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Evidence for u.v. induction of CDKN2 mutations in melanoma cell lines
P M Pollock1, F Yu, L Qiu
1Queensland Cancer Fund Research Laboratories, Joint Experimental Oncology Program, Queensland Institute of Medical Research, Herston, Australia.
Abstract:
The CDKN2 gene, encoding the cyclin dependent kinase inhibitor p16, is a tumour suppressor gene involved in melanoma and maps to chromosome band 9p22. Mutations or interstitial deletions of this gene have been found both in the germline of familial melanoma cases and somatically in melanoma cell lines. Previous mutation analyses of melanoma cell lines have indicated a high frequency of C:G to T:A transitions, with all of these mutations occurring at dipyrimidine sites. Including three melanoma cell lines carrying tandem CC to TT mutations, the spectrum of mutations so far reported indicates a possible role for u.v. radiation in the mutagenesis of this gene in some tumours. To further examine this hypothesis we have characterised mutations of the CDKN2 gene in 30 melanoma cell lines. Nineteen lines carried complete or partial homozygous deletions of the gene. Of the remaining cell lines, eight were shown by direct sequencing of PCR products from exon 1 and exon 2 to carry a total of nine different mutations of CDKN2. Two cell lines carried tandem CC to TT mutations and a high rate of C:G to T:A transitions was observed. This study provides further evidence for the role of u.v. light in the genesis of melanoma, with one target being the CDKN2 tumour suppressor gene.
Insights
The CDKN2 tumor suppressor gene is frequently deleted or mutated in melanoma cell lines. Observed mutations suggest ultraviolet (UV) radiation plays a role in melanoma development by damaging this critical gene.
Area of Science:
- Oncology
- Genetics
- Dermatology
Background:
- The CDKN2 gene, encoding p16, is a crucial tumor suppressor gene implicated in melanoma development.
- Germline and somatic mutations in CDKN2 are observed in familial melanoma and cell lines.
- Previous studies suggest a high frequency of C:G to T:A transitions at dipyrimidine sites, potentially linked to UV radiation.
Purpose of the Study:
- To investigate mutations within the CDKN2 gene in 30 melanoma cell lines.
- To further explore the hypothesis that UV radiation contributes to CDKN2 mutagenesis in melanoma.
Main Methods:
- Characterization of CDKN2 gene mutations in 30 melanoma cell lines.
- Analysis of homozygous deletions and point mutations via direct sequencing of PCR products from exons 1 and 2.
Main Results:
- Nineteen cell lines exhibited complete or partial homozygous deletions of the CDKN2 gene.
- Eight cell lines displayed nine distinct CDKN2 mutations, including tandem CC to TT transitions.
- A high rate of C:G to T:A transitions was observed, consistent with UV-induced damage.
Conclusions:
- The study provides compelling evidence for the involvement of UV radiation in melanoma genesis.
- The CDKN2 tumor suppressor gene is identified as a significant target of UV-induced mutagenesis in melanoma.