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 carrier's 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.

Malignant melanomas usually have an unfavourable prognosis and poor response to chemotherapy. Deregulation of cell proliferation, programmed cell death and intercellular interactions are among several important mechanisms that might lead to malignant transformation of melanocytes and melanoma progression. The S100A1, S100B, Bcl-2 and CD44 antigens have all been described as being involved in different processes of melanoma progression. The expression of these antigens, as well as the rate of cell proliferation, was analyzed retrospectively in melanocytic tumours from 126 patients (32 males and 94 females, age ranging from 11 to 91 years). The series included benign (45 intradermal, 27 compound and eight displastic naevi) and malignant (39 primary and 14 metastatic) melanocytic tumours. The proliferating rate assessed by Ki-67 staining was lower in naevi than in melanomas, with a correlation coefficient of r = 0814. There was no overlap for rate of proliferation between benign and malignant tumours. The expression of S100A1 was low in benign melanocytic tumours and increased in malignant melanomas (r = 0.61). In contrast, a higher percentage of S100B antigen-positive cells were observed in benign melanocytic lesions than in melanomas (Pearson correlation coefficient, 0.627). In addition, positive immunostaining for S100B antigen in malignant melanomas corresponded with the areas with increased proliferating rate. The expression of Bcl-2 was lower in melanomas than in benign melanocytic tumours (r = −0.53). Bcl-2-negative areas within melanomas had an increased proliferating rate. The expression of CD44 showed a large variation both in benign and malignant melanocytic tumours. CD44 antigen expression was higher in melanomas with known metastases than in those without metastases, but this difference was not statistically significant.

Triploidy in cancer is associated with poor prognosis, but its origins remain unclear. Here, we attempted to differentiate between random chromosomal and whole-genome origins of cancer triploidy. In silico meta-analysis was performed on 15 male malignant and five benign tumor cohorts (2928 karyotypes) extracted from the Mitelman Database, comparing their ploidy and combinations of sex chromosomes. A distinct near-triploid fraction was observed in all malignant tumor types, and was especially high in seminoma. For all tumor types, X-chromosome doubling, predominantly observed as XXY, correlated strongly with the near-triploid state (r ≈ 0.9, p < 0.001), negatively correlated with near-diploidy, and did not correlate with near-tetraploidy. A smaller near-triploid component with a doubled X-chromosome was also present in three of the five benign tumor types, especially notable in colon adenoma. Principal component analysis revealed a non-random correlation structure shaping the X-chromosome disomy distribution across all tumor types. We suggest that doubling of the maternal genome followed by pedogamic fusion with a paternal genome (a possible mimic of the fertilization aberration, 69, XXY digyny) associated with meiotic reprogramming may be responsible for the observed rearrangements of genome complements leading to cancer triploidy. The relatively frequent loss of the Y-chromosome results as a secondary factor from chromosome instability.

CD56, p53, and Cyclin D1 detection in plasma cells (PC) can help to predict prognosis of multiple myeloma (MM). Clinical and biochemical prognostic parameters were analysed in a group of 122 patients with primary diagnosed MM in the period 2011–2015. Bone marrow biopsies were analysed with Cyclin D1, p53, CD56 antibodies. Statistical analysis was performed using Microsoft Excel 2010 and Graph Pad Prism 5. Lack of CD56 expression and p53-positivity were significantly correlated with a low glomerular filtration rate (GFR), low platelet count and haemoglobin level, as well as with high serum creatinine levels. Patients with Cyclin D1 expression in PC had a significantly higher serum calcium level and more common osteolytic lesion in bones. CD56- negative as well as p53, Cyclin D1-positive groups had advanced Salmon–Durie MM stages by and significantly higher ß2-microglobulin. Expression of p53, Cyclin D1 and lack of CD56 antigen in PC are negative predictive factors in cases of MM, as these patients were diagnosed as having late Salmon–Durie stage and higher ß2-microglobulin level. Expression of p53 and lack of CD56 antigen in PC is associated with an increased creatinine level in blood and decreased GFR; therefore, these are criteria for chronic renal failure progression and poorer prognosis of MM.