstrate that TCDD and SAhRMs uniquely inhibit growth of ER-negative MDA-MB 453/BT-474 breast cancer cells through kinase independent pathways. However, the SAhRMs induced HES-1, an antiproliferative transcription factor, in both cell lines and this might represent a possible mechanism for the growth inhibitory effects observed with these compounds. We proved that ring substituted DIMs exhibit androgenic/antiandrogenic activities in androgen receptor/(AR)-positive LNCaP/22RV1 prostate cancer cell lines resulting in antiproliferative activities. These antiproliferative activities were accompanied by antiandrogenic activity and structure-dependent down regulation of AR. The ring-substituted DIMs also induced both non-steroidal anti-inflamatory drug-induced gene-1/(NAG-1) and activating transcription factor 3/(ATF-3), two anti-proliferative/apoptotic genes which are responsible in part for the inhibitory effects of these compounds on the proliferation of prostate cancer cells.

Prostate cancer is the second leading cause of death from cancer in men in the United States. Most men will die of the advanced, metastatic form of the disease. Thus, treatment strategies targeting the metastatic form of the disease are especially needed. Emerging research on metastatic cancer highlights the importance of the microenvironment in cancer progression and metastasis, with an emphasis on deregulated developmental signaling in cancer progression. Research in model organisms has shown that developmental signaling pathways are regulated by various components of the extracellular matrix, including heparan sulfate proteoglycans. In the model system Drosophila, the heparan sulfate proteoglycan Trol is needed for Hhdependent proliferation in quiescent neural stem cells. In collaboration with others, I have shown that the human homolog of Trol, PERLECAN, regulates SONIC HEDGEHOG-dependent proliferation in advanced prostate cancer by two different mechanisms. This makes PERLECAN a potential drug target and biomarker for prostate cancer screening and treatment. My results also validate the discoveries made in Drosophila in the context of human disease. With this validation, I propose and describe the Drosophila Ejaculatory Bulb (EjB) as model for prostate cancer and prostate aging.

Prostate cancer is one of the most common malignant tumors in solid organs of old men. Prostate-specific antigen (PSA) is a valuable prostate cancer biomarker that is now wildly used for population screening, diagnosis, and monitoring of patients with prostate cancer. Howere it is reported that PSA is not feasible to discriminate the progress of prostate cancer, so many investigators still works on developing new biomarker of prostate carcinoma. Here, we propose the study of differentially expressed prostate proteins in blood of patients. With the aid of two-dimensional polyacrylamide gel electrophoresis (2-DE) and matrix-assisted laser desorption-induced time of flight (MALDI-TOF) mass spectrometry, comparison of normal men and prostate cancer patients serum proteins and analysis protein variation of different stages of prostate cancer serum. We find 31 and 17 protein spots overexpression in cancer development and after treatment, respectively. At present, with the aid of SWISS-PORT database and MALDI-TOF mass spectrometry, we had identified fibrinogen gamma chain, fibrinogen alpha/alpha-E chain, major histocompatibility complex (MHC), class I, C and Mayven were overexpressed in prostate cancer development, where Mayven is fist reported by us.

Thesis (Ph. D.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves.

Thèse de doctorat : Sciences du vivant : Strasbourg 1 : 2007. / Thèse en français avec un extrait de publication en anglais. Titre provenant de l'écran-titre. Bibliogr. f. 185-203.

Reproduction de : Thèse d'exercice : Médecine. Oncologie - Radiothérapie : Nantes : 2008. / Bibliogr.