A critical role of Sp1 transcription factor in regulating the human Ki-67 gene expression.
Ki-67 plays a crucial role in cell proliferation as well as maintenance or regulation of cell division. The mechanism governing the Ki-67 gene expression remains unknown. Thus, we cloned the core promoter of the human Ki-67 gene and further investigated its transcriptional regulation. The putative Sp1 binding sites were confirmed by electrophoretic mobility shift assay together with an anti-Sp1 antibody-mediated supershift assay. Deletion mutagenesis and firefly luciferase reporter gene assay demonstrated the essential contribution of Sp1 on transcriptional activation of the Ki-67 gene. In this study, we first confirm that there are three Sp1 binding sites in the Ki-67 core promoter. Two Sp1 sites (one at position -159 to -145 nt and the other at position -14 to +12 nt) are mainly involved in transcriptional regulation of the Ki-67 gene. Overexpression of Sp1 can enhance the Ki-67 promoter activity. However, down-regulation of Sp1 expression using siRNA-Sp1 and mithramycin effectively inhibits the Ki-67 gene transcription. Our results suggest that Sp1 is essential for basal promoter activity of the human Ki-67 gene. Inhibition of the Ki-67 transcriptional activity through abolishment of Sp1 may provide the useful prospect for gene therapy.
Laboratory of Biological Cancer Therapy, Xuzhou Medical College, 84 West Huai-hai Road, Xuzhou, Jiangsu 221002, People's Republic of China.
Hui
H
Tian
Guo-Wei
GW
Qian
Wang
W
Li
Fei-Fei
FF
Chen
Jie-Hui
JH
Di
Bao-Fu
BF
Zhang
Dong-Sheng
DS
Pei
Ping
P
Ma
Jun-Nian
JN
Zheng
D000230:Adenocarcinoma / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D001483:Base Sequence; D045744:Cell Line, Tumor; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D019394:Ki-67 Antigen / Q000235:genetics / Q000378:metabolism*; D008175:Lung Neoplasms / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D008969:Molecular Sequence Data; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D008926:Plicamycin / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000494:pharmacology; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000502:physiology*; D002583:Uterine Cervical Neoplasms / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology
D019394:Ki-67 Antigen; D019384:Nucleic Acid Synthesis Inhibitors; D034741:RNA, Small Interfering; D016329:Sp1 Transcription Factor; D008926:Plicamycin