Melanization as unfavorable factor in amelanotic melanoma cell biology

The biology of three amelanotic melanoma cell lines (Ab, B16F10, and A375) of different species origin was analyzed during in vitro induced melanization in these cells. Melanin production was induced by DMEM medium characterized by a high level of L-tyrosine (a basic amino acid for melanogenesis). The biodiversity of amelanotic melanoma cells was confirmed by their different responses to melanogenesis induction; Ab hamster melanomas underwent intensive melanization, mouse B16F10 darkened slightly, while human A375 cells did not show any change in melanin content. Highly melanized Ab cells entered a cell death pathway, while slight melanization did not influence cell biology in a significant way. The rapid and high melanization of Ab cells induced apoptosis documented by phosphatidylserine externalization, caspase activation, and mitochondrial energetic state decrease. Melanoma cell type, culture medium, and time of incubation should be taken into consideration during amelanotic melanoma cell culture in vitro. L-tyrosine, as a concentration-dependent factor presented in the culture media, could stimulate some amelanotic melanoma cell lines (Ab, B16F10) to melanin production. The presence of melanin should be considered in the examination of antimelanoma compounds in vitro, because induction of melanin may interfere or be helpful in the treatment of amelanotic melanoma.

Novel blends of polylactide with ethylene glycol derivatives of POSS

Polylactide (PLA), a main biodegradable and biobased candidate for the replacement of petrochemical polymers, is stiff and brittle at room conditions. It is therefore of high interest to formulate new PLA-based materials suitable for applications demanding flexibility and toughness. In this work, novel blends of PLA with polyhedral oligomeric silsesquioxanes (POSS) grafted with longer (P1) and shorter (P2) arms of ethylene glycol derivatives were prepared and studied. It was hypothesized that, owing to their architecture with the central POSS cage grafted with arms, miscibility and stability of the blends could be improved. Indeed, PLA/P1 blends were homogeneous despite P1 relatively high M_w of 9,500 g mol^-1. The blend with 20 wt% of P1, having T_g at 16 °C, was transparent and flexible, elastomer-like material with excellent drawability. The blend remained homogeneous and retained its good drawability as well as flexibility during 6 months of aging at room temperature: a 2 % secant modulus of elasticity well below 100 MPa, a low yield stress below 2 MPa, and and a large strain at break of 8 (800 %). Contary to that, PLA/P2 blends were only partially miscible. Nevertheless, owing to the liquid state of the dispersed phase, the blend with 15 wt% of P2 was transparent and ductile, with T_g at 49 °C, a relatively high yield strength of 29 MPa, and a large strain at break of 2.3 (230 %). The toughening mechanism involved the initiation of crazes and facilitation of their propagation by the liquid inclusions via the local plasticization effect.

Joachim Oelhaf and the first public autopsy in Gdansk in 1613

The first both in Gdansk and in Central Europe alleged public autopsy was performed by Joachim Oelhaf in February 1613. It was an evidence for Gdansk status as one of the leading anatomical centres in Europe. The aim of the article is to present the history of teaching medicine in Gdansk in early modern era and the eminent anatomists working in Academic Gymnasium of Gdansk. The preserved report of the autopsy of a new-born child with congenital defects is analysed as one of the very first texts in pathological anatomy. The described by Oelhaf case is identified as limb-body wall complex.

Camptothecin-induced death of amelanotic and melanotic melanoma cells in different phases of cell cycle

Camptothecin and its analogues are used as S-phase specific antitumor drugs because of topoisomerase I inhibition providing cells to death by apoptosis. Our previous works documented that amelanotic hamster's melanoma is very sensitive to camptothecin. Because of the challenges in treating melanoma and S-phase specificity of camptothecin, we performed a study to search what melanoma cell cycle phases are susceptible to this substance. Melanotic (Ma) and amelanotic (Ab) lines of Bomirski hamster's melanoma were used. Camptothecin cytotoxicity was determined by TUNEL method and cell cycle analysis was done by DNA staining with propidium iodide. Camptothecin after short time killed amelanotic melanoma cells from S/G2/M phases but with extended time dying cells came from G0/G1. Melanotic melanoma had fewer cells in S/G2/M phases and 3-fold more of these cells spontaneously died in comparison to more aggressive amelanotic line. High susceptibility of amelanotic melanoma cells to camptothecin show that not only cells with proliferative activity were sensitive to this alkaloid but with extended time it killed cells from all cycle phases. High number of cells in S/G2/M phases and low rate of spontaneous death among amelanotic melanoma cells suggest that the expansive growth of this melanoma line depends mainly on the decreased ability to undergo spontaneous apoptosis. If the sensitivity of amelanotic melanoma is not only hamster's but also human melanoma feature, we can suspect that by choosing melanoma form for treatment with camptothecin we could improve effectiveness of this drug against melanoma.

Role of Interleukins and Nitric Oxide Secretion by Peritoneal Macrophages in Differential Tumoricidal Effect to Transplantable Melanomas as Regarding their Biological Properties

The secretion of interleukins (IL-18, IL-12) and Nitric Oxide (NO) by peritoneal macrophages from hamsters bearing two lines of transplantable melanoma was estimated. Macrophages of animals with melanoma lines secreted less IL-18 but more IL-12 and NO in comparison with the control macrophages. The distinctly higher cytotoxic activity of macrophages from animals with amelanotic line in comparison with the melanotic line was not accompanied by significant differences in the IL-18 and IL-12 secretion between studied groups of macrophages. Thus, it seems that IL-18 play the role in innate immunity but not in adaptive cellular immunity, whereas IL-12 and NO take part in macrophages tumoricidal activity.

Mitochondrial transmembrane potential in spontaneous and camptothecin-induced apoptosis of melanotic and amelanotic melanoma cells

In this work we tried to estimate the role of mitochondria in the ability of cells of two: melanotic and amelanotic transplantable melanoma lines to undergo spontaneous and camptothecin-induced apoptosis. We measured mitochondrial transmembrane potential (DeltaPsi) changes during culture without (spontaneous apoptosis) and with camptothecin (induced apoptosis) by using JC-1 staining and flow cytometry analysis. Cytochrome c release and PARP cleavage as the biological effects of DeltaPsim changes belonging to the phenomena observed during apoptosis were estimated by Western blotting. The results of our investigations showed in both transplantable melanoma cells the features indicating apoptosis: DeltaPsi changes, cytochrome c release and PARP cleavage, but the degree of observed changes depended on the phenotype of melanoma cells examined. After camptothecin treatment the changes were more pronounced in the amelanotic melanoma cells- the more aggressive line.

The DNA ploidy and proliferative activity of transplantable melanoma cells in regard to their secretory function

The study concerns DNA ploidy and proliferative activity of the cells of two hamster transplantable melanoma lines - differing in many biological features - in the light of possible changes in their secretory activity. DNA ploidy was determined from the index of propidium iodide (PI) stained DNA content (DI), while the proliferative activity was defined as the percentage of cells in S and G2/M cell cycle phases. The secretory activity was described by determining total protein, interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-alpha), oncostatin M (OSM), interleukin 10 (IL-10) and nitric oxide (NO) content in the supernatants after 1, 6, 24 and 48 hours in cell culture. Our results indicate that melanotic melanoma cells (Ma) have a near-tetraploid DNAcontent and about 18% of proliferating cells, while amelanotic melanoma cells (Ab) - have a near-triploid DNA content and almost twice as many proliferating cells. The Ab cells, in comparison with Ma cells, secreted in vitro less total protein and most of the cytokines examined except OSM, but a spontaneous alteration of transplantable melanoma was accompanied by an increase of the quantity and dynamics of NO secretion. So, the cells of two melanoma lines have their own characteristic pattern of secretory function. But, the aneuploidy which accompanied the changes in cell differentiation of the studied melanoma lines, although seemed to reflect their changes in the proliferative activity, nevertheless did not reflect, in a direct way, differences in the secretion of the substances studied.

Interrelationship between macrophage IL-12, IL-10 and NO secretion in expression of their tumoricidal activity

Peritoneal macrophage activity in the secretion of IL-12, IL-10, NO and interrelationship between these substances in hamster bearing two lines of transplantable melanomas with different biological properties were studied. It has been found that these macrophages lack of homogenous reactivity in the secretion of studied substances. Melanotic melanoma line evoked moderate increase secretion of all above mentioned substances, whereas amelanotic melanoma line, tumor with higher immunogenicity, tumorogenicity and with shorter survival time of animals induced considerably increase of IL-12 and NO with prominent decrease of IL-10 secretion. Results allow to assume that macrophage secretory activity and interrelationship between these substances is not uniform in two lines of the same neoplasma and that it depends on tumor biological properties. Such observation seems to be useful in case of tumor cytokine immunotherapy.

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.

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.

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.

RESULTS

It was observed that during melanoma progression the sensitivity of those two melanoma line cells to the antiproliferative effect of IL-6 and OSM did not change, while a spontaneous alteration of the melanotic line into an amelanotic one seemed to be accompanied by resistance of the amelanotic melanoma cells to the antiproliferative activity of TNF-alpha. Simultaneously, we observed a decreased ability of amelanotic melanoma cells (in comparison with the native line) to undergo spontaneous apoptosis.

CONCLUSIONS

The observed resistance to the TNF-alpha antiproliferative effect which appears during melanoma progression seems to be correlated with a lower ability of the amelanotic melanoma cells to undergo spontaneous apoptosis.

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.

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.

[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. The obtained results seem to suggest that the changed immunobiology of macrophages consisting of increase osteolytic activity and decreased osteoprotective abilities could be responsible for the loosening of hip prosthesis.

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. It has been demonstrated that a spontaneous alteration of the transplantable melanotic melanoma line into an amelanotic line connected with tumour progression was accompanied by an increase of OSM release.

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. It is possible that these differences in annexin V binding to melanoma cell membranes reflect some changes in the phospholipid bilayer, associated with the progression of these tumors.

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.

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. This may suggest that the biological features of melanomas can influence peritoneal macrophages to release the particular cytokines at different levels.

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. It is possible, that the activity of Pgp in the melanoma cell membranes reflects the degree of cell differentiation.

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. At the same time the results showed statistically significant increase of protein content in the supernatants of cultured macrophages from melanoma-bearing hamsters in comparison with the controls. However, it has not been possible to demonstrate any relationship between melanoma progression and changes in the secretion of OSM by peritoneal macrophages.

ESR study of plasmatic membrane of the transplantable melanoma cells in relation to their biological properties

Using the spin labelling method we studied changes in the structure and dynamics of molecular mobility in the plasmatic membrane accompanied by a spontaneous alteration of a melanotic melanoma line into an amelanotic form with a higher growth rate, changed antigenicity and immunogenicity. The calculated ratio of the low-field line (A) intensity to the central line (C) intensity of the spectrum showed statistically significant differences in the order of parameters in the plasmatic membranes of both forms of melanocytes. The significantly broader central line (deltaW0) in the spectra of labelled amelanotic melanoma cells than in the original cell line indicated changes in the membrane structure leading to a lowering of the degree of order in the phospholipid bilayer. It has been suggested that a progression of transplantable melanomas is accompanied by an increase in membrane fluidity and reduction in molecular mobility dynamics within it.

Surface glycoproteins of peritoneal macrophages in hamsters bearing transplantable melanomas

The influence of 2 kinds of transplantable melanomas differing in biological properties on the contents of glycoprotein components and heterogeneity of the surface material in hamster peritoneal macrophages was studied. Distinct changes in the content of protein and glycoprotein components were found. Biochemical differences in the degree of these changes in macrophage surface material in relation to the kind of melanoma were observed. The electrophoretic patterns of the surface material derived from macrophages of hamsters bearing 2 kinds of melanoma showed some differences as well. It has been suggested that these differences seem to be related to the biological properties of the melanoma lines and reflect alterations of macrophage tumoricidal activity.