Immunohistochemical profile of galectin-8 expression in benign and malignant tumors of epithelial, mesenchymatous and adipous origins, and of the nervous system

This study aims to investigate whether the immunohistochemical expression of galectin-8 could be used as a diagnostic marker in tumor tissues of various histogenetic origins including specimens from epithelial (n=145), mesenchymatous (n=16), adipous (n=10) and central and peripheral nervous system (n=25) tissue, and 4 mesotheliomas. Immunohistochemical reactions were carried out with a polyclonal anti-galectin-8 antibody and histological slides from tissues derived from the files of the Laboratory of Anatomopathology of University Erasmus Hospital, Brussels. Formalin-fixed paraffinembedded tissues of 45 normal cases as well as 41 benign and 114 malignant tumors were studied. Marked decreases in immunohistochemical galectin-8 expression were obsewed in colon (p=0.001), pancreas (p=0.007), liver (p=0.0008), skin (p=0.002) and larynx (p=0.02) tissue when comparing malignant tissue to normal tissue andlor benign tumors. The reverse relationship was observed for breast tissue (p=0.007). No statistically significant differences (p>0.05) were detected when comparing normal tissue andlor benign to malignant tumors in lung, bladder, kidney, prostate and stomach tissue. Significant galectin-8 expression was also measured in non-epithelial tissue including tumors of the central and peripheral nervous system as well as in skeletal muscle and mesotheliomas. Immunohistochemical monitoring of galectin-8 thus reveals an organtype- dependent regulation of expression upon malignant transformation of various tissue types of epithelial origin. This observation will prompt further studies to 0ffprin.int requests to: Roberl Kiss, Ph.D., Laboratory of Histopathology, Faculty of Medicine - Free University of Brussels, 808 route de Lennik - 1070 Brussels, Belgiurn. Fax: 322 555 62 85. e-rnail: [email protected] delineate any relationship with prognosi

The Shb Adaptor Protein Binds to Tyrosine 766 in the FGFR-1 and Regulates the Ras/MEK/MAPK Pathway via FRS2 Phosphorylation in Endothelial Cells

Stimulation of fibroblast growth factor receptor-1 (FGFR-1) is known to result in phosphorylation of tyrosine 766 and the recruitment and subsequent activation of phospholipase C-γ (PLC-γ). To assess the role of tyrosine 766 in endothelial cell function, we generated endothelial cells expressing a chimeric receptor, composed of the extracellular domain of the PDGF receptor-α and the intracellular domain of FGFR-1. Mutation of tyrosine 766 to phenylalanine prevented PLC-γ activation and resulted in a reduced phosphorylation of FRS2 and reduced activation of the Ras/MEK/MAPK pathway relative to the wild-type chimeric receptor. However, FGFR-1–mediated MAPK activation was not dependent on PKC activation or intracellular calcium, both downstream mediators of PLC-γ activation. We report that the adaptor protein Shb is also able to bind tyrosine 766 in the FGFR-1, via its SH2 domain, resulting in its subsequent phosphorylation. Overexpression of an SH2 domain mutant Shb caused a dramatic reduction in FGFR-1–mediated FRS2 phosphorylation with concomitant perturbment of the Ras/MEK/MAPK pathway. Expression of the chimeric receptor mutant and the Shb SH2 domain mutant resulted in a similar reduction in FGFR-1–mediated mitogenicity. We conclude, that Shb binds to tyrosine 766 in the FGFR-1 and regulates FGF-mediated mitogenicity via FRS2 phosphorylation and the subsequent activation of the Ras/MEK/MAPK pathway