Chemoresistance is a major problem in cancer therapy, but it is largely unclear how cancer cells become resistant. Deficiency in the mismatch-repair (MMR) proteins allows cells to resist toxic chemotherapeutic agents such as DNA methylators. However, the distinct MMR function that sensitizes cells to DNA methylation is not clearly defined given the multiple MMR functions. MMR proteins function to repair base mismatches after DNA replication, inhibit recombination between non-identical DNA sequences, as well as activate both checkpoint and apoptotic responses following DNA damage. Separation-of- function mutants, suggest that resistance to DNA methylation is dependent on a disrupted checkpoint. Recently, we established that both MMR proteins of the MutL1 complex (MLH1/PMS2) and BACH1/FANCJ (BRCA1-associated C- terminal helicase/Fanconi Anemia complementation group J) are required for checkpoint signaling. Specifically, we identified that BACH1 binds directly to MLH1 and that a mutant version of BACH1 ablated for MLH1 binding failed to elicit an interstrand crosslink (ICL)-induced checkpoint response. Since ICLs activate the intra S-phase checkpoint, and both MLH1 and BACH1 have been shown independently to function in the intra S-phase checkpoint, this checkpoint likely requires the formation of a BACH1/MutL1 complex. We will test this possibility directly. In addition, we will determine whether BACH1 also participates in the DNA-methylation-induced G2/M accumulation checkpoint similar to MutL1. Consistent with a role for BACH1 in the DNA methylation-induced response, our lab has shown that similar to MutL1 deficient cells, BACH1 deficient cells are resistant to DNA methylation. In contrast, BRCA1 deficient cells are sensitive to DNA methylation, suggesting that BACH1 uniquely functions in the DNA methylati1n response. We propose to dissect the role of a BACH1/MutL1 complex in both checkpoint and repair functions. We will determine whether the formation of an intact complex is required to restore chemosensitivity to resistant null BACH1 or MutL1 cells. Defining the function of the BACH1/MutL1 complex ideally will provide insight towards restoring chemosensitivity to cancer cells. Along these lines, we will test whether manipulation of the recombination function of the BACH1/BRCA1 complex will uniquely sensitizes MMR deficient cells to chemotherapies.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA129514-04
Application #
7895046
Study Section
Radiation Therapeutics and Biology Study Section (RTB)
Program Officer
Pelroy, Richard
Project Start
2007-09-21
Project End
2012-07-31
Budget Start
2010-08-01
Budget End
2011-07-31
Support Year
4
Fiscal Year
2010
Total Cost
$308,750
Indirect Cost
Name
University of Massachusetts Medical School Worcester
Department
Biology
Type
Schools of Medicine
DUNS #
603847393
City
Worcester
State
MA
Country
United States
Zip Code
01655
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Peng, Min; Xie, Jenny; Ucher, Anna et al. (2014) Crosstalk between BRCA-Fanconi anemia and mismatch repair pathways prevents MSH2-dependent aberrant DNA damage responses. EMBO J 33:1698-712
Xie, Jenny; Peng, Min; Guillemette, Shawna et al. (2012) FANCJ/BACH1 acetylation at lysine 1249 regulates the DNA damage response. PLoS Genet 8:e1002786
Cantor, Sharon B; Guillemette, Shawna (2011) Hereditary breast cancer and the BRCA1-associated FANCJ/BACH1/BRIP1. Future Oncol 7:253-61
Xie, Jenny; Guillemette, Shawna; Peng, Min et al. (2010) An MLH1 mutation links BACH1/FANCJ to colon cancer, signaling, and insight toward directed therapy. Cancer Prev Res (Phila) 3:1409-16
Cantor, Sharon B; Xie, Jenny (2010) Assessing the link between BACH1/FANCJ and MLH1 in DNA crosslink repair. Environ Mol Mutagen 51:500-7
Xie, J; Litman, R; Wang, S et al. (2010) Targeting the FANCJ-BRCA1 interaction promotes a switch from recombination to poleta-dependent bypass. Oncogene 29:2499-508
Siehler, Simone Yasmin; Schrauder, Michael; Gerischer, Ulrike et al. (2009) Human MutL-complexes monitor homologous recombination independently of mismatch repair. DNA Repair (Amst) 8:242-52