EXPRESSION OF HER-2 CORRELATED PROTEINS IN ILEAL CARCINOIDS Azzoni C., Giordano G., Bottarelli L., Tamburini E., D’Adda T., Pizzi S., Rindi G., Bordi C. Department of Pathology and Laboratory Medicine, Section of Pathological Anatomy, Parma University, Parma - Italy

BACKGROUND In a previous study of our laboratory we found a high HER-2/neu immunohistochemical expression in ileal midgut carcinoids (see data in Patients) at variance with other gastroenteropancreatic endocrine tumors HER-2/neu overexpression may be involved in the carcinogenetic process of malignant ileal carcinoids Involvement of metastasis-related proteins c-MET, MTA-1 and VEGF activated by HER-2/neu ?

C-MET chromosome 7q31 tyrosine kinase receptor for Scatter Factor (also known as Hepatocyte Growth Factor) stimulating cell proliferation, dissociation, motility, extracellular matrix invasion and metastatic behavior of a large array of neoplasms overexpressed in several type of tumors, including thyroid, pancreatic, colorectal and breast carcinomas in endocrine pancreatic tumors the expression of MET was found to be higher in tumors with metastases and worse prognosis

MTA-1 chromosome 14q32 nuclear regulatory protein that interacts with specific genes involved in cellular regulation, invasion and progression expression of MTA-1 gene was increased four-times in cerbB2/neu stable transfectants cells compared to untransfected cells MTA-1 is overexpressed in a variety of human cancers including cancers of the breast, ovary, lung, gastrointestinal system and colorectum

VEGF chromosome 6p12 highly specific mitogen for vascular endothelial cells clinical importance for tumor growth of solid malignancies in various organs including breast, lung, prostate and colon preclinical and clinical findings support VEGF as a promising target for anticancer therapy VEGF has been demonstrated to be highly expressed in midgut ileal carcinoids whereas it is focally expressed in other gastroenteropancreatic neuroendocrine tumors, suggesting the possible use of this protein as a serum marker for ileal carcinoid

EXPERIMENTAL DESIGN c-MET, MTA-1 and VEGF were examined by immunohistochemistry in 35 primary ileal carcinoids and in 5 metastatic tissues We also determined the association of these proteins with the status of Her- 2/neu expression

PATIENTS PRIMARY TUMORS METASTASES Legend: F, female; M, male; nd: not determined

METHODS AntibodyCloneRetrievalDilutionIncubationPositivity c-MET sc-161 Santa Cruz, Biotechology EDTA ph 91:50overnightmembrane, cytoplasmic MTA-1 Sc Santa Cruz, Biotechology EDTA ph 91:50overnightnuclear VEGF Sc-7269 Santa Cruz, Biotechology EDTA ph 91:100overnightcytoplasmic Semiquantitative analisys intensity and positivity of immunohistochemical staining c-MET, MTA-1, VEGF : 4-point scale: 0: no staining, 1: mild staining, 2: moderate staining, 3: intense staining

MTA-1 c-MET VEGF Intense staining of metastasis- related proteins in ileal carcinoids

RESULTS Increased expressions of c-MET and MTA-1 proteins in 78% and 79% of cases, respectively Increased expression of VEGF in 11% of cases No expression variations between primary and metastatic tumors c-METMTA-1VEGF NORMAL: score 0-2 OVEREXPRESSED: score 3

CONCLUSIONS The proteins c-Met and MTA-1 likely have a specific role in the malignant progression of ileal carcinoids Overexpression of VEGF could not be confirmed in our study The increased levels of the c-MET and MTA-1 proteins may depend on the Her-2/neu overexpression already documented in ileal carcinoids