Cell density-dependent reduction of dihydroceramide desaturase activity in neuroblastoma cells

Journal of Lipid Research

Jacek Bielawski¹  Jacqueline M. Kraveka¹  Christopher J. Clarke²  Lina M. Obeid²  Stefka D. Spassieva³  Mehrdad Rahmaniyan⁴ 

[1] and;Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425;Department of Medicine, Medical University of South Carolina, Charleston, SC 29425;Department of Pediatrics Division of Hematology/Oncology, Medical University of South Carolina, Charleston, SC 29425;

关键词: sphingolipid;    dihydroceramide;    ceramide;    cell-cycle arrest;   

DOI  :  

来源: DOAJ

【 摘 要 】

We applied a metabolic approach to investigate the role of sphingolipids in cell density-induced growth arrest in neuroblastoma cells. Our data revealed that sphingolipid metabolism in neuroblastoma cells significantly differs depending on the cells’ population context. At high cell density, cells exhibited G0/G1 cell-cycle arrest and reduced ceramide, monohexosylceramide, and sphingomyelin, whereas dihydroceramide was significantly increased. In addition, our metabolic-labeling experiments showed that neuroblastoma cells at high cell density preferentially synthesized very long chain (VLC) sphingolipids and dramatically decreased synthesis of sphingosine-1-phosphate (S1P). Moreover, densely populated neuroblastoma cells showed increased message levels of both anabolic and catabolic enzymes of the sphingolipid pathway. Notably, our metabolic-labeling experiments indicated reduced dihydroceramide desaturase activity at confluence, which was confirmed by direct measurement of dihydroceramide desaturase activity in situ and in vitro. Importantly, we could reduce dihydroceramide desaturase activity in low-density cells by applying conditional media from high-density cells, as well as by adding reducing agents, such as DTT and l-cysteine to the media. In conclusion, our data suggest a role of the sphingolipid pathway, dihydroceramides desaturase in particular, in confluence-induced growth arrest in neuroblastoma cells.

【 授权许可】

Unknown