Zorana Z. Nikolić

Endothelial nitric oxide synthase gene polymorphisms and prostate cancer risk in Serbian population

Genome‐wide association studies (GWAS) have identified over 46 SNPs associated with human prostate cancer (PCa). Some studies have shown correlation of the nitric oxide synthase (NOS) NOS3 gene polymorphisms with the risk and/or progression of PCa. This study aimed to evaluate the association of NOS3 gene polymorphisms (−786T>C, −764A>G, −714G>T, −690C>T, −649G>A and 894G>T) with PCa risk and progression. 150 patients with PCa, 150 patients with BPH and 100 age‐matched healthy controls were recruited in this study. Genotyping of promoter polymorphisms was performed by bi‐directional DNA sequencing, and for 894G>T by RFLP analysis. There was no significant association between the alleles and genotypes of these genetic variants and PCa risk. For −786T>C polymorphism, we found that C allele is associated with absence of metastases, assuming dominant genetic model (P = 0.049; OR, 0.50; 95% CI, 0.25–1.00). It was found that, compared with NOS3 −690C>T variant CC genotype, CT and TT genotypes confer decreased risk of developing metastases (dominant model, P = 0.015, OR, 0.24; 95% CI, 0.07–0.88) and show association with low clinical tumour stage, compared with stages T3 and T4 (dominant model, P = 0.046, OR, 0.20; 95% CI, 0.04–1.02). Genetic variants −764A>G, −714G>T, −649G>A were not detected in our study group. There is evidence of an inverse correlation of the NOS3 894G>T minor allele with high serum PSA (>20 ng/ml) (dominant model, P = 0.013, OR, 0.37; 95% CI, 0.17–0.82). Our results suggest that NOS3 gene polymorphisms are genetic susceptibility factors for the progression of PCa and patient outcome.

Assessment of association between genetic variants in microRNA genes hsa-miR-499, hsa-miR-196a2 and hsa-miR-27a and prostate cancer risk in Serbian population.

Due to their potentially functional significance, genetic variants within microRNA genes have been recognized as candidates for cancer-related genetic biomarkers. Among the most extensively studied so far are rs3746444, rs11614913 and rs895819. Nevertheless, only few previous studies in Asian population analyzed the association of rs3746444 and rs11614913 with prostate cancer (PCa) risk, while rs895819 was not evaluated in relation to this issue. The aim of this study was to assess the possible association between these genetic variants and PCa risk and progression in Serbian population. 355 samples of peripheral blood were obtained from the patients with PCa and 353 samples from patients with benign prostatic hyperplasia (BPH). 312 volunteers derived from general population who gave samples of buccal swabs were included in the control group. Genotyping of rs3746444, rs11614913 and rs895819 was performed by using PCR-RFLP method, HRM analysis and allele-specific PCR, respectively. Allelic and genotypic associations were evaluated by unconditional linear (for serum PSA level in PCa patients) and logistic regression method with adjustment for age. Minor allele C of rs895819 was found to be associated with the increased risk of developing PCa under dominant (P=0.035; OR=1.38, 95%CI 1.02-1.86) and overdominant (P=0.04; OR=1.37, 95%CI 1.01-1.85) genetic model. Same genetic variant was found to be associated with the clinical stage of localized PCa, as well as with the presence of distant metastases. Allele G of rs3746444 was also shown to be associated with the decreased risk of PCa progression. According to our data, rs3746444 qualifies for a genetic variant potentially associated with PCa aggressiveness in Serbian population. Furthermore, our study provided the first evidence of association between rs895819 and PCa risk, as well as for its genetic association with the presence of distant metastases among PCa patients.

Epidemiology of Rett Syndrome in Serbia: Prevalence, Incidence and Survival

Background: Rett syndrome (RTT) is a severe neurodevelopmental disorder that represents the second most common cause of mental retardation in females. However, incidence and prevalence of RTT are scarcely reported. Methods: A retrospective study included all patients with RTT diagnosed between 1981 and 2012 in Serbia. Estimation of incidence and prevalence was calculated on the basis of vital statistics reported by Statistical Office of Republic of Serbia. Results: From 1981 to 2012, RTT has been diagnosed in 102 girls in Serbia. Incidence of RTT in Serbia is estimated at 0.586:10,000 female live births. We estimated the prevalence of RTT in population of females younger than 19 years at 1:8,439. Death occurred in 19 patients (18.63%), with pneumonia as the most common cause. The lethal outcome by the age of 12 years could be expected for 11% of patients. The mean age at diagnosis was 3.5 years and we have confirmed a significant trend towards earlier dianosis during studied period. Conclusions: Rett syndrome incidence in Serbia is in accordance with reports from other countries. Serbian RTT patients have increased risk for early death when compared to patients in more developed countries, most commonly due to pneumonia. There was significant trend towards early diagnosis of RTT in Serbia over recent decades.

Association between a Genetic Variant in the hsa-miR-146a Gene and Cancer Risk: An Updated Meta-Analysis

Background and Aims: A large number of studies have investigated the association between the potentially functional genetic variant rs2910164 located in the hsa-miR-146a gene and susceptibility to various types of cancer. Nevertheless, the results obtained in these studies are contradictory. Therefore, we conducted a meta-analysis of data from eligible reports comprising a total of 28,359 cases and 41,678 controls. Methods: The literature included in this meta-analysis was selected from the PubMed database. Quantitative data synthesis was performed by using the OpenMeta-analyst software. Results: The meta-analysis yielded no evidence of an association between rs2910164 and the overall cancer risk. Conversely, the C allele of this genetic variant was found to be associated with a decreased risk of developing bladder and cervical cancer in multiple genetic models. The same direction of association was found for the C allele and liver cancer, gastric cancer and oral squamous cell carcinoma risk. In contrast to these results, the same allelic variant of rs2910164 was found to confer an increased risk of developing lung cancer. The stratified meta-analysis based on ethnicity did not show significant differences in the association between rs2910164 and cancer risk in populations with different ethnic backgrounds. Conclusion: We conclude that rs2910164 may represent a valuable biomarker associated with the risk of developing specific types of cancer.

Genetic Variants within Endothelial Nitric Oxide Synthase Gene and Prostate Cancer: A Meta‐Analysis

Several variants within gene‐encoding endothelial isoform of nitric oxide synthase have been reported to confer prostate cancer (PCa) susceptibility and/or progression. Nevertheless, studies referring to this issue have yielded inconsistent results. In order to elucidate the involvement of these variants in prostate carcinogenesis, we have conducted a meta‐analysis of previously published case‐control and relevant case‐only studies. Eleven studies comprising in total 3,806 cases and 4,466 controls were included in the meta‐analysis which yielded evidence of association of rs2070744 (ORCC = 1.43, 95% CI 1.04–1.97; p = 0.03) and intron 4a/b variant (ORab+aa = 1.47, 95% CI 1.00–2.14; p = 0.05) with PCa risk under recessive and dominant model, respectively. Furthermore, PCa patients carrying 4a/b a allele were found to have an increased risk of cancer progression to a less differentiated form, characterized by a high Gleason score (OR = 2.29, 95% CI 1.51–3.49; p < 0.01) and to higher TNM stage (OR = 2.55, 95% CI 1.71–3.81; p < 0.01). These results support the involvement of NOS3 variants in molecular pathogenesis of PCa.

Assessment of association between common variants at 17q12 and prostate cancer risk-evidence from Serbian population and meta--analysis.

This study aimed to evaluate possible association between genotypes and alleles of two 17q12 polymorphisms (rs3760511 and rs7501939) and prostate cancer (PCa) risk and progression. Two hundred seventy‐one patients with PCa, 261 patients with benign prostatic hyperplasia (BPH), and 171 controls were included in the study. Single nucleotide polymorphisms (SNPs) were genotyped by using PCR followed by restriction fragment length (PCR‐RFLP) analysis. We conducted meta‐analysis of published studies regarding association of these SNPs with PCa risk. Evidence of positive association between the AC genotype of the SNP rs3760511 and BPH risk for the best‐fitting overdominant model of association (BPH vs. controls comparison, p = 0.026; odds ratio [OR] = 1.58; 95% confidence interval [95%CI] 1.05–2.36) were obtained. The association between T allele of rs7501939 and PCa risk was determined in PCa versus controls comparison (p = 0.0032; OR = 0.66, 95%CI 0.50–0.87) with the best‐fitting model of inheritance being log‐additive. This variant was also found to be associated with the risk of BPH (p = 0.0023; OR = 0.65, 95%CI 0.49–0.86). We found no association between parameters of PCa progression and the analyzed SNPs. Meta‐analysis showed strong association between these variants and PCa risk. Our study shows association between SNPs at locus 17q12 and the risk of prostatic diseases in Serbian population. At the same time, results of meta‐analysis suggest the association of these SNPs with PCa risk.

NOS3 gene variants and male infertility: Association of 4a/4b with oligoasthenozoospermia

Results of recent studies confirmed that oxidative stress negatively affects sperm motility and causes sperm DNA damage. Produced by nitric oxide synthase 3 (NOS3), nitric oxide is considered to be one of the important mediators of oxidative stress in testis tissue. The aim of this study was to assess the possible association of three genetic variants (rs2070744, rs1799983 and intron variant 4a/4b) in NOS3 gene and infertility occurrence in two groups of infertile men (idiopathic azoospermia and oligoasthenozoospermia) and fertile controls. Genotypes for the single‐nucleotide genetic variants rs1799983 and rs2070744 were determined by PCR‐RFLP, while genotyping of intron 4 variant 4a/4b was performed by gel electrophoresis of PCR products. Statistical analysis was performed by SNPStats software. No significant association between the three genetic variants of the NOS3 gene and infertility risk was determined comparing allele and genotype frequencies among group of patients diagnosed with azoospermia and the control group. Nevertheless, there was a significant positive association between 4a/4b and infertility in the group of males diagnosed with oligoasthenozoospermia, under overdominant genetic model. Our findings suggest that tandem repeat variant within intron 4 of the NOS3 gene is associated with an increased risk of infertility in men diagnosed with idiopathic oligoasthenozoospermia.

Genetic Association Studies on Prostate Cancer

The modern research on molecular basis of prostate cancer (PCa) development includes studies aiming to identify potential genetic markers which could be used in diagnostics and/or monitoring of PCa. Genome-wide association studies (GWASs) have identified over 75 variants associated with PCa risk. One of the major PCarelated regions identified through GWASs is found to be a segment of 8q24. Other important PCa-susceptibility regions are 17q12, 17q24, 10q11, and 19q13. Candidategene based approach has also provided evidence of association between PCa risk and genetic variants located in functionally significant genes (both protein-coding and noncoding RNA genes) involved in normal prostatic cell growth, malignant transformation, or in the development of metastases. Nevertheless, the success of these studies is questionable, since numerous candidates for PCa-susceptibility variants were identified, but these results failed to replicate. The main aim of both types of genetic association studies on PCa is the identification of potential PCa genetic markers which could be used for constructing reliable algorithms for evaluating the risk for PCa development and/or PCa progression.

Assessment of possible association between rs378854 and prostate cancer risk in the Serbian population

Prostate cancer (PCa) is the second most commonly diagnosed cancer among men worldwide. Despite its high incidence rate, the molecular basis of PCa onset and its progression remains little understood. Genome-wide association studies (GWAS) have greatly contributed to the identification of single nucleotide polymorphisms (SNP) associated with PCa risk. Several GWAS identified 8q24 as one of the most significant PCa-associated regions. The aim of this study was to evaluate the association of SNP rs378854 at 8q24 with PCa risk in the Serbian population. The study population included 261 individuals diagnosed with PCa, 257 individuals diagnosed with benign prostatic hyperplasia (BPH) and 106 healthy controls. Data quality analysis yielded results showing deviations from Hardy-Weinberg equilibrium in groups of PCa patients and BPH patients as well as in the control group. There was no significant association between alleles and genotypes of the genetic variant rs378854 and PCa risk in the Serbian population. [Projekat Ministarstva nauke Republike Srbije, br. 173016]