Expression of the X-linked inhibitor of apoptosis (XIAP) is greatly enhanced in many classes of malignancy, and strategies to suppress XIAP function are showing great promise in the treatment of cancer. Although XIAP is principally thought to function as a suppressor of the apoptotic cell death pathway through the direct inhibition of caspases, our data have revealed a number of additional properties of XIAP. These activities implicate XIAP as playing a role in signal transduction pathways that are independent of its caspase inhibitory properties, and actually suggest that in vivo the caspase suppressive activity of XIAP may be a relatively minor function. These findings raise several important questions: are the caspase inhibitory activities of XIAP necessary and sufficient to support tumor development? Does XIAP suppress cell death by a mechanism independent of its caspase inhibitory functions? Or does XIAP support oncogenesis through a signaling pathway that is unrelated to apoptosis? To further understand these pathways, we have identified and begun to characterize a set of novel XIAP associated proteins, and the goals of this project are to understand the role of XIAP, as well as these new interacting proteins, in supporting oncogenesis.
In Aim 1 we take a mutagenesis approach to ask: which domains within XIAP are involved in caspase-independent signaling and interaction with our newly identified associated proteins? In Aim 2 we will address the question: what are the functional consequences of the interactions between XIAP and validated associated proteins? Finally, we will use the information contained in the first two Aims to ask the crucial question: in vivo how does XIAP support oncogenesis? This work will have profound implications for the development of strategies targeting XIAP for the treatment of tumors, because it will establish whether such strategies should address the caspase-inhibitory properties of the molecule or other aspects of its physiological functions. Finally, the studies will allow us to address whether our newly described XIAP-interacting proteins, including AIF, represent novel targets for the future design of therapies for the treatment of cancer.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
3R01GM067827-05S1
Application #
7917092
Study Section
Cancer Molecular Pathobiology Study Section (CAMP)
Program Officer
Zatz, Marion M
Project Start
2009-09-18
Project End
2011-03-31
Budget Start
2009-09-18
Budget End
2011-03-31
Support Year
5
Fiscal Year
2009
Total Cost
$67,594
Indirect Cost
Name
University of Michigan Ann Arbor
Department
Pathology
Type
Schools of Medicine
DUNS #
073133571
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
Fernau, Niklas S; Fugmann, Dominik; Leyendecker, Martin et al. (2010) Role of HuR and p38MAPK in ultraviolet B-induced post-transcriptional regulation of COX-2 expression in the human keratinocyte cell line HaCaT. J Biol Chem 285:3896-904
Galbán, S; Duckett, C S (2010) XIAP as a ubiquitin ligase in cellular signaling. Cell Death Differ 17:54-60
Brady, Graham F; Galbán, Stefanie; Liu, Xuwen et al. (2010) Regulation of the copper chaperone CCS by XIAP-mediated ubiquitination. Mol Cell Biol 30:1923-36
Brady, Graham F; Duckett, Colin S (2009) A caspase homolog keeps CED-3 in check. Trends Biochem Sci 34:104-7
Choi, Young Eun; Butterworth, Michael; Malladi, Srinivas et al. (2009) The E3 ubiquitin ligase cIAP1 binds and ubiquitinates caspase-3 and -7 via unique mechanisms at distinct steps in their processing. J Biol Chem 284:12772-82
Galbán, Stefanie; Hwang, Clara; Rumble, Julie M et al. (2009) Cytoprotective effects of IAPs revealed by a small molecule antagonist. Biochem J 417:765-71
Rumble, Julie M; Oetjen, Karolyn A; Stein, Paul L et al. (2009) Phenotypic differences between mice deficient in XIAP and SAP, two factors targeted in X-linked lymphoproliferative syndrome (XLP). Cell Immunol 259:82-9
Wright, Casey W; Duckett, Colin S (2009) The aryl hydrocarbon nuclear translocator alters CD30-mediated NF-kappaB-dependent transcription. Science 323:251-5
Csomos, Rebecca A; Wright, Casey W; Galbán, Stefanie et al. (2009) Two distinct signalling cascades target the NF-kappaB regulatory factor c-IAP1 for degradation. Biochem J 420:83-91
Csomos, Rebecca A; Brady, Graham F; Duckett, Colin S (2009) Enhanced cytoprotective effects of the inhibitor of apoptosis protein cellular IAP1 through stabilization with TRAF2. J Biol Chem 284:20531-9

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