In the genetic analysis of human cancer, focal gene copy number variation (CNV) and point mutations provide exquisite information on candidate driver genes by pinpointing their exact location. Recently, we conducted a large-scale analysis in which we integrated somatic point mutations and focal CNV information in a single framework to nominate new driver genes implicated in glioblastoma multiforme (GBM), one of the most aggressive types of human cancer. The top-ranking gene that emerged from this analysis is LZTR1, which codes for the substrate adaptor of a Cullin-3 (Cul3) ubiquitin ligase complex for which the substrates still await discovery. In GBM, LZTR1 is targeted by loss-of-function mutations and focal deletions, thus behaving as a new tumor suppressor gene, a notion recently confirmed in other tumors. From a mechanistic standpoint, we have discovered the unexpected capacity of LZTR1 to impair self-renewal and growth of the most aggressive cellular subpopulation in human GBM, the glioma stem cells (GSCs). The central objective of this proposal is to identify and functionally characterize the substrates of the LZTR1 ubiquitin ligase complex and decipher how mechanistically LZTR1 operates to prevent tumor development in normal neural cells. Our overarching hypothesis is that the LZTR1-Cul3 protein complex suppresses tumor growth through the regulated proteolysis of a particular set of substrates. Our preliminary data have already identified and validated a set of proteins with recognized mitochondrial activities as new LZTR1 substrates. Together with our recent observation that LZTR1 localizes at mitochondria, these results are exciting new findings that link alterations of LZTR1 to deregulation of mitochondrial functions in cancer.
In Aim 1, the LZTR1 substrates will be comprehensively identified from a novel mass spectrometry-based technology that has already successfully recognized exciting, new substrate candidates of LZTR1. The functional validation of the substrates will be pursued in highly relevant cellular models directly generated from primary human GBM and will be related to the landscape of mutations of LZTR1 discovered in human cancer.
In Aim 2, we will determine the normal activity of LZTR1 in the brain and model human GBM harboring inactivating mutations of LZTR1 in a new genetic mouse model in which the LZTR1 gene is conditionally knocked out in the nervous system. We will also use the Sleeping Beauty insertional mutagenesis system to identify the genetic alterations that cooperate with loss of LZTR1 for brain tumorigenesis.

Public Health Relevance

Ubiquitin ligases play critical roles in normal biology and pathogenesis by targeting broad substrate networks for degradation. This proposal is focused on LZTR1, which has emerged from our recent work as a new ubiquitin ligase endowed with potent tumor suppressor activity in malignant brain tumors. The expected overall impact of this innovative grant application is that it will fundamentally advance our mechanistic understanding of the LZTR1 ubiquitin ligase in normal brain and brain tumors and lay the foundation for the optimization of new therapeutic strategies precipitated by the discovery of LZTR1 mutations in human cancer.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA190891-04
Application #
9477584
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Espey, Michael G
Project Start
2015-05-15
Project End
2020-04-30
Budget Start
2018-05-01
Budget End
2019-04-30
Support Year
4
Fiscal Year
2018
Total Cost
Indirect Cost
Name
Columbia University (N.Y.)
Department
Neurology
Type
Schools of Medicine
DUNS #
621889815
City
New York
State
NY
Country
United States
Zip Code
10032
Frattini, VĂ©ronique; Pagnotta, Stefano M; Tala et al. (2018) A metabolic function of FGFR3-TACC3 gene fusions in cancer. Nature 553:222-227
Puchalski, Ralph B; Shah, Nameeta; Miller, Jeremy et al. (2018) An anatomic transcriptional atlas of human glioblastoma. Science 360:660-663
Lee, Sang Bae; Frattini, Veronique; Bansal, Mukesh et al. (2016) An ID2-dependent mechanism for VHL inactivation in cancer. Nature 529:172-7
Di Stefano, Anna Luisa; Fucci, Alessandra; Frattini, Veronique et al. (2015) Detection, Characterization, and Inhibition of FGFR-TACC Fusions in IDH Wild-type Glioma. Clin Cancer Res 21:3307-17
Frattini, Veronique; Trifonov, Vladimir; Chan, Joseph Minhow et al. (2013) The integrated landscape of driver genomic alterations in glioblastoma. Nat Genet 45:1141-9
Danussi, Carla; Akavia, Uri David; Niola, Francesco et al. (2013) RHPN2 drives mesenchymal transformation in malignant glioma by triggering RhoA activation. Cancer Res 73:5140-50
Singh, Devendra; Chan, Joseph Minhow; Zoppoli, Pietro et al. (2012) Transforming fusions of FGFR and TACC genes in human glioblastoma. Science 337:1231-5
Sumazin, Pavel; Yang, Xuerui; Chiu, Hua-Sheng et al. (2011) An extensive microRNA-mediated network of RNA-RNA interactions regulates established oncogenic pathways in glioblastoma. Cell 147:370-81
Coma, Silvia; Amin, Dhara N; Shimizu, Akio et al. (2010) Id2 promotes tumor cell migration and invasion through transcriptional repression of semaphorin 3F. Cancer Res 70:3823-32
Carro, Maria Stella; Lim, Wei Keat; Alvarez, Mariano Javier et al. (2010) The transcriptional network for mesenchymal transformation of brain tumours. Nature 463:318-25