Daniel Compagno

Modulation of endothelial cell migration and angiogenesis: a novel function for the “tandem-repeat” lectin galectin-8

Angiogenesis, the growth of new capillaries from preexisting blood vessels, is a complex process involving endothelial cell (EC) activation, disruption of vascular basement membranes, and migration and proliferation of ECs. Glycan‐mediated recognition has been proposed to play an instrumental role in mediating cell‐cell and cell‐matrix interactions. Ga‐lectins (Gal), a family of glycan‐binding proteins with affinity for β‐galactosides and a conserved sequence motif, can decipher glycan‐containing information and mediate cell‐cell communication. Galectin‐8 (Gal‐8), a member of this family, is a bivalent “tandem‐repeat”‐type galectin, which possesses 2 CRDs connected by a linker peptide. Here, we show that Gal‐8 is endowed with proangiogeneic properties. Functional assays revealed a critical role for this lectin in the regulation of capillary‐tube formation and EC migration. Moreover, Matrigel, either supplemented with Gal‐8 or vascular endothelial growth factor (VEGF), injected in mice resulted in induction of in vivo angiogenesis. Remarkably, Gal‐8 was expressed both in the cytoplasm and nucleus in ECs of normal and tumor vessels. Furthermore, CD166 [activated leukocyte cell adhesion molecule (ALCAM)] was identified as a specific Gal‐8‐binding partner in normal vascular ECs. Collectively, these data provide the first evidence demonstrating an essential role for Gal‐8 in the regulation of angiogenesis with critical implications in tumor biology.—CCárdenasrdenas Delgado, V. M., Nugnes, L. G., Colombo, L. L., Troncoso, M. F., Fernández, M. M., Malchiodi, E. L., Frahm, I., Croci, D. O., Compagno, D., Rabinovich, G. A., Wolfenstein‐Todel, C., Elola, M. T. Modulation of endothelial cell migration and angiogenesis: a novel function for the “tandem‐repeat” lectin galectin‐8. FASEB J. 25, 242–254 (2011). www.fasebj.org

Dissecting the signal transduction pathways triggered by galectin–glycan interactions in physiological and pathological settings

Galectins are a family of evolutionarily conserved animal lectins with pleiotropic functions and widespread distribution. Fifteen members have been identified in a wide variety of cells and tissues. Through recognition of cell surface glycoproteins and glycolipids, these endogenous lectins can trigger a cascade of intracellular signaling pathways capable of modulating cell differentiation, proliferation, survival, and migration. These cellular events are critical in a variety of biological processes including embryogenesis, angiogenesis, neurogenesis, and immunity and are substantially altered during tumorigenesis, neurodegeneration, and inflammation. In addition, galectins can modulate intracellular functions and this effect involves direct interactions with distinct signaling pathways. In this review, we discuss current knowledge on the intracellular signaling pathways triggered by this multifunctional family of β‐galactoside‐binding proteins in selected physiological and pathological settings. Understanding the “galectin signalosome” will be essential to delineate rational therapeutic strategies based on the specific control of galectin expression and function.

Glycans and galectins in prostate cancer biology, angiogenesis and metastasis

Prostate cancer is the second most common cause of cancer and the sixth leading cause of cancer death among men worldwide. While localized prostate cancer can be cured, advanced and metastatic prostate cancer remains a significant therapeutic challenge. Malignant transformation is associated with important modifications of the cellular glycosylation profile, and it is postulated that these changes have a considerable relevance for tumor biology. Metastasis is a multiphasic process that encompasses angiogenesis, the spread of tumor cells and their growth at distant sites from the primary tumor location. Recognition of glycoconjugates by galectins, among other lectins, plays a fundamental role in the metastatic spread, tumor immune escape and the neovascularization process. Particularly in prostate cancer, both carbohydrates and galectins have been implicated in many cellular processes such as proliferation, apoptosis, migration and invasion. However, a limited number of studies assessed their potential implications in the induction of metastasis in prostate cancer patients or in animal models. Moreover, the role of galectin-glycan interactions in vivo still remains poorly understood; concerted effort should thus be made in order to shed some light on this question. This review summarizes current evidence on both the expression and role of glycans and galectins in prostate cancer, particularly turning our attention to the angiogenic and metastatic processes.

Galectins: Major Signaling Modulators Inside and Outside the Cell

Galectins control cell behavior by acting on different signaling pathways. Most of the biological activities ascribed to these molecules rely upon recognition of extracellular glycoconjugates and establishment of multivalente interactions, which trigger adaptive biological responses. However, galectins are also detected within the cell in different compartments, where their regulatory functions still remain poorly understood. A deeper understanding of the entire galectin signalosome and its impact in cell behavior is therefore essential in order to delineate new strategies to specifically manipulate both galectin expression and function. This review summarizes our current knowledge of the signaling pathways activated by galectins, their glycan dependence and the cellular compartment where they become activated and are biologically relevant.

Dok-4 Is a Novel Negative Regulator of T Cell Activation

Dok-4 (downstream of tyrosine kinase-4) is a recently identified member of the Dok family of adaptor proteins, which are characterized by an amino-terminal pleckstrin homology domain, a phosphotyrosine-binding domain, and a carboxyl-terminal region containing several tyrosines and poly-proline-rich motifs. Two members of the Dok family, Dok-1 and Dok-2, have already been described as negative regulators in T cells. However, the function of Dok-4, which is also expressed in T cells, remains unknown. In this study, we report that Dok-4 is phosphorylated after TCR engagement and shuttled within the cytoplasm of T cells before being recruited to the polarized microtubule organizing center after the formation of the immunological synapse. Loss-of-function experiments using RNA interference constructs show that Dok-4 is a negative regulator of ERK phosphorylation, IL-2 promoter activity, and T cell proliferation. Exogenous expression of wild-type Dok-4 induces a significant activation of Rap1, which is involved in the regulation of ERK. The pleckstrin homology domain of Dok-4 is required both for its cytoplasmic shuttling and relocalization as well as for its inhibitory properties on T cell activation. Thus, Dok-4 represents a novel negative regulator of T cells.

Galectins as New Prognostic Markers and Potential Therapeutic Targets for Advanced Prostate Cancers

A better understanding of multimolecular interactions involved in tumor dissemination is required to identify new effective therapies for advanced prostate cancer (PCa). Several groups investigated protein-glycan interactions as critical factors for crosstalk between prostate tumors and their microenvironment. This review both discusses whether the “galectin-signature” might serve as a reliable biomarker for the identification of patients with high risk of metastasis and assesses the galectin-glycan lattices as potential novel targets for anticancer therapies. The ultimate goal of this review is to convey how basic findings related to galectins could be in turn translated into clinical settings for patients with advanced PCa.

Delineating the "galectin signature" of the tumor microenvironment

Galectins, a family of glycan-binding proteins, can control tumor progression by promoting transformation, angiogenesis and immune escape. We identified a dynamically regulated ‘galectin signature’, which delineates the progression of prostate cancer, highlighting galectin-1 as an attractive target for anti-angiogenic therapy in advanced stages of the disease.

Stable and high expression of Galectin-8 tightly controls metastatic progression of prostate cancer

Two decades ago, Galectin-8 was described as a prostate carcinoma biomarker since it is only expressed in the neoplastic prostate, but not in the healthy tissue. To date, no biological function has been attributed to Galectin-8 that could explain this differential expression. In this study we silenced Galectin-8 in two human prostate cancer cell lines, PC3 and IGR-CaP1, and designed a pre-clinical experimental model that allows monitoring the pathology from its early steps to the long-term metastatic stages. We show for the first time that the natural and conserved expression of Gal-8 in tumour cells is responsible for the metastatic evolution of prostate cancer. In fact, Gal-8 controls the rearrangement of the cytoskeleton and E-Cadherin expression, with a major impact on anoikis and homotypic aggregation of tumour cells, both being essential processes for the survival of circulating tumour cells during metastasis. While localized prostate cancer can be cured, metastatic and advanced disease remains a significant therapeutic challenge, urging for the identification of prognostic markers of the metastatic process. Collectively, our results highlight Galectin-8 as a potential target for anti-metastatic therapy against prostate cancer.

Abstract 2995: Loss of SHISA3 is an early event of the epithelial-to-mesenchymal transition associated with chemoresistance in prostate cancer

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA Background: Despite scientific advances over the past decade, prostate cancer still remains the fifth leading cause of death from cancer in men worldwide. Docetaxel has an established role in the treatment of metastatic castrate-resistant prostate cancer (CRPC). However, malignant cells frequently acquire Docetaxel resistance. Therefore, further research is required to understand the molecular mechanisms underlying Docetaxel-resistance, which could be helpful in formulating alternative and superior therapeutic strategies. Methods: Two Docetaxel-resistant prostate cancer cell lines (IGR-CaP1 and PC3) were obtained by continuous exposure to Docetaxel. By comparing genes and miRs expression profiles established in these two Docetaxel-resistant models, we observed an enrichment of genes involved in the epithelial-to-mesenchymal transition (EMT) in the chemoresistant models and identified new genes potentially implicated in the resistance mechanism. Results: We identified the SHISA3 gene as a highly down-regulated gene in resistant cells. This gene was originally identified as an inhibitor of Wnt and FGF signaling during development in Xenopus. We showed that SHISA3 was lost during the acquisition of resistance to Docetaxel possibly via an EMT mechanism. Knockdown of SHISA3 in the parental IGR-CaP1 and PC3 cells triggered loss of the tight junction protein Occludin, engaged the Cadherin switch and increased the migratory properties of cells in vitro. Loss of SHISA3, along with loss of E-cadherin expression and expression of the mesenchymal marker N-cadherin were also observed in Docetaxel-resistant tumors obtained from IGR-CaP1-R xenografted mice. Phylogenetic comparison of SHISA3 gene sequences suggested that it may correspond to transmembrane adapters capable of regulating the activity of membrane receptors such as growth factor receptors. We are currently studying the binding partners of SHISA3 in our models by a proteomic approach to identify the implicated signaling pathway in prostate cancer. Conclusion: Our results show that loss of SHISA3 is an early event linked to the EMT process associated with chemoresistance and suggest that SHISA3 could be a useful biomarker to identify chemoresistant cells. Moreover, identification of its mechanism of action may lead to the identification of new therapeutic targets to overcome Docetaxel resistance. Citation Format: Nicolas J-p Martin, Sophie Cotteret, Catherine Gaudin, Marine Garrido, Safae Aarab-Terrisse, Nader al Nakouzi, Lucas Gentilini, Daniel Compagno, Vasily Ogryzko, Guillaume Meurice, Karim Fizazi, Anne Chauchereau. Loss of SHISA3 is an early event of the epithelial-to-mesenchymal transition associated with chemoresistance in prostate cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2995. doi:10.1158/1538-7445.AM2015-2995

Endogenous Galectin-1 in T Lymphocytes Regulates Anti-prostate Cancer Immunity

The identification of effective new therapies for prostate cancer (PCa) requires a better understanding of the multiple molecular interactions between tumor cells and their associated microenvironment. In this context, galectin-1 (Gal-1) is a key molecule in the determination of the prostatic carcinoma microenviroment; therefore, it is essential to understand all the molecular processes in which this protein is involved. Most of the previous studies found in the literature have focused on the microenvironment remodeling properties of tumor-secreted Gal-1, through its interactions with the glyco-receptors at the cell membrane and the extracellular matrix. This report shows original aspects of the lectin by focusing on the role of lymphocyte endogenous Gal-1 in controlling anti-prostate tumor immunity. Using a murine preclinical model of prostate cancer, our results demonstrate that endogenous Gal-1 in lymphocytes modulates their proliferative rate and cytotoxic function in conditions of high extracellular Gal-1 concentration, mainly derived from tumor cells. In such conditions, the absence of Gal-1 in T lymphocytes potentiates anti-tumor immune responses. Further studies demonstrated that endogenous Gal-1 in CD4+, but mainly in CD8+T cells, acts as a negative regulator of anti-tumor immunity. In conclusion, prostate tumors require Gal-1 in lymphocytes to evade immune responses. This report lays the foundation for an original immunotherapy strategy for prostate cancer.