TRAIL is a candidate for cancer therapy that selectively induces apoptosis in transformed/tumor cells but not in normal cells. However, the mechanism for the tumor selectivity of TRAIL-induced apoptosis is poorly understood. FLICE Inhibitory Protein (c-FLIP) is a regulator of programmed cell death. Recently, we have demonstrated that full-length c-FLIPL interacts with one of the TRAIL receptors (DR5) in the absence of ligand to prevent apoptosis. Upon induction of apoptosis by TRAIL, the major c-FLIP variants at the TRAIL DISC (Death Inducing Signaling Complex) are c-FLIPp43 (product of caspase cleavage) and c-FLIPs. Our studies further indicate that elimination of c-FLIPL by proteolytic cleavage is an early step in TRAIL-induced apoptosis and that c-FLIPL, c-FLIPs and c-FLIPp43 have distinct roles in mediating TRAIL function. In support of this hypothesis, we have observed that c-FLIPL, but not c-FLIPp43, promotes activation of the c-Akt survival pathway. The overall goal of this application is to elucidate the molecular mechanisms by which the c-FLIP variants regulate TRAIL-induced apoptosis and the distinct roles of the c-FLIP variants in the tumor selectivity of TRAIL-induced apoptosis in vitro and in an in vivo model for Bcr-Abl-induced chronic myeloid leukemia.
In Aim 1, we will determine the specific functions of the c-FLIP variants and the role of caspase cleavage of c-FLIPL in TRAIL-induced apoptosis. This will be achieved in vitro by using c-FLIP (-/-) embryonic fibroblasts that stably express each of the c-FLIP variants, and by siRNAs that specifically target the c-FLIP variants. Furthermore, we will determine the molecular mechanism by which the c-FLIP variants regulate TRAIL-induced apoptosis by characterizing the distinct signaling complexes that they regulate.
In Aim 2, we will delineate the novel role of the c-Akt survival pathway in mediating the anti-apoptotic activity of c-FLIP. We will also investigate the molecular mechanism by which c-FLIP induces Akt activation.
In Aim 3, we will determine the specific roles of the c-FLIP variants in mediating selective tumor death by TRAIL and their utilization as a predictive marker for TRAIL-therapy. These studies will be performed in vitro using Bcr-Abl transformed cells and in an in vivo model for Bcr-Abl-induced leukemia.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL080192-04
Application #
7333222
Study Section
Drug Discovery and Molecular Pharmacology Study Section (DMP)
Program Officer
Thomas, John
Project Start
2004-12-01
Project End
2009-11-30
Budget Start
2007-12-01
Budget End
2008-11-30
Support Year
4
Fiscal Year
2008
Total Cost
$393,508
Indirect Cost
Name
Beth Israel Deaconess Medical Center
Department
Type
DUNS #
071723621
City
Boston
State
MA
Country
United States
Zip Code
02215
Bhasin, Manoj K; Ndebele, Kenneth; Bucur, Octavian et al. (2016) Meta-analysis of transcriptome data identifies a novel 5-gene pancreatic adenocarcinoma classifier. Oncotarget 7:23263-81
Bucur, Octavian; Gaidos, Gabriel; Yatawara, Achani et al. (2015) A novel caspase 8 selective small molecule potentiates TRAIL-induced cell death. Sci Rep 5:9893
Bucur, Octavian; Stancu, Andreea Lucia; Muraru, Maria Sinziana et al. (2014) PLK1 is a binding partner and a negative regulator of FOXO3 tumor suppressor. Discoveries (Craiova) 2:
Pennarun, B; Gaidos, G; Bucur, O et al. (2013) killerFLIP: a novel lytic peptide specifically inducing cancer cell death. Cell Death Dis 4:e894
Bucur, Octavian; Stancu, Andreea Lucia; Goganau, Ioana et al. (2013) Combination of bortezomib and mitotic inhibitors down-modulate Bcr-Abl and efficiently eliminates tyrosine-kinase inhibitor sensitive and resistant Bcr-Abl-positive leukemic cells. PLoS One 8:e77390
Bucur, Octavian; Pennarun, Bodvael; Stancu, Andreea Lucia et al. (2013) Poor antibody validation is a challenge in biomedical research: a case study for detection of c-FLIP. Apoptosis 18:1154-62
Bucur, O; Stancu, A L; Khosravi-Far, R et al. (2012) Analysis of apoptosis methods recently used in Cancer Research and Cell Death & Disease publications. Cell Death Dis 3:e263
Singh, Amrik; Plati, Jessica; Khosravi-Far, Roya (2011) Harnessing the tumor suppressor function of FOXO as an alternative therapeutic approach in cancer. Curr Drug Targets 12:1311-21
Plati, Jessica; Bucur, Octavian; Khosravi-Far, Roya (2011) Apoptotic cell signaling in cancer progression and therapy. Integr Biol (Camb) 3:279-96
Degli Esposti, Mauro; Tour, Julien; Ouasti, Sihem et al. (2009) Fas death receptor enhances endocytic membrane traffic converging into the Golgi region. Mol Biol Cell 20:600-15

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