On peripheral lymphocytes of 5 cancer patients undergone wholebody therapeutic irradiation (at daily dose of 10 cGy up to total dose 50 cGy of 60Co gamma-rays) the dose response of unstable and stable chromosomal exchanges detected by FISH was compared with the dose response of the some aberrations in lymphocytes irradiated in vitro. The dose response fitted well to linear function. For dicentrics the lower slope of dose-response curve was found for in vivo irradiated lymphocytes as compared to the dose-response curve obtained for in vitro irradiated lymphocytes of the same patients. No difference between in vivo and in vitro irradiation of lymphocytes was found for translocations. The frequency of translocations increased faster with the dose than the frequency of dicentrics only in lymphocytes irradiated in vivo.

The history of somatic cell genetics from the late 1950s to the present day is considered. Studies in this field provided for the elucidation of numerous fundamental and applied problems, including spontaneous mutagenesis, gene mapping with somatic cell hybrids, and genetic mechanisms of carcinogenesis (e.g., cell protooncogenes, oncogenes, and tumor suppressor genes were revealed). The knocking-out technique allowed the effects of various genes to be analyzed.

Similar changes in chromatin organization take place during development and carcinogenesis. The size of chromatin loop domains fixed on the nuclear skeleton (matrix) increased from 20 to approximately 200 kbp. These changes are accompanied by an increased size of replicons and altered specificity of loop attachment to the nuclear matrix. During carcinogenesis, inverse changes in the chromatin structure are observed, neoplastic cells are dedifferentiated and return to the initial state. In this review, we consider new experimental data on organization of the DFNA loops and nuclear matrix in embryogenesis and carcinogenesis.

Comparative Genomic Hybridization (CGH) is a molecular cytogenetic analysis that allows identification of genomic changes by comparing the copy number of DNA sequences in cells of tested tissue and the reference specimen. CGH is based on competitive suppressive in situ hybridization of two differently labeled DNA probes (tested and reference, karyotypically normal, fluorochrome-labeled DNAs) with metaphase chromosomes of a healthy subject. First described by Kallioniemi et al. in 1992, the CGH assay has been widely used for identification and characterization of both numerical and structural chromosome abnormalities in cells of different tissues at various pathological conditions in humans, especially in tumor diseases. We discuss the specific features and quality control of comparative genomic hybridization, its advantages and limitations in detection of genomic imbalance and the prospects for development of this technology.

The first experience with molecular diagnosis of retinoblastoma (RB) in Russia is presented. A protocol based on the use of up-to-date molecular diagnostic methods helps detect structural and functional abnormalities in RB1 gene, diagnose RB in disputable cases and at early stages of the disease. Forty-five families with various forms of RB were examined. Twenty-three mutations in various sites of RB1 gene were characterized. Abnormal methylation in the promotor area of RB1 gene was detected in 20% cases and loss of heterozysity by intragene microsatellite markers was detected in 70% cases. Hence, the causes of RB were detected in 80% families, which led to early diagnosis in close relatives of patients and helped evaluate the repeated risk of the tumor in families of patients with RB.

The genome of human papilloma viruses from a high-risk group (HPV types 16 and 18) has been detected in 90% of cervical tumors and, in some cases, in the adjacent normal tissues. The presence of viral DNA is the main molecular marker of this neoplasia. HPV genome may persist in the tumors as episomal and integrative forms at early and late stages of tumor progression. The status of viral DNA and the pattern of its expression are similar in all cells of this tumor cell population and seem to be a marker of tumor cell monoclonality. Antibodies to the products of viral oncogenes E6 and E7 were found only in 35% of the patients with tumor where HPV genome is present. Thus, this criteria cannot be used for diagnostic and prognostic purposes. On chromosome 6 in the cervical tumors, the specific marker of heterozygocity on loci 6p21.3 was found. The marker appears at the precancer stage and may be regarded as a marker of tumor monoclonality. Heterozygocity loss in the specific locus in the region 6q16-21 correlates with tumor progression and suggests that there are potential tumor-suppressor genes in this region of chromosome 6. A group of HPV positive tumors with a hypermethylator phenotype is described. These tumors are characterized by the simultaneous methylation and inactivation of multiple genes, including tumor suppressor genes.

Epstein-Barr virus (EBV) is known to be closely associated with the development of anaplastic nasopharyngeal carcinoma (NPC) in some malignancy endemic regions in South-East Asia. LMP1 gene is one of the EBV latent genes, which encodes a latent membrane protein. LMP1 gene is thought to be a classical oncogene since it morphologically transforms cells in vitro and induces tumors in experimental animals in vivo. LMP1 is one of a few genes which is expressed in NPC tissues. It was first shown that C-terminus of LMP1 gene obtained from NPC patients in South-East Asia contained a deletion of 30 base pairs (bp). However, this deleted LMP1 gene was then found in the EBV isolates persisting among healthy virus carriers and patients with other EBV-associated abnormalities from both NPC endemic and non-endemic regions. The aim of this investigation was to accomplish a molecular biological analysis of EBV LMP1 genes obtained from Russian NPC patients. To this end, the authors isolated and sequenced the LMP1 clones amplified from the tumor tissues from 7 NPC patients at the N. N. Blokhin Russian Cancer Research Center and primary blood lymphocytes (PBL) from 6 healthy donors. As a result, the authors could not find the deletion of the above-mentioned 30 bp in NPC LMP1 clones, but could in one healthy donor (PBL-2). A functional analysis revealed no significant differences between LMP1 variants with or without 30 bp deletion in their capacity to activate NF kappa B and jun/AP-1 transcription factors. Nevertheless, Russian NPC-derived LMP1 variants as compared with those from PBLs featured some specific amino acid exchanges. These data indicate that the 30 bp deletion of LMP1 gene is not a factor that predisposes to NPC in Russia.

The aim is to study the pattern of a cell population (ploidy) and to evaluate the latter's significance in the prognosis of different carcinomas. A total of 467 patients with primary carcinomas of the breast (n = 177), lung (n = 88), head and neck (n = 140), and colon and rectum (n = 62) were examined. All the patients underwent surgery alone or in combination with radiotherapy (X-ray)/chemotherapy. A follow-up lasted 6 to 120 months. DNA was measured in the operative tumor tissue specimens by using an ICP-22 flow cytometer. Diploid and aneuploid cancers occurred in 20.4-53.6 and 43.6-79.6% of cases, respectively. The frequency of recurrences was mainly associated with aneuploidy and it was more than thrice higher than that with diploidy (21.0-43.2 versus 4.5-14.4%). Five-year survival was twice worse in patients with aneuploid tumors than in those with diploid ones. The survival rates after one operation, preoperative, and postoperative radiation therapy was greater in patients with diploid tumors than in patients with aneuploid ones. Thus, DNA-ploidy of the study neoplasms is of high informative value in predicting the course of a tumorous process and in choosing treatment policy on an individual basis.

Clinical immunology involves studies of immunological diagnosis and monitoring of cancer patients, their immunity and treatment-induced changes, including those associated with immunotherapeutical exposures, immunodiagnosis of leukemias, estimation of solid tumor markers. Immunophenotyping of peripheral blood cells from patients with solid tumors treated with chemo- and immunotherapy has elucidated some relationships to evaluate the efficiency of treatment. Detailed characterization of the structure of leukemic clone has promoted development of individual treatment regimens. The authors' experimental studies will evaluate the effects of cytokines on the mechanisms of multidrug resistance caused by mdr-1 gene hyperexpression and on apoptosis processes diminished by bcl-2 gene hyperexpression.

The present review describes a hypothesis for a critical role of cell adhesive interactions in tumorigenesis. Dysregulation of tissue cell-cell interactions initiates first of all local (in the tissue) and then general (in whole body) conditions for tumor growth. Otherwise imbalance of tissue-specific adhesion factor at the very beginning of carcinogenesis is considered to trigger a cascade of pathological reactions responsible for more severe adhesive disorders that are in turn critical for the "totalitarian" behavior of a tumor and its "colonization" of other tissues and organs. Impaired disturbance is likely to be the key mechanism of carcinogenesis since it is significantly associated with the main features of a tumor: tissue proliferation control loss, anaplasia, invasion, metastasis, and immune surveillance deficit. The hypothesis is supported by evolutionary, biological, histological, immunological, and clinical arguments whose combination does not characterize any other known mechanisms of oncogenesis. The concept of adhesiveness opens new possibilities for the diagnosis, prevention, and treatment of tumors and also improves a strategy for designing new drugs.

The study has been concerned with DNA ploidy and its significance for prognosis of different neoplasms. The investigation included 314 patients: primary cancer of the lung (96), head and neck (146) and large bowel (72). Patients received surgery alone or surgery plus either radiotherapy or chemotherapy; they were followed up for 6-20 months. DNA levels were assayed in resected material using an ICP-22 flow cytometer. Diploid and aneuploid cancers were detected in 20.4-53.6 and 43.6-79.6%, respectively. The recurrence rates in cases of aneuploid cancers were more than 3 times those of diploidy (21.0-43.2 and 4.5-14.5%, respectively). Overall 5-year survival in diploid patients was twice that in aneuploid ones. Similarly, survival after surgery alone, preoperative chemotherapy and postoperative radiotherapy among diploid patients was longer than in aneuploid ones. Hence, DNA ploidy examination of tumors is of great informative value in prognosing tumor process and working out individually-tailored approach to treatment.

In order to characterize the molecular mechanisms of lymphoma formation in HIV-infected humans, a method of two-staged substractive cloning was used, which adequately detects genes whose expression is increased in cells of one lymphoma in comparison with another. Using this method, we determined the spectrum of genes whose expression was increased in centroblastic non-Hodgkin's lymphoma in comparison with immunoblastic non-Hodgkin's lymphoma. Several gene groups were distinguished in this spectrum; their probable involvement in lymphogenesis is discussed.

DNA of oncological patients, including Ashkenazi Jews and Slavs, living in St. Petersburg was collected, and the resultant collection was screened for three common mutations of genes BRCA1 and BRCA2 by means of heteroduplex analysis. The mutation 5382insC in exon 20 of the BRCA1 gene was found in four unrelated patients, including three Slavs and one Ashkenazi Jew, with a positive family history of breast cancer. The mutations 185delAG and 6174delT in the BRCA1 and BRCA2 genes, respectively, which are typical of Ashkenazi Jewish patients with breast cancer, were not found in the patients of either ethnicity living in St. Petersburg, although the 6174delT mutation was found in the control group of Ashkenazi Jews. A new 12-nucleotide duplication g.71741ins12nt found in intron 20 of the BRCA1 gene was described. The high frequency of the 5382insC mutation in the BRCA1 gene in patients with familial breast cancer in both St. Petersburg and Moscow indicates that Russian families with the history of breast cancer should be primarily tested for this mutation.

Deletions in the region located between the STS markers D13S1168 and D13S25 on chromosome 13 are the most frequent genomic changes in patients with B-cell chronic lymphocytic leukemia (B-CLL). After sequencing of this region, two novel candidate genes were identified: C13orf1 (chromosome 13 open reading frame 1) and PLCC (putative large CLL candidate). Analysis of the repeat distribution revealed two subregions differing in composition of repetitious DNA and gene organization. The interval D13S1168-D13S319 contains 131 Alu repeats accounting for 24.8% of its length, whereas the interval GCT16C05-D13S25, which is no more than 180 kb away from the former one is extremely poor in Alu repeats (4.1% of the total length). Both intervals contain almost the same amount of the LINE-type repeats L1 and L2 (20.3 and 21.24%, respectively). In the chromosomal region studied, 29 Alu repeats were found to belong to the evolutionary young subfamily Y, which is still capable of amplifying. A considerable proportion of repeats of this type with similar nucleotide sequences may contribute to the recombinational activity of the chromosomal region 13q14.3, which is responsible for its rearrangements in some tumors in humans.

Proteins of Ras family play an important role in regulation of cell growth and proliferation, and their mutations can lead to growth factor-independent proliferation due to constitutive activity of various signal transduction cascades. In the present work, we studied the activity of ERK, JNK and p38 MAP-kinase cascades in rat embryo fibroblast cells transformed with oncogenes E1A and cHa-ras. These transformed cells are characterized by a high and non-regulated activity of transcription factor AP-1 involved in the regulation of cell proliferation. Since phosphorylation of AP-1 depends on the activity of relevant MAP-kinase cascades (ERK, JNK and p38), we analysed the expression of non-phosphorylated forms of the kinases and their phosphorylated state in E1A + cHa-ras cells using antibodies specific to non-phosphorylated and phosphorylated proteins. It has been established that transformed cells contain higher amounts of non-phosphorylated ERK, JNK and p38 kinases, thus implying a reduced degradation of these and other proteins in the transformants. The content of phosphorylated (active) forms studied in Western blot-analysis with phosphoantibodies was shown to be also higher in exponentially growing E1A + cHa-ras cells. But serum stimulation of the starved cells gave insignificant rise to an increase of ERK, JNK and p38 phosphorylation. Nevertheless, an in vitro kinase assay performed with the kinases, either immunoprecipitated by antibody or bound to GST-fusion substrates, enabled us to show a certain level of stimulation of c-Jun-associated (JNK) and MEF2A-associated (p38) kinase activity in serum stimulated E1A + cHa-ras cells. Thus, the obtained results show that transformation of fibroblasts with E1A and ras oncogenes may contribute to constitutive activation of ERK, JNK and p38 kinase cascades responsible for a high and non-regulated activity of MAP-kinase-dependent transcription factors, in particular AP-1.