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Alterations of the INK4a‐ARF gene locus in pleomorphic adenoma of the parotid gland
Author(s) -
Weber Anette,
Langhanki Larissa,
Schütz Alexander,
Wittekind Christian,
Bootz Friedrich,
Tannapfel Andrea
Publication year - 2002
Publication title -
the journal of pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.964
H-Index - 184
eISSN - 1096-9896
pISSN - 0022-3417
DOI - 10.1002/path.1210
Subject(s) - microdissection , biology , pleomorphic adenoma , cdkn2a , pathology , immunohistochemistry , parotid gland , tumor suppressor gene , myoepithelial cell , methylation , cancer research , salivary gland , gene , carcinogenesis , medicine , genetics
Pleomorphic adenomas of the parotid gland are benign tumours composed of epithelial and mesenchymal cells. The INK4a‐ARF (CDKN2A) locus on chromosome 9p21 encodes two tumour suppressor proteins, p16 INK4a and p14 ARF , which act as upstream regulators of the Rb‐CDK4 and p53 pathways. To study the contribution of each pathway in pleomorphic adenomas, this study analysed alterations of p14 ARF , p16 INK4a , p53, and pRb in these tumours. After microdissecting the different histological components, 42 pleomorphic adenomas of the parotid gland were analysed for INK4a‐ARF inactivation by DNA sequence analysis, methylation‐specific PCR (MSP), restriction enzyme‐related polymerase chain reaction (RE‐PCR), mRNA expression, microsatellite analysis, and immunohistochemistry. In addition, microdeletion of p14 ARF and p16 INK4a were assessed by differential PCR. The status of p53 and Rb was examined by direct sequencing and immunohistochemistry. Using microdissection, it was possible to examine the tumour components, i.e. epithelial, mesenchymal, and transitional, separately after immunohistochemical identification. Methylation of p14 ARF was found in 1/42 cases and alterations of p16 INK4a occurred in 12/42 of pleomorphic adenomas, which correlated with loss of mRNA transcription. Microdeletions or specific mutations of either exon were not detected. Methylation was detected exclusively in the epithelial and transitional components and not within the mesenchymal part of the tumour. p53 mutations were detected in 4/42 adenomas, also occurring solely in the epithelial components of the tumours. pRb was detected immunohistochemically in 40/42 adenomas. In normal, corresponding parotid tissue, p14 ARF , p16 INK4a , p53, and pRb alterations were not observed. The observation that alterations of p14 ARF and p16 INK4a , and also p53 mutations, occurred exclusively in the epithelial and transitional components of pleomorphic adenoma supports the theory that these areas are prone to malignant transformation to carcinoma in adenoma. Copyright © 2002 John Wiley & Sons, Ltd.