Sulindac activates NF-κB signaling in colon cancer cells

Dessislava Mladenova,Elizabeth A Musgrove,Irvin Ng,Maija Rj Kohonen-Corish,Laurent Pangon,Nicola Currey,Shane T Grey

doi:10.1186/1478-811x-11-73

Abstract

BackgroundThe non-steroidal anti-inflammatory drug (NSAID) sulindac has shown efficacy in preventing colorectal cancer. This potent anti-tumorigenic effect is mediated through multiple cellular pathways but is also accompanied by gastrointestinal side effects, such as colon inflammation. We have recently shown that sulindac can cause up-regulation of pro-inflammatory factors in the mouse colon mucosa. The aim of this study was to determine the signaling pathways that mediate the transcriptional activation of pro-inflammatory cytokines in colon cancer epithelial cells treated with sulindac sulfide.ResultsWe found that sulindac sulfide increased NF-κB signaling in HCT-15, HCT116, SW480 and SW620 cells, although the level of induction varied between cell lines. The drug caused a decrease in IκBα levels and an increase of p65(RelA) binding to the NF-κB DNA response element. It induced expression of IL-8, ICAM1 and A20, which was inhibited by the NF-κB inhibitor PDTC. Sulindac sulfide also induced activation of the AP-1 transcription factor, which co-operated with NF-κB in up-regulating IL-8. Up-regulation of NF-κB genes was most prominent in conditions where only a subset of cells was undergoing apoptosis. In TNFα stimulated conditions the drug treatment inhibited phosphorylation on IκBα (Ser 32) which is consistent with previous studies and indicates that sulindac sulfide can inhibit TNFα-induced NF-κB activation. Sulindac-induced upregulation of NF-κB target genes occurred early in the proximal colon of mice given a diet containing sulindac for one week.ConclusionsThis study shows for the first time that sulindac sulfide can induce pro-inflammatory NF-κB and AP-1 signaling as well as apoptosis in the same experimental conditions. Therefore, these results provide insights into the effect of sulindac on pro-inflammatory signaling pathways, as well as contribute to a better understanding of the mechanism of sulindac-induced gastrointestinal side effects.

Highlights

The non-steroidal anti-inflammatory drug (NSAID) sulindac has shown efficacy in preventing colorectal cancer
The decrease in IkBα was accompanied by an increase in mRNA expression of Nuclear factor kappa B (NF-κB) target genes Zinc finger protein A20 (A20), Intercellular adhesion molecule 1 (ICAM1) and Interleukin 8 (IL-8), which was more pronounced with 50 or 120 μM sulindac sulfide (Figure 1D)
In sulindac sulfide-treated cells both the mutated activator protein-1 (AP-1) and NF-κB binding sites strongly reduced the up-regulation in luciferase activity (P < 0.05) (Figure 5C). These results indicate that the strong upregulation of IL-8 gene expression induced by sulindac sulfide treatment is dependent on both the NF-κB and activating protein (AP)-1 transcription factors, whereas Tumor necrosis factor α (TNFα) up-regulates IL-8 mainly through NF-κB

Summary

Introduction

The non-steroidal anti-inflammatory drug (NSAID) sulindac has shown efficacy in preventing colorectal cancer This potent anti-tumorigenic effect is mediated through multiple cellular pathways but is accompanied by gastrointestinal side effects, such as colon inflammation. The mechanism by which sulindac can up-regulate pro-inflammatory genes is not known, but some of these genes are regulated by NF-κB, whose activity is central to orchestrating the immune response [10]. This prompted us to investigate the molecular effects of sulindac sulfide on the NF-κB pathway in vitro

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