Our long-term goal is to define the mechanisms by which anti-cancer chemotherapeutic agents (ACCAs) induce anti-proliferative responses (proliferation inhibition and programmed cell death) in tumor cells by focusing on human alkaline ceramidase 2 (ACER2) and its lipid substrate (ceramide) and product (sphingosine). Many ACCAs induce the generation of the bioactive sphingolipid ceramide in tumor cells, and blocking ceramide generation inhibits anti-proliferative effects of the drugs, suggesting that ceramide is an important mediator of ACCAs in this anti-proliferative response. Ceramide can be hydrolyzed into sphingosine by ceramidases in human cells and, like ceramide, SPH can potently induce anti-proliferative effects in tumor cells both in vitro and in animal models. Increasing expression of neutral ceramidase ASAH2 on the plasma membrane also attenuates cell apoptosis induced by TNF-1, a known ceramide-generating cytokine. In contrast, our preliminary studies show that increasing the conversion of ceramide to SPH by the Golgi alkaline ceramidase 2 (ACER2) markedly enhances the cytotoxicity of doxorubicin, a known ceramide-inducing ACCA, in HeLa cells, whereas knocking down ACER2 has the opposite effect. This exciting finding led us to the hypotheses that ACCAs exert anti-proliferative responses in cancer cells through the ceramide/ACER2/SPH pathway and that activation of this pathway will augment chemotherapy action in cancer treatment. To test this hypothesis, we will establish that the ceramide/ACER2/SPH pathway is an important mediator of the anti- proliferative responses of ACCAs in cancer cells by determining 1) if ACCAs induce the anti-proliferative responses in cancer cells by activating the ceramide/ACER2/SPH pathway;2) if ACER2-inducing agents enhance whereas ACER2-inhibiting agents attenuate the ACCA-induced anti-proliferative effects in cancer cells (Aim 1).
In Aim 2, we will test the hypothesis that its Golgi localization is required for ACER2 to mediate the ACCA-induced anti-proliferative responses in cancer cells by investigating 1) if targeting ACER2 to the endoplasmic reticulum (ER) abolishes its ability to mediate the ACCA-induced anti-proliferative effects in tumor cells;and 2) if targeting ASAH2 to the Golgi complex confers the ability to mediate ACCA-induced anti- proliferative effects in tumor cells.
For Aim 3, we will test the hypothesis that the activation of the ACER2/SPH pathway enhances anti-proliferative responses of ACCAs in tumor cells through Golgi fragmentation. We will determine 1) if ACCAs induces Golgi fragmentation by activating the ceramide/ACER2/SPH pathway;2) if SPH induces Golgi fragmentation and inhibits Golgi reassembly in vitro;3) if activating the ceramide/ACER2/SPH inhibits Golgi assembly by inhibiting the stacking function of GRASP65 (Golgi reassembly stacking protein of 65 kD) and GRASP55;and 4) if activation of the ceramide/ACER2/SPH pathway induces mitotic arrest and apoptosis through Golgi fragmentation. These studies will provide insights into the role and mechanism of action of ACER2 and its product SPH in mediating anti-proliferative responses in cancer cells.

Public Health Relevance

Approximately 1500 people die each day in the United States due to cancer. Therefore, better strategies for cancer treatment are necessary. PI's group and others have demonstrated that a group of lipids called sphingolipids, especially, ceramide and sphingosine (SPH), which are found in human cells, can potently kill tumor cells. The PI's group has identified a human enzyme called alkaline ceramidase 2 (ACER2) responsible for the generation of SPH from ceramide in tumor cells. The PI's group finds that increasing ACER2 expression substantially augments the efficacy of doxorubicin, a ceramide-inducing chemotherapeutic agent, in killing cancer cells by increasing the generation of SPH cancer cells. The PI's group is investigating whether and how increasing ACER2 expression also enhances the efficacy of other chemotherapeutic agents against cancer cells. Based on this study, the PI hopes to develop novel approaches for cancer treatment.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
1R01CA163825-01
Application #
8221194
Study Section
Basic Mechanisms of Cancer Therapeutics Study Section (BMCT)
Program Officer
Yassin, Rihab R,
Project Start
2012-07-13
Project End
2017-04-30
Budget Start
2012-07-13
Budget End
2013-04-30
Support Year
1
Fiscal Year
2012
Total Cost
$325,775
Indirect Cost
$118,275
Name
State University New York Stony Brook
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
804878247
City
Stony Brook
State
NY
Country
United States
Zip Code
11794
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
Li, Fang; Xu, Ruijuan; Low, Benjamin E et al. (2018) Alkaline ceramidase 2 is essential for the homeostasis of plasma sphingoid bases and their phosphates. FASEB J 32:3058-3069
Zhou, Y; Lin, X-W; Begum, M-A et al. (2017) Identification and characterization of Laodelphax striatellus (Insecta: Hemiptera: Delphacidae) neutral sphingomyelinase. Insect Mol Biol 26:392-402
Coant, Nicolas; Sakamoto, Wataru; Mao, Cungui et al. (2017) Ceramidases, roles in sphingolipid metabolism and in health and disease. Adv Biol Regul 63:122-131
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
Janecke, Andreas R; Xu, Ruijuan; Steichen-Gersdorf, Elisabeth et al. (2017) Deficiency of the sphingosine-1-phosphate lyase SGPL1 is associated with congenital nephrotic syndrome and congenital adrenal calcifications. Hum Mutat 38:365-372
Begum, Mahfuj A; Shi, Xiao-Xiao; Tan, Ye et al. (2016) Molecular Characterization of Rice OsLCB2a1 Gene and Functional Analysis of its Role in Insect Resistance. Front Plant Sci 7:1789
Edvardson, Simon; Yi, Jae Kyo; Jalas, Chaim et al. (2016) Deficiency of the alkaline ceramidase ACER3 manifests in early childhood by progressive leukodystrophy. J Med Genet 53:389-96
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

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