Content and Structure of Ceramide and Sphingomyelin and Sphingomyelinase Activity in Mouse Hepatoma-22

S. N. Rylova¹, O. G. Somova¹, E. S. Zubova², L. B. Dudnik², L. S. Kogtev¹, A. M. Kozlov³, A. V. Alesenko², and E. V. Dyatlovitskaya^1*

¹Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, Moscow, GSP-7, 117871 Russia; fax: (095) 335-7103; E-mail: dyatl@ibch.siobc.ras.ru

²Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, ul. Kosygina 4, Moscow, 117977 Russia

³Institute of Experimental Diagnostics and Therapy of Tumors, Oncology Research Center, Russian Academy of Medical Sciences, Kashirskoe Shosse 24, Moscow, 115478 Russia

^* To whom correspondence should be addressed.

Received July 2, 1998; Revision received October 27, 1998

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The relative content of phosphatidylcholine is lower and that of sphingomyelin is higher in transplantable fast growing mouse hepatoma-22, thus decreasing their ratio ~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.

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KEY WORDS: ganglioside, dihydrosphingosine, fatty acids, sphingosine, sphingomyelin, sphingomyelinase, ceramide, liver, tumor

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