Ming Li1, Jianfeng Yao2, Xiangxi Zhang1, Xuan Chen3, Juan Chen3, Yingying Guan1, Xiaoyu Yang4. 1. The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350108, PR China. 2. Quanzhou Maternity & Child Healthcare Hospital, Quanzhou, 362000, PR China. 3. The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350108, PR China; Fujian Institute of Traditional Chinese Medicine, Fuzhou, 350001, PR China. 4. The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350108, PR China; Fuzhou Maternity & Child Healthcare Hospital, Fuzhou, 350005, PR China; Fuzhou First Hospital, Fujian Medical University, Fuzhou, 350004, PR China. Electronic address: yangxiaoyu683@163.com.
Abstract
INTRODUCTION: Certain procaspase-8 mutations are reported to be associated with the progression and prognosis of multiple tumors. However, it remains unclear whether the poor chemotherapy response and frequent relapse after complete remission of patients with acute myeloid leukemia (AML) is also related to procaspase-8 abnormalities. METHODS: Polymerase chain reaction (PCR) amplification and Sanger sequencing of the procaspase-8 gene (CASP8) were performed. Apoptotic rates were analyzed with Annexin V-FITC staining in cells expressing wild-type (WT) procaspase-8, the Q482H or C360S mutant, or control vector after treatment with or without tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Western blot analysis was performed to detect activation of procaspase-8 and downstream apoptotic signaling pathway components in those cells. The Co-immunoprecipitation (Co-IP) assays were performed to detect interaction between WT and mutant procaspase-8 proteins. RESULTS: AML patients carrying the Q482H mutation were likely to develop chemotherapy resistance. Similar to C360S, The Q482H mutation abolished caspase-8-mediated apoptotic signaling and inhibited TRAIL-induced apoptosis. The Q482H mutation impaired procaspase-8 dimerization, thus preventing the self-activation of procaspase-8. CONCLUSION: The procaspase-8 Q482H mutation in AML patients abolishes caspase-8-mediated apoptosis by impairing procaspase-8 dimerization.
INTRODUCTION: Certain procaspase-8 mutations are reported to be associated with the progression and prognosis of multiple tumors. However, it remains unclear whether the poor chemotherapy response and frequent relapse after complete remission of patients with acute myeloid leukemia (AML) is also related to procaspase-8 abnormalities. METHODS: Polymerase chain reaction (PCR) amplification and Sanger sequencing of the procaspase-8 gene (CASP8) were performed. Apoptotic rates were analyzed with Annexin V-FITC staining in cells expressing wild-type (WT) procaspase-8, the Q482H or C360S mutant, or control vector after treatment with or without tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Western blot analysis was performed to detect activation of procaspase-8 and downstream apoptotic signaling pathway components in those cells. The Co-immunoprecipitation (Co-IP) assays were performed to detect interaction between WT and mutant procaspase-8 proteins. RESULTS:AMLpatients carrying the Q482H mutation were likely to develop chemotherapy resistance. Similar to C360S, The Q482H mutation abolished caspase-8-mediated apoptotic signaling and inhibited TRAIL-induced apoptosis. The Q482H mutation impaired procaspase-8 dimerization, thus preventing the self-activation of procaspase-8. CONCLUSION: The procaspase-8 Q482H mutation in AMLpatients abolishes caspase-8-mediated apoptosis by impairing procaspase-8 dimerization.