Cancer Management and Research (Nov 2019)
Reciprocal Role Of DNA Methylation And Sp1 Binding In Ki-67 Gene Transcription
Abstract
Lian-Tao Li,1–3,* Xun Wang,4,* Wen-Tao Zhu,5,* Guo-Wei Qian,6 Dong-Sheng Pei,1,5 Jun-Nian Zheng1,2 1Cancer Institute, Xuzhou Medical University, Xuzhou 221000, People’s Republic of China; 2Center of Clinical Oncology, Affiliated Hospital of Xuzhou Medical University, Xuzhou 221000, People’s Republic of China; 3Department of Radiation Oncology, Affiliated Hospital of Xuzhou Medical University, Xuzhou 221000, People’s Republic of China; 4Department of Interventional Radiology, Affiliated Hospital of Xuzhou Medical University, Xuzhou 221000, People’s Republic of China; 5Department of Pathology, Xuzhou Medical University, Xuzhou 221000, People’s Republic of China; 6Department of Medical Oncology, Shanghai Sixth People’s Hospital, Shanghai 200000, People’s Republic of China*These authors contributed equally to this workCorrespondence: Dong-Sheng Pei; Jun-Nian Zheng 84 West Huaihai Road, Xuzhou, Jiangsu, People’s Republic of ChinaTel +8605168558230Email [email protected]; [email protected]: DNA methylation plays major regulatory roles in gene transcription. Our previous studies confirmed that Ki-67 promoter is hypomethylated and Sp1 is a transcriptional activator of Ki-67 gene in cancer cells. However, whether Sp1-mediated transcriptional activation of Ki-67 is related to its methylation has not been studied yet.Materials and methods: In this study, we confirmed that methylated CpG binding protein 2 (MBD2) binding to methylated DNA hindered the binding of Sp1 to Ki-67 promoter and then repressed Ki-67 transcription through chromatin immunoprecipitation (ChIP) and quantitative real-time PCR (qRT-PCR). Co-immunoprecipitation (Co-IP), ChIP, methylation-specific PCR (MS-PCR) and Western blot were utilized to analyze the effects of Sp1 binding to Ki-67 promoter on its methylation status.Results: Less DNA methyltransferase 1 (DNMT1) bound to the Ki-67 promoter in MKN45 cells than in HK-2 cells. Histone acetyltransferase p300 that was recruited by Sp1 to Ki-67 promoter could attenuate the methylation level of Ki-67 promoter. Furthermore, higher expression of Sp1 and Ki-67 was related to the overall survival (OS), first progression (FP) and post-progression survival (PPS) in gastric cancer by scrutinizing bioinformatics datasets.Conclusion: Taken together, our findings suggested that hypomethylation of Ki-67 promoter enhanced the binding of Sp1, which in turn maintained hypomethylation of promoter, leading to increase Ki-67 expression in cancer cells. Sp1 and Ki-67 could act promising prognostic biomarkers for clinical diagnosis and treatment of cancer.Keywords: methylation, Ki-67, Sp1, promoter, cancer
