The MAP30 protein from bitter gourd (Momordica charantia) seeds promotes apoptosis in liver cancer cells in vitro and in vivo Evandro Fei Fang a,1,2 , Chris Zhi Yi Zhang b,c,1 , Jack Ho Wong a , Jia Yun Shen d , Chuan Hao Li e , Tzi Bun Ng a,⇑ a School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong b State Key Laboratory of Oncology in Southern China, Sun Yat-Sen University Cancer Center, Guangzhou, China c Department of Pathology, Sun Yat-Sen University Cancer Center, Guangzhou, China d Institute of Digestive Disease and Department of Medicine and Therapeutics, Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong e Department of Chemistry, Faculty of Science, The Chinese University of Hong Kong, Hong Kong article info Article history: Received 17 March 2012 Received in revised form 28 April 2012 Accepted 2 May 2012 Keywords: MAP30 Bitter gourd Momordica charantia Hepatocellular carcinoma Apoptosis abstract Human hepatocellular carcinoma Hep G2 cells and Hep G2-bearing mice were used as in vitro and in vivo models to assess the efficacy and safety of MAP30, a natural component from Momordica charantia, as an anticancer agent against liver cancer. Molecular studies disclosed the contribution of both caspase-8 reg- ulated extrinsic and caspase-9 regulated intrinsic caspase cascades in MAP30-induced cell apoptosis. The antitumor potential was also effective in Hep G2-bearing nude mice. Since bitter gourd is a staple in many Asian countries, MAP30 would serve as a novel and relatively safe agent for prophylaxis and treat- ment of liver cancer. Ó 2012 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Bitter gourd/BG (binominal name Momordica charantia belong- ing to Family Cucurbitaceae) is widely distributed in Asia, Africa, and some places in South America [1,2]. Its bitter fruit is a common and popular vegetable in Asian countries because of its rich taste and nutritional value. Furthermore, BG is also applied in folklore medicine to treat illnesses such as metabolic disorders and viral infections [1]. In recent decades, a large number of nutritional/ medicinal components in BG have been purified and characterized, such as cucurbitane-type triterpenoids, linolenic acids, potato- and squash-type protease inhibitors, ribonucleases (RNase MC1 and RNase MC2), type 1 ribosome inactivating proteins/RIPs (napin- like RIP, momorcharins, and MAP30), and a type 2 RIP ( M. charantia lectin/MCL) [1,3,4]. The credited anti-diabetic, anti-HIV, and anti- tumor potentials of BG are at least partially attributed to the re- ported components [1,5,6]. RIPs are RNA glycosylases that cleave an adenine–ribose glycosidic bond within a conserved loop in the 28S ribosomal RNA which is necessary for the binding of elongation factors [7]. The representative RIP protein MAP30 was first purified by Lee- Huang and coworkers in 1990 [8] where in-depth mechanistic studies of the anti-HIV activity of MAP30 have been carried out. MAP30 was active against infection and replication of both herpes simplex virus (HSV) [9] and human immunodeficiency virus (HIV) [10,11]. For example, MAP30 could inhibit the HIV-1 infection in T lymphocytes/monocytes and repress virus replication in cells already infected, both with mechanisms associated with impedi- ment of HIV viral DNA integration [10,11]. Furthermore, MAP30 inhibited proliferation of AIDS-related lymphoma cells infected with Kaposi’s sarcoma-associated virus by modulation of different viral and cellular genes necessary for viral and cell proliferation and apoptosis [12]. Intriguingly, recombinant MAP30 produced in different expression systems, such as E. coli and squash leaves, man- ifested comparable biological activities against HIV-1, HSV, and HHV8 viruses as its native counterpart [13,14]. The anti-HIV and anti-cancer properties may be attributed to its functions as a DNA glycosylase and/or DNA apurinic/apyrimidinic lyase [11], but pre- clude its RNA N-glycosidase (ribosome inactivating) activity [15]. Besides anti-HIV activity, initial screening studies disclosed that MAP30 inhibited proliferation of tumor cells, such as brain glio- blastoma U87GM, breast carcinoma BT20, epidemoid carcinoma A431, melanoma Malme-3 M, myeloma U266, neuroblastoma SK-N-SH, prostate carcinoma DU145, and hepatoma Hep 3B cells 0304-3835/$ - see front matter Ó 2012 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.canlet.2012.05.005 ⇑ Corresponding author. E-mail address: b021770@mailserv.cuhk.edu.hk (T.B. Ng). 1 These authors contributed equally to this work. 2 Present address: Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA. Cancer Letters 324 (2012) 66–74 Contents lists available at SciVerse ScienceDirect Cancer Letters journal homepage: www.elsevier.com/locate/canlet