Eksperimental'naia onkologiia最新文献

Thromboembolic events represent well-recognised complications of neoplastic disease contributing, in a significant manner, to the morbidity and mortality from cancer. The close relationship between the activation of blood coagulation and tumor growth is known since 1865, when Armand Trousseau first described the clinical association between primary or idiopathic venous thromboembolism and an underlying occult malignancy. However, only in the last decades significant advances in this field have been achieved, both on the comprehension of the complex interactions between the tumor and the hemostatic system, and on the prophylaxis and therapy of the thromboembolic manifestations in cancer patients.

Aim: To test the effect of 2'-deoxyisoguanosine as a specific substrate of HIV reverse transcriptase on the growth of cultured normal and cancer cells.

Methods: The effect of 2'-deoxyisoguanosine on the growth of cells of two normal (telomerase-negative) and five cancer cell lines have been tested. Cell viability was assessed by MTT assay.

Results: We have found that this nucleoside analogue has low potency and specificity in inhibiting tumor cell growth. IC50 ranged from 0.5 mM to 2 mM for tumor cells, and from 1 mM to more than 4 mM for normal cells.

Conclusions: 2'-deoxyisoguanosine has low potency and specificity in inhibiting tumor cell growth, similar to other telomerase inhibitors.

Aim: To express recombinant S6K2 in baculovirus expression system; to purify large quantities of recombinant S6K2 for biochemical studies; to generate and characterise specific MABs against recombinant S6K2; to study the patterns S6K1 and S6K2 expression and subcellular localization in normal, benign and malignant breast tissues.

Methods: Recombinant baculovirus, expressing wild type S6K2 was generated using Bac-to-Bac system (Invitrogen); recombinant S6K was purified from infected Sf9 cells using affinity purification approach; monoclonal antibodies against recombinant S6K2 were generated; the specificity of generated MABs towards recombinant and endogenous S6K2 were examined by ELISA, Western blotting, immunoprecipitation and immuhohistochemical staining; immunohistochemical detection of S6K1 and S6K2 in human breast tissues was performed using specific monoclonal antibodies towards S6K1 and S6K2.

Results: Large amounts of enzymatically active S6K2 were purified using baculovirus expression system; highly purified preparations of S6K2 were used to generate and characterize anti-S6K2 MABs; elevated levels of S6K1 and S6K2 were found in breast tumors when compared to normal breast tissues; S6K2 is frequently localized in the nuclei of adenocarcinoma tissues, but rarely in fibroadenoma or "normal" breast tissues.

Conclusion: Production of recombinant S6K2 in large amount and generation of specific monoclonal antibodies towards S6K2 has provided us with excellent tools to study the function and regulation of this important signalling molecule in normal and cancer cells. Immunnohistochemical analysis of S6K1 and S6K2 expression in normal and malignant breast clearly indicates that both kinases are overexpressed in breast tumors, when compared to "normal" tissues. The retention of S6K2 in the nuclei of malignant cells may be caused by disregulation of nucleocytoplasmic shuttling and could subsequently affect cell growth and proliferation.

Objective: To analyze the expression of DRET gene in hepatocellular carcinomas (HCCs) tissue specimens in comparison with normal liver tissue to evaluate the relationship between DRET gene and HCC.

Methods: 250 primary HCCs and 50 normal liver tissue samples from Qidong area, China, were studied for DRET mRNA and protein expression with the use of Northern blot analysis, in situ hybridization and immunohistochemistry.

Results: By Northern analysis, moderate to strong DRET mRNA expression was present in normal liver samples. In contrast, DRET mRNA expression in tissue samples of primary HCCs was markedly decreased compared with normal controls. Primary HCCs that gave rise to metastasis showed significantly lower DRET mRNA levels than nonmetastasizing HCCs. By in situ hybridization analysis, nonmetastatic HCCs samples didn't differ from controls. In contrast, most of the primary metastasizing HCC showed only faint or moderate DRET mRNA expression. Tissue sections of nonmetastatic HCC exhibited lower DRET immunoreactivity than control samples, but higher labeling index than metastatic HCC samples.

Conclusions: Expression of DRET on mRNA and protein levels in HCC cells is related to HCC metastatic ability.

Aim: To identify novel PTEN-binding partners.

Methods: The technique of yeast two-hybrid screening was used in this study. A panel of bait constructs was created, containing the C-terminal domain of PTEN, full length PTEN, activated and phosphatase-dead mutants. The expression of LexA-fused baits, their nuclear localization and autoactivation potential were tested according to the standard protocol of Duplex A system. CDNA libraries from Colon Cancer, HeLa and Mouse Embryo were screened with two selected bait constructs. Isolated positive clones were further analysed by mating assay and identified by automated DNA sequencing and database searching.

Results: Extensive screening of cDNA libraries with the full length and the C-terminal domain of PTEN led to the identification of 43 positive clones, which were confirmed in mating assay. Sequence analysis indicated that two clones encode AEBP1 (Adipocyte Enhancer Binding Protein 1).

Conclusion: Our data indicate that the interaction between PTEN and AEBP1 is mediated by their C-terminal and N-terminal domains, respectively. The functional importance of PTEN-AEBP1 interaction is currently under investigation.

Basing on the current data and results of the author's own clinical and experimental studies the possibility to intensify the antitumoural resistivity of the organism was established. This may be performed due to demasking of tumour cells using fibrinolytic agents, selective inhibition of tumour cell division by keilons, tissue-specific inhibitors, and also by normalization of the interferon system function.

A Monoclonal Antibody Program was launched at the National Institute of Oncology and Radiobiology (INOR) in Cuba in 1985. Eleven MAbs have been obtained which recognize different leukocyte antigens. Four MAbs a series of reagents raised against different types of cytokeratins, carcino-embryonic antigen and the membrane receptor for Epidermal Growth Factor. These MAbs are especially useful in immunohistochemistry for the study of human tumours, leukemias and lymphomas. Three ultramicro-ELISA systems have being deviced using MAbs. First trials are being made with radioactive MAbs for immunoscintigraphy. The use of anti T-cell MAbs for the prevention of rejection crisis in patients receiving organ transplantation and for the treatment of patient with cutaneous T-cell lymphoma is still mostly a matter for research.

Comparative studies of clonogenic ability of twenty four lung cancer samples have been performed in semisolid agar in vitro and in diffusion chambers in vivo. It is concluded that plating efficiency of lung cancer cells varies from 0.00002% to 0.03% in vitro assays and from 0.01% to 0.11% in vivo. A small number of colonies (less than 20) in 15 specimens from 16 does not permit using this method for preclinical individual sensitivity test. The cloning of lung cancer in vitro gives the efficiency more than twenty colonies per a dish in 5 cases of 11. There is some evidence that these models can be used for prediction of treatment response of individual tumors to chemotherapy.

A method of the restriction analysis by Msp I enzyme has been used to analyze the 12th codon of Ha-ras-1 protooncogene in 10 human carcinomas and in the stomach mucosa adjacent to them their 5 metastases into the regional lymph nodes and in 2 ulcers. No point mutation was found.