Abstract: FR-PO1004
Jade-1 in Double-Strand Break Repair in Kidney Cancer
Session Information
- Onco-Nephrology: Basic
November 08, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Onco-Nephrology
- 1500 Onco-Nephrology
Authors
- Lopez, Delia, Boston University School of Medicine, Boston, Massachusetts, United States
- Ho, Kun-Lin, University of Georgia, Athens, Georgia, United States
- Niu, Leili, Boston University School of Medicine, Boston, Massachusetts, United States
- Bharti, Ajit K., Boston University School of Medicine, Boston, Massachusetts, United States
- Cohen, Herbert T., Boston University School of Medicine, Boston, Massachusetts, United States
Background
Like many solid tumors, kidney cancer is characterized by chromosomal breaks and instability, which arise from defects in DNA double-strand break (DSB) repair. We have established that Jade-1 is a renal tumor suppressor that induces apoptosis, inhibits proliferation, and inhibits oncoproteins Akt and β-catenin. Jade-1 also functions on DNA, through gene transcription, histone acetylation and DNA replication. As an unbiased approach to identify new Jade-1 tumor suppressor functions, Jade-1 was immunoprecipitated with Flag antibody in kidney cells to discover novel interactors via mass spectrometry. Surprisingly, many DNA repair proteins were found associated with Jade-1, including those involved in DSB repair, such as DNA-dependent protein kinase catalytic subunit (DNA-PKcs) and Ku70 and Ku80.
Methods
Kidney and kidney cancer cells were treated with a variety of agents that induce DSBs, including neocarzinostatin (NCS), a radiomimetic agent that induces DSBs. Immunofluorescence (IF) studies were done to visualize Jade-1 and DNA damage indicator γH2AX. Additionally, sensitivity assays were performed to assess for Jade-1 dose-dependent survival differences in kidney proximal tubule-derived HK-2 cells, which serve as a model of renal cancer precursor cells.
Results
Interaction of endogenous Jade-1 and DNA-PKcs was confirmed in coimmunoprecipitations. Jade-1 was found to be inducible in kidney and kidney cancer cells in response to DSBs. IF studies demonstrated colocalization of Jade-1, γH2AX, and phospho-DNA-PKcs following DNA damage. Moreover, silencing of Jade-1 in HK-2 cells offered protection against DNA damage in cell survival assays, supporting a direct role for Jade-1 in the DNA repair process.
Conclusion
We hypothesize that Jade-1 directly promotes DSB repair in part by binding and regulating DNA-PKcs, thereby favoring homologous recombination over error-prone repair through non-homologous end-joining. Our findings indicate that Jade-1 helps maintain genomic stability and further underscore its importance as a renal tumor suppressor. In short, understanding the molecular underpinnings of DNA repair may be critical for developing strategies for deterring progression of renal cancer and other solid tumors as well.