Sphingosine-1-phosphate (S1P) mediates pleiotropic cellular responses such as cell proliferation, survival (anti-apoptosis), and motility. It has also been implicated in cardiovascular development, angiogenesis, inflammation, and tumorigenicity. S1P acts as a specific ligand for G-protein coupled receptors or an intracellular signaling molecule. It is now clear that S1P is only generated from sphingosine, which is in turn essentially derived from ceramide through the action of ceramidases. However, much remains unknown about the regulation of the levels of this important signaling molecule. The Pl's compelling preliminary data suggest that haCER2, one of three distinct human alkaline ceramidases that the PI recently cloned, has an important role in regulating the levels of S1P by controlling hydrolysis of ceramides, a rate-limiting step for the formation of S1P, and importantly, haCER2 is capable of regulating S1P-mediated tumor cell survival, angiogenesis, and tumor growth. The PI's long-term goals are to define the role of haCER2 in regulating the levels of S1P and S1P-mediated tumor growth and angiogenesis and to develop this concept into novel strategies for anti-cancer therapeutics. The Pl's central hypothesis is that haCER2 regulates the levels of S1P and S1P-mediated biological processes, particularly tumor angiogenesis and growth, which will be tested by the following specific aims.
Aim 1 is to understand catalytic mechanisms of haCER2, haCER2 will be expressed in the yeast system, purified, reconstituted, and characterized biochemically.
Aim 2 is to test the hypothesis that haCER2 regulates the generation of S1P in response to proangiogenic cytokines and growth factors, haCER2 regulation by these agonists will be studied in HeLa tumor cells and human umbilical vein endothelial cells by expression and activity studies, haCER2 promoter will be characterized and cis-acting elements responsive to cytokines, and growth factors will be identified.
Aim 3 is to test the hypothesis that haCER2 has a role in regulating tumor growth and angiogenesis in vivo. Tumor cell lines that express the wild type, up-regulated, or down-regulated level of haCER2 will be established to define the roles of haCER2 in tumor angiogenesis and growth using Matrigel implant assay and tumor xenograft mouse models. These studies will firmly establish a role for haCER2 in regulating S1P and S1P-mediated biology and will pave the way for novel therapeutic approaches to cancer. ? ?

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA104834-05
Application #
7392691
Study Section
Cell Development and Function Integrated Review Group (CDF)
Program Officer
Ault, Grace S
Project Start
2004-07-01
Project End
2010-04-30
Budget Start
2008-05-01
Budget End
2010-04-30
Support Year
5
Fiscal Year
2008
Total Cost
$218,035
Indirect Cost
Name
Medical University of South Carolina
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
183710748
City
Charleston
State
SC
Country
United States
Zip Code
29425
Xu, Ruijuan; Garcia-Barros, Monica; Wen, Sally et al. (2018) Tumor suppressor p53 links ceramide metabolism to DNA damage response through alkaline ceramidase 2. Cell Death Differ 25:841-856
Lin, Chih-Li; Xu, Ruijuan; Yi, Jae Kyo et al. (2017) Alkaline Ceramidase 1 Protects Mice from Premature Hair Loss by Maintaining the Homeostasis of Hair Follicle Stem Cells. Stem Cell Reports 9:1488-1500
Wang, K; Xu, R; Snider, A J et al. (2016) Alkaline ceramidase 3 deficiency aggravates colitis and colitis-associated tumorigenesis in mice by hyperactivating the innate immune system. Cell Death Dis 7:e2124
Xu, Ruijuan; Wang, Kai; Mileva, Izolda et al. (2016) Alkaline ceramidase 2 and its bioactive product sphingosine are novel regulators of the DNA damage response. Oncotarget 7:18440-57
Yi, Jae Kyo; Xu, Ruijuan; Jeong, Eunmi et al. (2016) Aging-related elevation of sphingoid bases shortens yeast chronological life span by compromising mitochondrial function. Oncotarget 7:21124-44
Zhu, Congyi; Wang, Weili; Wang, Mingshuang et al. (2015) Deletion of PdMit1, a homolog of yeast Csg1, affects growth and Ca(2+) sensitivity of the fungus Penicillium digitatum, but does not alter virulence. Res Microbiol 166:143-52
Wang, Kai; Xu, Ruijuan; Schrandt, Jennifer et al. (2015) Alkaline Ceramidase 3 Deficiency Results in Purkinje Cell Degeneration and Cerebellar Ataxia Due to Dyshomeostasis of Sphingolipids in the Brain. PLoS Genet 11:e1005591
Zhou, Ying; Lin, Xian-Wen; Yang, Qiong et al. (2011) Molecular cloning and characterization of neutral ceramidase homologue from the red flour beetle, Tribolium castaneum. Biochimie 93:1124-31
Yang, Qiong; Gong, Zhong-Jun; Zhou, Ying et al. (2010) Role of Drosophila alkaline ceramidase (Dacer) in Drosophila development and longevity. Cell Mol Life Sci 67:1477-90
Sun, Wei; Jin, Junfei; Xu, Ruijuan et al. (2010) Substrate specificity, membrane topology, and activity regulation of human alkaline ceramidase 2 (ACER2). J Biol Chem 285:8995-9007

Showing the most recent 10 out of 19 publications