title: Altered expression and new mutations in DNA mismatch repair genes MLH1 and MSH2 in melanoma brain metastases.
abstract: Brain metastases, including those of malignant melanoma (known for its high genomic instability), are the most common intracranial tumors. The main objective of this study was to investigate expression and mutation in the DNA mismatch repair system in melanoma brain metastases. Expression of MLH1, MSH2, PMS1 and PMS2 was investigated immunohistochemically in 31 melanoma metastatic tumors. Mutational analysis of MLH1 and MSH2 was performed in 17 melanoma brain metastases. Loss of MLH1 and MSH2 expression was found in 10/31 and 12/31 tumors. PMS1 (27/31) and PMS2 (28/31) expression was preserved in the majority of lesions. Potential missense mutation was found in MSH2 (exon 13) in 2/17 melanomas. Mutation in the intron sequence between exon 14 and 15 of MLH1 (exon 15) was observed in 4/17 cases. Our results indicate that the two major DNA mismatch repair genes, MLH1 and MSH2, are more frequently affected by alterations in the DNA mismatch repair system than the helper genes PMS1 and PMS2. The presence of mutations of MSH2 and MLH1 in melanoma brain metastases, which has not been found in primary melanomas, indicates the high genomic instability of melanoma brain metastases.
authors.affiliation: Department of Cytopathology, Georg-August University, Robert Koch Str. 40, 37075 Göttingen, Germany.
authors.forename: Monika
authors.initials: M
authors.lastname: Korabiowska
authors.forename: Fatima
authors.initials: F
authors.lastname: König
authors.forename: Raphaela
authors.initials: R
authors.lastname: Verheggen
authors.forename: Thilo
authors.initials: T
authors.lastname: Schlott
authors.forename: Carlos
authors.initials: C
authors.lastname: Cordon-Cardo
authors.forename: Bernd
authors.initials: B
authors.lastname: Romeike
authors.forename: Ulrich
authors.initials: U
authors.lastname: Brinck
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000328:Adult; D000368:Aged; D020137:Base Pair Mismatch; D001932:Brain Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000556:secondary*; D002352:Carrier Proteins; D004260:DNA Repair / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics*; D005260:Female; D015870:Gene Expression; D042822:Genomic Instability / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008545:Melanoma / Q000235:genetics* / Q000378:metabolism / Q000556:secondary*; D008875:Middle Aged; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein; D009154:Mutation; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics*; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; C501486:MLH1 protein, human; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; C497172:MSH2 protein, human; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein