[A comparative study of sphingolipids in transplanted melanomas with high and low metastatic activity].

The content of sphingolipids in M3 and B16/F10 melanomas with a high metastatic potential and in Claudman's and B16/F1 melanomas with a low metastatic potential was studied. It was shown that the content of total lipid-bound sialic acids and ganglioside GM3 in melanomas with a high metastatic potential is considerably higher than that in melanomas with a low metastatic potential. On the other hand, the ceramide to glucosylceramide molar ratio is higher in melanomas with a low metastatic potential. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2008, vol. 34, no. 2; see also http://www.maik.ru.

Kinetics of hybridization on surface oligonucleotide microchips: theory, experiment, and comparison with hybridization on gel-based microchips.

The optimal design of oligonucleotide microchips and efficient discrimination between perfect and mismatch duplexes strongly depend on the external transport of target DNA to the cells with immobilized probes as well as on respective association and dissociation rates at the duplex formation. In this paper we present the relevant theory for hybridization of DNA fragments with oligonucleotide probes immobilized in the cells on flat substrate. With minor modifications, our theory also is applicable to reaction-diffusion hybridization kinetics for the probes immobilized on the surface of microbeads immersed in hybridization solution. The main theoretical predictions are verified with control experiments. Besides that, we compared the characteristics of the surface and gel-based oligonucleotide microchips. The comparison was performed for the chips printed with the same pin robot, for the signals measured with the same devices and processed by the same technique, and for the same hybridization conditions. The sets of probe oligonucleotides and the concentrations of probes in respective solutions used for immobilization on each platform were identical as well. We found that, despite the slower hybridization kinetics, the fluorescence signals and mutation discrimination efficiency appeared to be higher for the gel-based microchips with respect to their surface counterparts even for the relatively short hybridization time about 0.5-1 hour. Both the divergence between signals for perfects and the difference in mutation discrimination efficiency for the counterpart platforms rapidly grow with incubation time. In particular, for hybridization during 3 h the signals for gel-based microchips surpassed their surface counterparts in 5-20 times, while the ratios of signals for perfect-mismatch pairs for gel microchips exceeded the corresponding ratios for surface microchips in 2-4 times. These effects may be attributed to the better immobilization efficiency and to the higher thermodynamic association constants for duplex formation within gel pads.

[Biologically active sphingolipids in transplantable tumors of different histogenesis].

The composition of biologically active sphingolipids in hepatoma 22, breast adenocarcinoma, Lewis lung carcinoma, large intestine adenocarcinoma, cervical carcinoma, and melanomas M3 and B16 was compared to elucidate the similarity and differences in sphingolipids of subcutaneously transplantable murine tumors. The sphingolipid composition of the tumors was found to widely vary. The sphingomyelin, ceramide, glucosyl- and lactosylceramide, and ganglioside GD3 contents in hepatoma 22 are higher than those in normal tissue. No common regularities for tumors of different origin were observed in the ratios of bioeffectors inhibiting proliferation and stimulating apoptosis and bioeffectors stimulating cell growth and survival. However, the Cer/(GlcCer + LacCer) ratios were very low and practically equal in two melanoma strains, which probably indicates the degree of tumor malignancy. The results suggest that the content and composition of sphingolipids in tumors depend on their histogenesis.

[Ganglioside (GD3) in serum of cancer patients]. / Gangliozid (GD3) v syvorotke krovi rakovykh bol'nykh.

Gangliosides were studied in blood serum of healthy volunteers and of patients with cancer of mammary gland and stomach. Blood serum of the majority of patients with cancer and only 15% of healthy persons were shown to contain ganglioside GD3 which was detected in blood of patients with some other tumors.

Kinetic effects on signal normalization in oligonucleotide microchips with labeled immobilized probes.

Among various factors affecting operation of oligonucleotide microchips, the variations in concentration and in homogeneous distribution of immobilized probes over the cells are one of the most important. The labeling of immobilized probes ensures the complete current monitoring on the probe distribution and is reliable and convenient. Using hydrogel-based oligonucleotide microchips, the applicability of Cy3-labeled immobilized probes for quality control and signal normalization after hybridization with Cy5-labeled target DNA was investigated. This study showed that proper signal normalization should be different in thermodynamic conditions and in transient regime with hybridization far from saturation. This kinetic effect holds for both hydrogel-based and surface oligonucleotide microchips. Besides proving basic features, the technique was assessed on a sampling batch of 50 microchips developed for identifying mutations responsible for rifampicin and isoniazid resistance of Mycobacterium tuberculosis.

Comparative investigation of sphingoid bases and fatty acids in ceramides and sphingomyelins from human ovarian malignant tumors and normal ovary.

Fatty acid and sphingoid base compositions of ceramides and sphingomyelins were investigated in malignant tumors and normal tissue of human ovaries. It has been established that fatty acid compositions of ceramide and sphingomyelin isolated from one tissue are significantly different: the predominant acids are oleic (18:1) in ceramide and palmitic (16:0) in sphingomyelin, which contains much more other saturated acids. These differences are characteristic of both normal and tumor tissues. Sphingoid base compositions of ceramide and sphingomyelin in normal tissue are identical: the major component is sphingenine (over 96%), while ceramides from tumors contain, in addition to sphingenine, a significant amount of sphinganine. In sphingomyelins from tumors, sphinganine content is significantly lower than in ceramides and depends on the type of tumor.

[Gangliosides of murine B-lymphoma MORC-406]. / Gangliozidy B-limfomy MORC-406 myshei.

Gangliosides of murine B-lymphoma MOPC-406 were studied, using biochemical methods and specific antibodies. The lymphoma was found to contain 12 ganglioside components which were identified as N-acetyl and N-glycoloyl forms of SiaLacCer, SiaGgOse3Cer, II3SiaGgOse4Cer, IV3SiaGgOse4Cer and II3IV3Sia2GgOse4Cer.

Ganglioside shedding and changes in ceramide biosynthesis in human ovarian tumors.

The contents and composition of ceramides and gangliosides were measured in human ovarian tumors (benign and malignant) and sera of tumor patients. In tumors (especially malignant) the content of ceramides is decreased compared to that in normal tissue, and the malignant tumor ceramides contain significant amounts of sphinganine which is absent in the ceramides of normal tissue, suggesting an alteration in ceramide biosynthesis. The content of gangliosides in tumors is also decreased. The major gangliosides of normal and tumor ovarian tissues are GM3 (sialocsyllactosyl ceramide) and GD3 (disialosyllactosyl ceramide). In tumors, the GD3 content is significantly decreased. The ceramide/ganglioside molar ratio in tumors is shifted toward gangliosides. In sera of tumor patients, ceramide content does not change, ganglioside content (especially that of GD3) increases compared to that in sera of healthy subjects due to ganglioside shedding from the surface of tumor cells, and the ceramide/ganglioside molar ratio decreases. These changes may stimulate tumor growth because of the opposite effects of ceramides and gangliosides: ceramides suppress tumor growth and gangliosides suppress antitumor activity.

Change in contents of biologically active sphingolipids modulating cell growth and survival in hepatoma 27 compared to rat liver.

The contents of bioactive sphingolipids (sphingomyelin, ceramide, glucosyl- and lactosylceramides, gangliosides) were studied in rat hepatoma 27 and rat liver. The amounts of sphingomyelin, ceramide, and glucosyl- and lactosylceramides were about twofold and that of gangliosides was about 3.5-fold increased in the tumor compared to normal tissue. Since sphingomyelin promotes angiogenesis, glucosyl- and lactosylceramides stimulate proliferation, gangliosides inhibit apoptosis, but ceramides suppress proliferation and stimulate apoptosis, it is obvious that the balance of these effectors in hepatoma 27 moves with the tumor growth.

[Comparative study of gangliosides from murine B- and T-lymphomas]. / Sravintel'noe izuchenie gangliozidov B- i T-limfom myshei.

Gangliosides from murine B-lymphomas (MOPC 21 and MOPC 406) and T-lymphoma EL-4 were studied by thin-layer chromatography, immunoprecipitation with specific antisera to gangliosides and by treatment with neuraminidase. It was found that the gangliosides of all three lymphomas differ in their interaction with antisera and neuraminidase although they are similar in their chromatographic behaviour.

Sphinganine in sphingomyelins of tumors and mouse regenerating liver.

Contents of sphingenine (sphingosine) and sphinganine were studied in sphingomyelins of transplantable mouse tumors (hepatoma-22, melanoma B16, Lewis lung carcinoma, intestine carcinoma) and rat nephroma RA. The content of sphinganine was increased in sphingomyelins of hepatoma-22 and nephroma RA compared to sphingomyelins of liver and kidneys. Significant contents of sphinganine were also found in sphingomyelins of other studied tumors. The content of sphinganine in regenerating mouse liver (30 h after hepatectomy) was normal. The data suggest that disorders should exist in biosynthesis of sphingoid bases in tumors but not in normal rapidly proliferating tissue.

[Gangliosides GM3 and GD3 in human stomach and breast tumors]. / Gangliozidy GM3 i GD3 v opukholiakh zheludka i molochnoi zhelezy cheloveka.

Gangliosides of human gastric and mammary tumours and of homologous normal tissues were studied by using biochemical methods and specific antisera. It was found that in most cases GM3, GD3 and GM1 are predominant gangliosides, whereas several polar components are minor ones. A comparison of the relative amount of ganglioside fractions revealed that in gastric tumours the per cent content of polar compounds is higher than in intact tissue; however, the absolute content of all gangliosides is markedly increased. A comparative study of the composition of mammary tumour and normal tissue gangliosides demonstrated two types of changes: i) the absolute content of all gangliosides in tumour tissue was increased and, ii) the increase in the content of total gangliosides was paralleled with the appearance of a new fraction (presumably GM4), the decrease of the GD3 content and the disappearance of polar gangliosides. A possible mechanism of this effect is discussed.

[Gangliosides from human placenta]. / Gangliozidy platsenty cheloveka.

Gangliosides of human placenta were studied, using biochemical methods and specific antibodies. The placenta was found to contain three types of gangliosides with oligosaccharide chains Lac, GgOse4 and nLcOse4.

Comparative study of lipid composition and proliferative activity of rat cholangiocarcinoma RS1 and sarcoma M1 depending on the transplantation organ.

The proliferative activity and lipid composition (phospholipids, gangliosides) were studied in rat cholangiocarcinoma RS1 and sarcoma M1 transplanted subcutaneously or intrahepatically. The mitotic index was higher in the tumors transplanted into the heterologous organ. The total phospholipid and sphingomyelin contents were higher in the tumors transplanted intrahepatically. GM3 and GD3 were the main gangliosides in both variants of each tumor. A significant amount of GM3 ganglioside lactone was found in the intrahepatic variants whereas it was absent in the subcutaneous tumors. Both the mitotic index and lipid composition of the tumors studied depended on their microenvironment.

[Ganglioside GD3 in the serum of tumor patients]. / Gangliozid GD3 v syvorotke krovi opukholenositelei.

Gangliosides of normal human blood serum and of blood serum of tumour hosts were studied. It has been shown the first time that ganglioside (NeuAc)2LacCer is present in the blood serum of different tumour hosts, but is absent in normal blood serum. The reasons for the appearance of this ganglioside in blood serum are discussed.

Sphingolipids of transplantable rat nephroma-RA.

Contents of sphingolipids (ceramide, sphingomyelin, gangliosides) and the composition of their sphingoid bases were studied in the transplantable rat nephroma-RA and in rat kidneys. The content of sphingomyelin was about 1.3-fold decreased and the content of ceramide was about 1.4-fold increased in the nephroma compared to normal kidneys, and this correlated with a 1.4-fold increased activity of neutral sphingomyelinase; however, the activity of the acidic isoform of the enzyme was virtually unchanged. The content of gangliosides was also increased in the nephroma. Ceramide and sphingomyelin of the nephroma, in addition to sphingosine, contained a significant amount of sphinganine, although a considerable amount of the latter was also found in the renal ceramide. The ratio sphingosine/sphinganine in sphingomyelins changed from 65:1 in kidneys to 5:1 in the nephroma. Thus, the biosynthesis of sphingoid bases seems to be disturbed in the transplantable rat nephroma-RA compared to normal kidneys.

Content and structure of ceramide and sphingomyelin and sphingomyelinase activity in mouse hepatoma-22.

The relative content of phosphatidylcholine is lower and that of sphingomyelin is higher in transplantable fast growing mouse hepatoma-22, thus decreasing their ratio approximately 2.5-fold versus normal liver. The ceramide content and the neutral sphingomyelinase activity is markedly higher (3- and 6.5-fold, respectively), whereas the acid sphingomyelinase activity is 4-fold lower in hepatoma-22 versus normal liver. The content of saturated fatty acids in ceramide and sphingomyelin of hepatoma-22 is higher than in normal liver. All sphingolipids of hepatoma-22 contain a considerable amount (25-37%) of sphinganine (dihydrosphingosine) along with sphingenine (sphingosine), whereas sphingolipids of normal liver contain predominantly sphingenine (over 95%). These results indicate that the activity of enzymes involved in sphingolipid biosynthesis and catabolism is disturbed in the transplantable mouse hepatoma-22 compared to normal liver.

Differences in lipid composition and proliferative activity of rat hepatoma-27 depending on the target organ.

Proliferative activity and lipid composition (phospholipids and gangliosides) were studied in rat hepatoma-27 transplanted subcutaneously or intrahepatically (as models for primary and metastasizing tumors). The mitotic index of subcutaneously transplanted hepatoma far exceeded that of the intrahepatically transplanted tumor. The overall amounts of both phospholipids and gangliosides increased appreciably in the subcutaneously growing hepatoma (in contrast to the intrahepatically growing tumor) in comparison to the control hepatic tissue. The ganglioside composition in the tumors differs from that in the liver: ganglioside GD3 appears, whereas gangliosides GD1b and GT1b decrease in amount in the intrahepatic tumor compared to the control liver and disappear in the subcutaneously transplanted hepatoma. In both tumor types, the amounts of both phosphatidylethanolamine and sphingomyelin exceed the control values. Comparison of these results with previously reported data concerning the phospholipid and ganglioside composition in the regenerating rat liver indicates that the difference in the lipid composition between the subcutaneously and intrahepatically growing hepatomas-27 is due to their different proliferative status and also their microenvironment.