In order to detect possible dysplastic melanocytic naevi (DMN) associated melanoma risk factors and lesion specific differences in the mutation spectrum of dysplastic and congenital melanocytic naevi (CMN), we screened 19 specimens of human sporadic DMN derived from 19 patients for the presence of mutations in five genes, which we had investigated in a former study in 19 CMN 1 and which have been reported to be associated with human cutaneous melanoma (N-ras, 2 p53, 3 CDKN2A, 4 CDK4, 5 and MC1R 7). METHODSDNA was extracted from selected paraffin embedded DMN resection specimens using the QIAamp DNA Mini Kit (Qiagen) according to the recommendations of the supplier. The relative number of atypical melanocytes in the DMN and the histological subtype of the DMN were determined in parallel slides by an experienced dermatologist (Dr Regina Zimmermann) (table 1). The screening strategy for the detection of activating point mutations in the oncogenes N-ras and CDK4 as well as for germline sequence variants in the MC1R gene by combined RFLP-PCR/SSCP analysis, and the screening strategy for the detection of homozygous deletions and point mutations in the tumour suppressor genes p53 and CDKN2A by combined multiplex-PCR/SSCP analysis, have been described previously.1 In order to find out if the SSCP screening system that is used in our laboratory is suitable to detect point mutations in minor cellular subpopulations of the DMN lesions investigated (for example, N-ras point mutations in the atypical melanocyte fraction), we added gradually decreasing amounts of N-ras mutation harbouring genomic DNA (CAA to AAA mutation at one allele) to genomic N-ras wild type DNA before PCR and SSCP analysis. As a result, we could show that the aberrant mutation associated SSCP band is still visible at an admixture of less than 1% of mutation harbouring DNA (fig 1).In the present study we extended our MC1R screening system in order to allow the detection of two additional sequence variants (R151C and R160W), which like V92M and D294H 6 have been reported to be associated with red hair and light skin. 8 For reamplification of the 899 bp MC1R PCR preamplification product 1 with primer pair MC1R4A (5′ TCGCC GTGGA CCGCT ACATC 3′)/MC1R4B (5′ GCGTG CTGAA GACGA CACTG 3′) (120 bp PCR product, suitable for codon 151 and Key points• Nineteen specimens of human sporadic dysplastic melanocytic naevi (DMN) were screened for the presence of mutations in N-ras, p53, p16INK4a, p14ARF, CDK4, and MC1R.• In contrast to human congenital melanocytic naevi, a very low frequency of N-ras mutations seems to be characteristic of DMN.

Eighteen congenital melanocytic naevi (CMN) from 17 patients and 18 dysplastic melanocytic naevi (DMN) from 18 patients were screened for mutations in the BRAF oncogene (present study) and the N-ras oncogene (in the course of two foregoing studies) by single-strand conformational polymorphism (SSCP)/sequencing analysis. BRAF mutations were demonstrated in both types of lesion. As a whole, 17 of 18 CMN (94.4%) and five of 18 DMN (27.7%) harboured either BRAF or N-ras mutations. As the BRAF oncogene is frequently found to be mutated in human cutaneous melanomas, it may constitute a risk factor for melanoma formation within CMN and DMN.

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Malignant melanoma is a highly aggressive cancer that retains functional p53 and p73, and drug unresponsiveness largely depends on defects in death pathways after epigenetic gene silencing in conjunction with an imbalanced p73/DNp73 ratio. We constructed oncolytic viruses armed with an inhibitor of deacetylation and/or p73 to specifically target metastatic cancer. Arming of the viruses is aimed at lifting epigenetic blockage and re-opening apoptotic programs in a staggered manner enabling both, efficient virus replication and balanced destruction of target cells through apoptosis. Our results showed that cooperative expression of shHDAC1 and p73 efficiently enhances apoptosis induction and autophagy of infected cells which reinforces progeny production. In vitro analyses revealed 100% cytotoxicity after infecting cells with OV.shHDAC1.p73 at a lower virus dose compared to control viruses. Intriguingly, OV.shHDAC1.p73 acts as a potent inhibitor of highly metastatic xenograft tumors in vivo. Tumor expansion was significantly reduced after intratumoral injection of 3 × 108 PFU of either OV.shHDAC1 or OV.p73 and, most important, complete regression could be achieved in 100% of tumors treated with OV.shHDAC1.p73. Our results point out that the combination of high replication capacity and simultaneous restoration of cell death routes significantly enhance antitumor activity.

Parkinson's disease is not caused by mutations in the genes of these three detoxifying enzymes. The exon 9 variant in the catalase gene in the one family with PD is most likely a silent mutation and not the genetic cause of PD in this family.