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Increased Melanocytic Nevi and Nevus Density in a G-34T CDKN2A/p16 Melanoma-Prone Pedigree

2008; Elsevier BV; Volume: 128; Issue: 8 Linguagem: Inglês

10.1038/jid.2008.51

1523-1747

Scott R. Florell, Laurence J. Meyer, Kenneth M. Boucher, Douglas Grossman, Lisa Cannon‐Albright, Ronald M. Harris, Wolfram E. Samlowski, John J. Zone, Sancy A. Leachman,

Cancer Genomics and Diagnostics

total nevus density total nevus number TO THE EDITOR Cyclin-dependent kinase inhibitor 2A (CDKN2A/p16) is a high-penetrance, autosomal-dominant melanoma predisposition gene (Cannon-Albright et al., 1992Cannon-Albright L.A. Goldgar D.E. Meyer L.J. Lewis C.M. Anderson D.E. Fountain J.W. et al.Assignment of a locus for familial melanoma, MLM, to chromosome 9p13–p22.Science. 1992; 258: 1148-1152Crossref PubMed Scopus (479) Google Scholar; Kamb et al., 1994Kamb A. Shattuck-Eidens D. Eeles R. Liu Q. Gruis N.A. Ding W. et al.Analysis of the p16 gene (CDKN2) as a candidate for the chromosome 9p melanoma susceptibility locus.Nat Genet. 1994; 8: 23-26Crossref PubMed Scopus (739) Google Scholar) and mutations of this tumor suppressor are associated with a markedly increased risk of melanoma (Goldstein and Tucker, 1995Goldstein A.M. Tucker M.A. Genetic epidemiology of familial melanoma.Dermatol Clin. 1995; 13: 605-612PubMed Google Scholar; Kefford et al., 1999Kefford R.F. Newton Bishop J.A. Bergman W. Tucker M.A. Counseling and DNA testing for individuals perceived to be genetically predisposed to melanoma: a consensus statement of the Melanoma Genetics Consortium.J Clin Oncol. 1999; 17: 3245-3251Crossref PubMed Scopus (180) Google Scholar). CDKN2A/p16 activity is required for melanocyte senescence in vitro (Gray-Schopfer et al., 2006Gray-Schopfer V.C. Cheong S.C. Chong H. Chow J. Moss T. Abdel-Malek Z.A. et al.Cellular senescence in naevi and immortalisation in melanoma: a role for p16?.Br J Cancer. 2006; 95: 496-505Crossref PubMed Scopus (288) Google Scholar). Pathogenic mutations have been discovered in approximately 10% of Utah melanoma pedigrees (Eliason et al., 2006Eliason M.J. Larson A.A. Florell S.R. Zone J.J. Cannon-Albright L.A. Samlowski W.E. et al.Population-based prevalence of CDKN2A mutations in Utah melanoma families.J Invest Dermatol. 2006; 126: 660-666Abstract Full Text Full Text PDF PubMed Scopus (51) Google Scholar). We recently reported in the Journal the results of a longitudinal follow-up study of members of a Utah melanoma-prone kindred with a temperature-sensitive V126D CDKN2A/p16 mutation. Mutation carriers accumulated significantly more melanocytic nevi over a 15-year interval than non-carrier family members or spouse control subjects (Florell et al., 2004Florell S.R. Meyer L.J. Boucher K.M. Porter-Gill P.A. Hart M. Erickson J. et al.Longitudinal assessment of the nevus phenotype in a melanoma kindred.J Invest Dermatol. 2004; 123: 576-582Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar). Moreover, carrier subjects possessed more nevi on warm body regions, such as the head, neck, and trunk (Florell et al., 2005Florell S.R. Meyer L.J. Boucher K.M. Hart M. Cannon-Albright L.A. Harris R.M. et al.Nevus distribution in a Utah melanoma kindred with a temperature-sensitive CDKN2A mutation.J Invest Dermatol. 2005; 125: 1310-1312Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar). These findings suggest that in addition to conferring melanoma susceptibility, CDKN2A/p16 mutation contributes to nevus development and distribution. To this end, we hypothesized that (1) pedigree members with a non-temperature-sensitive pathogenic CDKN2A/p16 mutation would possess more melanocytic nevi and have a larger nevus density than non-carrier subjects; and (2) a temperature-sensitive nevus distribution would not be identified. To obtain additional evidence regarding the effect of a different CDKN2A/p16 mutation on nevus formation, we studied a second Utah melanoma pedigree with a promoter-region (G-34T) CDKN2A/p16 mutation in the 5′ untranslated region that results in a false initiation site with reduced translation of wild-type CDKN2A/p16 (Liu et al., 1999Liu L. Dilworth D. Gao L. Monzon J. Summers A. Lassam N. et al.Mutation of the CDKN2A 5′ UTR creates an aberrant initiation codon and predisposes to melanoma.Nat Genet. 1999; 21: 128-132Crossref PubMed Scopus (208) Google Scholar) and segregates with melanoma susceptibility in melanoma pedigrees (Liu et al., 1999Liu L. Dilworth D. Gao L. Monzon J. Summers A. Lassam N. et al.Mutation of the CDKN2A 5′ UTR creates an aberrant initiation codon and predisposes to melanoma.Nat Genet. 1999; 21: 128-132Crossref PubMed Scopus (208) Google Scholar; Harland et al., 2000Harland M. Holland E.A. Ghiorzo P. Mantelli M. Bianchi-Scarra G. Goldstein A.M. et al.Mutation screening of the CDKN2A promoter in melanoma families.Genes Chromosomes Cancer. 2000; 28: 45-57Crossref PubMed Scopus (63) Google Scholar). This study was approved by the University of Utah Institutional Review Board (Utah IRB no. 7916) and was conducted according to the Declaration of Helsinki principles utilizing informed written consent. Thirty-one members of the G-34T pedigree and 13 spouse control subjects participated approximately 12 years earlier in this follow-up examination. All subjects were examined by the same dermatologist (LJM) for the initial and follow-up studies. Neither the participants nor the examiner were aware of the CDKN2A/p16 mutational status. The initial and follow-up studies included a total body skin examination in which the location and size of all nevi that were ≥2 mm in diameter were recorded on a body map diagram. Warm regions were defined as the head, neck, and trunk and cold regions as the upper and lower extremities. Total nevus number (TNN) was defined as the number of clinically detectable nevi ≥2 mm in diameter. Total nevus density (TND) was estimated by calculating the area of all nevi divided by the estimated body surface area of the individual, as described previously (Goldgar et al., 1991Goldgar D.E. Cannon-Albright L.A. Meyer L.J. Piepkorn M.W. Zone J.J. Skolnick M.H. Inheritance of nevus number and size in melanoma and dysplastic nevus syndrome kindreds.J Natl Cancer Inst. 1991; 83: 1726-1733Crossref PubMed Scopus (38) Google Scholar; Meyer et al., 1992Meyer L.J. Goldgar D.E. Cannon-Albright L.A. Piepkorn M.W. Zone J.J. Risman M.B. et al.Number, size, and histopathology of nevi in Utah kindreds.Cytogenet Cell Genet. 1992; 59: 167-169Crossref PubMed Scopus (14) Google Scholar). Mutational status of the family members was determined by sequencing the promoter region and exons 1α–3 of CDKN2A/p16 and exon 1β (ARF) or by site-specific screening for G-34T. Genetic testing was performed at one of three CLIA-certified laboratories, including GeneDx Inc. (Gaithersburg, MD), Myriad Genetic Laboratories (Salt Lake City, UT), or Yale Diagnostic Laboratory (New Haven, CT). TNN and TND data were analyzed using multiple linear regression with carrier status, age at first visit, and gender as predictors (Florell et al., 2004Florell S.R. Meyer L.J. Boucher K.M. Porter-Gill P.A. Hart M. Erickson J. et al.Longitudinal assessment of the nevus phenotype in a melanoma kindred.J Invest Dermatol. 2004; 123: 576-582Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar). Nevus distribution data were analyzed by absolute number of nevi and by the mean change of nevi in warm and cold regions of the body over time using two-sided Mann–Whitney U-test (Florell et al., 2005Florell S.R. Meyer L.J. Boucher K.M. Hart M. Cannon-Albright L.A. Harris R.M. et al.Nevus distribution in a Utah melanoma kindred with a temperature-sensitive CDKN2A mutation.J Invest Dermatol. 2005; 125: 1310-1312Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar). Seven carrier subjects were male and 5 were female with a mean age of 37 years at the initial and 49 years at the follow-up examination; 10 non-carrier subjects were male and 9 were female with a mean age of 34 years at the initial and 46 years at the follow-up examination; 5 spouse control subjects were male and 8 were female with a mean age of 45 years at the initial and 59 years at the follow-up examination. The mean follow-up period was 11.3, 12.6, and 14.0 years for the mutation carrier, non-carrier, and spouse control subjects, respectively. Similar to the V126D CDKN2A/p16 pedigree, G-34T mutation carriers (n=12) had significantly larger TNN and TND over the follow-up interval compared with non-carrier (n=19; P=0.04 TNN; P=0.03 TND; multiple regression) and spouse control subjects (n=13; P=0.02 TNN; P=0.03 TND; multiple regression) (Figure 1; Table 1). The non-carrier subjects had an intermediate TNN and TND between carrier and spouse control subjects at the initial and follow-up examinations, although differences were not significant (Figure 1; Table 1). Mutation carriers developed a median of 0.76 nevi (per year) (range 0.09–4.37, mean±SD 1.08±1.25) versus 0.30 nevi (range 0.01–2.39, mean 0.59±0.72) for non-carriers and 0.14 nevi (range 0–0.58, mean 0.02+0.21) for spouse control subjects (carrier versus non-carrier P=0.33; carrier versus spouse control P=0.003; non-carrier versus spouse control P=0.014; two-sided Mann–Whitney U-test). However, unlike the V126D pedigree, a temperature-sensitive distribution was not observed in the G-34T pedigree; similar changes were seen in TNN and TND in warm (P=0.70 and P=0.48, respectively; two-sided Mann–Whitney U-test) and cold (P=0.13 and 0.73, respectively; two-sided Mann–Whitney U-test) regions among mutation carriers and non-carriers. Carrier subjects had significantly more clinically atypical nevi than non-carrier subjects (carriers: median 4, range 0–9, mean 4 atypical nevi; non-carriers: median 0, range 0–11, mean 2 atypical nevi; P=0.03; two-sided Mann–Whitney U-test). Six carriers (50%) and one non-carrier (5.3%) had invasive malignant melanoma (P=0.007; Fisher's Exact Test). Significant differences in Fitzpatrick skin type and markers of chronic UV irradiation (rhytides, poikiloderma, solar lentigines, actinic keratoses, and so on) were not identified among the genotypic groups (data not shown).Table 1Nevus phenotype characteristics among mutation carriers, non-carriers, and spouse control subjectsResponseMean carrierMean non-carrierUnadjusted differenceAdjusted difference (95% CI)P-valueCarrier compared with non-carrier Initial TNN31.815.915.916.5 (3.3–30.0)0.016 Final TNN42.822.620.221.3 (1.5–41.1)0.036 Change in TNN11.06.74.34.8 (-5.0–14.6)0.32 Initial TND134.561.573.076.3 (19.3–133.4)0.011 Final TND144.872.971.974.9 (9.1–140.8)0.027 Change in TND10.311.4-1.1-1.4 (-58.5–55.7)0.96Carrier compared with spouse controls Initial TNN31.812.719.112.2 (-2.0–26.4)0.089 Final TNN42.89.033.824.4 (4.2–44.4)0.020 Change in TNN11.0-3.714.712.2 (2.2–22.4)0.020 Initial TND134.539.894.773.2 (9.2–137.2)0.027 Final TND144.839.0105.881.4 (9.4–153.2)0.029 Change in TND10.3-0.711.08.0 (-51.4–67.4)0.78Non-carrier compared with spouse controls Initial TNN15.912.73.20.8 (-8.4–10.0)0.86 Final TNN22.69.013.69.2 (-4.0–22.4)0.16 Change in TNN6.7-3.710.48.4 (0.17–16.7)0.046 Initial TND61.539.821.712.8 (-26.4–51.9)0.51 Final TND72.939.033.918.4 (-26.6–63.4)0.41 Change in TND11.4-0.712.15.7 (-34.4–45.7)0.77CI, confidence interval; TND, total nevus density; TNN, total nevus number.The "unadjusted difference" is the difference between the means of the two groups. The "adjusted difference" accounts for differences in age and gender among the genotypic groups. Note that the "change in TNN" and "change in TND" between carriers and non-carriers over the follow-up interval are not significant, suggesting that the difference in TNN and TND is present by the time of the initial visit. The incremental change in TNN and TND between visits appears to be approximately the same for carriers and non-carriers. These are F-tests for the "group" effect from multiple linear regression analyses, with age as a continuous predictor and gender and group as factors. In each analysis, the group factor had two levels (carrier and non-carrier, or carrier and spouse, or non-carrier and spouse). Open table in a new tab CI, confidence interval; TND, total nevus density; TNN, total nevus number. The "unadjusted difference" is the difference between the means of the two groups. The "adjusted difference" accounts for differences in age and gender among the genotypic groups. Note that the "change in TNN" and "change in TND" between carriers and non-carriers over the follow-up interval are not significant, suggesting that the difference in TNN and TND is present by the time of the initial visit. The incremental change in TNN and TND between visits appears to be approximately the same for carriers and non-carriers. These are F-tests for the "group" effect from multiple linear regression analyses, with age as a continuous predictor and gender and group as factors. In each analysis, the group factor had two levels (carrier and non-carrier, or carrier and spouse, or non-carrier and spouse). Increased numbers of cutaneous melanocytic nevi are a well-known and major risk factor for cutaneous melanoma (Swerdlow et al., 1986Swerdlow A.J. English J. MacKie R.M. O'Doherty C.J. Hunter J.A. Clark J. et al.Benign melanocytic naevi as a risk factor for malignant melanoma.Br Med J (Clin Res Ed). 1986; 292: 1555-1559Crossref PubMed Scopus (285) Google Scholar; Bataille et al., 1996Bataille V. Bishop J.A. Sasieni P. Swerdlow A.J. Pinney E. Griffiths K. et al.Risk of cutaneous melanoma in relation to the numbers, types and sites of naevi: a case-control study.Br J Cancer. 1996; 73: 1605-1611Crossref PubMed Scopus (185) Google Scholar, Bataille et al., 1998Bataille V. Grulich A. Sasieni P. Swerdlow A. Newton Bishop J. McCarthy W. et al.The association between naevi and melanoma in populations with different levels of sun exposure: a joint case–control study of melanoma in the UK and Australia.Br J Cancer. 1998; 77: 505-510Crossref PubMed Scopus (87) Google Scholar; Kefford and Mann, 2003Kefford R.F. Mann G.J. Is there a role for genetic testing in patients with melanoma?.Curr Opin Oncol. 2003; 15: 157-161Crossref PubMed Scopus (45) Google Scholar). Of all known risk factors, inheritance of a pathogenic CDKN2A/p16 mutation confers the highest risk, although the nevus phenotype correlates poorly with genotype (Bishop et al., 2000Bishop J.A. Wachsmuth R.C. Harland M. Bataille V. Pinney E. Mac K.P. et al.Genotype/phenotype and penetrance studies in melanoma families with germline CDKN2A mutations.J Invest Dermatol. 2000; 114: 28-33Crossref PubMed Scopus (95) Google Scholar). Indeed, in our previous study, we noticed that the nevus phenotype was quite variable within genotypic groups (Florell et al., 2004Florell S.R. Meyer L.J. Boucher K.M. Porter-Gill P.A. Hart M. Erickson J. et al.Longitudinal assessment of the nevus phenotype in a melanoma kindred.J Invest Dermatol. 2004; 123: 576-582Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar) suggesting coexistence of additional nevogenic genes or modifying loci. Nonetheless, CDKN2A/p16 mutation carriers in this -34G>T pedigree as well as the previously studied V126D pedigree had significantly more nevi and a larger nevus density than non-carrier or spouse control subjects and continued to develop additional nevi at a faster rate than non-carrier subjects. However, carrier subjects from the -34G>T pedigree have fewer nevi than carrier subjects from the V126D pedigree (Figure 1), although the difference is not significant. It is possible that the number of subjects may not be sufficient to detect a small difference between the two pedigrees and among the genotypic groups. In summary, these longitudinal follow-up data from a second CDKN2A/p16 melanoma family (1) confirm our previous observation that CDKN2A/p16 mutations are associated with a higher nevus number and density, although differences in the rate of nevus development were not identified among mutation carriers and non-carriers in this pedigree; (2) fail to demonstrate a temperature-sensitive distribution, adding additional support to our observation that a temperature-sensitive CDKN2A/p16 mutation may confer a temperature-sensitive nevus distribution; and (3) demonstrate that the absolute nevus count is not a useful marker of CDKN2A/p16 mutation status in the clinical setting due to the considerable variability between genotypic groups and pedigrees. These findings provide additional evidence that the presence of a CDKN2A/p16 mutation promotes nevus development and the type of mutation can influence nevus distribution, and suggest a clinical correlation between the nevus phenotype and melanocyte senescence. The authors state no conflict of interest. This work was supported by grants from the Skin Cancer Foundation (SRF); the Dermatology Foundation Leaders Society Dermatologist Investigator Research Fellowship and Clinical Career Development Award (SRF); the National Institutes of Health Grant nos. K23 RR17525-01 (SRF), R01 CA102422 (LAC), and R01 AR50102 (DG); the Doris Duke Charitable Foundation (SAL); the Fellowship-To-Faculty Transition Award from the University of Utah funded in part by the Howard Hughes Medical Institute (SAL); the Huntsman Cancer Foundation (SAL, DG); the Tom C Mathews Jr Familial Melanoma Research Clinic at Huntsman Cancer Institute; the Huntsman General Clinical Research Center Public Health Service Grant (no. MO1 RR00064); the National Cancer Institute (NCI) Cancer Center Support Grant no. 5P30CA420-14; and the Utah Cancer Registry, funded by Contract no. N01-PC-35141 from the NCI with additional support from the Utah Department of Health and the University of Utah. We thank the Pedigree and Population Resource (funded by the Huntsman Cancer Foundation) for its valuable role in the ongoing collection, maintenance, and support of the Utah Population Database, which was initially used to identify the family for this melanoma research. We acknowledge the willing participation of all the family members in this study.