Eksperimental'naia onkologiia最新文献

The intracellular Na+/K+ ratio was studied for its effect on expression gene beta-actin and oncogene c-fos and activity of these genes during the mitotic cycle in ascites cells of leukemia P-388 and Ehrlich tumour. It was established that gene beta-actin was activated at high and low ratios of Na+/K+, while c-fos only at high ones. The expression of these genes during the mitotic cell cycle was due to changes in the intracellular Na+/K+ ratio. The obtained data showed an important role of intracellular homeostasis of monovalent cations in regulation of gene expression during the mitotic cell cycle.

Results of investigations on the role of protooncogenes in the regulation of proliferation and differentiation of normal hemopoietic cells and in the pathogenesis of tumoral hemopoietic diseases are reviewed. The ways of the protooncogene activation in leukemias are discussed.

An antimetastatic effect associated with macrophage activation by liposome-encapsulated glucosaminylmuramyldipeptide was found to enhance in malnourished mice with the Lewis lung carcinoma. These changes were not matched by further increase in the functional activity of macrophages. It has been suggested that enhancement of the antimetastatic effect in malnourished animals is due to the inhibition of neovascularization necessary for the beginning of metastatic exponential growth. The induction of neovascularization may be caused by the tumor necrosis factor, main product of activated macrophages.

Data from literature as well as the results of the author's investigations on the genotoxic and carcinogenic effects of sodium nitrite (SN) are presented. Carcinogenicity of SN detected in animal experiments proved to be connected with the formation of nitroso compounds from endogenous nitrosable precursors. Sodium nitrite possessed the transforming and promoting effects in the cell cultures as well as the mutagenic effects in the bacterial systems where predominant effect of SN as compared with N-nitrosodimethylamine (NDMA) was registered. The prolonged pretreatment with SN amplified the liver DNA damage in rats in case of NDMA endogenous synthesis.

Cells of the Lewis lung carcinoma (3LL), B16 melanoma and Ehrlich carcinoma pre-treated in vitro by a recombinant tumour necrosis factor (rTNF) were studied for their spontaneous and experimental metastatic spreading. The rTNF (1000 u/ml) was determined to stimulate a metastatic potential of the Lewis carcinoma cells after their treatment with the factor for 6 h and, vice versa, to inhibit it after 96 h prolonged treatment. The efficacy of the stimulating effect of rTNF on a metastatic spreading depends on the peculiarities of the studied cells.

It has been determined that prostaglandins E2 and F2 alpha being exogenously inoculated during the premetastatic period to mice with metastatic Lewis lung carcinoma in equal degree activate neurocytes of supraoptic and paraventricular hypothalamus nuclei, playing the important role in secretion of peptidergic hypophysial adrenal gland complex, but they exert unequal influence on pituitary body, adrenal cortex and thyroid apparatus. F2 alpha stimulates the pituitary body corticotrophic function, secretory function of spongiocytes and thyrocytes, identifies the thyroxin and triiodothyronine utilization, E2, on the contrary, does not influence these indices or reduces them. Obviously, the mentioned above differences between E2 and F2 alpha may be explained by their different influences on antimetastatic resistance.

It was shown previously that cells of sarcoma PS-103 induced in mouse by subcutaneous transplantation of plastic film produce growth-stimulating activity. In this communication clone 3 sb, isolated from sarcoma PS-103, was studied. Growth factor produced by the cells of this clone stimulated proliferation of quasi-normal (3T3, NRK) cells and transformed cells both in monolayer and in semi-solid medium. It was shown by gel filtration chromatography that the main growth-stimulating activity migrated with the protein fraction m.m. 10-15 kDa. The addition of this growth factor to the culture medium significantly (90%) inhibited 125I-EGF (epidermal growth factor) binding by A-431 cells. These data suggest that the growth factor produced by the studied tumor cells is transforming growth factor alpha.

It has been shown in vitro with human acidic gastric juice the nitrosomorpholine (NMOR) formation from small doses of precursors (sodium nitrite and morpholine) with a significant difference relative to the control. The presented data suggest the possibility of the nitrosation reaction in the human gastric juice under hypo- and anacidic conditions. The data obtained are one more experimental confirmation of the epidemiological evidence of the potential role of nitrates (nitrites) in the etiology of stomach and esophageal cancers.

To clarify the role of the ribosome apparatus in the differentiation and maturation, the nucleolar ultrastructure, ribosome level and maturation stages of lymphocytes and their phorbol ester-induced differentiation capacity were studied immunologically, cytochemically and electron-microscopically in 16 patients with B-chronic lymphoid leukemia (B-CLL) and in one with small lymphocyte lymphoma. Most B-CLL cases had the clones mainly consisting of cells at an intermediate maturation stage. The cases with immature and mature lymphocyte clones were observed more rarely. The acid phosphatase activity did not correlate with the maturation stages of the lymphoid cells. The nucleolus activity ranged from virtually zero to high one. In general, there was a relationship between the ribosome content and nucleolus activity, although there were exceptions suggesting the impaired ribosome biogenesis. There was no correlation between the ribosome content and maturation degree of B-CLL lymphocytes and their phorbol-ester-induced differentiation capacity.

The system of proteolytic enzymes and their inhibitors was studied in tissues of ovarian tumours of Wistar rats. It has been revealed that activation of proteolysis enzymes is observed in the genesis of tumour growth against a background of the absence of protease inhibitors. The correction of revealed disturbances by introducing the inhibitors of proteolytic enzymes and hormone preparations has shown that contrical and norcolute are the most effective. The results obtained suggest the further search of preparation normalizing the condition of the given system.