MDM2 and CDK4 amplifications are rare events in salivary duct carcinomas
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Inga Grünewald1, Marcel Trautmann1, Alina Busch2, Larissa Bauer1, Sebastian Huss1, Petra Schweinshaupt3, Claudia Vollbrecht3,4, Margarete Odenthal3, Alexander Quaas3, Reinhard Büttner3, Moritz F. Meyer5, Dirk Beutner5, Karl-Bernd Hüttenbrink5, Eva Wardelmann1, Markus Stenner2, Wolfgang Hartmann1
1Department of Pathology, University Hospital Muenster, Muenster, Germany
2Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Muenster, Muenster, Germany
3Institute of Pathology, University Hospital Cologne, Cologne, Germany
4Current address: Institute of Pathology, Charité University Hospital Berlin, Berlin, Germany
5Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Cologne, Cologne, Germany
Inga Grünewald, email: firstname.lastname@example.org
Keywords: salivary gland carcinoma, p53, MDM2, CDK4, HMGA2
Received: February 15, 2016 Accepted: September 12, 2016 Published: September 20, 2016
Salivary duct carcinoma (SDC) is an aggressive adenocarcinoma of the salivary glands associated with poor clinical outcome. SDCs are known to carry TP53 mutations in about 50%, however, only little is known about alternative pathogenic mechanisms within the p53 regulatory network. Particularly, data on alterations of the oncogenes MDM2 and CDK4 located in the chromosomal region 12q13-15 are limited in SDC, while genomic rearrangements of the adjacent HMGA2 gene locus are well documented in subsets of SDCs. We here analyzed the mutational status of the TP53 gene, genomic amplification of MDM2, CDK4 and HMGA2 rearrangement/amplification as well as protein expression of TP53 (p53), MDM2 and CDK4 in 51 de novo and ex pleomorphic adenoma SDCs.
25 of 51 cases were found to carry TP53 mutations, associated with extreme positive immunohistochemical p53 staining levels in 13 cases. Three out of 51 tumors had an MDM2 amplification, one of them coinciding with a CDK4 amplification and two with a HMGA2 rearrangement/amplification. Two of the MDM2 amplifications occurred in the setting of a TP53 mutation. Two out of 51 cases showed a CDK4 amplification, one synchronously being MDM2 amplified and the other one displaying concurrent low copy number increases of both, MDM2 and HMGA2.
In summary, we here show that subgroups of SDCs display genomic amplifications of MDM2 and/or CDK4, partly in association with TP53 mutations and rearrangement/amplification of HMGA2. Further research is necessary to clarify the role of chromosomal region 12q13-15 alterations in SDC tumorigenesis and their potential prognostic and therapeutic relevance.
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