ABSTRACT
Radiochemoresistance is considered the main cause of local recurrence and distant metastasis in lung cancer. However, the underlying mechanisms of radiochemoresistance remain to be uncovered. In this study, we determine the functions of cell cycle-related kinase (CDK20) in radiochemoresistance. CDK20 is a newly identified protein kinase, which plays critical roles in cell growth and proliferation in several types of cancer. Using tandem affinity purification technology, we provide evidences that CDK20 binds to the ubiquitin ligase Kelch-like ECH-associated protein 1 (KEAP1), which targets transcriptional factor nuclear factor erythroid-2-related factor 2 (NRF2) for degradation. We show that this interaction is mediated by an evolutionarily conserved ETGE motif on CDK20. Furthermore, we demonstrate that CDK20 competes with NRF2 for KEAP1 binding, enhances the transcriptional activity of NRF2 and lowers the cellular reactive oxygen species level. Moreover, CDK20-depleted cells display impaired cell proliferation, defective G2/M arrest and increased radiochemosensitivity in lung cancer. These phenotypes induced by CDK20 knockdown are partially dependent on NRF2 inactivation. More importantly, CDK20 is overexpressed in human lung cancer tissues, as determined by immunostaining. Collectively, our results suggest that CDK20 positively modulate the KEAP1-NRF2 cytoprotective pathway to regulate tumor progression and radiochemoresistance, implying that CDK20 is a novel, promising therapeutic target for lung cancer.
Subject(s)
Cyclin-Dependent Kinases/metabolism , Kelch-Like ECH-Associated Protein 1/metabolism , Lung Neoplasms/metabolism , Lung Neoplasms/therapy , NF-E2-Related Factor 2/metabolism , A549 Cells , Cell Line, Tumor , Cell Proliferation/physiology , Chemoradiotherapy , Cyclin-Dependent Kinases/genetics , Drug Resistance, Neoplasm , Humans , Kelch-Like ECH-Associated Protein 1/genetics , Lung Neoplasms/genetics , Lung Neoplasms/pathology , NF-E2-Related Factor 2/genetics , Radiation ToleranceABSTRACT
BACKGROUND: Dapsone is used in the treatment of infections and inflammatory diseases. The dapsone hypersensitivity syndrome, which is associated with a reported mortality of 9.9%, develops in about 0.5 to 3.6% of persons treated with the drug. Currently, no tests are available to predict the risk of the dapsone hypersensitivity syndrome. METHODS: We performed a genomewide association study involving 872 participants who had received dapsone as part of multidrug therapy for leprosy (39 participants with the dapsone hypersensitivity syndrome and 833 controls), using log-additive tests of single-nucleotide polymorphisms (SNPs) and imputed HLA molecules. For a replication analysis, we genotyped 24 SNPs in an additional 31 participants with the dapsone hypersensitivity syndrome and 1089 controls and performed next-generation sequencing for HLA-B and HLA-C typing at four-digit resolution in an independent series of 37 participants with the dapsone hypersensitivity syndrome and 201 controls. RESULTS: Genomewide association analysis showed that SNP rs2844573, located between the HLA-B and MICA loci, was significantly associated with the dapsone hypersensitivity syndrome among patients with leprosy (odds ratio, 6.18; P=3.84×10(-13)). HLA-B*13:01 was confirmed to be a risk factor for the dapsone hypersensitivity syndrome (odds ratio, 20.53; P=6.84×10(-25)). The presence of HLA-B*13:01 had a sensitivity of 85.5% and a specificity of 85.7% as a predictor of the dapsone hypersensitivity syndrome, and its absence was associated with a reduction in risk by a factor of 7 (from 1.4% to 0.2%). HLA-B*13:01 is present in about 2 to 20% of Chinese persons, 1.5% of Japanese persons, 1 to 12% of Indians, and 2 to 4% of Southeast Asians but is largely absent in Europeans and Africans. CONCLUSIONS: HLA-B*13:01 was associated with the development of the dapsone hypersensitivity syndrome among patients with leprosy. (Funded by the National Natural Science Foundation of China and others.).
