Research article

Differential regulation of iron chelator-induced IL-8 synthesis via MAP kinase and NF-κB in immortalized and malignant oral keratinocytes

Hwa-Jeong Lee^{* 1} , Jun Lee^{* 2} , Sun-Kyung Lee¹ , Suk-Keun Lee³ and Eun-Cheol Kim¹

¹Department of Oral & Maxillofacial Pathology, College of Dentistry, Wonkwang University, Iksan, Republic of Korea

²Department of Oral and Maxillofacial Surgery, College of Dentistry, Wonkwang University, Iksan, Republic of Korea

³Department of Oral Pathology, College of Dentistry, Kangnung National University, Gangneung, Republic of Korea

author email corresponding author email* Contributed equally

BMC Cancer 2007, 7:176doi:10.1186/1471-2407-7-176

Published:	13 September 2007

Abstract

Background

Interleukin-8 (IL-8) is a cytokine that plays an important role in tumor progression in a variety of cancer types; however, its regulation is not well understood in oral cancer cells. In the present study, we examined the expression and mechanism of IL-8 in which it is involved by treating immortalized (IHOK) and malignant human oral keratinocytes (HN12) cells with deferoxamine (DFO).

Methods

IL-8 production was measured by an enzyme-linked immunoabsorbent assay and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Electrophoretic mobility shift assays was used to determine NF-κB binding activity. Phosphorylation and degradation of the I-κB were analyized by Western blot.

Results

IHOK cells incubated with DFO showed increased expression of IL-8 mRNA, as well as higher release of the IL-8 protein. The up-regulation of DFO-induced IL-8 expression was higher in IHOK cells than in HN12 cells and was concentration-dependent. DFO acted additively with IL-1β to strongly up-regulate IL-8 in IHOK cells but not in HN12 cells. Accordingly, selective p38 and ERK1/2 inhibitors for both kinases abolished DFO-induced IL-8 expression in both IHOK and HN12 cells. Furthermore, DFO induced the degradation and phosphorylation of IκB, and activation of NF-κB. The IL-8 inducing effects of DFO were mediated by a nitric oxide donor (S-nitrosoglutathione), and by pyrrolidine dithiocarbamate, an inhibitor of NF-κB, as well as by wortmannin, which inhibits the phosphatidylinositol 3-kinase-dependent activation of NAD(P)H oxidase.

Conclusion

This results demonstrate that DFO-induced IL-8 acts via multiple signaling pathways in immortalized and malignant oral keratinocytes, and that the control of IL-8 may be an important target for immunotheraphy against human oral premalignant lesions.