Zerumbone inhibits interleukin-6 and induces apoptosis and cell cycle arrest in ovarian and cervical cancer cells Siddig Ibrahim Abdelwahab a, ⁎, Ahmad Bustamam Abdul b , Zetty Nadia Mohd Zain b , A. Hamid A. Hadi c a Department of Pharmacy, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia b UPM-MAKNA Cancer Research Laboratory, Institute of Bioscience, University Putra Malaysia, 43400 UPM Serdang, Malaysia c Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia abstract article info Article history: Received 14 November 2011 Received in revised form 27 January 2012 Accepted 30 January 2012 Available online 11 February 2012 Keywords: Zerumbone Gynecological cancers Interleukin Apoptosis Cell cycle arrest Interleukin-6 is one of the factors affecting sensitivity to cytotoxic agents. Therefore, the current study was designed to investigate the role of IL-6 and IL6 receptors in the cytotoxic effects of zerumbone in ovarian and cervical cancer cell lines (Caov-3 and HeLa, respectively). Exposure of both cancer cells to zerumbone or cisplatin demonstrated growth inhibition at a dose-dependent manner as determined by the MTT (3-[4,5-dimethylthiazol-2-yl]-2,Sdiphe- nyltetrazolium bromide) reduction assay. Both laser scanning confocal microscopy and TUNEL assay showed typical apoptotic features in treated cells. The studies conducted seems to suggest that zerumbone induces cell death by stimulating apoptosis better than cisplatin, based on the significantly higher percentage of apoptotic cells in zerumbone's treated cancer cells as compared to cisplatin. In addition, zerumbone and cisplatin arrest cancer cells at G2/M phase as analyzed by flow cytometry. Our results indicated that zerumbone significantly decreased the levels of IL-6 secreted by both cancer cells. In contrast, HeLa and Caov-3 cells were still sensitive to cisplatin and zerumbone, even in the presence of exogenous IL-6. However, membrane-bound IL-6 receptor is still intact after zerumbone treatment as demonstrated using an immune-fluorescence technique. This study concludes that the compound, zerumbone inhibits both cancer cell growth through the induction of apoptosis, arrests cell cycle at G2/M phase and inhibits the secretion levels of IL-6 in both cancer cells. Therefore, zerumbone is a potential candidate as a useful chemotherapeutic agent in treating both cervical and ovarian cancers in future. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Ovarian cancer is the number one gynaecologic killer in the West- ern world and is the fourth most common malignancy in women [1]. Approximately 1 in 75 women in the developed world will be affected by ovarian cancer with at least two thirds of women presenting late with the disease because of non-specificity symptoms and often a delay in the diagnosis [2]. Despite improvements in the management of patients with ovarian cancer, the mortality rate is essentially unchanged over the last few decades whilst the annual worldwide incidence of ovarian cancer exceeds 140,000. However, most ovarian cancer patients (approximately 75%) presented an advanced stage with metastatic effects beyond the ovaries at the time of diagnosis causing a high mortality rate from ovarian cancer [3]. In some countries, there is a lack of effective cervical cancer screening programs. The incidence of cervical cancer has not reduced significantly during the past three decades [4]. Interleukin 6 (IL-6) is a pleiotropic cytokine that is produced by many different cell types, which plays a role in a wide range of responses. IL-6 can be regarded as multifunctional protein in which it regulates immune responses and acute-phase reactions and mediates the host response against tissue injuries [5,6]. In addition, IL-6 plays a central role in the differentiation and growth of haemato- poietic precursor cells, B-cells, T-cells, keratinocytes, neuronal cells, endothelial cells, osteoclasts and osteoblasts [7]. Moreover, IL-6 International Immunopharmacology 12 (2012) 594–602 ⁎ Corresponding author. Tel.: + 60 126565990. E-mail address: siddigroa@um.edu.my (S.I. Abdelwahab). Fig. 1. Molecular structure of zerumbone. 1567-5769/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.intimp.2012.01.014 Contents lists available at SciVerse ScienceDirect International Immunopharmacology journal homepage: www.elsevier.com/locate/intimp