Chi-Che Hsieh1, Sen-Huei Hsu2, Chih-Yu Lin1, Hung-Jiun Liaw2, Ting-Wei Li2, Kuan-Ying Jiang1, Nai-Jung Chiang1,3,4, Shang-Hung Chen1,5, Bo-Wen Lin6, Po-Chuan Chen6, Ren-Hao Chan6, Peng-Chan Lin5,7,8, Yu-Min Yeh5, Che-Hung Shen9,10. 1. National Institute of Cancer Research, National Health Research Institutes, Tainan, 704, Taiwan. 2. Department of Life Sciences, National Cheng Kung University, Tainan, 701, Taiwan. 3. Department of Oncology, Taipei Veterans General Hospital, Taipei, 112, Taiwan. 4. School of Medicine, National Yang Ming Chiao Tung University, Taipei, 112, Taiwan. 5. Department of Oncology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, 704, Taiwan. 6. Department of Surgery, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, 704, Taiwan. 7. Department of Genomic Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, 704, Taiwan. 8. Department of Computer Science and Information Engineering, College of Electrical Engineering and Computer Science, National Cheng Kung University, Tainan, 701, Taiwan. 9. National Institute of Cancer Research, National Health Research Institutes, Tainan, 704, Taiwan. chshen@nhri.edu.tw. 10. Ph.D. Program in Tissue Engineering and Regenerative Medicine, Biotechnology Center, National Chung Hsing University, Taichung, 402, Taiwan. chshen@nhri.edu.tw.
Abstract
BACKGROUND: Colorectal cancer (CRC), the most common cancer type, causes high morbidity and mortality. Patients who develop drug resistance to oxaliplatin-based regimens have short overall survival. Thus, identifying molecules involved in the development of oxaliplatin resistance is critical for designing therapeutic strategies. METHODS: A proteomic screen was performed to reveal altered protein kinase phosphorylation in oxaliplatin-resistant (OR) CRC tumour spheroids. The function of CHK2 was characterised using several biochemical techniques and evident using in vitro cell and in vivo tumour models. RESULTS: We revealed that the level of phospho-CHK2(Thr68) was elevated in OR CRC cells and in ~30% of tumour samples from patients with OR CRC. We demonstrated that oxaliplatin activated several phosphatidylinositol 3-kinase-related kinases (PIKKs) and CHK2 downstream effectors and enhanced CHK2/PARP1 interaction to facilitate DNA repair. A phosphorylation mimicking CHK2 mutant, CHK2T68D, but not a kinase-dead CHK2 mutant, CHK2D347A, promoted DNA repair, the CHK2/PARP1 interaction, and cell growth in the presence of oxaliplatin. Finally, we showed that a CHK2 inhibitor, BML-277, reduced protein poly(ADP-ribosyl)ation (PARylation), FANCD2 monoubiquitination, homologous recombination and OR CRC cell growth in vitro and in vivo. CONCLUSION: Our findings suggest that CHK2 activity is critical for modulating oxaliplatin response and that CHK2 is a potential therapeutic target for OR CRC.
BACKGROUND: Colorectal cancer (CRC), the most common cancer type, causes high morbidity and mortality. Patients who develop drug resistance to oxaliplatin-based regimens have short overall survival. Thus, identifying molecules involved in the development of oxaliplatin resistance is critical for designing therapeutic strategies. METHODS: A proteomic screen was performed to reveal altered protein kinase phosphorylation in oxaliplatin-resistant (OR) CRC tumour spheroids. The function of CHK2 was characterised using several biochemical techniques and evident using in vitro cell and in vivo tumour models. RESULTS: We revealed that the level of phospho-CHK2(Thr68) was elevated in OR CRC cells and in ~30% of tumour samples from patients with OR CRC. We demonstrated that oxaliplatin activated several phosphatidylinositol 3-kinase-related kinases (PIKKs) and CHK2 downstream effectors and enhanced CHK2/PARP1 interaction to facilitate DNA repair. A phosphorylation mimicking CHK2 mutant, CHK2T68D, but not a kinase-dead CHK2 mutant, CHK2D347A, promoted DNA repair, the CHK2/PARP1 interaction, and cell growth in the presence of oxaliplatin. Finally, we showed that a CHK2 inhibitor, BML-277, reduced protein poly(ADP-ribosyl)ation (PARylation), FANCD2 monoubiquitination, homologous recombination and OR CRC cell growth in vitro and in vivo. CONCLUSION: Our findings suggest that CHK2 activity is critical for modulating oxaliplatin response and that CHK2 is a potential therapeutic target for OR CRC.
Authors: Johanna C Bendell; Tanios S Bekaii-Saab; Allen L Cohn; Herbert I Hurwitz; Mark Kozloff; Haluk Tezcan; Nancy Roach; Yong Mun; Susan Fish; E Dawn Flick; Darshan Dalal; Axel Grothey Journal: Oncologist Date: 2012-09-26
Authors: Richard M Goldberg; Daniel J Sargent; Roscoe F Morton; Charles S Fuchs; Ramesh K Ramanathan; Stephen K Williamson; Brian P Findlay; Henry C Pitot; Steven R Alberts Journal: J Clin Oncol Date: 2003-12-09 Impact factor: 44.544