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See detailINTRA-TUMORAL HETEROGENEITY AND RATIONAL SELECTION OF ANTIGENS FOR TARGETED THERAPY OF LIVER METASTASES
Turtoi, Andrei ULg; Blomme, Arnaud ULg; Delvaux, David ULg et al

in Acta Chirurgica Belgica (2012, May), 112(3), 8953

Objectives: Targeted therapies of liver metastases are gaining a major stake in current and future treatment options. However, the malignant lesions are heterogeneous in nature offering niches for cancer ... [more ▼]

Objectives: Targeted therapies of liver metastases are gaining a major stake in current and future treatment options. However, the malignant lesions are heterogeneous in nature offering niches for cancer cells causing treatment resistance and relapse. Therefore, a rational strategy is needed to select targetable antigens that would overcome this intra-tumoral heterogeneity. Methods: After ethical committee approval, 48 fresh liver metastases of colorectal origin were prospectively collected from patients undergoing liver resection. Here we macroscopically divided the lesion in different zones and generated a unique quantitative picture of the proteome heterogeneity in colorectal carcinoma liver metastases. Particular focus was laid on accessible proteins, a protein subclass comprising cell membrane associated and extracellular proteins. Accordingly, the tissues were ex-vivo biotinylated, affinity purified and analyzed for each zone separately using nano-UPLC-MSe proteomics technique. In total over 1500 unique proteins were statistically divided into different patterns of expression. Results: We have generated a quantitative picture of the proteome heterogeneity in colorectal carcinoma liver metastases. The study offers insight into novel targets but also antigens against which the antibodies are already involved in clinical trials or treatment of liver metastases. Extensive clustering and validation experiments highlight novel markers that offer the potential to homogeneously cover the metastatic lesion and become better targets. Conclusions: Two such antigens, LTBP2 and TGFBI were selected for functional analysis in colorectal carcinoma cells. In vitro and in vivo experiments showed that in particular TGFBI is relevant for migration and proliferation capacity of colorectal cancer cells. The suppression of this protein led to significant inhibition of tumor growth, crystalizing it as bona fide target for the development of anti-metastases therapies. [less ▲]

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See detailDifferential proteomic analysis of a human breast tumor and its matched bone metastasis identifies cell membrane and extracellular proteins associated with bone metastasis
Dumont, Bruno ULg; Castronovo, Vincenzo ULg; Peulen, Olivier ULg 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 ▲]

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See detailThe angiogenesis suppressor gene AKAP12 is under the epigenetic control of HDAC7 in endothelial cells.
Turtoi, Andrei ULg; Mottet, Denis ULg; Matheus, Nicolas ULg 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 ▲]

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See detailIdentification of novel accessible proteins bearing diagnostic and therapeutic potential in human pancreatic ductal adenocarcinoma
Turtoi, Andrei ULg; Musmeci, Davide; Wang, Yinghong et al

in Journal of Proteome Research (2011), 10(9), 4302-13

Pancreas ductal adenocarcinoma (PDAC) remains a deadly malignancy with poor early diagnostic and no effective therapy. Although several proteomic studies have performed comparative analysis between normal ... [more ▼]

Pancreas ductal adenocarcinoma (PDAC) remains a deadly malignancy with poor early diagnostic and no effective therapy. Although several proteomic studies have performed comparative analysis between normal and malignant tissues, there is a lack of clear characterization of proteins that could be of clinical value. Systemically reachable ("potentially accessible") proteins, suitable for imaging technologies and targeted therapies represent a major group of interest. The current study explores potentially accessible proteins overexpressed in PDAC, employing innovative proteomics technologies. In the discovery phase, potentially accessible proteins from fresh human normal and PDAC tissues were ex vivo biotinylated, isolated and identified using 2D-nano-HPLC-MS/MS method. The analysis revealed 422 up-regulated proteins in the tumor, of which 83 (including protein isoforms) were evaluated as potentially accessible. Eleven selected candidates were further confirmed as up-regulated using Western blot and multiple reaction monitoring protein quantification. Of these, transforming growth factor beta-induced (TGFBI), latent transforming growth factor beta binding 2 (LTBP2), and asporin (ASPN) were further investigated by employing large scale immunohistochemistry-based validations. They were found to be significantly expressed in a large group of clinical PDAC samples compared to corresponding normal and inflammatory tissues. In conclusion, TGFBI, LTBP2, and ASPN are novel, overexpressed, and potentially accessible proteins in human PDAC. They bear the potential to be of clinical value for diagnostic and therapeutic applications and merit further studies using in vivo models. [less ▲]

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See detailNovel comprehensive approach for accessible biomarker identification and absolute quantification from precious human tissues
Turtoi, Andrei ULg; Dumont, Bruno ULg; Greffe, Yannick et al

in Journal of Proteome Research (2011), 10(7), 3160-82

The identification of specific biomarkers obtained directly from human pathological lesions remains a major challenge, because the amount of tissue available is often very limited. We have developed a ... [more ▼]

The identification of specific biomarkers obtained directly from human pathological lesions remains a major challenge, because the amount of tissue available is often very limited. We have developed a novel, comprehensive, and efficient method permitting the identification and absolute quantification of potentially accessible proteins in such precious samples. This protein subclass comprises cell membrane associated and extracellular proteins, which are reachable by systemically deliverable substances and hence especially suitable for diagnosis and targeted therapy applications. To isolate such proteins, we exploited the ability of chemically modified biotin to label ex vivo accessible proteins and the fact that most of these proteins are glycosylated. This approach consists of three successive steps involving first the linkage of potentially accessible proteins to biotin molecules followed by their purification. The remaining proteins are then subjected to glycopeptide isolation. Finally, the analysis of the nonglycosylated peptides and their involvement in an in silico method increased the confident identification of glycoproteins. The value of the technique was demonstrated on human breast cancer tissue samples originating from 5 individuals. Altogether, the method delivered quantitative data on more than 400 potentially accessible proteins (per sample and replicate). In comparison to biotinylation or glycoprotein analysis alone, the sequential method significantly increased the number (≥30% and ≥50% respectively) of potentially therapeutically and diagnostically valuable proteins. The sequential method led to the identification of 93 differentially modulated proteins, among which several were not reported to be associated with the breast cancer. One of these novel potential biomarkers was CD276, a cell membrane-associated glycoprotein. The immunohistochemistry analysis showed that CD276 is significantly differentially expressed in a series of breast cancer lesions. Due to the fact that our technology is applicable to any type of tissue biopsy, it bears the ability to accelerate the discovery of new relevant biomarkers in a broad spectrum of pathologies. [less ▲]

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See detailProteomic analysis of human pancreas cancers for the identification of targetable biomarkers
Castronovo, Vincenzo ULg; Wang, Ying Hong; Musmeci, Davide et al

(2010)

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See detailVersican overexpression in human breast cancer lesions: Known and new isoforms for stromal tumor targeting.
Kischel, Philippe ULg; Waltregny, David ULg; Dumont, Bruno ULg et al

in International Journal of Cancer = Journal International du Cancer (2010), 126(3), 640-50

Proteoglycans play a key role in cancer development and progression by participating in the constitution of a specific fertile tumor microenvironment. As they are largely overexpressed in the malignant ... [more ▼]

Proteoglycans play a key role in cancer development and progression by participating in the constitution of a specific fertile tumor microenvironment. As they are largely overexpressed in the malignant stroma, proteoglycans provide a reservoir of potential new targets for anticancer therapies, because they can serve to convey toxic payloads in the close proximity of cancer cells and subsequently destroy them. In this context, versican, a proteoglycan largely overexpressed in several solid cancers, bears the potential to be such an ideal target. As 4 main versican isoforms have been characterized, we sought to determine which isoform could represent the best target in human breast cancer. We used a series of 10 primary breast cancer lesions that were characterized as overexpressing the versican protein, when compared with matched normal breast tissues, using shotgun mass spectrometry and immunohistochemistry experiments. Quantitative polymerase chain reaction and western-blotting experiments were used to evaluate versican isoform expression in breast cancer/normal tissue pairs for which ARN quality was excellent. All known isoforms were significantly overexpressed in the malignant lesions, both at the mRNA and at the protein levels. In the course of this study, we also identified and cloned a new alternatively spliced versican isoform, referred to as V4, which was also found to be upregulated in human breast cancer. This study provides for the first time a comprehensive mRNA and protein analysis of versican isoforms expression in human breast tissues, and offers insights into which therapeutic strategy would be best suited to target versican in human breast cancer lesions. [less ▲]

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See detailCell membrane proteomic analysis identifies proteins differentially expressed in osteotropic human breast cancer cells.
Kischel, Philippe ULg; Guillonneau, Francois; Dumont, Bruno ULg et al

in Neoplasia : An International Journal for Oncology Research (2008), 10(9), 1014-20

Metastatic breast cancer cells are characterized by their high propensity to colonize the skeleton and form bone metastases, causing major morbidity and mortality. Identifying key proteins involved in the ... [more ▼]

Metastatic breast cancer cells are characterized by their high propensity to colonize the skeleton and form bone metastases, causing major morbidity and mortality. Identifying key proteins involved in the osteotropic phenotype would represent a major step toward the development of both new prognostic markers and new effective therapies. Cell surface proteins differentially expressed in cancer cells are preferred potential targets for antibody-based targeted therapies. In this study, using cell surface biotinylation and a mass spectrometric approach, we have compared the profile of accessible cell surface proteins between the human breast cancer cell line MDA-MB-231 and its highly osteotropic B02 subclone. This strategy allowed the identification of several proteins either up- or downregulated in the osteotropic cell line, and differential protein expressions were validated using antibody-based techniques. Class I HLAs were down-regulated in the bone metastatic variant, whereas alpha(v)beta(3) integrins, among others, were consistently up-regulated in this latter cell line. These results show that comprehensive profiling of the cell surface proteome of mother cancerous cell lines and derived organ-specific metastatic cell lines provides an effective approach for the identification of potential accessible marker proteins for both prognosis and antibody-based targeted therapies. [less ▲]

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