Document Type

Journal Article

Department/Unit

School of Chinese Medicine

Title

A novel anticancer effect of Astragalus saponins: Transcriptional activation of NSAID-activated gene

Language

English

Abstract

Astragalus membranaceus has been used to ameliorate the side effects of antineoplastic drugs because of its immunomodulating nature. We had recently demonstrated that total Astragalus saponins (AST) possess anticarcinogenic and proapoptotic properties in human colon cancer cells and tumor xenograft. In this study, we identified NSAID-activated gene (NAG-1) as a potential molecular target of AST. The growth-inhibitory and proapoptotic effects of AST were assessed in a panel of human cancer cell lines. Hoechst 33342 nuclear staining, Annexin V-FITC/propidium iodide staining, Western immunoblotting, real-time PCR, luciferase reporter assay and electrophoretic mobility shift assay were conducted to determine the association of NAG-1 and related transcription factors with AST during its regulation of apoptotic activities. Moreover, the combined proapoptotic and NAG-1 promoting activities of AST and/or inhibitors of the PI3K-Akt pathway were also examined. AST caused overexpression of NAG-1, leading to PARP cleavage and apoptosis. The induction of NAG-1 promoter activity by the drug was associated with increased gene expression, in addition to prior increase in Egr-1 expression and DNA binding activity. AST-induced NAG-1 activation was intensi-fied when PI3K inhibitor LY294002 or Akt inhibitor was cotreated and reversed by NAG-1 siRNA transfection. Nevertheless, the extent of NAG-1 induction could not be altered by the ERK inhibitor PD98059. Our results indicate that NAG-1 is a potential molecular target of AST in its antitumorigenic and proapoptotic actions, which would have additive effects when used along with PI3K-Akt inhibitors. The information obtained could facilitate future development of a novel target-specific chemotherapeutic agent with known molecular pathway. © 2009 UICC.

Keywords

Apoptosis, Astragalus saponins, Chemotherapy, NAG-1, PI3K-Akt inhibitors

Publication Date

2009

Source Publication Title

International Journal of Cancer

Volume

125

Issue

5

Start Page

1082

End Page

1091

Publisher

Wiley

DOI

10.1002/ijc.24397

Link to Publisher's Edition

http://dx.doi.org/10.1002/ijc.24397

ISSN (print)

00207136

ISSN (electronic)

10970215

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