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.

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.

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Our previous studies have shown that camptothecin and doxorubicin triggered ceramide accumulation via de novo synthesis pathway. De novo ceramide generation was responsible for the drug-induced apoptosis through a caspase-3-dependent pathway and a decrease of thrombospondin-1 expression in human thyroid carcinoma FTC-133 cells. Here, we demonstrate that Jun N-terminal kinases play a critical role in camptothecin- and doxorubicin-induced down-regulation of thrombospondin-1 expression: i) de novo ceramide synthesis pathway activates Jun N-terminal kinase 1/2 resulting in activating transcription factor 2 phosphorylation; ii) cell treatment by SP600125, a Jun N-terminal kinase specific inhibitor, strongly reduced activating transcription factor 2 phosphorylation and completely abolished camptothecin and doxorubicin effects; and iii) activating transcription factor 2 expression silencing greatly attenuated camptothecin- and doxorubicin-induced down-regulation of thrombospondin-1 expression and apoptosis. The set of our data established that camptothecin- and doxorubicin-induced activation of Jun N-terminal kinase/activating transcription factor 2 pathway via de novo ceramide synthesis down-regulates thrombospondin-1 expression and apoptosis in human thyroid carcinoma FTC-133 cells. This article is part of a Special Issue entitled: 11th European Symposium on Calcium.

Hodgkin lymphoma (HL) represents a category of lymphoid neoplasms with unique features, notably the usual scarcity of tumour cells in involved tissues. The most common subtype of classical HL, nodular sclerosis HL, characteristically comprises abundant fibrous tissue stroma. Little information is available about the protein composition of the stromal environment from HL. Moreover, the identification of valid protein targets, specifically and abundantly expressed in HL, would be of utmost importance for targeted therapies and imaging, yet the biomarkers must necessarily be accessible from the bloodstream. To characterize HL stroma and to identify potentially accessible proteins, we used a chemical proteomic approach, consisting in the labelling of accessible proteins and their subsequent purification and identification by mass spectrometry. We performed an analysis of potentially accessible proteins in lymph node biopsies from HL and reactive lymphoid tissues, and in total, more than 1400 proteins were identified in 7 samples. We have identified several extracellular matrix proteins overexpressed in HL, such as versican, fibulin-1, periostin, and other proteins such as S100-A8. These proteins were validated by immunohistochemistry on a larger series of biopsy samples, and bear the potential to become targets for antibody-based anti-cancer therapies.