Expression of CD44 on two lines of transplantable melanoma cells--relationship with cytokine secretion and tumor progression.

In the present work it was investigated if a spontaneous alteration of the native melanotic transplantable melanoma form into amelanotic form, connected with the tumor progression, is accompanied by changes of CD44 surface glycoprotein expression. We also tried to find out if there exists any correlation between changes in CD44 expression and IL-6, TNF-alpha, and IL-10 secretion. Cells of two hamster transplantable melanoma lines: melanotic and amelanotic were used.

Characterization of interleukin 10 and NO release by transplantable melanoma cell lines with regard to their progression.

The results from our investigations concerning the secretory activity of interleukin 10 (IL-10) by two transplantable melanoma cells showed that a spontaneous alteration of the native-melanotic line into an amelanotic form and the tumor progression connected with it, were accompanied by a 6-fold decrease of the IL-10 content in the supernatant of these melanoma line cell culture. Simultaneously, the intracellular content of IL-10 indicated that there was only a small population of IL-10 positive cells, numerically similar in both melanoma cell lines. A comparison of the IL-10 and nitric oxide (NO) secreted by both melanoma lines does not show any correlation between the changes in the content of these substances, which seems to indicate that NO does not act as an autocrine regulator of IL-10 secretion.

Implication of macrophage no and cytokine secretion in the cytotoxicity of transplantable melanomas as regards the progression of these tumors.

We studied the connection between the secretion of TNF-alpha, IL-6, OSM and NO by hamster peritoneal macrophages (animals bearing two forms of hamster transplantable melanomas of common origin but differing in growth rates, levels of differentiation and immunogenicity) and the cytotoxic effect of these macrophages on the cells of those two melanoma lines. The melanotic melanoma, the native form of melanoma, evoked an increase of cytokine secretion, especially of TNF-alpha, while the amelanotic melanoma line caused an increase of macrophage cytotoxic activity and of NO release. These observations seem to reveal that the biological features of transplantable melanomas and their progression influenced changes in the cytotoxic activity of peritoneal macrophages by changing the effector mechanism of this phenomenon.

Estimation of macrophage IL-10 and NO secretion in the cytotoxicity against transplantable melanomas in relation to the progression of these tumours.

The relationship between the secretion of interleukin 10 (IL-10) and nitric oxide (NO) by hamster peritoneal macrophages and their cytotoxic effects on the cells of those two melanoma lines was studied. The nonuniform reaction of macrophages from hamsters bearing two transplantable melanoma lines has been observed. An increase in the cytotoxicity of macrophages from hamsters bearing the amelanotic melanoma line was accompanied by an inverse correlation between IL-10 and NO secretion.

Sensitivity of transplantable melanoma cells to cytokines with regard to their spontaneous apoptosis.

Objectives: Changes in the sensitivity of two lines of transplantable melanoma cells to the antiproliferative activity of interleukin 6 (IL-6), oncostatin M (OSM), tumor necrosis factor-alpha (TNF-alpha) during melanoma progression were the subject of this study. We were looking for a correlation between these changes and the ability of melanoma cells to undergo spontaneous apoptosis.

Methods: The influence of exogenous cytokines on the proliferation of melanoma cells was measured by colorimetric methods with MTT and apoptosis of these cells was estimated by staining with annexin V/propidium iodide, measurement of DNA degradation and cell cycle analysis.

Tumoricidal effect of macrophages on transplantable melanoma cells with regard to their sensitivity to exogenous cytokines.

We studied the correlation between the cytotoxic effect of hamster peritoneal macrophages from animals bearing transplantable melanomas of common origin but differing in many biological features on the cells of those melanomas and the sensitivity of the melanoma cells to exogenous OSM, TNF-alpha and IL6. Our results did not show such a correlation.

Heterogeneous susceptibility to spontaneous and induced apoptosis characterizes two related transplantable melanomas with different biological properties.

A family of phenotypically and biologically different transplantable hamster melanomas was derived from a single tumor more than 40 yr ago. In this work, we were seeking the differences between the abilities of the cells from two biologically heterogeneous (melanotic and amelanotic) members of this family to undergo spontaneous or camptothecin-induced apoptosis. We studied these differences by looking at three important features of the apoptotic process, i.

A study on nitric oxide secretion by transplantable melanoma cell lines with regard to their spontaneous apoptosis.

In the study we investigated if there exists any correlation in the nitric oxide (NO) secretion by two types of melanoma cells of the same origin but differing in their biological properties and ability to undergo spontaneous apoptosis. Our results suggest that there exists an inverse correlation between the dynamics of NO secretion by cells of two melanoma lines and their ability to undergo spontaneous apoptosis.

[The role of cytokines in aseptic loosening of total hip prosthesis].

The aim of this study was estimation of the secretory activity of macrophages isolated from granulomatotic tissue in aseptic total hip prosthesis loosening (particularly in regard to IL-6, TNF-alpha and OSM secretion). A considerable increase of IL-6 and TNF-alpha (proosteolytic cytokines) content was noted. At the same time a prominent decrease in OSM (an osteoprotective cytokine) was noted.

Characterization of NO and cytokine release by transplantable melanoma cell lines in relationship to their differentiation.

Changes in the secretory activity of two transplantable melanoma lines (differing in many biological features) as regards nitric oxide (NO) release and interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-alpha) and oncostatin M (OSM) secretion were the subject of the present study. The results obtained show that a spontaneous alteration of the hamster native melanoma line into an amelanotic one is accompanied by a global change of the secretory activity, but there was not a distinct correlation between the endogenous cytokine secretion and NO secretion by cells of both melanoma lines.

A comparative study on oncostatin M secretion by transplantable melanoma cells with regard to their biological properties and progression.

The authors have studied oncostatin M secretory activity of cells of two lines of transplantable melanoma with different biological properties. The level of OSM in melanoma cells supernatant was determined by ELISA test and OSM bioactivity was measured by using biotest line sensitive to OSM cytostatic activity--A 375 melanoma cells. OSM presence was confirmed in cellular lysates by western blot.

Expression and activity of P-glycoprotein in transplantable hamster melanomas.

In the study described here we investigated the possibility of an association between the aggressiveness of melanoma and multidrug resistance phenotype by analyzing the expression and activity of P-glycoprotein (Pgp) in two genetically related transplantable hamster melanomas--a melanotic (Ma) and an amelanotic (Ab) form --which differed in aggressiveness and metastatic potential. Flow cytometric analysis of Pgp activity (using a verapamil-sensitive rhodamine R123 exclusion test) as well as Western blotting of cellular lysates showed its preferential (although not very marked) expression in the Ab melanoma cells. The Ab melanoma cells also exhibited a higher proportion of tumor-infiltrating lymphocytes (TIL), mostly of T cell phenotype, that may have reflected a higher immunogenicity of the tumor.

Flow cytometric estimation of the plasma membrane diversity of transplantable melanomas, using annexin V.

Using a recently described flow cytometric assay probing for cell surface exposure of phosphatidylserine with fluoresceine-labeled annexin V, we attempted to establish if there existed any differences in the phospholipid bilayer of the plasma membranes of melanoma cells isolated from two lines of a hamster transplantable melanoma characterized by a common origin but differing in many biological features. In contrast to control nonstaining cells, the cells of both melanoma lines bound annexin V, but at a different rate: 88% of melanotic and 94% of amelanotic melanoma cells were annexin V positive. Among cells of the native melanotic melanoma line we distinguished only one cell population binding annexin but in some experiments with the amelanotic melanoma we observed two annexin V positive cell populations with a different fluorescence intensity.

Influence of transplantable melanomas on the secretion of cytokines by hamster peritoneal macrophages.

The subject of the study was the influence of two lines of transplantable melanomas on the secretion of cytokines (IL-6, TNF-alpha, OSM) and total proteins by hamster peritoneal macrophages. The results showed a statistically significant increase of total protein content and decrease of cytokine content in the supernatants of 24 h cultured macrophages from melanoma-bearing animals in comparison with control macrophages. Changes in the secretory function were more marked in the case of macrophages from hamsters bearing amelanotic melanoma.

Diversity of the plasma membrane properties of transplantable hamster melanomas with regard to the expression of P-glycoprotein.

A comparison of the expression of P-glycoprotein (Pgp) was performed in two forms of hamster transplantable melanomas of common origin, but differing in growth rates and levels of differentiation. The expression of P-glycoprotein in plasma membranes of these two forms of melanomas was estimated by the western blot analysis and the transport activity of the Pgp compared by flow cytometry. It was observed that a spontaneous alteration in the original melanotic melanoma leading to a formation of the amelanotic form characterized by higher growth rate, greater anaplasticity and leading to the animals' death after a shorter time from inoculation, was accompanied by a decrease in the Pgp expression and activity, due to simultaneous appearance of a small population of amelanotic cells with high Pgp expression and activity, and disappearance of this activity from the major population.

Estimation of oncostatin M (OSM) secretion by peritoneal macrophages with regard to the progression of transplantable melanomas.

The authors have studied the influence of two kinds of transplantable melanomas on the secretion of oncostatin M (OSM) and total proteins by peritoneal macrophages. Culture supernatant samples were tested by ELISA. The macrophages of melanoma-bearing animals released a lower amount of OSM than those of the controls.