La famille des protéines SIBLINGs comprend la sialoprotéine osseuse (BSP), lostéopontine (OPN), la sialophosphoprotéine de dentine (DSPP), la protéine de matrice de dentine 1 (DMP1), la phosphoglycoprotéine de matrice extracellulaire (MEPE) et lénameline (ENAM). Comme leur nom lindique, ces protéines ont dabord été identifiées au niveau de la matrice minéralisée de los et de la dent. Durant la dernière décennie, notre Laboratoire et dautres équipes ont démontré que cette famille de protéines est également exprimée par un certain nombre de tissus tumoraux. Nous avons entrepris ce doctorat dans la continuité des projets de recherche menés au Laboratoire sintéressant à létude des SIBLINGs au cours de la progression tumorale et métastatique. La première partie de notre projet a consisté à investiguer les mécanismes de régulation de lexpression du gène de la BSP humaine au niveau de cellules ostéoblastiques. Le facteur de transcription Runx2 est un facteur clé de la régulation des gènes osseux. Dès lors, nous avons émis lhypothèse selon laquelle linduction de lexpression du gène de la BSP observée au cours de la différenciation ostéoblastique pourrait être sous la dépendance de ce facteur. Nous avons ensuite étudié la régulation du gène de la BSP au niveau de cellules cancéreuses mammaires. En effet, nous avons voulu déterminer si lexpression de la BSP était sous la dépendance de mécanismes de régulation transcriptionnelle différents de ceux observés au niveau de cellules dorigine osseuse. Lobjectif final étant de bloquer spécifiquement lexpression de la BSP au niveau des tumeurs. Notre stratégie a dabord consisté à identifier les principaux facteurs transcriptionnels impliqués dans cette régulation puis à en étudier limpact sur lactivité du promoteur de la BSP au niveau des deux types cellulaires considérés. Dans la deuxième partie de ce projet, nous nous sommes consacrés à létude dun autre membre de la famille des SIBLINGs, lOPN, afin den identifier le rôle au niveau des gliomes humains. Précédemment, il a été démontré que lOPN est surexprimée dans les gliomes et ce, en corrélation avec le grade de la tumeur. Cependant, il ny a que peu détudes décrivant le rôle de lOPN dans les gliomes. Dès lors, nous avons voulu vérifier limportance de lOPN au cours du développement des gliomes en utilisant la technique dinterférence à lARN.

Endothelial Progenitor Cells (EPCs) are thought to participate in the healing of injured vascular endothelium by incorporating into the defect sites to mediate endothelial recovery. Recently, osteopontin (OPN) was shown to be fundamental in accelerating estrogen-dependent healing of injured blood vessels. Here, we are investigating the effect OPN has on EPC behavior. Late outgrowth human EPCs (LEPCs) were derived from circulating monocytes isolated by leukophoresis, and grown in culture until passage six. L-EPCs were then assayed for adhesion, spreading, chemotaxis, and haptotaxis, as well as resistance to detachment by flow electric cellsubstrate impedance sensing (ECIS). The results of standard and ECIS methods showed both dose and time dependent responses in cell adhesion and spreading. In addition, OPN promoted haptotactic migration of EPCs in Boyden chamber assays. LEPCs seeded onto 10μM OPN substrates and exposed to laminar flow had grater survival and higher resistance to detachment than OPN/static and flow only conditions. CD44 and !1 integrins were only responsible for approximately 50% of LEPCs adhesion to OPN compared to the unblocked condition. Western blots showed that Rho GTPases were activated in L-EPCs seeded on OPN. However, this activation could not be completely blocked by either CD44 or !1 integrin antagonists. These data confirm the direct effects of OPN on EPCs adhesion, and suggest that OPN works by mediating cell adhesion during vascular injury.

Endothelial Progenitor Cells (EPCs) are thought to participate in the healing of injured vascular endothelium by incorporating into the defect sites to mediate endothelial recovery. Recently, osteopontin (OPN) was shown to be fundamental in accelerating estrogen-dependent healing of injured blood vessels. Here, we are investigating the effect OPN has on EPC behavior. Late outgrowth human EPCs (LEPCs) were derived from circulating monocytes isolated by leukophoresis, and grown in culture until passage six. L-EPCs were then assayed for adhesion, spreading, chemotaxis, and haptotaxis, as well as resistance to detachment by flow electric cellsubstrate impedance sensing (ECIS). The results of standard and ECIS methods showed both dose and time dependent responses in cell adhesion and spreading. In addition, OPN promoted haptotactic migration of EPCs in Boyden chamber assays. LEPCs seeded onto 10μM OPN substrates and exposed to laminar flow had grater survival and higher resistance to detachment than OPN/static and flow only conditions. CD44 and !1 integrins were only responsible for approximately 50% of LEPCs adhesion to OPN compared to the unblocked condition. Western blots showed that Rho GTPases were activated in L-EPCs seeded on OPN. However, this activation could not be completely blocked by either CD44 or !1 integrin antagonists. These data confirm the direct effects of OPN on EPCs adhesion, and suggest that OPN works by mediating cell adhesion during vascular injury.

Endothelial Progenitor Cells (EPCs) are thought to participate in the healing of injured vascular endothelium by incorporating into the defect sites to mediate endothelial recovery. Recently, osteopontin (OPN) was shown to be fundamental in accelerating estrogen-dependent healing of injured blood vessels. Here, we are investigating the effect OPN has on EPC behavior. Late outgrowth human EPCs (LEPCs) were derived from circulating monocytes isolated by leukophoresis, and grown in culture until passage six. L-EPCs were then assayed for adhesion, spreading, chemotaxis, and haptotaxis, as well as resistance to detachment by flow electric cellsubstrate impedance sensing (ECIS). The results of standard and ECIS methods showed both dose and time dependent responses in cell adhesion and spreading. In addition, OPN promoted haptotactic migration of EPCs in Boyden chamber assays. LEPCs seeded onto 10μM OPN substrates and exposed to laminar flow had grater survival and higher resistance to detachment than OPN/static and flow only conditions. CD44 and !1 integrins were only responsible for approximately 50% of LEPCs adhesion to OPN compared to the unblocked condition. Western blots showed that Rho GTPases were activated in L-EPCs seeded on OPN. However, this activation could not be completely blocked by either CD44 or !1 integrin antagonists. These data confirm the direct effects of OPN on EPCs adhesion, and suggest that OPN works by mediating cell adhesion during vascular injury.

Endothelial Progenitor Cells (EPCs) are thought to participate in the healing of injured vascular endothelium by incorporating into the defect sites to mediate endothelial recovery. Recently, osteopontin (OPN) was shown to be fundamental in accelerating estrogen-dependent healing of injured blood vessels. Here, we are investigating the effect OPN has on EPC behavior. Late outgrowth human EPCs (LEPCs) were derived from circulating monocytes isolated by leukophoresis, and grown in culture until passage six. L-EPCs were then assayed for adhesion, spreading, chemotaxis, and haptotaxis, as well as resistance to detachment by flow electric cellsubstrate impedance sensing (ECIS). The results of standard and ECIS methods showed both dose and time dependent responses in cell adhesion and spreading. In addition, OPN promoted haptotactic migration of EPCs in Boyden chamber assays. LEPCs seeded onto 10μM OPN substrates and exposed to laminar flow had grater survival and higher resistance to detachment than OPN/static and flow only conditions. CD44 and !1 integrins were only responsible for approximately 50% of LEPCs adhesion to OPN compared to the unblocked condition. Western blots showed that Rho GTPases were activated in L-EPCs seeded on OPN. However, this activation could not be completely blocked by either CD44 or !1 integrin antagonists. These data confirm the direct effects of OPN on EPCs adhesion, and suggest that OPN works by mediating cell adhesion during vascular injury.

No description available.

Prostate cancer is the second most common cancer in the United States that affects men today. To better treat this disease accurate biomarkers and successful therapeutic treatments are needed. A novel approach to understand the mechanisms behind prostate cancer tumor formation lies in identifying dysregulated micro-RNAs (miRNAs), which are a class of small (18-24 nucleotides) non-coding RNAs that regulate gene expression posttranscriptionally by either inhibiting protein synthesis or signaling messenger-RNA for degradation. Multiple miRNAs were discovered in our highly tumorigenic and metastatic prostate cancer progression model M12 cell line compared to its weakly tumorigenic P69 parental cell line. Various analyses such as human panel analyses, single-miR analyses and patient tumor biopsy samples were analyzed to determine dysregulated miRNAs that contributed to the progression and metastasis of prostate cancer. Together with performing experiments to identify miRNAs, a de novo next generation sequencing approach was applied to identify miRNAs naturally present in biological fluids of normal and healthy subjects. Since, these miRNAs are highly dysregulated in many diseases, including cancer, they can act as potential biomarkers or therapeutic targets to improve treatments for prostate cancer. Essential miRNAs studied for this research were miR-17-3p that is known to target the ErbB2 mRNA; miR-299-5p that directly targets osteopontin (OPN) mRNA, and miR-147b that directly targets many mRNAs, such as COL4A2, ALDH5A1, NDUFA4, SDHD, and IER5. A wide range of miRNAs were identified in six biological fluids: venous blood, menstrual blood, vaginal fluid, semen, saliva, and feces. There were some miRNAs that were common to all 6 body fluids, some unique to each body fluid, and some miRNAs that literature suggested could potentially be biomarkers or normalizers for body fluid characterization.

A prognostic factor is a marker or a feature that can be used to estimate the risk of recurrence of disease, metastatic spread and clinical outcome. Despite intensive search for more sophisticated markers in renal cell carcinoma (RCC), few have added prognostic information to earlier described factors like stage of disease, nuclear grade, tumour type, and in metastatic disease; performance status, anaemia, hypercalcaemia and increased erythrocyte sedimentation. In the dominating tumour type, clear cell renal RCC (cRCC), hypoxia is common, leading to an up-regulation of hypoxia inducible factor (HIF). The majority of cRCC have a mutation in the von Hippel Lindau gene (VHL-gene), which regulates HIF and in turn leads to up-regulation of a number of target genes for potential growth factors. The aim of the study was to evaluate the possible prognostic information of a few factors associated to pVHL/HIF, anemia and/or hypercalcaemia in RCC; erythropoietin (EPO) and it´s receptor (EPO-R), carbonic anhydrase IX (CA IX), parathyroid hormone-related protein (PTHrP) and osteopontin (OPN). Patients diagnosed with RCC between 1982-2007 were included in the studies. The tumour tissue expressions of EPO, EPO-R and PTHrP were assessed using immunohistochemistry. Serum/plasma levels of EPO, CA IX, PTHrP and OPN were also analyzed using immunometric methods. Our study demonstrated that the expression of EPO and EPO-R were related, and the expressions differed significantly between RCC types. The serum EPO levels did not associate to the tumour expression of EPO or EPO-R, indicating that circulating EPO derives from other sources than tumour cells. Erythropietin receptor expression was more frequent in advanced stages of disease, but neither EPO, nor EPO-R, were independent prognostic factors for survival. Serum CA IX levels were higher in cRCC compared to papillary RCC (pRCC). In cRCC, the CA IX serum levels correlated positively to TNM stage, but serum CA IX did not add independent prognostic information. Parathyroid hormone-related protein is a cause of hypercalcaemia in malignancy, and we observed that circulating PTHrP related to hypercalcaemia in RCC. The tumour expression of PTHrP associated positively to serum PTHrP, but not to serum calcium. We found an association between PTHrP and OPN in plasma, and both plasma PTHrP and OPN were positively associated to TNM stage.  Neither serum/plasma PTHrP nor tumour expression of PTHrP were independent prognostic factors for survival. The serum OPN levels were higher in pRCC but no impact on survival was observed in this RCC type. In contrast, plasma/serum OPN was an independent prognostic factor for disease-specific survival in cRCC. Our results support a role for these factors in RCC. The expressions vary between tumour types, which can be explained by different gene aberrations. Some of the factors have a close relation to para-malignant symptoms like hypercalcaemia. Most of the factors correlate positively to TNM-stage, reflecting a relation to advanced disease. Although expression of EPO, EPO-R, PTHrP and CA IX did not add independent prognostic information, the results might contribute to greater understanding of important mechanisms and associations in RCC. Osteopontin is a strong independent prognostic factor in cRCC, and should be further evaluated as a tool in the clinic when treating RCC patients.

Cardiovascular disease (CVD) is the leading cause of death in the United States. A common feature in most cardiac pathologies is the dysregulation of beta-adrenergic receptors (β-AR) and changes in the extracellular matrix (ECM). The ECM maintains strength and normal organization of cardiac tissue, while fibrosis (connective tissue scarring) is necessary for repair of damaged cardiac tissue. However, the dysregulation of the ECM leads to a number of cardiac disease pathologies. Osteopontin (OPN) is a protein with diverse biological functions in regulating the ECM such as bone resorption and calcification, wound healing, cell adhesion, cell survival, and apoptosis. OPN is expressed at low levels in the heart but increases with injury by promoting collagen synthesis, cardiac fibroblast growth, and adhesions to ECM proteins. Furthermore, as the heart ages, increases in ECM reorganization leads to cardiac damage and failure. Several studies have examined the role of OPN in the heart, but to date, no studies exist on the role of OPN in response to β-AR signaling and cardiac remodeling or the role that aging plays in this response. The goal of this study was to examine the effects of OPN on cardiac ECM remodeling following chronic beta-adrenergic stimulation. We proposed that OPN expression increases cardiac remodeling and dysfunction following ISO treatment in the aging heart evidenced by increased fibrosis. For this study, young (4 months) and middle age (14 months) mice with (WT) and without (KO) the OPN gene were treated with isoproterenol (ISO) for 28 days. Echocardiography was used to assess cardiac function. Mice were euthanized, and the hearts were analyzed for fibrosis using Masson’s Trichrome Staining. Results showed ISO increased fibrosis in the WT-ISO, but not KO-ISO compared to the respective controls (SHAM, no ISO treatment) for the middle age mice (p≤0.05). Furthermore, the aged WT-ISO group exhibited a 3-fold increase in fibrosis compared to the young WT-ISO group. Results from echocardiography will be analyzed and we expect to see compromised cardiac function in the WT-ISO groups compared to KO-ISO groups. OPN is currently being examined as a potential biomarker in heart failure. The results from this study will provide new insight on changes in the cardiac vasculature in the aging heart following injury and the role OPN plays in this process.

Calcific aortic valve disease (CAVD) is the most common cause of aortic valve failure and replacement in the elderly population, affecting 25% of the population over 65 years of age. Current pharmacological approaches for preventing the onset and progression of calcific aortic valve disease have not shown consistent benefits in clinical studies. Differentiation of valvular interstitial cells (VICs) into osteoblast–like cells is an integral step in the calcification process. Although clinical evidence suggests hypertension as a potential candidate contributing to the development of CAVD, the underlying molecular mechanisms that cause de-differentiation remain unclear. The present study investigates the role of elevated cyclic pressure in modulating osteoblast differentiation pathways in VICs in vitro. We used a combination of systems biology modeling and pathway-based analyses to identify novel genes and molecular mechanisms that are activated in valve tissue during exposure to elevated pressure conditions. Our results show that elevated pressure induces a gene expression pattern in valve tissue that is considerably similar to that seen in CAVD, underlining the key role of hypertension as an initiating factor in the onset of pathogenesis. In addition, our analysis revealed a set of genes that was not previously known to be regulated in valve tissue in a pressure dependent manner. Currently, the molecular mechanisms involved in CAVD and their associations with changes in local mechanical environment are poorly understood, and thus a better understanding of the cell based process mediating CAVD progression will improve our ability to develop potential medical therapies for this disease.