Inactivation of tumor suppressors and activation of protooncogenes are critical events in malignant cell transformation and tumor progression. Pdcd4 encodes a protein with tumor suppressor functions, which accounts for an increased interest to Pdcd4 as a potential diagnostic and prognostic marker, as well as a target for antineoplastic therapy. This review summarizes well-known properties and functions of Pdcd4 tumor suppressor and mechanisms of its regulation in tumor cells. It is also focused to the role of Pdcd4 in cellular transformation and tumor progression, as well as on its potential practical application in oncology.

Using the RT-PCR method for allele discrimination, we examined nine known SNPs in seven genes (GHR, IGFBP3, IGFR1, IRS1, FMN1, ANXA2, TaGLN) in ethnic Russians and in patients with prostate cancer (PC). For Russian population data on genotype distribution in studied SNPs was obtained. It was revealed that six of nine analyzed sites in examined locus were polymorphic. Distributions of alleles and genotypes frequency of polymorphic site 1388 T/C (Leu463Pro) in gene FMN1 (rs2306277) were distinguished between patients and control groups (delta = 0.019; chi2 = 7.884). In particular, correlation of OO genotype with increased risk of PC was observed (OR = 2.1591 95% CI 1.2055-3.8726). Moreover, the analysis of the polymorphic site 2911G/A (Glu917Arg) in gene IRS1 (rs1801278) revealed the accumulation of allele A in cancer group in comparison with control group (chi2 = 4.038; p = 0.044). Thus, the obtained data indicate the possibility of participation of polymorphism in genes FMN1 and IRS1 in formation of predisposition to PC.

The frequency of mutant forms p53 and N-Ras genes was investigated in DNA from peripheral blood of the patients by method Polymerase Chain Reaction - Single Strand Conformation Polymorphism Analysis. The patients were investigated in late period after radiation accidents exhibited acute radiation syndrome. It is established that the mutations among patients in areas of codons 246-250 exon 7 of p53 gene and codon 12 of N-Ras gene were meet more often than in control group. It is shown that these mutations possibly arise in insignificant number of the cells with the radiation-induced genomic instability. Possibility of use of mutations in protooncogenes and tumour suppressor genes as markers of risk of development of the main thing from delayed effects of exposure to ionizing radiation - malignant tumours is discussed.

The association between polymorphisms in genes COMT, HFE that takes part in oxidative stress regulation, and chromosome aberration frequency in lymphocytes was assessed in 278 female residents of radiation polluted regions of Central Russia: Bryansk (322 kBk/m2) and Tula Districts (137Cs - 171 kBk/m2). The C187G, G845A genotyping of HFE and G1947A (H/L) of COMT was done by means of polymerase chain reaction-restriction fragment length polymorphism. Studied population was divided into 3 subgroups by level of chromosome aberrations per cell (0-2, 3-4, >5). There was shown statistically significant difference in distribution of COMTand HFE genotypes between the groups. The high frequency of chromosome aberrations (> or = 5%) was associated with homozygotes of the high activity COMT G/G and HFE CC. Heterozygotes for G1947A COMT and C187G HFE reveal negative association with the high frequency of chromosome aberrations and correspond to "resistance factors".

Deletions in the fifth and the eighth exons of FHIT gene were detected using intragenic microsatellites D3s1540 and D3s1234 in the patients with esophageal cancer. Samples were provided from 17 males and 5 females, residents of province Hebei, China. Homozygotic deletions in the fifth or eighth exon were detected in 16 patients. Hypermethylation in FHITgene was found in healthy tissue of only one patient while in 17 patients it appeared in the cancerous tissues. Homozygosis of FHIT gene that was made by deletion or methylation had been found in all the cancerous tissues of the studied patients.

The ploidy of 56,000 epithelial cell nuclei was studied at different stages of carcinogenesis by Imager-CG computer image analyzer. The linear relationship between carcinogenesis stages and quantitative parameters (indexes of mean ploidy of cell nuclei) at a certain stage was detected and mathematically described. A step-by-step increase of DNA content in cell nuclei by one unit of ploidy leads to emergence of new biological properties, measured by the number of units surpassing the normal cell nuclear ploidy values, which was called "the malignancy code".

Comparative morphometric and densitometric study of tumor cells and adjacent hepatocyte nuclei was carried out in hepatocellular cancer. Enlargement of the nuclei and increase in DNA content and index of proliferation of Ki-67 tumor cells inversely correlated with differentiation degree of hepatocellular cancer, which reflects the regularity of staged development of tumors.

The protein Merlin is involved in the regulation of cell proliferation and differentiation in the eyes and wings of Drosophila and is a homolog of the human protein encoded by the Neurofibromatosis 2 (NF2) gene whose mutations cause auricular nerve tumors. Recent studies show that Merlin and Expanded cooperatively regulate the recycling of membrane receptors, such as the epidermal growth factor receptor (EGFR). By performing a search for potential genetic interactions between Merlin (Mer) and the genes important for vesicular trafficking, we found that ectopic expression in the wing pouch of the clathrin adapter protein Lap involved in clathrin-mediated receptor endocytosis resulted in the formation of extra vein materials. On the one hand, coexpression of wild-type Merlin and lap in the wing pouch restored normal venation, while overexpression of a dominant-negative mutant Mer(DBB) together with lap enhanced ectopic vein formation. Using various constructs with Merlin truncated copies, we showed the C-terminal portion of the Merlin protein to be responsible for the Merlin-lap genetic interaction. Furthermore, we showed that the Merlin and Lap proteins colocalized at the cortex of the wing imaginal disc cells.

Gastrointestinal stromal tumours (GIST) are the commonest mesenchymal tumours of gastrointestinal organs accounting for 1-3% of all gastrointestinal neoplasms and almost 5% of all soft tissue sarcomas. Most GIST (95%) express transmembrane receptor KIT or CD117, CD34 (70%), vimentin (80%), specific smooth muscle and neurogenic markers (with different frequency). Up to 85% of the stromal tumours have mutations in the KIT gene (exones 9, 11, 13, 17) and 3-18% in the PDGFRA (platelet-derived growth factor receptor-alpha) gene (exones 12, 14, 18). Mutations are absent in 5% of KITand PDGFRA genes. Mutational status, mitotic index, size and location of the tumour are the most informative criteria for the choice of treatment strategy and prognosis of the disease.

A relationship was studied between generation of glucose-induced reactive oxygen species capable of causing damage to DNA (genotoxic or G-effect) and insulin secretion (endocrine or hormonal effect - H-effect) in primary menopausal patients with endomrnetrial carcinoma (EC) (32) or colonic cancer (CC) (16). The study group was compared with healthy menopausal women (25) and patients with an impaired glucose tolerance (IGT) (21). Besides, we examined 32 menopausal patients (CC--6 and EC--26) more than 12 months after surgery. The following basic patterns were established: (1) H-effect was reported in EC-1 and 1GT groups nmore often than in healthy peers and those with EC-2: (2) G-effect tended to prevail in CC patients and those with EC-2 and in patients with EC-1 twelve months after operation; (3) G-effect occurred more often in primary EC patients, particularly, those with EC-2 (71%) and IGT (58%) (as compared with CC patients (33%) and healthy females (p < or = 0.001). It is suggested that a comparison of the two effects might provide a criterion for use of relevant means of prevention of certain malignancies or correction of disorders in cancer patients following radical treatment.

An attempt was made to identify molecular markers of different clinical stages of cervical carcinoma caused by papilloma virus (HPV). Presence of viral genome, telomerase level and expression of a gene, which coded the catalytic activity of that enzyme (hTERT), were assayed in 89 patients. HPV (type 16) genome harboring tumors were detected in 73% which was in conformity with the literature and our own data. Telomerase was identified (TRAP) in all tumors and tumor cells cultured in vitro. hTERT-specific RNA was found in all tumor samples, however, increase in its expression was insignificant. As far as the three markers are concerned, no significant differences between clinical stages of tumor were reported.

Tumor regression was reported in 20-30% of patients with inoperable non-small-cell lung cancer (NSLC) following standard first-line chemotherapy. Clinical trials with second-line gefitinib (Iressa) showed a strikingly high response in patients with mutated EGFR. However, clinical experience with gefitinib as first-line therapy had been limited to small-scale trials mostly among subjects of Asian origin. Our study was not associated with the drug manufacturer and included 25 chemotherapy-naive patients with mutated EGFR inoperable lung adenocarcinoma. Standard dose was 250 mg/day. Complete response was observed in 1 patient (4%), partial--11 (44%), sustained stabilization--13 (52%); median time until tumor progression--186 days. Median overall survival failed to be registered within the duration of the study. Among most frequent side-effects were skin rash (19; 76%) and diarrhea (14; 56%): marked side-effect -toxicity grade III (4; 16%). Gefitinib appeared highly efficient and tolerable and may be recommended as first-line treatment of mutated EGFR inoperable NSLC.

Experiments on transplantation of wing imaginal discs homozygous for a mutation in the tumor suppressor gene Merlin have demonstrated that this mutation does not induce malignant tumors. Marking of the wing disc compartment borders by specific antibodies showed the absence of essential compartment border defects in case of the Merlin mutation. Drosophila melanogaster cells mutant for Merlin have shorter cell cycle than normal cells. Proliferation of imaginal discs lasts longer in case of the mutation. It is known that beginning from some moment of development, wing veins serve as clonal restriction lines that cannot be crossed by growing mosaic clones. We showed that the Merlin mutation leads to depression of vein clonal restriction property. This means that this gene is involved not only in the control of cell proliferation, but also in the control of cell mobility and adhesion.

Fluorescence of H3-p histone and DAPI was studied at different stages of interphase and mitosis in cells of imaginal disks of third-instar Drosophila melanogaster larvae. Three stages differing in the spatial organization of the chromosome set in mitosis were revealed. At the first stage (prophase, prometaphase), the histone 3 phosphorylation level rises, and the volume occupied by the chromosome set in the nucleus increases. The distinctive features of the second stage (metaphase) are a gradual decrease in the histone 3 phosphorylation (the density ofphosphorylation remaining constant) and a reduction of the volume occupied by the chromosome set. At the third stage (anaphase, telophase), the intensity and density of the signal from H3-p histone decrease, and the volume occupied by the chromosome set reduces. At this stage, in Mer4 larvae, in contrast to the control strain, the cells prematurely pass from anaphase into telophase. In addition, a subpopulation of cells with an abnormally large volume of nuclear DNA during the G1 period was revealed in Mer4 larvae. The cells of this subpopulation do not enter into the DNA synthesis and quit the cycle.

Aneuploidy is among the most serious impairments of hereditary material in somatic and germline cells of living organisms. Chromosome loss or the appearance of an extra homolog in the chromosome set can result in either cell death or the development of various neoplasms with high probability of malignancy. It was traditionally believed that ionizing radiation produces primarily a clastogenic effect. However, there is apparently an aneugenic component of radiation, with mechanism different from that of structural chromosome damage. The present review focuses on the evidence for the existence of the aneugenic effect of ionizing radiation in mammalian and human somatic cells.

An abnormality in expression of genes encoding proteins responsible for the cell cycle regulation frequently results to a malignant cell transformation and switches the cellular program from differentiation and apoptosis to continuous cell division. To evaluate therapeutic potential resulted from silencing gene expression of key cell circle regulators in different human cancer cells the siRNAs targeted to HER2, protein kinase C (PKC), and cyclin B1 (CCNB1) mRNAs were used. An effective and specific reducing the CCNB1, HER2 or PKC mRNA level was observed through 48 h after the siCycB1, siHER2 or siPKC transfection, respectively. The HER2, PKC, and CCNB1 gene silencing substantially reduced a growth rate of the cell lines, except HL-60, but did not affect the cell death and apoptosis. The best cell division inhibition was induced by the siCycB1 in SK-N-MC cells and by the siPKC in MCF-7 cells. The data obtained suggest the siRNAs selected inhibit the cell division, and the genes investigated may be used as effective targets for curing oncologic diseases.

The purpose of this study is to assess clinical, morphofunctional and molecular factors of prognosis in patients with malignant cerebral gliomas.

Leukemia is a clonal proliferative disorder of the multipotent hematopoietic stem cells that leads to abnormal cell growth and (or) differentiation. The hallmark of the disease is the presence of oncogene expression in bone marrow or peripheral blood as a result of some chromosome translocations. The development of leukemia with transfer to disease progression presents a multistage process implicating series of molecular changes leading to chromosomal instability and aneuploidy. The most possible of these changes include the followings: appearance of additional chromosome translocations, activation of other not previously expressed oncogenes, loss of tumor suppressor genes, abnormal centrosome duplication, and dysfunction of the genes which coordinate the accurate chromosome alignment and chromosome segregation during mitosis. The two latter molecular changes which are controlled by mitotic spindle checkpoints play the role in leukemogenesis and are probably involved in apoptosis.

There may be a number of tumors made up by small round blue cells in the kidneys of children. One of them is primitive neuroectodermal tumor (PNET). The differences in therapeutic approaches determine the need to establish an accurate diagnosis. The differential diagnosis of PNET and the blastemal component of Wilms tumor can be difficult due to the similar histological pattern. There is a need for a close analysis of morphological manifestations, by keeping in mind the age of patients, and supplementary studies. A strong CD99 membrane expression and nuclear FLI1 expression in tumor cells are the signs of PNET. Reverse transcriptase-polymerase chain reaction and fluorescence in situ hybridization can determine PNET-specific translocations [t(11;22)(q24;q12), by involving the EWS gene.