Sphingolipids of Transplantable Rat Nephroma-RA

A. G. Kandyba¹, O. G. Somova¹, A. M. Kozlov², E. S. Zubova³, L. B. Dudnik³, A. V. Alessenko³, V. I. Shvetz⁴, and E. V. Dyatlovitskaya^1*

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

²Institute of Experimental Diagnostics and Therapy of Tumors, Oncology Research Center, Russian Academy of Medical Sciences, Kashirskoe Shosse 24, Moscow, 115478 Russia

³Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, ul. Kosygina 4, Moscow, 117977 Russia

⁴Lomonosov State Academy of Fine Chemical Technology, pr. Vernadskogo 86, Moscow, 117571 Russia

^* To whom correspondence should be addressed.

Received September 8, 1999; Revision received October 18, 1999

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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.

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KEY WORDS: ganglioside, dihydrosphingosine, nephroma, sphingosine, sphingomyelin, sphingomyelinase, ceramide, kidneys, tumor

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