[The cellular mechanisms and regulation of metastasis formation].

Recent data obtained at the junction of biochem: istry, molecular and cell biology and experimental oncology, showed that the formation of secondary foci of tumor growth during cancer progression--metastasis formation--is a highly determinate and regulated process. This process includes on the one hand the appearance of metastatic population of cells with special characteristics that allow their dissemination and seeding in distant organs and on the other.hand the formation of specific attractive micro environment in target organs. These cells show the ability to switch their motility to the most effective mode depending on the properties of the surrounding tissues (plasticity), appearance of specific receptors on the cell surface, which enhance their directed migration to target organs and acquisition of some characteristics of stem cells, allowing them to survive and reproduce in alien microenvironment. These alterations are strongly coordinated with development of a specific nichein the target organ which stimulates initiation and growth of a future metastasis, so-called premetastatic niche. In this review we analyzed recent data concerning mechanisms which regulate the emergence of metastatic population of cells, development of premetastatic niches and coordination of these processes:.

[Comparative research of normal and transformed fibroblast spreading. The role of microfilament polymerization and actin-myosin contractility].

Polymerization of microfilaments and their subsequent rearrangements under control of actin-myosin interactions are two main processes underlined morphogenetic reactions of cells. We studied their role during spreading of normal and transformed REF52tetRas fibroblasts with adjustable ras oncogene expression. Treatment with inhibitors of cell contractility (Y27532 or blebbistatin) led to disappearance of actin bundles and focal adhesions, but both normal and transformed cells preserved high pseudopodial activity. Spreading was considerably accelerated in normal cells and less accelerated in ras-transformed cells under these conditions. When actin polymerization was suppressed with low concentrations of latrunculin A, stress-fibrills and focal contacts were preserved, but lamellipodial activity was lost in normal cells, so spreading was dramatically inhibited. In the case of transformed fibroblasts, actin bundles and focal adhesions virtually disappeared, but pseudopofial activity was not lost and spreading was suppressed to a lesser extent. Therefore, the most essential process in regulation of cell spreading and polarization is microfilament polymerization at the leading edge. Incidentally, ras-transformed cells are less sensitive to inhibitors affecting cytoskeletal structure than non-transformed ones. Possible mechanisms underlying these diversities are discussed.

[Analysis of changes induced by oncogene N-RAS expression in pattern and distribution of pseudopodial activity of fibroblasts].

It is not known which morphological properties of fibroblasts induced by malignant transformation modulate their migration pattern. We studied the changes in the distribution and dynamics of the leading edge of 10(3) mouse fibroblasts after their transformation by oncogene N-RAS(asp13) and analyzed the changes in the pattern of cell migration. Transformation proved to increase the leading edge proportion and to considerably redistribute pseudopodial activity along the cell edge. As the result of transformation, small pseudopodia are formed in the stable lateral regions of the cell edge typical of normal fibroblasts, i.e., the lateral edge is no more truly stable. In addition, pseudopodial activity of the leading edge in transformed fibroblasts proved higher compared to normal ones. It is necessary to notice, the leading edge activity is equally high immediately after induction in both normal and transformed fibroblasts; although, it is suppressed with time in normal cells but not in transformed ones where it remains steadily high. These properties promote the random component of malignant cell motility and modify the cell migration pattern after transformation.

[Biochemical features of gallbladder bile in biliary tract diseases].

Sixty-two and 58 patients with hypo- and hypermotor biliary tract dysfunction (BTD), respectively, as well as 59 patients with chronic acalculous cholecystitis (CAC) and 63 with opisthorchiasis-complicated CAC were examined. A control group comprised 33 patients of the same sex and age. All the patients underwent fractional duodenal intubation, followed by clinical, biochemical, and serological bile studies. All the examinees were found to increased gallbladder bile lithogenicity, minor changes being observed in biliary tract dysfunction and more pronounced ones being in opisthorchiasis. A biochemical study of gallbladder bile, followed by its lithogenicity correction, is recommended in the treatment of different forms of BTD.

[Psychovegetative disturbances in patients with chronic non-calculous cholecystitis combined with chronic opisthorchosis].

A complex clinico-instrumental, laboratory and psychological examination of 122 patients with chronic non-calculous cholecystitis (CNCC), 63 of who had chronic opisthorchosis (CO), was conducted. The controls were 33 healthy individuals. Patients with CNCC and CO had hypomotoric dyskinesia, Oddi's sphincter dysfunction, higher levels of personal anxiety and depression more often than others.

[Effect of actomyosin contractility on focal contacts of myofibroblasts and structure of stress fibers]. / Vliianie aktomiozinovoi sokratimosti na fokal'nye kontakty miofibroblastov i strukturu stress-fibrill.

Myofibroblasts from rat lung were cultivated. These cells in addition to beta- and gamma-cytoplasmic actins, expressed alpha-smooth muscle actin (alpha-SMA) and formed a system of "supermature" focal contacts, which were connected with thick stress-fibers expressing alpha-SMA and myosin II. Reduction of actin-myison contractility by inhibitors BDM and ML-7 lead to stress fiber reorganization, e.g., decrease in their thickness, a selective disappearance of alpha-SMA expression and myosin translocation from bundles to the cytoplasm. Using immunofluorescence, interference-reflection microscopy and morphometry, we have demonstrated that an inhibition of actin-myosin contractility also leads to dispersion of myofibroblastic focal contacts. Phase-contrast and DIC video-enhanced microscopy of live cells showed morphological reorganization at the leading edge after inhibitory treatment. Thus, actin-myosin contractility controls the structure of "supermature" focal contacts of myofibroblasts and alpha-SMA expression in stress fibers.

[Immunomorphological research on the formation of the extracellular matrix in epithelial cell cultures]. / Immunomorfologicheskoe issledovanie formirovaniia vnekletochnogo matriksa v kul'turakh épitelial'nykh kletok.

Formation of extracellular matrix structures in cultures of rat liver epithelial nontransformed cell line IAR2 was studied with antisera to fibronectin, laminin and type IV collagen by immunofluorescence and immunoelectron microscopy of platinum replicas. Fibronectin formed peripheral spots of variable size some of which outlined free cell edges, as well as fibrils located towards the center of single cells or of cellular islands. Similarly distributed structures were seen in isolated matrices. Codistribution of fibronectin and actin was observed only for the peripheral line of fibronectin spots and marginal circular actin bundle. Basement membrane components. laminin and type IV collagen, formed mainly spots of variable size predominantly beneath the cell or each cell in an island. Occasional fibrils were seen also. Essentially the same results were obtained by immunofluorescence and immunogold electron microscopy. Cytochalasin D treated cells displayed spots of both fibronectin and laminin. The relevance of previously postulated receptor-mediated assembly of extracellular matrix structures to the epithelial cells is discussed.

[Contact interactions of spreading thrombocytes]. / Kontaktnye vzaimodeistviia rasplastyvaiushchikhsia trombotsitov.

Contact interactions of rabbit platelets was studied in the course of their spreading over the siliconized glass surface. When the density of cells adhered to the substratum surface is high enough, the platelets are spreading in such a way that their edges are in a close proximity, while the overlapping of cells is very rare and scarcely pronounced. A morphometric analysis of the probability of such an organization of platelets at their random and independent disposition on the substratum proves the existence of a contact inhibition of platelets spreading on the substratum. Thus, a phenomenon of the contact inhibition seems to be a common feature not only of large nucleated cells but also of small anuclear platelets.

[Redistribution of concanavalin A receptors on the thrombocyte surface]. / Pereraspredelenie retseptorov k konkanavalinu A na poverkhnisti trombotsitov.

Using the indirect immunofluorescence method, it has been shown for the first time that concanavalin A receptors can undergo a redistribution over the surface of platelets spread on the substrate. The distribution of receptors in the intact cells is diffuse and random. Con A receptors, cross-linked by their ligand, are removed from the surface of the lamellar cytoplasm of living substrate-spread platelets. These receptors move into the central part of cell surface. This phenomenon is similar to capping or clearing of lamellar cytoplasm of big nucleated cells. Cytochalasin B (10 mcg/ml) does not prevent the formation of patches of receptors but inhibits the clearing of the lamellar cytoplasm of spread platelets. This result suggests that microfilaments may be involved in the redistribution of receptors.

[Quantitative patterns of concanavalin A receptor redistribution on the surface of normal and transformed cells]. / Kolichestvennye zakonomernosti pereraspredeleniia retseptorov konkanavalina A na poverkhnosti normal'nykh i transformirovannykh kletok.

Redistribution of concanavalin A receptors on the surface of normal and transformed cell lines was studied by indirect immunofluorescence. Normal murine fibroblasts are compared with line L transformed murine cells, whereas NRK line cells from normal rat kidney with their transformed counterparts of Ki-MSV line. It was shown that the total area occupied by the transformed cells on the substratum and the size of lamellar cytoplasm (i. e. the peripheral part attached to the substratum) are diminished as compared to those in normal cells. The surface zone from which concanavalin A-agglutinated receptors are eliminated is approximately equal to the area of lamellar cytoplasm of normal cells and is less as compared to that of transformed cells.