Suberoylanilide Hydroxamic Acid Potentiates Apoptosis, Inhibits Invasion, and Abolishes Osteoclastogenesis by Suppressing Nuclear Factor-κB Activation

Bharat B. Aggarwal,Haruyo Ichikawa,Yasunari Takada,Ann Gillenwater

doi:10.1074/jbc.m507213200

Abstract

Because of its ability to suppress tumor cell proliferation, angiogenesis, and inflammation, the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA) is currently in clinical trials. How SAHA mediates its effects is poorly understood. We found that in several human cancer cell lines, SAHA potentiated the apoptosis induced by tumor necrosis factor (TNF) and chemotherapeutic agents and inhibited TNF-induced invasion and receptor activator of NF-kappaB ligand-induced osteoclastogenesis, all of which are known to require NF-kappaB activation. These observations corresponded with the down-regulation of the expression of anti-apoptotic (IAP1, IAP2, X chromosome-linked IAP, Bcl-2, Bcl-x(L), TRAF1, FLIP, and survivin), proliferative (cyclin D1, cyclooxygenase 2, and c-Myc), and angiogenic (ICAM-1, matrix metalloproteinase-9, and vascular endothelial growth factor) gene products. Because several of these genes are regulated by NF-kappaB, we postulated that SAHA mediates its effects by modulating NF-kappaB and found that SAHA suppressed NF-kappaB activation induced by TNF, IL-1beta, okadaic acid, doxorubicin, lipopolysaccharide, H(2)O(2), phorbol myristate acetate, and cigarette smoke; the suppression was not cell type-specific because both inducible and constitutive NF-kappaB activation was inhibited. We also found that SAHA had no effect on direct binding of NF-kappaB to the DNA but inhibited sequentially the TNF-induced activation of IkappaBalpha kinase, IkappaBalpha phosphorylation, IkappaBalpha ubiquitination, IkappaBalpha degradation, p65 phosphorylation, and p65 nuclear translocation. Furthermore, SAHA inhibited the NF-kappaB-dependent reporter gene expression activated by TNF, TNFR1, TRADD, TRAF2, NF-kappaB-inducing kinase, IkappaBalpha kinase, and the p65 subunit of NF-kappaB. Overall, our results indicated that NF-kappaB and NF-kappaB-regulated gene expression inhibited by SAHA can enhance apoptosis and inhibit invasion and osteoclastogenesis.

Highlights

Transferases and deacetylation by histone deacetylases [1]
We investigated whether suberoylanilide hydroxamic acid (SAHA) affects such apoptosis in KBM-5 cells by using the Live and Dead, poly(adenosine diphosphate-ribose)polymerase (PARP) cleavage, annexin V staining, TUNEL staining, and MTT methods
The results of annexin V staining indicated that SAHA up-regulated tumor necrosis factor (TNF)-induced early apoptosis (Fig. 1C), and the results of TUNEL staining showed that TNF-induced apoptosis was enhanced by incubation with SAHA (Fig. 1D)

Summary

Introduction

Transferases and deacetylation by histone deacetylases [1]. Several inhibitors of histone deacetylases, including simple compounds such as butyrate, cyclic tetrapeptides, benzamides (e.g. MS-275), and hydroxamic acids (e.g. suberoylanilide hydroxamic acid; SAHA), are being considered as potential therapeutic agents with which to treat cancer. SAHA has been shown to induce differentiation, growth arrest, and apoptosis of transformed human cells in culture at micromolar concentrations. Because genes involved in the regulation of apoptosis, proliferation, angiogenesis, and inflammation are regulated by the transcription factor NF-␬B, we postulated that SAHA mediates its effects by modulating NF-␬B activation and the associated gene expression. The results showed that SAHA potentiated apoptosis induced by TNF and chemotherapeutic agents and inhibited cell invasion and osteoclastogenesis. These effects were associated with the inhibition of NF-␬B activation and NF-␬B-regulated gene expression. The ability of SAHA to enhance apoptosis, suppress invasion, and inhibit osteoclastogenesis provides novel targets for cancer therapy

Methods

Results

Conclusion