Chinese Journal of Physiology 57(5): 249-255, 2014 249 DOI: 10.4077/CJP.2014.BAB190 Corresponding author: Dr. Imad M. Al-Ani, Department of BMS, Kulliyyah of Medicine, International Islamic University Malaysia, P.O. Box 141, Kuantan 25710, Pahang, Malaysia. Tel: +60179776014, E-mail: imad_alani @ yahoo.com Received: December 24, 2012; Revised (Final Version): September 24, 2013; Accepted: March 19, 2014. † WHO/ICO Information centre on HPV and cervical cancer. “HPV and cervical cancer in the 2007 report”. Vaccine 25 “Suppl” 3: Cl-230, 2007. 2014 by The Chinese Physiological Society and Airiti Press Inc. ISSN : 0304-4920. http://www.cps.org.tw Apoptotic Activities of Thymoquinone, an Active Ingredient of Black Seed ( Nigella sativa ), in Cervical Cancer Cell Lines Solachuddin J. A. Ichwan 1, 6 , Imad M. Al-Ani 2 , Hakim G. Bilal 3 , Wastuti H. Suriyah 4 , Muhammad Taher 5 , and Masa A. Ikeda 7 1 Department of Basic Medical Science, Kulliyyah of Dentistry, International Islamic University Malaysia, Kuantan 25710, Pahang, Malaysia 2 Department of Basic Medical Science, Kulliyyah of Medicine, International Islamic University Malaysia, Kuantan 25710, Pahang, Malaysia 3 Department of Obstetrics and Gynecology, Royal College of Medicine, University Kuala Lumpur, Malaysia 4 Department of Basic Medical Science, Kulliyyah of Pharmacy, International Islamic University Malaysia, Kuantan, Pahang, Malaysia 5 Department of Pharmaceutical Technology, Kulliyyah of Pharmacy, International Islamic University Malaysia, Kuantan 25710, Pahang, Malaysia 6 Human Molecular Cellular Biology Research Unit, Integrated Centre of Research and Animal Care and Use (HMCB-ICRACU), International Islamic University, Kuantan, Pahang, Malaysia and 7 Section of Molecular Craniofacial Embryology, Tokyo Medical and Dental University, Japan Abstract Thymoquinone (TQ) is the main constituent of black seed ( Nigella sativa, spp) essential oil which shows promising in vitro and in vivo anti-neoplastic activities in different tumor cell lines. However, to date there are only a few reports regarding the apoptotic effects of TQ on cervical cancer cells. Here, we report that TQ stimulated distinct apoptotic pathways in two human cervical cell lines, Siha and C33A. TQ markedly induced apoptosis as demonstrated by cell cycle analysis in both cell lines. More- over, quantitative PCR revealed that TQ induced apoptosis in Siha cells through p53-dependent pathway as shown by elevated level of p53-mediated apoptosis target genes, whereas apoptosis in C33A cells was mainly associated with the activation of caspase-3. These results support previous findings on TQ as a potential therapeutic agent for human cervical cancer. Key Words: apoptosis, caspase, cervical cancer, Nigella sativa, thymoquinone Introduction Cervical cancer is one of the most common malignancies of women in the world, accounting for 15% of all cancer-related deaths (7). It was estimated that almost 500,000 women died every year from cervical cancer worldwide, of which > 80% of the mortality occur in developing countries, where mor- tality from this disease is the highest among deaths caused by the neoplasm. † In the United States, there are an estimated 13,000 annual new cases of cervical cancer and 50,000 of advanced pre-cancerous condi- tions (38). Cervical cancer is the second most com- mon cancer in women, next to breast cancer and is