These findings may help researchers develop cancer therapies that target one enzyme, while leaving the other alone.

In the November issue of the Journal of Biological Chemistry, Sarah Spiegel, Ph.D., professor and chair in the Department of Biochemistry at the VCU School of Medicine and co-leader of the Massey Cancer Center Cell Signaling program, and researchers in her lab showed that sphingosine kinases called SphK1 and SphK2, a family of enzymes that forms the potent lipid mediator sphingosine-1-phosphate (S1P), have opposing roles in the regulation of ceramide biosynthesis. S1P is a molecule that has been shown to promote tumor cell growth and inhibit cell death.

They found that the different effects of SphK1 and SphK2 may arise because they act at different locations within the cell. In addition, the data suggest that SphK2 can sensitize cancer cells to chemotherapy, and therefore may be a potential target for cancer therapy.

"In this study, we found that it is not what the reaction produces, but where it occurs that determines the ultimate effects," said lead author Michael Maceyka, Ph.D., a Massey Cancer Center trainee in the Department of Biochemistry at VCU.

"Understanding that SphK1 and SphK2 have opposite effects on cell growth may be helpful in creating more effective chemotherapeutic agents designed to target a specific sphingosine kinase without acting on the other."

Maceyka and the Spiegel group showed that SphK1 decreased levels of the sphingolipid known as ceramide, while SphK2 increased these levels. According to Maceyka many chemotherapy agents increase the level of ceramide in a cell, which is necessary in order for the agent to kill tumor cells. Sphingolipids are essen
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Contact: Sathya Achia-Abraham
sbachia@vcu.edu
804-827-0890
Virginia Commonwealth University
4-Nov-2005