Dace Pjanova

Predictors of Sun Protection Behaviors and Severe Sunburn in an International Online Study

Background: The incidence of melanoma continues to increase in many countries, and primary prevention of melanoma includes avoidance of sunburn as well as adequate sun protection behavior. The aim of this study was to examine the prevalence of self-reported sun protection behaviors and sunburn in users of the Internet, and to identify the demographic, clinical, and attitudinal/motivational correlates of sun protection behaviors. Methods: Self-report data were gathered on behalf of the GenoMEL consortium using an online survey available in 10 different languages, and 8,178 individuals successfully completed at least 80% of survey items, with 73% of respondents from Europe, 12% from Australia, 7% from the United States, 2% from Israel, and 6% from other countries. Results: Half of all respondents and 27% of those with a previous melanoma reported at least one severe sunburn during the previous 12 months. The strongest factors associated with sun protection behavior were perceived barriers to protection (β = −0.44/β = −0.37), and respondents who reported a positive attitude toward suntans were less likely to protect (β = −0.16/β = −0.14). Reported use of protective clothing and shade, as well as avoidance of midday sun exposure, were more strongly related to reduced risk of sunburn than sunscreen use. Conclusions: Despite widespread dissemination of public health messages about the importance of sun protection, a substantial proportion of this international sample, including respondents with a previous melanoma, reported inadequate sun protection behaviors resulting in severe sunburn. Impact: Future strategies to decrease sunburn should target the practical, social, and psychological barriers associated with nonuptake of sun protection. Cancer Epidemiol Biomarkers Prev; 19(9); 2199–210. ©2010 AACR.

Melanoma prone families with CDK4 germline mutation: phenotypic profile and associations with MC1R variants

Background CDKN2A and CDK4 are high risk susceptibility genes for cutaneous malignant melanoma. Melanoma families with CDKN2A germline mutations have been extensively characterised, whereas CDK4 families are rare and lack a systematic investigation of their phenotype. Methods All known families with CDK4 germline mutations (n=17) were recruited for the study by contacting the authors of published papers or by requests via the Melanoma Genetics Consortium (GenoMEL). Phenotypic data related to primary melanoma and pigmentation characteristics were collected. The CDK4 exon 2 and the complete coding region of the MC1R gene were sequenced. Results Eleven families carried the CDK4 R24H mutation whereas six families had the R24C mutation. The total number of subjects with verified melanoma was 103, with a median age at first melanoma diagnosis of 39 years. Forty-three (41.7%) subjects had developed multiple primary melanomas (MPM). A CDK4 mutation was found in 89 (including 62 melanoma cases) of 209 tested subjects. CDK4 positive family members (both melanoma cases and unaffected subjects) were more likely to have clinically atypical nevi than CDK4 negative family members (p<0.001). MPM subjects had a higher frequency of MC1R red hair colour variants compared with subjects with one tumour (p=0.010). Conclusion Our study shows that families with CDK4 germline mutations cannot be distinguished phenotypically from CDKN2A melanoma families, which are characterised by early onset of disease, increased occurrence of clinically atypical nevi, and development of MPM. In a clinical setting, the CDK4 gene should therefore always be examined when a melanoma family tests negative for CDKN2A mutation.

Inherited variants in the MC1R gene and survival from cutaneous melanoma: a BioGenoMEL study

Inherited MC1R variants modulate MITF transcription factor signaling, which in turn affects tumor cell proliferation, apoptosis, and DNA repair. The aim of this BioGenoMEL collaborative study in 10 melanoma cohorts was to test the hypothesis that inherited variants thereby moderate survival expectation. A survival analysis in the largest cohort (Leeds) was carried out adjusting for factors known to impact on survival. The results were then compared with data from nine smaller cohorts. The absence of any consensus MC1R alleles was associated with a significantly lower risk of death in the Leeds set (HR, 0.64; 95% CI, 0.46–0.89) and overall in the 10 data sets (HR, 0.78; 95% CI, 0.65–0.94) with some support from the nine smaller data sets considered together (HR, 0.83; 95% CI, 0.67–1.04). The data are suggestive of a survival benefit for inherited MC1R variants in melanoma patients.

CDKN2A and CDK4 variants in Latvian melanoma patients: analysis of a clinic-based population.

Germline mutations of the CDKN2A and CDK4 genes explain a significant proportion of familial melanoma. To date, there have been few published estimations of the prevalence of such mutations in sporadic melanoma patients. In this study, we investigated CDKN2A and CDK4 exon 2 for germline mutations in 125 consecutive cutaneous malignant melanoma patients recruited through the Latvian Oncological Center, using amplicon melting analysis and sequencing. No disease-related CDKN2A germline mutations were identified in any of the melanoma patients analysed but the previously described CDK4 mutation, Arg24His, was found in one patient with a family history of melanoma. CDKN2A polymorphisms were studied as putative low penetrance susceptibility genes. The proportion of cases with polymorphisms in this Latvian melanoma population was Ala148Thr (c.442G>A) (6%), 500 C/G (c.*29C>G) (18%), and 540 C/T (c.*69C>T) (20%); however, only the frequency of the Ala148Thr polymorphism was higher in melanoma patients than in 203 controls (6 versus 1%, P=0.03). Ala148Thr has also been reported in association with melanoma in a Polish series but not in an English series. We therefore examined the Ala148Thr carriers haplotype in 10 Latvian and 39 Polish samples. No significant difference was seen between these populations and the predominant haplotype observed in English samples, giving no indication that the discrepancy could be explained by population differences in linkage disequilibrium. In summary, our results show that germline mutations at the CDKN2A locus are rare in sporadic melanoma in Latvia. The study does, however, provide some additional evidence for a role for the CDKN2A polymorphism Ala148Thr as a low penetrance susceptibility gene. The detected CDK4 exon 2 mutation was found in only the seventh family identified worldwide with a germline CDK4 mutation.

An inherited variant in the gene coding for vitamin D-binding protein and survival from cutaneous melanoma: a BioGenoMEL study

An association between low serum vitamin D levels and poorer melanoma survival has been reported. We have studied inheritance of a polymorphism of the GC gene, rs2282679, coding for the vitamin D‐binding protein, which is associated with lower serum levels of vitamin D, in a meta‐analysis of 3137 melanoma patients. The aim was to investigate evidence for a causal relationship between vitamin D and outcome (Mendelian randomization). The variant was not associated with reduced overall survival (OS) in the UK cohort, per‐allele hazard ratio (HR) for death 1.23 (95% confidence interval (CI) 0.93, 1.64). In the smaller cohorts, HR in OS analysis was 1.07 (95% CI 0.88, 1.3) and for all cohorts combined, HR for OS was 1.09 (95% CI 0.93, 1.29). There was evidence of increased melanoma‐specific deaths in the seven cohorts for which these data were available. The lack of unequivocal findings despite the large sample size illustrates the difficulties of implementing Mendelian randomization.

Inherited variation in the PARP1 gene and survival from melanoma

We report the association of an inherited variant located upstream of the poly(adenosine diphosphate‐ribose) polymerase 1 (PARP1) gene (rs2249844), with survival in 11 BioGenoMEL melanoma cohorts. The gene encodes a protein involved in a number of cellular processes including single‐strand DNA repair. Survival analysis was conducted for each cohort using proportional hazards regression adjusting for factors known to be associated with survival. Survival was measured as overall survival (OS) and, where available, melanoma‐specific survival (MSS). Results were combined using random effects meta‐analysis. Evidence for a role of the PARP1 protein in melanoma ulceration and survival was investigated by testing gene expression levels taken from formalin‐fixed paraffin‐embedded tumors. A significant association was seen for inheritance of the rarer variant of PARP1, rs2249844 with OS (hazard ratio (HR) = 1.16 per allele, 95% confidence interval (CI) 1.04–1.28, p = 0.005, eleven cohorts) and MSS (HR = 1.20 per allele, 95% CI 1.01–1.39, p = 0.03, eight cohorts). We report bioinformatic data supportive of a functional effect for rs2249844. Higher levels of PARP1 gene expression in tumors were shown to be associated with tumor ulceration and poorer OS.

Identification of a CDK4 R24H mutation-positive melanoma family by analysis of early-onset melanoma patients in Latvia.

We have analysed 47 early-onset (≤40 years) Latvian melanoma patients for the involvement of the melanoma susceptibility loci CDKN2A and CDK4. We observed no disease-related mutations in CDKN2A, but one patient had a CDK4 R24H mutation and strong family history of melanoma. Haplotype analysis using microsatellite markers and single nucleotide polymorphisms showed that the Latvian haplotype is unique compared with that of other melanoma families with the R24H mutation. This finding supports the proposal that codon 24 is a mutational hotspot in the CDK4 gene.

Analysis of Latvian familial melanoma patients shows novel variants in the noncoding regions of CDKN2A and that the CDK4 mutation R24H is a founder mutation.

Hereditary cutaneous melanoma is associated with mutations in the high-risk CDKN2A gene in about 40% of melanoma-prone families. Mutations in the CDK4 gene are the cause in only a few pedigrees. In this study, we analyzed 20 Latvian familial melanoma probands and carried out a comprehensive analysis of CDKN2A including sequencing of its promoter/intronic regions and deletion screening. We also analyzed the critical second exon of the CDK4 gene. One novel intronic variant (IVS2+82C>T) of the CDKN2A gene and a small deletion (c.−20677_−20682delGTACGC) in its promoter region were found. Genotyping of the novel variants in larger melanoma and control groups indicated that the deletion increases the risk of melanoma (odds ratio=6.353, 95% confidence interval: 1.34–30.22, P=0.0168). The CDK4 gene analysis showed a Latvian melanoma family with the mutation R24H carried on the same haplotype as in two previously described Latvian CDK4-positive families. Our study suggests that the main risk gene in Latvian families with a strong family history of melanoma is CDK4 and that most of the other cases analyzed could be sporadic or associated with low-penetrance risk genes.

Melanoma epidemiology, prognosis and trends in Latvia

Background Melanoma incidence and mortality rates are increasing worldwide within the white population. Clinical and histological factors have been usually used for the prognosis and assessment of the risk for melanoma.

Replacement of short segments within transmembrane domains of MC2R disrupts retention signal

The proteolysis of the pro-opiomelanocortin precursor results in the formation of melanocortins (MCs), a group of peptides that share the conserved -H-F-R-W- sequence, which acts as a pharmacophore for five subtypes of MC receptors (MCRs). MC type 2 receptor (MC2R; also known as ACTHR) is the most specialized of all the MCRs. It is predominantly expressed in the adrenal cortex and specifically binds ACTH. Unlike other MCRs, it requires melanocortin receptor accessory protein 1 (MRAP) for formation of active receptor and for its transport to the cell membrane. The molecular mechanisms underlying this specificity remain poorly understood. In this study, we used directed mutagenesis to investigate the role of various short MC2R sequence segments in receptor membrane trafficking and specific activation upon stimulation with ligands. The strategy of the study was to replace two to five amino acid residues within one MC2R segment with the corresponding residues of MC4R. In total, 20 recombinant receptors C-terminally fused to enhanced green fluorescent protein were generated and their membrane trafficking efficiencies and cAMP response upon stimulation with α-MSH and ACTH(1-24) were estimated during their stand-alone expression and coexpression with MRAP. Our results indicate that both the motif that determines the ligand-recognition specificity and the intracellular retention signal are formed by a specific extracellular structure, which is supported by the correct alignment of the transmembrane domains. Our results also indicate that the aromatic-residue-rich segment of the second extracellular loop is involved in the effects mediated by the second ACTH pharmacophore (-K-K-R-R-).