Antisense regulation of gene expression is a widespread but poorly understood mechanism of gene expression regulation. The potential role of antisense transcripts in tumorigenesis is the most intriguing for the functional research. Here we experimentally characterize an antisense mRNA asLZK overlapping human MAP3K13/LZK gene that is involved in mitogenesis related JNK/SAPK signal transduction pathway. According to the functional annotation of the human genome, asLZK transcript (LOC647276) is expressed at the relatively high level and overrepresented in tumor samples. To our surprise, experimental study of human asLZK revealed that this sequence is not expressed, but represents a silent pseudogene of ribosomal protein L4 encoding gene RPL4. This pseudogene resulted from relatively recent retroposition of RPL4 mRNA into the first intron of MAP3K13 gene and does not participate in the regulation of MAP3K13 expression. This study stresses that, after initial in silico mapping efforts, experimental verification of the expression landscape is warranted.

Analysis of microsatellite TNFalpha marker and (-308(G/A) polymorphisms in promoter of TNFalpha gene was conducted in 167 patients with various types of sporadic breast cancer (BC) as well as in 139 healthy Russian donors. It was shown that frequency of allele 7 in TNFalpha microsatellite marker was significantly higher in BC patients than in healthy donors (17.9% versus 10.4%; P = 0.02) mainly due to the patients with invasive ductal BC (19.2% versus 10.4%; P = 0.008). The TNFalpha allele 9 was observed significantly more frequently in patients with invasive-ductal cancer (6.4% versus 1%; P= 0.01). The studies of-308(G/A)TNFalpha polymorphism in BC patients and healthy donors have shown no differences in the distribution frequency of highly secreted allele (-308A)TNFalpha. However, invasive lobular BC patients carrying (-308AG)TNFalpha genotype were observed significantly more frequently than invasive-ductal BC patients carrying the same allele (34.0 versus 17.3%; P = 0.034). Thus it has been shown for the first time that invasive-ductal and invasive-lobular BC patients differ in distribution of TNFalpha and -308(G/A)TNFalpha alleles.

Survival after surgery of pancreas carcinoma is still poor. Despite an apparently curative resection, tumor rapidly recur. Thus, the arsenal of diagnostic means should be enriched by sensitive methods to detect the minimal residual disease. The frequency of micrometastases in corresponding paraortic lymph nodes after an apparently curative operation was detected using routine histological, immunohistological and polymerase chain reaction for mutated K-ras methods. Tumor tissue was used for the control. 3 cases out of 69 revealed a positive tumor histological reaction, and 5--immunohistological staining. K-ras mutations are detected in 42 (61%) patients, 12 (17%) of those revealed a positive tumor reaction. Only one patient of a control group showed K-ras mutation. All K-ras positive patients revealed a poor survival prognosis and had a tumor relapse after resection.

Expression rates of chromosome fragile sites in peripheral blood lymphocytes have been studied in clinically healthy individuals of different age groups (20-38 yrs and 75-86 yrs) and breast cancer patients (8 cases). In individuals with a normal check-up of different age groups the heavy metal (nickel, zinc and cobalt) ions were also examined on their influence on the expression of the fragile sites and the peptide bioregulators (Livagen and Epithalon) were tested on their ability to correct the pattern of expression. Short-term lymphocyte cultures were used as tested material. The analysis showed that the chromosomes of people from young and old age groups differ from each other by the expression pattern of fragile sites - the chromosomes of young individuals were found to be more active by spontaneous formation of fragile sites. They were also sensitive to their induction by heavy metals. Both tested bioregulators lessen heavy metals effect that was statistically reliable only for the young people group. As for the patients with breast cancer general elevated fragility of chromosomes and specific distribution of the fragile sites along the chromosomes were revealed.

There was analyzed single nucleotide polymorphisms of DNA excision repair enzyme genes hOGG, XPD, XPG, XRCC1 in 98 Siberian Group of Chemical Enterprises cancer patients and 148 healthy donors. No association was observed between the analyzed polymorphisms and malignant tumors in both control and subgroup (under study) of persons exposed to occupational ionizing radiation. Heterozygosis for the genes hOGG and XPD was found to be a protective factor to malignant tumors in exposed persons: the odds ratio = 0.42 (95% CI 0.18-0.98; p = 0.044) for the 326Ser/Cys genotype of the hOGG gene and 0.48 (95% CI 0.23-0.99; p = = 0.047) the 751Lys/Gln genotype of the XPD gene. The data obtained show a possible modifying role of the hOGG and XPD gene polymorphisms for malignant tumors risk in exposed persons.

The protein encoded by RAR-beta (retinoic acid receptor) gene is a member of the superfamily, of nuclear receptors of retinoids which are involved in regulation of cell differentiation and proliferation. The level of RAR-beta2 mRNA is downregulated in a number of cell lines derived from human epithelial tumors. Inactivation of the RAR-beta2 gene is associated with methylation of its promoter region, which is observed in various carcinomas at a frequency of 30-70%. In renal and ovarian tumors, methylation at this region is poorly studied, the data being contradictory. We report a high methylation frequency in the gene promoter region in RCC (59%, 36/61) and a somewhat lower frequency in EOC (30%, 15/50). Methylation frequency in BC (46%, 26/56) is consistent with the published data. Significant correlation of methylation frequency in promoter region of RAR-beta2 gene with RCC progression (P < or = 0.005 by Fisher's exact test) was established.

The authors describe 4 cases of clinically, morphologically, and immunohistochemically typical intraneural perineuriomas that occurred in women aged 17 to 24 years. The tumors involved median, radial, ulnar, and palmar nerves and were 3, 2.5, 1.5, and 1.2 cm in the largest diameter. None patients had signs ofneurofibromatosis type 2 (NF2). One case was studied for mutation of the NF2 gene and heterozygous splice-site mutation at the acceptor splice site between exons 12 and 13 (agGG --> aaGG) was revealed. Two patients were followed up: they were disease-free for 10 and 15 years.

A tumor emerges due to the structural and functional abnormalities occurring in the genes, which causes a change in the spectrum of protein molecules. Strong correlations between the gene damages and following changes in the protein spectrum make it possible to study different stages of carcinogenesis and to create a more complete system of molecular markers for the diagnosis of different types of tumors, which comprises protein markers and DNA markers. The present investigation has studied a correlation between the inactivation mechanisms (structural and functional) of the suppressor gene p16/INK4a, which occur at the level of DNA, and the results of its protein expression examined by immunohistochemical methods in the tumor specimens from patients with breast cancer. The investigation could indicate that p16/INK4a gene damage frequently occurred in the tumors of the above type. In the majority of study cases, molecular damages revealed in the gene diminish on its protein expression; however, there are still cases that defy generally accepted explanations.

To compare diagnostic efficacy of B-cell clonality determination in application of different electrophoretic methods.

Forty invasive breast ductal carcinoma biopsy specimens were investigated. The techniques of fluorescence and chromogenic in situ hybridization were used to study HER-2/neu gene amplification and the concordance of these techniques was examined. The advantages and disadvantages of both techniques are shown. The optimum ranges of using these techniques in the determination of the herzept status of breast cancer are given.

The cytogenetic profile of chromosome 17 was studied in 180 medlloblastomas by the interphasic FISH technique, which revealed the high incidence of this aberration and its association with the poor clinical course of the disease. The interphasic cytogenetic analysis of chromosome 17 abnormalities in medulloblastoma biopsy specimens may be recommended for its inclusion into a complex of laboratory diagnostic methods used in the examination of these tumors.

In a past decade became evident that phosphatidylinositol-3-kinase controlled signal transduction cascade (PI3K/Akt/PTEN/mTOR) is implicated in resistance of tumor cells to anticancer drugs. Another well studied mechanism of multidrug resistance is associated with the activity of drug transporters of ABC superfamily (first of all P-glycoprotein (Pgp), MRP1, BCRP). Several mechanisms of cell defense can be turned on in one cell. The interconnections between different mechanisms involved in drug resistance are poorly studied. In the present study we used PC3 and DU145 human prostate cell lines to show that PTEN functional status determines level of cell resistance to some drugs, it correlates with expression level of MRP1 and BCRP proteins. We showed that Pgp is not involved in development of drug resistance in these cells. Transfection of PTEN into PTEN-deficient PC3 as well as rapamycin treatment caused the inhibition of PI3K/Akt/mTOR signaling and resulted in cell sensitization to the action of doxorubicin and vinblastine. We showed that PTEN transfection leads to the change in expression of MRP1 and BCRP. Our results show that in prostate cancer cells at least two mechanisms of drug resistance are interconnected. PTEN and mTOR signaling were shown: to be involved into regulation of MRP1 and BCRP.

Flap endonuclease-1 (FEN1) is a structure specific endonuclease. The natural substrates of FEN1 are 5'-flap structures formed by three DNA chains one of them has unannealed flapped 5'-end (flap). Flap structures are the intermediates of different processes of DNA metabolism, such as DNA recombination, Okazaki fragment maturation during replication of lagging strand, as well as strand displacement DNA synthesis in base excision repair. FEN1 also possesses 5'-exonuclease activity and newly discovered gap endonuclease activity. FEN1 is known to interact physically and functionally with a number of DNA replication and repair proteins such as the proliferating cell nuclear antigen, helicase/nuclease Dna2, WRN and BLM proteins, replication protein A, apurinic/apyrimidinic endonuclease 1, DNA polymerase beta, poly(ADP-riboso) polymerase 1, high mobility group protein 1, integrase of human immunodeficiency virus, transcription coactivator p300, chromatin proteins, cyclin-dependent kinases (Cdk1, Cdk2, Cyclin A). FEN1 activity is significant for maintaining the integrity of repeat sequences in genome. Recent data suppose the correlation between the abnormality of hFEN1 activity and arising/progression of neurodegenerative and cancer diseases. FEN1 has the dramatic effect on cell growth and development thereby attracting the interest to this enzyme.

The dependence of the level of unstable chromosome aberrations and nononcological diseases on the genotype in 57 liquidators of the ChNPP accident was studied. Candidate genes presumably affecting radiosensitivity were highly polymorphic loci of xenobiotic detoxication genes (glutathione-S-transferases GSTM1, GSTT1, GSTP1) and the 5,10-methylenetetrahydrofolate reductase gene (MTHFR) involved in DNA methylation and synthesis. An increased frequency (0.014 +/- 0.001 per cell) of unstable chromosome aberrations, including radiation-specific dicentrics and centric rings (0.0015 +/- 0.0002 per cell), has been found to be preserved in the group of liquidators examined in 2006-2007. No associations of polymorphism for each of the studied genes with cytogenetic parameters were revealed. Increased frequencies of chromosome aberrations were recorded in homozygous carriers of a deletion at the GSTM1 locus in combination with homozygosity for minor alleles at the MTHFR and GSTP1 loci (p = 0.00002 and p = 0.0233, respectively). The number of homozygous carriers of the minor allele GSTP1 was increased among patients with chronic obstructive pulmonary disease and in liquidators with acute circulation disturbances (p = 0.014 and p = 0.04, respectively). Double homozygotes for GSTM1 and GSTT1 deletions were significantly more frequent among subjects with benign tumors (cysts, polyps, p = 0.015) and with benign thyroid tumors (p = 0.017). This genotype has proved to be protective for patients with severe cardiovascular diseases (acute circulation disturbances, p = 0.027).

Total repair capability is a widely used phenotypic marker of predisposition to cancer. Evaluation of this parameter implies using a challenge mutagen in an in vitro system to unmask latent genetic instability and repair insufficiency in the target cells. Traditionally, these investigations involve two tests, evaluation of mutagenic susceptibility (chromosomal aberrations) and genotoxic effect (DNA comet assay). The present study was focused on analysis of the effect of methylnitrosourea (MNU) on resting and PHA-stimulated lymphocytes from healthy donors and patients with gynecological cancer. Cytotoxic effect of MNU (apoptotic lymphocyte death) was estimated using two parameters, interaction of the cells with the annexin V-FITC complex, and morphological changes of the nuclei after their staining with the mixture of two DNA tropic dyes. The genotoxic effect of MNU, namely, secondary double-strand DNA breaks, was scored using the neutral comet assay, modified for the calculation of the comets produced exclusively by BrUdr-labeled proliferating lymphocytes. The proportion of these comets was represented as the proliferative cell index. It was shown that resting lymphocytes were resistant to genotoxic and cytotoxic effects of MNU. The response of proliferating cells to the action of MNU was expressed as the development of secondary DNA breaks (P <0.01), along with the increased frequency of apoptosis (P <0.05). The genotoxic effect of MNU on stimulated lymphocytes of gynecological cancer patients was fourfold lower compared to healthy donor lymphocytes. In response to the MNU action, patient lymphocytes did not change their proliferative index, while in healthy donor lymphocytes proliferative index was two times decreased in response to the MNU action. The data obtained pointed to the association between the cytotoxic response of the lymphocytes to the action of MNU and gynecological cancer. Since only proliferating lymphocytes response to the genotoxic effect of MNU, and the effect is revealed a day after the mutagen action, it is suggested that this phenomenon is associated with postreplicative repair, MMR, the substrate of which is O6-methylguanin. The MMR deficiency in patient lymphocytes determines their tolerance to the action of MNU. Genotoxic effect of lymphocytes to the action of MNU can serve as a marker of MMR, as well as of the MMR deficiency-associated gynecological cancer.

The article presents some risk factors of breast cancer development and prognosis of the disease in Ukrainian patients. The frequency of 5382ins and 185delAG mutations in gene BRCA 1 and mutations of 6174delT in gene BRCA 2 was detected in the group of patients from Ukraine.

Allelic imbalances (AI) of polymorphic markers at the short arm of chromosome 3 (3p) were mapped using DNA samples of renal cell carcinoma (RCC, 80 cases), breast carcinoma (BC, 95 cases), and epithelial ovarian cancer (EOC, 50 cases) at the same dense panel of markers (up to 24 loci). Six regions with the increased AI frequency (versus the average values determined for all the analyzed 3p markers) at RCC, BC or EOC were found in 3p chromosome. Four 3p regions presumably contain suppressor genes of tumor growth (TSG) observed in the epithelial tumors of various types. Region between D3S2409 and D3S3667 markers in the 3q21.31 region was identified in this study for the first time. The AI peak in D3S2409-D3S3667 region was statistically significant (P < 0.001, according to Fisher) when representative sample of 95 BC patients was analyzed. The data on increased frequency of polymorphic marker allele amplification suggest that the D3S2409-D3S3667 region contains both putative TSG and protooncogenes.