One of the most common features that distinguishes cancer cells from normal cells is the presence of aneuploidy. We have recently discovered a cause of aneuploidy in a substantial fraction of malignant human tumors - deletions, somatic mutations, and loss of expression of the STAG2 gene (Science 336:1039-1043, 2011). The encoded STAG2 protein is a key component of the multi-protein cohesin complex which regulates sister chromatid cohesion and helps ensure faithful chromosome segregation during mitosis. In this grant we propose a multi-faceted effort to further define the mechanism through which STAG2 inactivation leads to chromosomal instability, aneuploidy, and cancer.
In Aim #1 we will evaluate the effects of tumor-derived mutations in STAG2 on sister chromatid cohesion and protein-protein interactions. The goal is to functionally evaluate mutations in STAG2 to reveal the key activities of STAG2 that are lost during tumorigenesis.
In Aim #2 we will determine the effect of STAG2 truncating mutations on the protein composition of cohesin and its ability to interact with chromatin at different phases of the cell cycle. These experiments wil enable us to identify key mechanisms by which STAG2 inactivation leads to chromosomal instability and aneuploidy.
In Aim #3 we will determine the role of STAG2 inactivation on the initiation and maintenance of transformation in human astrocytes and GBM cells. These experiments will enable us to determine if STAG2 inactivation results in enhanced susceptibility to malignant transformation.
In Aim #4 we will determine if mutations in STAG2 cause GBM cells to be sensitized to ionizing radiation and DNA damaging chemotherapeutic drugs. The broad goal of the proposed research program is to determine the mechanism through which STAG2 inactivation leads to chromosomal instability, aneuploidy, and cellular transformation, making it possible to develop strategies for identifying novel anticancer therapeutics that specifically target aneuploid cells.

Public Health Relevance

Aneuploidy, defined as an abnormal number of chromosomes, is present in >90% of human tumors. When referring to cancer cells, the term aneuploidy is also used to denote the presence of structurally abnormal chromosomes and chromosome fragments. We have recently discovered a cause of aneuploidy in a substantial fraction of human cancers - inactivating mutations of the STAG2 gene. In this application we propose to determine the mechanism(s) by which STAG2 inactivation contributes to aneuploidy and cancer pathogenesis. Defining the molecular basis of aneuploidy in human cancer will make it possible to develop strategies for the identification of novel anticancer therapeutics that specifically kill aneuploid cancer cells, but which spare the patient's normal tissues.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
1R01CA169345-01A1
Application #
8501829
Study Section
Cancer Genetics Study Section (CG)
Program Officer
Mietz, Judy
Project Start
2013-03-07
Project End
2018-02-28
Budget Start
2013-03-07
Budget End
2014-02-28
Support Year
1
Fiscal Year
2013
Total Cost
$322,317
Indirect Cost
$114,817
Name
Georgetown University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
049515844
City
Washington
State
DC
Country
United States
Zip Code
20057
Bailey, Melanie L; O'Neil, Nigel J; van Pel, Derek M et al. (2014) Glioblastoma cells containing mutations in the cohesin component STAG2 are sensitive to PARP inhibition. Mol Cancer Ther 13:724-32
Solomon, David A; Kim, Jung-Sik; Waldman, Todd (2014) Cohesin gene mutations in tumorigenesis: from discovery to clinical significance. BMB Rep 47:299-310
Solomon, David A; Kim, Jung-Sik; Bondaruk, Jolanta et al. (2013) Frequent truncating mutations of STAG2 in bladder cancer. Nat Genet 45:1428-30