The TNF superfamily death ligand TRAIL is emerging as a potential tool in the treatment of many cancers based on its ability to selectively kill cancer cells and repress tumor metastasis. Unfortunately, many tumor cell lines are resistant to TRAIL, suggesting the molecular basis of TRAIL action and how TRAIL-sensitivity can be restored is crucial for maximizing the potential of this promising cancer therapeutic. The long-term goal is to understand precisely how cancer cells become resistant to TRAIL therapy and how this knowledge can, in turn, lead to novel therapeutic interventions that restore TRAIL-sensitivity. The objective in this particular application is to determine how TRAIL kills cancer cells by switching the multifunctional sorting protein PACS-2 to an apoptotic effector and how dysregulation of PACS-2 enables cancers to resist TRAIL-induced cell death. Specifically, Akt-phosphorylated PACS-2 mediates homeostasis in healthy cells by coordinating the localization of antiapoptotic calcium channels to the endoplasmic reticulum (ER) with ER-mitochondria communication. In response to TRAIL, PACS-2 becomes dephosphorylated, promoting mitochondria permeabilization and cell death by coordinating apoptotic calcium signaling with lysosome-mitochondria communication that mediates Bid activation. The central hypothesis is that dysregulation of PACS-2 enables cancer cells to resist TRAIL killing in two different ways: in cancers with elevated Akt, PACS-2 apoptotic activity is repressed by persistent Akt phosphorylation, whereas in cancers with loss of the PACS-2 locus, TRAIL-induced apoptosis is repressed independent of Akt status. The rationale for the proposed research is that successful completion will establish a causal relationship between PACS-2 dysregulation and tumor progression and will determine how TRAIL switches PACS-2 to an apoptotic mediator that coordinates the complex interorganellar communication required for mitochondria permeabilization and cancer cell death. Guided by strong preliminary data, this hypothesis will be test- ed by pursuing three specific aims: 1) Determine to what extent loss or repression of PACS-2 accelerates tumor progression, 2) Identify the mechanism used by TRAIL to induce apoptotic activation of PACS-2 to mediate ER-mitochondria calcium signaling, and 3) Determine how TRAIL induces PACS-2 to coordinate lysosome membrane permeabilization with cathepsin B-mediated Bid cleavage on mitochondria. The approach is innovative because it uses a comprehensive, multi-disciplinary design to dissect the molecular basis of TRAIL action. The proposed research is significant because it presents a novel and testable model of how PACS-2 acts as a molecular switch to integrate cell homeostasis with TRAIL-induced apoptosis and, therefore, how PACS-2 dysregulation may accelerate tumor progression and cause resistance to TRAIL therapy.

Public Health Relevance

The proposed research is relevant to public health because understanding precisely how cancer cells become resistant to TRAIL therapy and how this knowledge can lead, in turn, to novel therapeutic interventions that restore TRAIL-sensitivity is crucial for maximizing the potential of this promising cancer therapeutic. Thus, the proposed research is relevant to the part of NIH's mission supporting fundamental research that will ultimately cure disease.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA151564-02
Application #
8236931
Study Section
Tumor Cell Biology Study Section (TCB)
Program Officer
Salnikow, Konstantin
Project Start
2011-03-04
Project End
2012-07-31
Budget Start
2012-03-01
Budget End
2012-07-31
Support Year
2
Fiscal Year
2012
Total Cost
$180,950
Indirect Cost
$63,450
Name
Oregon Health and Science University
Department
Neurosciences
Type
Schools of Medicine
DUNS #
096997515
City
Portland
State
OR
Country
United States
Zip Code
97239
Olson, Heather E; Jean-Marçais, Nolwenn; Yang, Edward et al. (2018) A Recurrent De Novo PACS2 Heterozygous Missense Variant Causes Neonatal-Onset Developmental Epileptic Encephalopathy, Facial Dysmorphism, and Cerebellar Dysgenesis. Am J Hum Genet 102:995-1007
Dombernowsky, Sarah L; Schwarz, Jeanette; Samsøe-Petersen, Jacob et al. (2017) Loss of PACS-2 delays regeneration in DSS-induced colitis but does not affect the ApcMin model of colorectal cancer. Oncotarget 8:108303-108315
Thomas, Gary; Aslan, Joseph E; Thomas, Laurel et al. (2017) Caught in the act - protein adaptation and the expanding roles of the PACS proteins in tissue homeostasis and disease. J Cell Sci 130:1865-1876
Barroso-González, J; Auclair, S; Luan, S et al. (2016) PACS-2 mediates the ATM and NF-?B-dependent induction of anti-apoptotic Bcl-xL in response to DNA damage. Cell Death Differ 23:1448-57
Barroso-González, Jonathan; Thomas, Gary (2015) Endosome traffic machinery meets the p53-p21 axis. Mol Cell Oncol 2:e975075
Dombernowsky, Sarah Louise; Samsøe-Petersen, Jacob; Petersen, Camilla Hansson et al. (2015) The sorting protein PACS-2 promotes ErbB signalling by regulating recycling of the metalloproteinase ADAM17. Nat Commun 6:7518
Atkins, Katelyn M; Thomas, Laura L; Barroso-González, Jonathan et al. (2014) The multifunctional sorting protein PACS-2 regulates SIRT1-mediated deacetylation of p53 to modulate p21-dependent cell-cycle arrest. Cell Rep 8:1545-57
Guicciardi, Maria Eugenia; Werneburg, Nathan W; Bronk, Steven F et al. (2014) Cellular inhibitor of apoptosis (cIAP)-mediated ubiquitination of phosphofurin acidic cluster sorting protein 2 (PACS-2) negatively regulates tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) cytotoxicity. PLoS One 9:e92124
Williamson, Danielle M; Elferich, Johannes; Ramakrishnan, Parvathy et al. (2013) The mechanism by which a propeptide-encoded pH sensor regulates spatiotemporal activation of furin. J Biol Chem 288:19154-65
Smithgall, Thomas E; Thomas, Gary (2013) Small molecule inhibitors of the HIV-1 virulence factor, Nef. Drug Discov Today Technol 10:e523-9

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