Ljiljana Lukovic

Cancer genes alterations and HPV infection in oral squamous cell carcinoma

The aim of this study was to gain a better understanding of cancer genes contributing to oral squamous cell (OSCC) development and progression and correlate genetic changes to clinical parameters. Human papilloma virus (HPV) 16 detection is also included in the study. 60 samples of OSCC were analysed for c-erbB2 and c-myc amplification by dPCR, H-ras and p53 point mutations by PCR/SSCP. HPV was detected via amplification of its E1 and E6 genes. c-erbB2 was altered in 45%, c-myc in 35%, H-ras in 22% and p53 in 60% of samples. HPV was detected in 10% of cases. The frequency of p53 gene mutations showed a statistically significant association with tumour stage. Patients with c-erbB2 and H-ras alterations had lower survival than patients without these alterations. The number of detected genetic changes was remarkable but statistical association with tumour natural history was poor, indicating high clonal heterogeneity and multiple pathways of carcinogenesis.

Association between the methylenetetrahydrofolate reductase polymorphisms and risk of acute lymphoblastic leukemia in Serbian children.

Methylenetetrahydrofolate reductase (MTHFR) regulates the metabolism of folate and methionine, essential components of DNA synthesis and methylation. Polymorphisms in the MTHFR gene have been associated with susceptibility to some types of cancer. We investigated a possible association of MTHFR polymorphisms (677C>T and 1298A>C) and increased risk for acute lymphoblastic leukemia in 78 affected children. The frequencies of both MTHFR 677 genotypes and alleles were significantly different between patients and controls. A significant association between CT/TT individuals and reduced risk of acute lymphoblastic leukemia was found. The odds ratios were 0.53 (95% confidence interval, 032-0.89) and 0.30 (95% confidence interval, 0.12-0.81). Polymorphism 1298 did not show statistical difference between patients and controls.

Bcl-2 Expression in Oral Squamous Cell Carcinoma

Abstract:  Apoptosis is a genetically regulated process involved in tissue size regulation, morphogenesis, and elimination of genetically damaged cells. A pallet of genes is involved in the control of apoptosis, such as bcl‐2 family whose oncogenic potential has been demonstrated in oral tumorigenesis. Different members of bcl‐2 family may promote or inhibit apoptosis by synthesizing anti‐ and proapoptotic proteins. One of antiapoptotic proteins, bcl‐2, with a crucial role in apoptosis regulation was the object of our study. By means of immunohistochemistry we estimated the level of overexpression of bcl‐2 proteins in a series of the 26 formalin fixed, paraffin‐embedded samples of oral squamous cell carcinoma (OSCC). Analyzed tumors originated from different sites of oral cavity; 7/26 belonged to stage II, 14/26 to stage III, and 5/26 to stage IV. Immunoreactivity was scored according to the percentage and intensity of positive cytoplasmic bcl‐2 staining. All tumors had low percentage of positively stained bcl‐2 cells, with mean values for lower/higher intensity of 8.3 ± 2.5/34.4 ± 7, 7.5 ± 1.1/31.9 ± 4.3, and 8.4 ± 5.8/31.5 ± 5.8 within stages II, III, and IV, respectively. Low level of bcl‐2 expression in our sample seems to be associated with higher survival rate: 77% for the 5‐year follow‐up period. Comparing clinicopathologic and risk factors data within each and between three groups of analyzed tumors (lip–tongue P= 0.58, tongue–floor of the mouth, P= 0.21, lip–floor of the mouth, P= 0.50) there was no significant difference. However, our results suggest that the level of bcl‐2 expression could be a valuable predictor of tumor behavior and disease outcome.

Sister chromatid exchanges in patients with carcinoma in situ of cervix uteri

Sister chromatid exchange (SCE) was analyzed in lymphocytes of 21 patients with carcinoma in situ of cervix uteri and 19 control subjects. The mean SCE frequencies were 8.92 +/- 0.31 (n = 417) and 6.94 +/- 0.23, (n = 375) per metaphase in patients and controls, respectively. The increase of SCE levels in cancer patients was highly significant in respect to controls (p less than 0.001). Together with data of other authors in patients with precancerous and cancerous lesions of the cervix, our results suggest that there is no correlation between SCE rate and severity of cancerous lesions.

High levels of Paleolithic Y-chromosome lineages characterize Serbia.

Whether present-day European genetic variation and its distribution patterns can be attributed primarily to the initial peopling of Europe by anatomically modern humans during the Paleolithic, or to latter Near Eastern Neolithic input is still the subject of debate. Southeastern Europe has been a crossroads for several cultures since Paleolithic times and the Balkans, specifically, would have been part of the route used by Neolithic farmers to enter Europe. Given its geographic location in the heart of the Balkan Peninsula at the intersection of Central and Southeastern Europe, Serbia represents a key geographical location that may provide insight to elucidate the interactions between indigenous Paleolithic people and agricultural colonists from the Fertile Crescent. In this study, we examine, for the first time, the Y-chromosome constitution of the general Serbian population. A total of 103 individuals were sampled and their DNA analyzed for 104 Y-chromosome bi-allelic markers and 17 associated STR loci. Our results indicate that approximately 58% of Serbian Y-chromosomes (I1-M253, I2a-P37.2 and R1a1a-M198) belong to lineages believed to be pre-Neolithic. On the other hand, the signature of putative Near Eastern Neolithic lineages, including E1b1b1a1-M78, G2a-P15, J1-M267, J2-M172 and R1b1a2-M269 accounts for 39% of the Y-chromosome. Haplogroup frequency distributions in Western and Eastern Europe reveal a spotted landscape of paleolithic Y chromosomes, undermining continental-wide generalizations. Furthermore, an examination of the distribution of Y-chromosome filiations in Europe indicates extreme levels of Paleolithic lineages in a region encompassing Serbia, Bosnia-Herzegovina and Croatia, possibly the result of Neolithic migrations encroaching on Paleolithic populations against the Adriatic Sea.

Proximal dystrophin gene deletions and protein alterations in becker muscular dystrophy.

Abstract: Alterations in production of cytoskeletal protein dystrophin caused by in‐frame gene mutations lead to the Becker muscular dystrophy. In this study we analyzed genotype‐phenotype correlation in a group of Becker muscular dystrophy patients with deletions affecting the proximal part of dystrophin gene, encompassing exons 3–13. Four patients with deletions affecting N terminal dystrophin domain had early onset and faster progression of the disease, while three patients with deletions in the proximal part of dystrophins rod domain had a more benign disease course. Our study suggests that proximal gene deletions in Becker muscular dystrophy have various phenotypic effects depending on the affected domain of protein dystrophin.

Polymorphisms of the eNOS gene are associated with disease activity in rheumatoid arthritis

Nitric oxide (NO) is a mediator in autoimmune responses and thus involved in the pathogenesis of a variety of rheumatic diseases. Genetic factors that influence the expression of the enzyme endothelial nitric oxide synthase (eNOS) that catalyzes NO synthesis are important for the control of NO level and consequently its activity. We have analyzed three functionally relevant polymorphisms of eNOS gene: T-786C, G894T and VNTR (4a/b), to investigate whether they are predisposing factors in pathogenesis of RA in Serbian population and to evaluate their role in clinical manifestations of RA. We performed genotyping of 196 patients with RA and the control group of 132 healthy individuals from Serbian population, using PCR and polymerase chain reaction–restriction fragment length polymorphism methods. Disease activity was prospectively assessed using number of tender joints, number of swollen joints and 28-joints disease activity score (DAS28). There were no differences between the patients and control groups in the genotypes and alleles frequencies of the three analyzed SNPs. Our results showed statistically significant differences in all three analyzed parameters of disease severity between 786TT/786CT and 786CC genotypes and between 894GG/894GT and 894TT genotypes. In the case of 4a/b polymorphism, carriers of minor allele had significantly lower DAS28 values. In conclusion, our results do not support the implication of analyzed eNOS gene polymorphisms in susceptibility to RA but associate them with the disease activity and give assumption that minor alleles are indicators of better clinical course.

Chromosomal assignment of loci susceptible to replication errors by radiation hybrid mapping

Genetic instability due to a DNA mismatch repair deficiency leads to the replication error (RER) phenotype in cancer cells. Certain loci are more susceptible to replication errors than the genomic average. The mapping of such loci is important, because it could indicate chromosomal domains preferentially affected by RER. Here, we report the radiation hybrid mapping of five markers known to be highly sensitive to RER in carcinomas. They were localized in chromosomes 2q34-q36.1, 6p24.3-25.2, 7q22.1-q13.2, 16q23.2-q23.3 and Xq13.1-q21.2 near genes that could be involved in oncogenesis.