Elevation of de novo ceramide synthesis in tumor masses and the role of microsomal dihydroceramide synthase
| Autor: | Yoshiko Hosoda, Shiroshi Shibuya, Shinji Soeda, Hiroshi Shimeno, Satoru Koyanagi, Takeshi Akiyama, Tsutomu Yokomatsu, Hiroaki Takechi, Minoru Kuga |
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| Rok vydání: | 2003 |
| Předmět: |
Male
Cancer Research Ceramide Melanoma Experimental Organophosphonates Apoptosis Biology Ceramides Fumonisins Catalysis Gene Expression Regulation Enzymologic Malignant transformation chemistry.chemical_compound Mice Microsomes Tumor Cells Cultured Animals Enzyme Inhibitors chemistry.chemical_classification Mice Inbred ICR ATP synthase Molecular mass Dose-Response Relationship Drug Liver Neoplasms Lewis lung carcinoma Amides Mice Inbred C57BL Kinetics Enzyme Oncology Biochemistry chemistry Liver Microsome biology.protein Chromatography Gel Microsomes Liver Cattle Sphingomyelin Oxidoreductases |
| Zdroj: | International journal of cancer. 105(1) |
| ISSN: | 0020-7136 |
| Popis: | Ceramide is formed through sphingomyelin hydrolysis or de novo synthesis and may play a key role in cell growth, differentiation and apoptosis. To clarify which pathway tumor cells use to form ceramide and how its formation is regulated, we determined the levels of dihydroceramide and ceramide in mice inoculated with Sarcoma 180, B16 melanoma or Lewis lung carcinoma cells. The levels in these tumor masses were very high compared to those in other healthy tissues. The high levels were significantly reduced by a single administration of the dihydroceramide synthase inhibitor fumonisin B(1), but not by a sphingomyelinase inhibitor, sphingomyelin analog-1 (SMA-1), suggesting that the tumor cells have a very effective means of synthesizing dihydroceramide and ceramide. To investigate the characteristics of dihydroceramide synthase, we prepared microsomes from Sarcoma 180 tumor masses and healthy mouse liver cells, and compared their catalytic activities on dihydroceramide formation. A kinetic analysis using sphinganine and palmitoyl CoA as substrates revealed that the enzyme present in the tumor formed dihydroceramide 3 times more efficiently than that in healthy liver cells. Partial purification of dihydroceramide synthase from bovine liver microsomes revealed that the enzyme was present in healthy tissues as a 333 kDa form constructed of 47 kDa subunit proteins. However, gel filtration of the enzyme solubilized from the Sarcoma 180 tumor masses demonstrated that its molecular weight was 1300 kDa. These results suggest that malignant transformation causes the cell to produce a form of dihydroceramide synthase with a larger than normal molecular mass; the increased molecular mass may account for the enzyme's increased catalytic efficiency. |
| Databáze: | OpenAIRE |
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