HDAC6 Regulates Radiosensitivity of Non-Small Cell Lung Cancer by Promoting Degradation of Chk1
Niko Moses,
Mu Zhang,
Jheng-Yu Wu,
Chen Hu,
Shengyan Xiang,
Xinran Geng,
Yue Chen,
Wenlong Bai,
You-Wei Zhang,
Gerold Bepler,
Xiaohong Mary Zhang
Affiliations
Niko Moses
Cancer Biology Graduate Program, Department of Oncology, Wayne State University School of Medicine, Karmanos Cancer Institute, Detroit, MI 48201, USA
Mu Zhang
Molecular Therapeutics Program, Department of Oncology, Karmanos Cancer Institute, Wayne State University School of Medicine, 4100 John R. Street Detroit, MI 48201, USA
Jheng-Yu Wu
Molecular Therapeutics Program, Department of Oncology, Karmanos Cancer Institute, Wayne State University School of Medicine, 4100 John R. Street Detroit, MI 48201, USA
Chen Hu
Molecular Therapeutics Program, Department of Oncology, Karmanos Cancer Institute, Wayne State University School of Medicine, 4100 John R. Street Detroit, MI 48201, USA
Shengyan Xiang
Department of Pathology & Cell Biology, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd., Tampa, FL 33612, USA
Xinran Geng
Department of Pharmacology, Case Comprehensive Cancer Center, School of Medicine, Case Western Reserve University,2109 Adelbert Road, Wood Building W343A, Cleveland, OH 44106, USA
Yue Chen
Department of Biochemistry, Molecular Biology and Biophysics, The University of Minnesota at Twin Cities, Minneapolis, MN 55455, USA
Wenlong Bai
Department of Pathology & Cell Biology, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd., Tampa, FL 33612, USA
You-Wei Zhang
Department of Pharmacology, Case Comprehensive Cancer Center, School of Medicine, Case Western Reserve University,2109 Adelbert Road, Wood Building W343A, Cleveland, OH 44106, USA
Gerold Bepler
Molecular Therapeutics Program, Department of Oncology, Karmanos Cancer Institute, Wayne State University School of Medicine, 4100 John R. Street Detroit, MI 48201, USA
Xiaohong Mary Zhang
Molecular Therapeutics Program, Department of Oncology, Karmanos Cancer Institute, Wayne State University School of Medicine, 4100 John R. Street Detroit, MI 48201, USA
We have previously discovered that HDAC6 regulates the DNA damage response (DDR) via modulating the homeostasis of a DNA mismatch repair protein, MSH2, through HDAC6’s ubiquitin E3 ligase activity. Here, we have reported HDAC6’s second potential E3 ligase substrate, a critical cell cycle checkpoint protein, Chk1. We have found that HDAC6 and Chk1 directly interact, and that HDAC6 ubiquitinates Chk1 in vivo and in vitro. Specifically, HDAC6 interacts with Chk1 via the DAC1 domain, which contains its ubiquitin E3 ligase activity. During the cell cycle, Chk1 protein levels fluctuate, peaking at the G2 phase, subsequently resolving via the ubiquitin-proteasome pathway, and thereby allowing cells to progress to the M phase. However, in HDAC6 knockdown non-small cell lung cancer (NSCLC) cells, Chk1 is constitutively active and fails to resolve post-ionizing radiation (IR), and this enhanced Chk1 activity leads to preferential G2 arrest in HDAC6 knockdown cells accompanied by a reduction in colony formation capacity and viability. Depletion or pharmacological inhibition of Chk1 in HDAC6 knockdown cells reverses this radiosensitive phenotype, suggesting that the radiosensitivity of HDAC6 knockdown cells is dependent on increased Chk1 kinase activity. Overall, our results highlight a novel mechanism of Chk1 regulation at the post-translational level, and a possible strategy for sensitizing NSCLC to radiation via inhibiting HDAC6’s E3 ligase activity.
