Sp1 and Sp3 are involved in the full transcriptional activity of centromere protein H in human nasopharyngeal carcinoma cells

Abstract

The overexpression of centromere protein H (CENPH), one of the fundamental components of the human active kinetochore, has been shown to be closely associated with human cancers. However, the mechanism of its transcriptional regulation has not been reported. The aim of the present study was to investigate the regulatory elements for the transcriptional regulation of CENPH in nasopharyngeal carcinoma cells. To characterize the CENPH promoter and identify regulatory elements, we cloned 1015 bp ()975 ⁄ +40 bp) of the 5¢-flanking region of the CENPH gene from immortalized normal nasopharyngeal epithelial cells (Bmi-1 ⁄ NPEC). Functional analysis established a minimal region ()140 ⁄ )87 bp) involved in the regulation of human CENPH promoter activity. Through site-directed mutagenesis, a transactivation assay, chromatin immunoprecipitation, and electrophoretic mobility shift assay, we found that the Sp1 ⁄ Sp3 transcription factors could bind to the CENPH promoter in vitro and in vivo, and that they regulated CENPH promoter activation in human nasopharyngeal carcinoma cells. Furthermore, Sp1 and Sp3 were highly expressed in nasopharyngeal carcinoma cells. Knockdown of Sp1 and Sp3 by small interfering RNA or inhibition of Sp1 and Sp3 activity by mithramycin A decreased CENPH mRNA expression, whereas the exogenous expression of Sp1 and Sp3 upregulated CENPH mRNA expression. Taken together, our results indicate that Sp1 and Sp3 bind to the CENPH minimal promoter and function as a regulator of the transcription of CENPH in human nasopharyngeal carcinomas.

Down-regulation of Sp1 suppresses cell proliferation, clonogenicity and the expressions of stem cell markers in nasopharyngeal carcinoma

“…We previously reported that Sp1 activates the transcription of Bmi1 and CENPH in nasopharyngeal carcinoma [32],[33]. Both Bmi1 and CENPH are oncogenes which are elevated in various malignancies originating in the breast, esophagus and nasopharynx [39]–[41].…”

“…We previously identified Sp1 as an important transcription factor for oncogenes in NPC, including B-lymphoma mouse Moloney leukemia virus insertion region 1 (Bmi1) and centromere protein H (CENPH), but the role of Sp1 in the development of NPC remains obscure [32],[33]. In the present study, we found the level of Sp1 was elevated in advanced NPC tissues and silencing of Sp1 significantly inhibited cell proliferation, clonogenicity, anchorage-independent growth and the stem-cell like phenotype of NPC cells, suggesting Sp1 as a potential therapeutic target for NPC.…”

EGR1 is critical for gastrin‐dependent upregulation of anion exchanger 2 in gastric cancer cells

“…Collectively, these findings indicate that EGR1 plays an important role in gastrin‐induced upregulation of AE2 protein. In the case of the AE2 gene, SP1, as a ubiquitous transcription factor, may participate in basal transcription .…”

Sp1 and c‐Myc regulate transcription of BMI1 in nasopharyngeal carcinoma

“…This construct was named pCDNA6-myc-HisB-MYC. An SP1 expression vector named pCDNA6-myc-HisB-SP1 was generated in our previous study [52]. All constructs were confirmed by direct sequencing.…”

“…EMSA EMSA was performed as described previously [52]. Briefly, complementary oligonucleotide pairs containing either the putative binding site for Sp1 (Sp1 probe) or the mutant binding site for Sp1 (mutant Sp1 probe) were labeled with [ Wellesley, MA, USA).…”