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Analysis and significance of c-MET expression in adenoid cystic carcinoma of the salivary gland a

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Diana Bell , Renata Ferrarotto , Melanie D Fox , Dianna Roberts , Ehab Y Hanna , Randal S c

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Weber & Adel K El-Naggar a

Department of Pathology; The University of Texas MD Anderson Cancer Center; Houston, TX USA b

Department of Thoracic/ Head and Neck Medical Oncology; The University of Texas MD Anderson Cancer Center; Houston, TX USA c

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Department of Head and Neck Surgery; The University of Texas MD Anderson Cancer Center; Houston, TX USA Accepted author version posted online: 29 Apr 2015.Published online: 29 Apr 2015.

To cite this article: Diana Bell, Renata Ferrarotto, Melanie D Fox, Dianna Roberts, Ehab Y Hanna, Randal S Weber & Adel K ElNaggar (2015) Analysis and significance of c-MET expression in adenoid cystic carcinoma of the salivary gland , Cancer Biology & Therapy, 16:6, 834-838, DOI: 10.1080/15384047.2015.1030554 To link to this article: http://dx.doi.org/10.1080/15384047.2015.1030554

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BEDSIDE TO BENCH REPORT Cancer Biology & Therapy 16:6, 834--838; June 2015; © 2015 Taylor and Francis Group, LLC

Analysis and significance of c-MET expression in adenoid cystic carcinoma of the salivary gland Diana Bell1,*, Renata Ferrarotto2, Melanie D Fox1, Dianna Roberts3, Ehab Y Hanna3, Randal S Weber3, and Adel K El-Naggar1 1

Department of Pathology; The University of Texas MD Anderson Cancer Center; Houston, TX USA; 2Department of Thoracic/ Head and Neck Medical Oncology; The University of Texas MD Anderson Cancer Center; Houston, TX USA; 3Department of Head and Neck Surgery; The University of Texas MD Anderson Cancer Center; Houston, TX USA

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Keywords: adenoid cystic carcinoma, c-Met, salivary, targeted therapy

Adenoid cystic carcinoma (ACC), a rare salivary gland malignancy, is a histogenetic, morphologic, and clinical heterogeneous disease. Extensive efforts have been made to characterize molecular events associated with these tumors, including the identification of prognostic and predictive biomarkers. Increased copy number gain and amplification of c-Met, the cell surface receptor for hepatocyte growth factor, has been shown to enhance tumor growth and invasiveness and promote metastasis in certain tumor types. In this study, we evaluated the expression of c-Met by immunohistochemistry (IHC) in a large cohort of salivary gland ACCs and examined its clinicopathologic implications. Archival formalin-fixed paraffin-embedded blocks from 200 ACC patients were used in this study. Pathologic patterns and phenotypic expression of c-Met were recorded and compared with clinical factors including gender, age, disease stage at diagnosis, and clinical outcomes. Correlations between c-MET expression and clinical characteristics were assessed by Pearson’s chi-square test or by the 2-tailed Fisher exact test. Curves describing overall survival were generated by Kaplan-Meier product limit method. Strong c-MET expression was seen in inner ductal and outer myoepithelial cells in 53.2% of the cases. There was no correlation between c-Met overexpression and clinicopathologic parameters or patient’s overall survival ( p D .94074). In conclusion, c-MET expression is high in a significant subgroup of ACC patients. While c-MET expression is not a prognostic factor in ACC, its role as a predictive marker of benefit from MET inhibitors deserves further investigation.

Introduction

Materials and Methods

Adenoid cystic carcinoma (ACC), the second most frequent malignancy of the major and minor salivary glands, makes up approximately 15%–23% of all carcinomas at these locations.1,2 Despite undergoing resection with clear margins, up to 60% of patients have locoregional or distant recurrence. The median survival duration of patients with distant metastases is about 3 years, although up to 10% of these patients may survive 10 y or longer with indolent metastases. Extensive efforts have been made to characterize molecular events associated with these tumors, including the identification of biomarkers for prognostication and therapy guidance. Copy number gain and amplification of c- MET, the cell surface receptor for hepatocyte growth factor (HGF), has been shown to enhance tumor growth and invasiveness and promote metastasis in certain tumor types (Fig. 1).3 The relevance of c-MET expression in ACC of salivary gland origin was first described in 2003 in a study published by Suzuki, et al.4 Although the findings of Suzuki, et al. were novel, the study’s small number of cases limited its impact. In the present study, we evaluated the expression of c- MET in a large cohort of salivary ACCs and examined its clinicopathologic implications.

Archival formalin-fixed paraffin-embedded blocks of 200 ACCs patients accessioned at The University of Texas MD Anderson Cancer Center between 1988 and 2006 formed this study cohort. Appropriate written informed consent was obtained after the study was approved by the Institutional Review Board. The material for tissue microarray was created by using 2 1.0-mm-diameter cores of spatially different areas of representative tumor from each paraffin block. Pathologic patterns and phenotypic expression of c- MET were recorded and correlated with patient’s clinical characteristics including gender, age, stage, and clinical outcome. Cytospins prepared from a newly validated ACC cell line5 were also used. Immunohistochemical and immunoreactivity analyses Immunohistochemical (IHC) analysis of c-MET was performed with use of the BOND MAX IHC staining protocol by Vision Biosystems (Norwell, MA) on 4-mm paraffin sections of the tissue microarray material. In brief, after the slides were dewaxed, washed, and rehydrated with use of xylene and graded alcohol washes, Tris-EDTA buffer was used for antigen retrieval. Slides were subsequently treated with 3% hydrogen peroxide to block endogenous peroxidase. After incubation with the c- MET primary antibody (Novocastra, 1:50 dilution), the secondary

*Correspondence to: Diana Bell; Email: [email protected] Submitted: 03/03/2015; Accepted: 03/08/2015 http://dx.doi.org/10.1080/15384047.2015.1030554

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Figure 1. c-Met-mediated oncogenic signaling (from Peruzzi et al). Activation of c-Met-mediated oncogenic signaling occurs most commonly through aberrant paracrine HGF stimulation and consequent receptor overexpression or through autocrine HGF production, receptor mutation, gene amplification or rearrangement. Increased cell proliferation, survival, motility, and extracellular matrix degradation resulting from pathway activation contributes to tumor growth, invasiveness, and metastasis. At least 3 routes of pathway intervention have been followed as selective anticancer drug development strategies: antagonism of ligand binding, inhibition of TK catalytic function, and blockade of interactions between activated receptors and downstream intracellular effectors. © American Association for Cancer Research. Reproduced by permission of American Association for Cancer Research. Permission to reuse must be obtained from the rightsholder.

conjugate antibody was applied. Finally, each specimen-containing slide was developed by using the chromogen DAB and counterstained with hematoxylin. c- MET IHC staining was independently evaluated by 2 pathologists. Only cytoplasmic and membranous staining was considered positive. Lesional tissues with strong staining in >50% of the neoplastic cells were scored as strongly positive. Weak staining or strong staining in

Analysis and significance of c-MET expression in adenoid cystic carcinoma of the salivary gland.

Adenoid cystic carcinoma (ACC), a rare salivary gland malignancy, is a histogenetic, morphologic, and clinical heterogeneous disease. Extensive effort...
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