EXPEL: A Novel Non-Destructive Method for Mining Soluble Tumor Biomarkers
Costanza, Brunella ; ; Bellahcene, Akeila et al
Poster (2015, January)Detailed reference viewed: 23 (6 ULg)
Asporin Is a Fibroblast-Derived TGF-beta1 Inhibitor and a Tumor Suppressor Associated with Good Prognosis in Breast Cancer.
; ; et al
in PLoS medicine (2015), 12(9), 1001871
BACKGROUND: Breast cancer is a leading malignancy affecting the female population worldwide. Most morbidity is caused by metastases that remain incurable to date. TGF-beta1 has been identified as a key ... [more ▼]
BACKGROUND: Breast cancer is a leading malignancy affecting the female population worldwide. Most morbidity is caused by metastases that remain incurable to date. TGF-beta1 has been identified as a key driving force behind metastatic breast cancer, with promising therapeutic implications. METHODS AND FINDINGS: Employing immunohistochemistry (IHC) analysis, we report, to our knowledge for the first time, that asporin is overexpressed in the stroma of most human breast cancers and is not expressed in normal breast tissue. In vitro, asporin is secreted by breast fibroblasts upon exposure to conditioned medium from some but not all human breast cancer cells. While hormone receptor (HR) positive cells cause strong asporin expression, triple-negative breast cancer (TNBC) cells suppress it. Further, our findings show that soluble IL-1beta, secreted by TNBC cells, is responsible for inhibiting asporin in normal and cancer-associated fibroblasts. Using recombinant protein, as well as a synthetic peptide fragment, we demonstrate the ability of asporin to inhibit TGF-beta1-mediated SMAD2 phosphorylation, epithelial to mesenchymal transition, and stemness in breast cancer cells. In two in vivo murine models of TNBC, we observed that tumors expressing asporin exhibit significantly reduced growth (2-fold; p = 0.01) and metastatic properties (3-fold; p = 0.045). A retrospective IHC study performed on human breast carcinoma (n = 180) demonstrates that asporin expression is lowest in TNBC and HER2+ tumors, while HR+ tumors have significantly higher asporin expression (4-fold; p = 0.001). Assessment of asporin expression and patient outcome (n = 60; 10-y follow-up) shows that low protein levels in the primary breast lesion significantly delineate patients with bad outcome regardless of the tumor HR status (area under the curve = 0.87; 95% CI 0.78-0.96; p = 0.0001). Survival analysis, based on gene expression (n = 375; 25-y follow-up), confirmed that low asporin levels are associated with a reduced likelihood of survival (hazard ratio = 0.58; 95% CI 0.37-0.91; p = 0.017). Although these data highlight the potential of asporin to serve as a prognostic marker, confirmation of the clinical value would require a prospective study on a much larger patient cohort. CONCLUSIONS: Our data show that asporin is a stroma-derived inhibitor of TGF-beta1 and a tumor suppressor in breast cancer. High asporin expression is significantly associated with less aggressive tumors, stratifying patients according to the clinical outcome. Future pre-clinical studies should consider options for increasing asporin expression in TNBC as a promising strategy for targeted therapy. [less ▲]Detailed reference viewed: 74 (11 ULg)
Histone deacetylases and cancer-associated angiogenesis: current understanding of the biology and clinical perspectives.
Turtoi, Andrei ; ; Castronovo, Vincenzo et al
in Critical reviews in oncogenesis (2015), 20(1-2), 119-37
Histone deacetylase enzymes (HDACs) have been shown to be important to the development and progression of human cancers. Angiogenesis is a vital process that facilitates tumor growth and survival. More ... [more ▼]
Histone deacetylase enzymes (HDACs) have been shown to be important to the development and progression of human cancers. Angiogenesis is a vital process that facilitates tumor growth and survival. More than a dozen of different activators and inhibitors are involved in at least as many diverse mechanisms to control angiogenesis. HDACs directly or indirectly control many of these regulators. In the current review, we give a brief overview of molecular mechanisms of HDAC actions and link these to the current knowledge concerning HDAC-mediated regulation of tumor-associated angiogenesis. HDAC specific knockdown studies and the use of pan-HDAC inhibitors (HDACi) contributed to the identification of: (i) HDACs that are key to angiogenesis and (ii) their multiple protein targets essential for angiogenic process. The clinical development of HDACi is an active area of investigation. In the scope of this review, we highlight several preclinical studies that examine the anti-angiogenic role of HDACi. Certainly, there is still much to be learned about the use of HDACi to inhibit tumoral angiogenesis. Recent efforts in the clinics aiming to combine broad HDACi (mainly vorinostat, which is FDA approved for T-cell lymphoma) with other anti-angiogenic therapies could, however, bring the proof that the lack of specificity of pan-HDACi may not be a major issue as compared with (long-time idealized) selective inhibitors targeting one particular HDAC. [less ▲]Detailed reference viewed: 31 (1 ULg)
Identification of Cytotoxic and Antioxidant Compounds from Allium gramineum Flowers
; ; Tits, Monique et al
in International Journal of Pharmaceutical Sciences and Drug Research (2015), 7
The present study evaluates the in vitro anticancer, antiplasmodial and antioxidant activity of the ethanolic crude extract from the flowers of Allium gramineum growing in Georgia and of one flavonol and ... [more ▼]
The present study evaluates the in vitro anticancer, antiplasmodial and antioxidant activity of the ethanolic crude extract from the flowers of Allium gramineum growing in Georgia and of one flavonol and two steroidal glycosides which were isolated from this plant. The flowers were extracted with ethanol and this total extract was subjected to successive bioguided fractionations to provide glycosides 1-3. Their structures were elucidated on the basis of NMR and ESI-MS spectrometric data in comparison with the existing literature and have been identified as: isorhamnetin-3-O-β-D-glucopyranoside (1), diosgenin-3-O-α-rhamnopyranosyl-(1→2)-β-D-glucopyranoside (Prosapogenin A of dioscin) (2), diosgenin-3-O-α-rhamnopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→4)-]-β-D-glucopyranoside (Deltonine) (3). The ethanolic extract has been shown to strongly inhibit the growth of breast adenocarcinoma cell lines, with an IC50 of 4.5 ± 0.7μg/mL for MDAMB-231 and 4.8 ± 0.9μg/mL for MCF-7 cells. The cytotoxic activity was related to 2 and 3 which exhibited potent cytotoxicity, with an IC50 of ± 3μM. Concerning antiplasmodial activities, only weak activities were observed using the ethanolic extract and the two saponins. The flavonoid was almost inactive. Finally, the radical-scavenging activity of the ethanolic extract was tested in presence of ABTS·+ solution. A decrease of the absorbance intensity was observed, with an IC50 value of 22.1 ± 0.6μg/mLwhile trolox, used as Standard drug, showed a pronounced activity (IC50 = 12.7±0.5μM). The glycoside 1 showed the lowest IC50 value of 20.1 ± 0.8μM while both 2 and 3 exhibited very weak radical scavenging activity. [less ▲]Detailed reference viewed: 124 (22 ULg)
Triple negative tumors accumulate significantly less methylglyoxal specific adducts than other human breast cancer subtypes
Chiavarina, Barbara ; Nokin, Marie-Julie ; Durieux, Florence et al
in Oncotarget (2014)
Metabolic syndrome and type 2 diabetes are associated with increased risk of breast cancer development and progression. Methylglyoxal (MG), a glycolysis by- product, is generated through a non-enzymatic ... [more ▼]
Metabolic syndrome and type 2 diabetes are associated with increased risk of breast cancer development and progression. Methylglyoxal (MG), a glycolysis by- product, is generated through a non-enzymatic reaction from triose-phosphate intermediates. This dicarbonyl compound is highly reactive and contributes to the accumulation of advanced glycation end products. In this study, we analyzed the accumulation of Arg-pyrimidine, a MG-arginine adduct, in human breast adenocarcinoma and we observed a consistent increase of Arg-pyrimidine in cancer cells when compared with the non-tumoral counterpart. Further immunohistochemical comparative analysis of breast cancer subtypes revealed that triple negative lesions exhibited low accumulation of Arg-pyrimidine compared with other subtypes. Interestingly, the activity of glyoxalase 1 (Glo-1), an enzyme that detoxifies MG, was significantly higher in triple negative than in other subtype lesions, suggesting that these aggressive tumors are able to develop an efficient response against dicarbonyl stress. Using breast cancer cell lines, we substantiated these clinical observations by showing that, in contrast to triple positive, triple negative cells induced Glo-1 expression and activity in response to MG treatment. This is the first report that Arg- pyrimidine adduct accumulation is a consistent event in human breast cancer with a differential detection between triple negative and other breast cancer subtypes. [less ▲]Detailed reference viewed: 87 (21 ULg)
Myoferlin is a Key Regulator of HER Receptor Family Function in Breast Cancer
Costanza, Brunella ; ; Bellahcene, Akeila et al
Scientific conference (2014)Detailed reference viewed: 26 (4 ULg)
Changes in the transcriptional profile in response to overexpression of the osteopontin-c splice isoform in ovarian (OvCar-3) and prostate (PC-3) cancer cell lines.
; Bellahcene, Akeila ; Castronovo, Vincenzo et al
in BMC cancer (2014), 14
BACKGROUND: Especially in human tumor cells, the osteopontin (OPN) primary transcript is subject to alternative splicing, generating three isoforms termed OPNa, OPNb and OPNc. We previously demonstrated ... [more ▼]
BACKGROUND: Especially in human tumor cells, the osteopontin (OPN) primary transcript is subject to alternative splicing, generating three isoforms termed OPNa, OPNb and OPNc. We previously demonstrated that the OPNc splice variant activates several aspects of the progression of ovarian and prostate cancers. The goal of the present study was to develop cell line models to determine the impact of OPNc overexpression on main cancer signaling pathways and thus obtain insights into the mechanisms of OPNc pro-tumorigenic roles. METHODS: Human ovarian and prostate cancer cell lines, OvCar-3 and PC-3 cells, respectively, were stably transfected to overexpress OPNc. Transcriptomic profiling was performed on these cells and compared to controls, to identify OPNc overexpression-dependent changes in gene expression levels and pathways by qRT-PCR analyses. RESULTS: Among 84 genes tested by using a multiplex real-time PCR Cancer Pathway Array approach, 34 and 16, respectively, were differentially expressed between OvCar-3 and PC-3 OPNc-overexpressing cells in relation to control clones. Differentially expressed genes are included in all main hallmarks of cancer, and several interacting proteins have been identified using an interactome network analysis. Based on marked up-regulation of Vegfa transcript in response to OPNc overexpression, we partially validated the array data by demonstrating that conditioned medium (CM) secreted from OvCar-3 and PC-3 OPNc-overexpressing cells significantly induced endothelial cell adhesion, proliferation and migration, compared to CM secreted from control cells. CONCLUSIONS: Overall, the present study elucidated transcriptional changes of OvCar-3 and PC-3 cancer cell lines in response to OPNc overexpression, which provides an assessment for predicting the molecular mechanisms by which this splice variant promotes tumor progression features. [less ▲]Detailed reference viewed: 44 (3 ULg)
Multiple myeloma cells instruct myeloid-derived suppressor cells to release pro-angiogenic cytokines
Binsfeld, Marilène ; Heusschen, Roy ; et al
in Belgian Journal of Hematology (2014)Detailed reference viewed: 34 (11 ULg)
ASSOCIATION BETWEEN CHONDROCYTE HYPERTROPHY AND ANGIOGENESIS OF CARTILAGE IN OSTEOARTHRITIS
Pesesse, Laurence ; Sanchez, Christelle ; et al
Conference (2013, November)Detailed reference viewed: 24 (5 ULg)
Myoferlin is a key regulator of EGFR activity in breast cancer.
Turtoi, Andrei ; Blomme, Arnaud ; Bellahcene, Akeila et al
in Cancer Research (2013), 73
Myoferlin is a member of the ferlin family of proteins that participate in plasma membrane fusion, repair and endocytosis. While some reports have implicated myoferlin in cancer, the extent of its ... [more ▼]
Myoferlin is a member of the ferlin family of proteins that participate in plasma membrane fusion, repair and endocytosis. While some reports have implicated myoferlin in cancer, the extent of its expression in and contributions to cancer are not well established. In this study, we show that myoferlin is overexpressed in human breast cancers and that it is has a critical role in controlling degradation of the EGFR after its activation and internalization in breast cancer cells. Myoferlin depletion blocked EGF-induced cell migration and epithelial-to-mesenchymal transition. Both effects were induced as a result of impaired degradation of phosphorylated EGFR via dysfunctional plasma membrane caveolae and alteration of caveolin homooligomerization. In parallel, myoferlin depletion reduced tumor development in a chicken chorioallantoic membrane xenograft model of human breast cancer. Considering the therapeutic significance of EGFR targeting, our findings identify myoferlin as an novel candidate function to target for future drug development. [less ▲]Detailed reference viewed: 101 (17 ULg)
A new murine model of osteoblastic/osteolytic lesions from human androgen-resistant prostate cancer.
; ; et al
in PloS one (2013), 8(9), 75092
BACKGROUND: Up to 80% of patients dying from prostate carcinoma have developed bone metastases that are incurable. Castration is commonly used to treat prostate cancer. Although the disease initially ... [more ▼]
BACKGROUND: Up to 80% of patients dying from prostate carcinoma have developed bone metastases that are incurable. Castration is commonly used to treat prostate cancer. Although the disease initially responds to androgen blockade strategies, it often becomes castration-resistant (CRPC for Castration Resistant Prostate Cancer). Most of the murine models of mixed lesions derived from prostate cancer cells are androgen sensitive. Thus, we established a new model of CRPC (androgen receptor (AR) negative) that causes mixed lesions in bone. METHODS: PC3 and its derived new cell clone PC3c cells were directly injected into the tibiae of SCID male mice. Tumor growth was analyzed by radiography and histology. Direct effects of conditioned medium of both cell lines were tested on osteoclasts, osteoblasts and osteocytes. RESULTS: We found that PC3c cells induced mixed lesions 10 weeks after intratibial injection. In vitro, PC3c conditioned medium was able to stimulate tartrate resistant acid phosphatase (TRAP)-positive osteoclasts. Osteoprotegerin (OPG) and endothelin-1 (ET1) were highly expressed by PC3c while dikkopf-1 (DKK1) expression was decreased. Finally, PC3c highly expressed bone associated markers osteopontin (OPN), Runx2, alkaline phosphatase (ALP), bone sialoprotein (BSP) and produced mineralized matrix in vitro in osteogenic conditions. CONCLUSIONS: We have established a new CRPC cell line as a useful system for modeling human metastatic prostate cancer which presents the mixed phenotype of bone metastases that is commonly observed in prostate cancer patients with advanced disease. This model will help to understand androgen-independent mechanisms involved in the progression of prostate cancer in bone and provides a preclinical model for testing the effects of new treatments for bone metastases. [less ▲]Detailed reference viewed: 25 (3 ULg)
Les proteines SIBLING - Outils moleculaires de la progression tumorale et de l'angiogenese.
; Nokin, Marie-Julie ; Henry, Aurélie et al
in Medecine sciences : M/S (2013), 29(11), 1018-25
The small integrin-binding ligand N-linked glycoprotein (SIBLING) family consists of osteopontin (OPN), bonesialoprotein (BSP), dentin matrix protein 1 (DMP1), dentin sialophosphoprotein (DSPP) and matrix ... [more ▼]
The small integrin-binding ligand N-linked glycoprotein (SIBLING) family consists of osteopontin (OPN), bonesialoprotein (BSP), dentin matrix protein 1 (DMP1), dentin sialophosphoprotein (DSPP) and matrix extracellular phosphoglycoprotein (MEPE). These proteins, initially identified in bone and teeth, share many structural characteristics. It is now well established that they are over expressed in many tumors and play a critical role at different steps of cancer development. In this review, we describe the roles of SIBLING proteins at different stages of cancer progression including cancer cell adhesion, proliferation, migration, invasion, metastasis and angiogenesis. [less ▲]Detailed reference viewed: 97 (19 ULg)
Identification and Quantification of the Main Active Anticancer Alkaloids from the Root of Glaucium flavum
; ; Wauters, Jean-Noël et al
in International Journal of Molecular Sciences (2013), 14
Glaucium flavum is used in Algerian folk medicine to remove warts (benign tumors). Its local appellations are Cheqiq el-asfar and Qarn el-djedyane. We have recently reported the anti-tumoral activity of ... [more ▼]
Glaucium flavum is used in Algerian folk medicine to remove warts (benign tumors). Its local appellations are Cheqiq el-asfar and Qarn el-djedyane. We have recently reported the anti-tumoral activity of Glaucium flavum root alkaloid extract against human cancer cells, in vitro and in vivo. The principal identified alkaloid in the extract was protopine. This study aims to determine which component(s) of Glaucium flavum root extract might possess potent antitumor activity on human cancer cells. Quantitative estimation of Glaucium flavum alkaloids was realized by HPLC-DAD. Glaucium flavum effect on human normal and cancer cell viability was determined using WST-1 assay. Quantification of alkaloids in Glaucium flavum revealed that the dried root part contained 0.84% of protopine and 0.07% of bocconoline (w/w), while the dried aerial part contained only 0.08% of protopine, glaucine as the main alkaloid, and no bocconoline. In vitro evaluation of the growth inhibitory activity on breast cancer and normal cells demonstrated that purified protopine did not reproduce the full cytotoxic activity of the alkaloid root extract on cancer cell lines. On the other hand, bocconoline inhibited strongly the viability of cancer cells with an IC50 of 7.8 µM and only a low cytotoxic effect was observed against normal human cells. Our results showed for the first time that protopine is the major root alkaloid of Glaucium flavum. Finally, we are the first to demonstrate a specific anticancer effect of Glaucium flavum root extract against breast cancer cells, which can be attributed, at least in part, to bocconoline. [less ▲]Detailed reference viewed: 66 (5 ULg)
Consequences of chondrocyte hypertrophy on osteoarthritic cartilage: potential effect on angiogenesis.
Pesesse, Laurence ; Sanchez, Christelle ; et al
in Osteoarthritis and cartilage / OARS, Osteoarthritis Research Society (2013), 21(12), 1913-23
OBJECTIVE: The aim of this study was to investigate the link between the hypertrophic phenotype of chondrocytes and angiogenesis in osteoarthritis (OA) and more particularly to demonstrate that OA ... [more ▼]
OBJECTIVE: The aim of this study was to investigate the link between the hypertrophic phenotype of chondrocytes and angiogenesis in osteoarthritis (OA) and more particularly to demonstrate that OA hypertrophic chondrocytes potentially express a phenotype promoting angiogenesis through the expression of factors controlling endothelial cells migration, invasion and adhesion. METHOD: Human OA chondrocytes were cultivated in alginate beads in medium supplemented with 10% fetal bovine serum (FBS) to induce chondrocyte hypertrophy. The hypertrophic phenotype was characterized throughout 28 days of culture by measuring the expression of specific genes and by a microscopic observation of cellular morphology. The effect of media conditioned by OA hypertrophic chondrocyte on endothelial cells migration, invasion and adhesion was evaluated in functional assays. Moreover, hypertrophic OA chondrocytes were tested for the expression of angiogenic factors by real-time RT-PCR. RESULTS: Specific markers of hypertrophy and observation of cellular morphology attested of the hypertrophic phenotype of chondrocytes in our culture model. Functional angiogenesis assays showed that factors produced by hypertrophic chondrocytes stimulated migration, invasion and adhesion of endothelial cells. Among the evaluated angiogenic factors, bone sialoprotein (BSP) was the most highly upregulated in hypertrophic chondrocytes. The inhibition of endothelial cell adhesion by a GRGDS peptide confirmed the implication of RGD domain proteins, like BSP, in hypertrophic chondrocyte-induced adhesion of endothelial cells. CONCLUSION: Hypertrophic differentiation of chondrocyte may promote angiogenesis. Our findings established the relation of BSP with OA chondrocyte hypertrophy and suggested that this factor could constitute a potential target to control cartilage neovascularisation in OA. [less ▲]Detailed reference viewed: 32 (8 ULg)
Revealing the anti-tumoral effect of Algerian Glaucium flavum roots against human cancer cells.
; ; Peixoto, Paul et al
in Phytomedicine : International Journal of Phytotherapy and Phytopharmacology (2013), 20(13), 1211-1218
Glaucium flavum (G. flavum) is a plant from the Papaveraceae family native to Algeria where it is used in local traditional medicine to treat warts. G. flavum root crude alkaloid extract inhibited breast ... [more ▼]
Glaucium flavum (G. flavum) is a plant from the Papaveraceae family native to Algeria where it is used in local traditional medicine to treat warts. G. flavum root crude alkaloid extract inhibited breast cancer cell proliferation and induced G2/M phase cycle arrest and apoptosis without affecting normal cells, which is a highly awaited feature of potential anti-cancer agents. G. flavum significantly reduced growth and vascularization of human glioma tumors on chicken chorioallantoic membrane (CAM) in vivo. The chromatographic profile of the dichloromethane extract of G. flavum root showed the presence of different constituents including the isoquinoline alkaloid protopine, as the major compound. We report for the first time that G. flavum extract may represent a new promising agent for cancer chemotherapy. [less ▲]Detailed reference viewed: 273 (37 ULg)
The angiogenesis suppressor gene AKAP12 is under the epigenetic control of HDAC7 in endothelial cells.
Castronovo, Vincenzo ; Matheus, Nicolas ; Dumont, Bruno et al
Conference (2012, April 21)Detailed reference viewed: 86 (30 ULg)
Differential proteomic analysis of a human breast tumor and its matched bone metastasis identifies cell membrane and extracellular proteins associated with bone metastasis
Dumont, Bruno ; Castronovo, Vincenzo ; Peulen, Olivier et al
in Journal of Proteome Research (2012)
The classical fate of metastasizing breast cancer cells is to seed and form secondary colonies in bones. The molecules closely associated with these processes are predominantly present at the cell surface ... [more ▼]
The classical fate of metastasizing breast cancer cells is to seed and form secondary colonies in bones. The molecules closely associated with these processes are predominantly present at the cell surface and in the extracellular space, establishing the first contacts with the target tissue. In this study, we had the rare opportunity to analyze a bone metastatic lesion and its corresponding breast primary tumor obtained simultaneously from the same patient. Using mass spectrometry, we undertook a proteomic study on cell surface and extracellular protein-enriched material. We provide a repertoire of significantly modulated proteins, some with yet unknown roles in the bone metastatic process as well as proteins notably involved in cancer cell invasiveness and in bone metabolism. The comparison of these clinical data with those previously obtained using a human osteotropic breast cancer cell line highlighted an overlapping group of proteins. Certain differentially expressed proteins are validated in the present study using immunohistochemistry on a retrospective collection of breast tumors and matched bone metastases. Our exclusive set of selected proteins supports the set-up of further investigations on both clinical samples and experimental bone metastasis models that will help to reveal the finely coordinated expression of proteins that favor the development of metastases in the bone microenvironment. [less ▲]Detailed reference viewed: 134 (21 ULg)
Overexpression of CD9 in human breast cancer cells promotes the development of bone metastases.
; Bellahcene, Akeila ; et al
in Anticancer Research (2012), 32(12), 5211-20
BACKGROUND: Bone is a preferred target for circulating metastatic breast cancer cells. We found that the CD9 protein was up-regulated in the B02 osteotropic cell line, derived from the aggressive parental ... [more ▼]
BACKGROUND: Bone is a preferred target for circulating metastatic breast cancer cells. We found that the CD9 protein was up-regulated in the B02 osteotropic cell line, derived from the aggressive parental MDA-MB-231 breast cancer cell line. Here, we investigated the putative relationship between CD9 expression and the osteotropic phenotype. MATERIALS AND METHODS: Overexpression of CD9 was analyzed by immunoblotting in different cell lines. Immunohistochemistry was used to assess CD9 expression in primary tumors and metastatic lesions. In vivo experiments were conducted in mice using a monoclonal antibody against CD9. RESULTS: CD9 overexpression was confirmed in osteotropic cells. CD9 was significantly overexpressed in bone metastases versus primary tumors and visceral metastatic lesions. Finally, in vivo experiments showed that an antibody against CD9 delays homing of B02 cells in bone marrow, slowing down bone destruction. CONCLUSION: Our study reveals a potential implication of CD9 in the formation of bony metastases from breast cancer cells. [less ▲]Detailed reference viewed: 33 (3 ULg)
The angiogenesis suppressor gene AKAP12 is under the epigenetic control of HDAC7 in endothelial cells.
Turtoi, Andrei ; Mottet, Denis ; Matheus, Nicolas et al
in Angiogenesis (2012)
Histone deacetylases (HDACs) are a family of 18 enzymes that deacetylate lysine residues of both histone and nonhistone proteins and to a large extent govern the process of angiogenesis. Previous studies ... [more ▼]
Histone deacetylases (HDACs) are a family of 18 enzymes that deacetylate lysine residues of both histone and nonhistone proteins and to a large extent govern the process of angiogenesis. Previous studies have shown that specific inhibition of HDAC7 blocks angiogenesis both in vitro and in vivo. However, the underlying molecular mechanisms are not fully understood and hence preclude any meaningful development of suitable therapeutic modalities. The goal of the present study was to further the understanding of HDAC7 epigenetic control of angiogenesis in human endothelial cells using the proteomic approach. The underlying problem was approached through siRNA-mediated gene-expression silencing of HDAC7 in human umbilical vein endothelial cells (HUVECs). To this end, HUVEC proteins were extracted and proteomically analyzed. The emphasis was placed on up-regulated proteins, as these may represent potential direct epigenetic targets of HDAC7. Among several proteins, A-kinase anchor protein 12 (AKAP12) was the most reproducibly up-regulated protein following HDAC7 depletion. This overexpression of AKAP12 was responsible for the inhibition of migration and tube formation in HDAC7-depleted HUVEC. Mechanistically, H3 histones associated with AKAP12 promoter were acetylated following the removal of HDAC7, leading to an increase in its mRNA and protein levels. AKAP12 is responsible for protein kinase C mediated phosphorylation of signal transducer and activator of transcription 3 (STAT3). Phosphorylated STAT3 increasingly binds to the chromatin and AKAP12 promoter and is necessary for maintaining the elevated levels of AKAP12 following HDAC7 knockdown. We demonstrated for the first time that AKAP12 tumor/angiogenesis suppressor gene is an epigenetic target of HDAC7, whose elevated levels lead to a negative regulation of HUVEC migration and inhibit formation of tube-like structures. [less ▲]Detailed reference viewed: 46 (12 ULg)
Both osteopontin-c and osteopontin-b splicing isoforms exert pro-tumorigenic roles in prostate cancer cells.
; ; et al
in Prostate (2012)
BACKGROUND: Alternative splicing of the osteopontin (opn, spp1) gene generates three protein splicing isoforms (OPN-SI), designated as OPNa, OPNb, and OPNc, which have demonstrated specific roles in ... [more ▼]
BACKGROUND: Alternative splicing of the osteopontin (opn, spp1) gene generates three protein splicing isoforms (OPN-SI), designated as OPNa, OPNb, and OPNc, which have demonstrated specific roles in different tumor models. This work aims to investigate the roles of each OPN-SI in prostate cancer (PCa) progression by using in vivo and in vitro functional assays. METHODS: The expression levels of OPN-SI in prostate cell lines were analyzed by qRT-PCR. PC-3 was stably transfected with expression vectors containing OPNa, OPNb, and OPNc, as well as empty vector controls. PC-3 cells overexpressing each construct were analyzed for in vivo tumor growth and in relation to different aspects mimicking tumor progression, such as cell proliferation, migration, invasion, and soft agar colony formation. RESULTS: OPN-SI are overexpressed in PCa as compared to non-tumoral prostate cell lines. OPNc and OPNb overexpressing cells significantly activated enhanced xenograft tumor growth and PC-3 proliferation, migration, invasion, and soft agar colony formation, as well as the expression of MMP-2, MMP-9, and VEGF. These isoforms also support sustained proliferative survival. We found that both OPNc and OPNb pro-tumorigenic roles are mainly mediated through PI3K signaling. Inhibition of this pathway by using LY294002 specifically inhibited tumor progression features evoked by OPNc and OPNb overexpression. CONCLUSIONS: Our data provide evidence that both OPNc and OPNb splicing isoforms promote distinct aspects of PCa progression by inducing PI3K signaling. These data give support to strategies aiming to downregulate OPNc and OPNb expression as an approach to inhibit PCa progression. Prostate (c) 2012 Wiley Periodicals, Inc. [less ▲]Detailed reference viewed: 52 (8 ULg)