1. ¹Department of Obstetrics and Gynecology, Lin-Kou Medical Center, Chang Gung Memorial Hospital, Tao-Yuan, Taiwan
2. ²Genomic Medicine Research Core Laboratory (GMRCL), Chang Gung Memorial Hospital, Tao-Yuan, Taiwan
3. ³Department of Biotechnology, Min Chuan University, Tao-Yuan, Taiwan
4. ⁴Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
5. ⁵Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, Gwei-Shan, Tao-Yuan, Taiwan

Correspondence: Dr H-S Wang, Graduate Institute of Clinical Medical Sciences, Chang Gung University and Department of Obstetrics and Gynecology, Chang-Gung Memorial Hospital, 5 Fu-Hsing Street, Gwei-Shan, Tao-Yuan 333, Taiwan. E-mail: hswang@cgmh.org.tw

Received 20 June 2005; Revised 23 January 2006; Accepted 6 February 2006; Published online 20 March 2006.

Abstract

Paclitaxel (Taxol) is an antineoplastic agent that specifically targets microtubules and arrests cells at the G2/M phase of the cell cycle. In addition to mitotic arrest, the activation of c-Jun N-terminal kinase (JNK) signaling pathway has been demonstrated to be involved in the process leading to apoptosis. In an attempt to explore what genes are transcriptionally regulated by the activated JNK signaling pathway upon paclitaxel treatment, we used cDNA microarrays to analyse the changes of gene expression in human ovarian cancer cells that were treated with paclitaxel and/or the JNK inhibitor SP600125. Among 20 genes that were specifically regulated by the paclitaxel-activated JNK pathway, interleukin (IL)-6 was shown to elicit function through the JAK–STAT signaling pathway in an autocrine and/or paracrine fashion. Subsequently, we identified that 87.5% of eight tested ovarian cancer lines secreted detectable levels of IL-6, which could be further upregulated 2–3.2 fold by 1 M paclitaxel. Dissection on regulatory pathways for IL-6 indicated that (i) when ovarian cancer cells were treated with paclitaxel at low but clinically achievable concentrations (exemplified by 1 M in this study), the JNK signaling pathway was the major stimulator of IL-6 gene regulation and (ii) at suprapharmacologically high concentrations (exemplified by 50 M), paclitaxel exerted lipopolysaccharide-like effects, most likely through the Toll-like receptor 4 signaling pathway. Collectively, these results suggest that paclitaxel upregulates functional IL-6 expression in human ovarian cancer cells through multiple signaling pathways.