Rabbit Anti-Human SP1 monoclonal antibody, clone KG1061

Objective. To study the effects of Huaier polysaccharide SP1 on the proliferation, apoptosis, migration, and invasion of gastric cancer cell line MGC-803 and the underlying mechanism. Methods. MGC-803 cells were cultured in vitro and treated with SP1. The effects of SP1 on the proliferation, apoptosis, migration, and invasion of MGC-803 cells were detected by CCK-8 assay, flow cytometry analysis, and Transwell assay, respectively. Western blot and qRT-PCR were used to detect the expression of related genes. Results. Our study showed that Huaier polysaccharide SP1 could inhibit proliferation, migration, invasion, and promote the apoptosis of MGC-803 cells in vitro in a dose-dependent manner. Huaier polysaccharide SP1 could inhibit the activation of TGF-beta/SMAD signal pathway by upregulating SMAD7 expression, thereby downregulating the expression of SOX4, ZEB2, MMP9, Snail, and Slug. Conclusion. Huaier polysaccharide SP1 can regulate the proliferation, apoptosis, migration, and invasion of gastric cancer cells by promoting the expression of SMAD7 and inhibiting the activation of TGF-beta/SMAD signal pathway as well as the expression of the downstream oncogenes.

Specificity protein 1 (Sp1) is an important transcription factor implicated in numerous cellular processes. However, whether Sp1 is involved in the regulation of RNA polymerase III (Pol III)-directed gene transcription in human cells remains unknown. Here, we first show that filamin A (FLNA) represses Sp1 expression as well as expression of TFIIB-related factor 1 (BRF1) and general transcription factor III C subunit 2 (GTF3C2) in HeLa, 293T, and SaOS2 cell lines stably expressing FLNA-silencing shRNAs. Both BRF1 promoter 4 (BRF1P4) and GTF3C2 promoter 2 (GTF3C2P2) contain putative Sp1-binding sites, suggesting that Sp1 affects Pol III gene transcription by regulating BRF1 and GTF3C2 expression. We demonstrate that Sp1 knockdown inhibits Pol III gene transcription, BRF1 and GTF3C2 expression, and the proliferation of 293T and HeLa cells, whereas Sp1 overexpression enhances these activities. We obtained a comparable result in a cell line in which both FLNA and Sp1 were depleted. These results indicate that Sp1 is involved in the regulation of Pol III gene transcription independently of FLNA expression. Reporter gene assays showed that alteration of Sp1 expression affects BRF1P4 and GTF3C2P2 activation, suggesting that Sp1 modulates Pol III?mediated gene transcription by controlling BRF1 and GTF3C2 gene expression. Further analysis revealed that Sp1 interacts with and thereby promotes the occupancies of TATA box?binding protein, TFIIA?, and p300 at both BRF1P4 and GTF3C2P2. These findings indicate that Sp1 controls Pol III?directed transcription and shed light on how Sp1 regulates cancer cell proliferation.