Lectin Galactoside-binding Soluble 3 Binding Protein Research Articles

LGALS3BP, lectin galactoside-binding soluble 3 binding protein, promotes oncogenic cellular events impeded by antibody intervention

The extracellular matrix protein lectin galactoside-binding soluble 3 binding protein (LGALS3BP) constitutes a negative prognostic marker of cancer onset and progression with increasing value in clinical application. Since its discovery, however, although the glycoprotein has been implicated in a growing number of disease-related processes, its actual role and mechanism of action have remained ambiguous, thus hindering opportunities for therapeutic development. In this study, we have determined that LGALS3BP constitutes a novel ligand for integrins α1β1, α5β1, αvβ1 and α6β1 and have identified that these newly established partnerships at the membrane level are responsible for exerting the molecule's involvement in cancer through manipulation of multiple canonical 'outside-in' integrin signalling events. We demonstrate that LGALS3BP-mediated integrin activation results into signal transmission via Akt, JNK and the Ras cascade via the Raf-ERK axis while p38 activity is kept at baseline levels. Transient cellular adherence to LGALS3BP favours survival and proliferation signalling while apoptosis is kept at bay. Sustained cellular exposure to LGALS3BP significantly supports viability, motility and migration. Importantly, an anti-LGALS3BP antibody, SP2 is capable of impeding these newly defined LGALS3BP-driven processes without, however, compromising cell viability. These novel findings reveal the mechanism of action of LGALS3BP during cellular adherence and warrant its further validation as a potential pharmacological target for anticancer therapies.

Comparative proteomic analysis coupled with conventional protein assay as a strategy to identify predictors of successful testicular sperm extraction in patients with non‐obstructive azoospermia

Among infertile couples, approximately half have to face with male infertility. In men with non-obstructive azoospermia, surgical retrieval testicular sperm extraction (TESE) of spermatozoa can be attempted, but with low success rates. A specific biomarker that could predict residual spermatogenesis would obviously be of interest before performing TESE. Thus, our aim was to identify biomarkers of residual spermatogenesis in seminal plasma of patients with non-obstructive azoospermia (NOA) using an isotope-coded protein label (ICPL)-based proteomic strategy coupled with conventional protein assay. This retrospective study was conducted in 40 men with NOA at the University Hospital of Nantes and Proteomics Core facility Biogenouest - Inserm U1085 - IRSET, Rennes, France. Comparative ICPL proteomic screening of frozen seminal plasma and correlation with TESE outcome allowed the identification of some differentially expressed proteins. Among them, lectin galactoside-binding, soluble 3 binding protein (LGALS3BP) expression was further confirmed using conventional protein assay, and its interest as a predictor of TESE outcome was then evaluated and compared with conventional clinical and hormonal markers of residual spermatogenesis. Among the 12 differentially expressed proteins identified with comparative ICPL proteomic strategy, seminal LGALS3BP expression was found to be significantly higher in men with successful TESE. Finally, comparative ICPL proteomic screening of seminal plasma appears to be a promising approach for the identification of biomarkers of residual spermatogenesis. LGALS3BP, associated with clinical and hormonal markers, could potentially be used as a predictive marker of successful TESE outcome in patients with NOA.

LGALS3BP, lectin galactoside-binding soluble 3 binding protein, induces vascular endothelial growth factor in human breast cancer cells and promotes angiogenesis

Elevated serum or tissue levels of lectin galactoside-binding soluble 3 binding protein (LGALS3BP) have been associated with short survival and development of metastasis in a variety of human cancers. However, the role of LGALS3BP, particularly in the context of tumor-host relationships, is still missing. Here, we show that LGALS3BP knockdown in MDA-MB-231 human breast cancer cells leads to a decreased adhesion to fibronectin, a reduced transendothelial migration and, more importantly, a reduced expression of vascular endothelial growth factor (VEGF). Production of VEGF, that was restored by exposure of silenced cells to recombinant LGALS3BP, required an intact PI3k/Akt signaling. Furthermore, we show that LGALS3BP was able to directly stimulate HUVEC tubulogenesis in a VEGF-independent, galectin-3-dependent manner. Immunohistochemical analysis of human breast cancer tissues revealed a correlation among LGALS3BP expression, VEGF expression, and blood vessel density. We propose that in addition to its prometastatic role, LGALS3BP secreted by breast cancer cells functions critically as a pro-angiogenic factor through a dual mechanism, i.e by induction of tumor VEGF and stimulation of endothelial cell tubulogenesis.

SILAC-based quantitative proteomic approach to identify potential biomarkers from the esophageal squamous cell carcinoma secretome

The identification of secreted proteins that are differentially expressed between non-neoplastic and esophageal squamous cell carcinoma (ESCC) cells can provide potential biomarkers of ESCC. We used a SILAC-based quantitative proteomic approach to compare the secretome of ESCC cells with that of non-neoplastic esophageal squamous epithelial cells. Proteins were resolved by SDS-PAGE, and tandem mass spectrometry analysis (LC-MS/MS) of in-gel trypsin-digested peptides was carried out on a high-accuracy qTOF mass spectrometer. In total, we identified 441 proteins in the combined secretomes, including 120 proteins with >2-fold upregulation in the ESCC secretome vs. that of non-neoplastic esophageal squamous epithelial cells. In this study, several potential protein biomarkers previously known to be increased in ESCC including matrix metalloproteinase 1, transferrin receptor, and transforming growth factor beta-induced 68 kDa were identified as overexpressed in the ESCC-derived secretome. In addition, we identified several novel proteins that have not been previously reported to be associated with ESCC. Among the novel candidate proteins identified, protein disulfide isomerase family a member 3 (PDIA3), GDP dissociation inhibitor 2 (GDI2), and lectin galactoside binding soluble 3 binding protein (LGALS3BP) were further validated by immunoblot analysis and immunohistochemical labeling using tissue microarrays. This tissue microarray analysis showed overexpression of protein disulfide isomerase family a member 3, GDP dissociation inhibitor 2, and lectin galactoside binding soluble 3 binding protein in 93%, 93% and 87% of 137 ESCC cases, respectively. Hence, we conclude that these potential biomarkers are excellent candidates for further evaluation to test their role and efficacy in the early detection of ESCC.

Biological indicators of prognosis in Ewing's sarcoma: An emerging role for lectin galactoside‐binding soluble 3 binding protein (LGALS3BP)

Starting from an experimental model that accounts for the 2 most important adverse processes to successful therapy of Ewing's sarcoma (EWS), chemoresistance and the presence of metastasis at the time of diagnosis, we defined a molecular signature of potential prognostic value. Functional annotation of differentially regulated genes revealed 3 major networks related to cell cycle, cell-to-cell interactions and cellular development. The prognostic impact of 8 genes, representative of these 3 networks, was validated in 56 EWS patients. High mRNA expression levels of HINT1, IFITM2, LGALS3BP, STOML2 and c-MYC were associated with reduced risk to death and lower risk to develop metastasis. At multivariate analysis, LGALS3BP, a matricellular protein with a role in tumor progression and metastasis, was the most important predictor of event-free survival and overall survival. The association between LGALS3BP and prognosis was confirmed at protein level, when expression of the molecule was determined in tumor tissues but not in serum, indicating a role for the protein at local tumor microenvironment. Engineered enhancement of LGALS3BP expression in EWS cells resulted in inhibition of anchorage independent cell growth and reduction of cell migration and metastasis. Silencing of LGALS3BP expression reverted cell behavior with respect to in vitro parameters, thus providing further functional validation of genetic data obtained in clinical samples. Thus, we propose LGALS3BP as a novel reliable indicator of prognosis, and we offer genetic signatures to the scientific communities for cross-validation and meta-analysis, which are indispensable tools for a rare tumor such as EWS.