Latifah Saiful Yazan et al, /J. Pharm. Sci. & Res. Vol.2(4), 2010, 197-207 197 BCL-2 was Downregulated in G2/M-Arrest Breast Cancer Cells MCF-7- Treated with Nordamnacanthal Latifah Saiful Yazan*, 1,2 , Norsyafini Ishak 2 , Nordin Haji Lajis 3 1 Laboratory of Molecular Biomedicine, Institute of Bioscience, 2 Department of Biomedical Science, Faculty of Medicine and Health Sciences, 3 Natural Product Laboratory, Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor Abstract: ISSN:0975-1459 Nordamnacanthal, an anthraquinone extracted from the root of Morinda elliptica has cytotoxic properties towards various cancer cell lines and antitumor-promoting activities. This study was conducted to determine the effects of nordamnacanthal on the cell cycle, and the expression of Bcl-2 and Bax in breast cancer (MCF-7) and acute t- lymphoblastic leukemia (MOLT-4) cells at 50% of the total cell population underwent apoptosis. Nordamnacanthal caused 50% of MCF-7 and MOLT-4 cells underwent apoptosis at 15 µg/ml and 70 µg/ml, respectively, as analyzed by using a fluorescence microscope following staining with the acridine orange (AO) and propidium iodide (PI). The apoptotic cells exhibited nuclear fragmentation, chromatin condensation in the nucleus and membrane blebbing. Cell cycle analysis by flow cytometry indicated that nordamnacanthal arrested MCF-7 cells at the G2/M phase. For MOLT-4, no cell cycle arrest was observed. Bcl-2 and Bax were downregulated in nordamnacanthal-treated MCF-7 cells. On the other hand, expression of the proteins in MOLT-4 was not significantly different (p>0.05) from the control. In conclusion, treatment of MCF-7 cells with nordamnacanthal at the concentration that caused 50% of the total cell population underwent apoptosis, induced the G2/M arrest with downregulation of Bcl-2. Keywords: Nordamnacanthal; apoptosis; cell cycle arrest; Bcl-2 family proteins 1. Introduction: Morinda elliptica is a small plant from the Rubiaceae family also known as “mengkudu kecil”, is a native plant from Asia and Polynesia. This plant has been used in traditional folk medicine for treatment of cholera, diarrhea, piles, headache and to increase appetite (Ali et al., 2000). Roots of the plant are usually rich in anthraquinones (AQs), which most often occur as glycones and glycosides. Nordamnacanthal or 2-formyl-1,3- dihydroxyanthraquinone (C 15 H 8 O 5 ) is one of the 11 anthraquinones which has been extracted from Morinda elliptica (Nor Hadiani et al., 1997) (Figure 1). Some studies have indicated that nordamnacanthal has a number of biological properties, including antioxidant activities and antitumor effects on human B- lymphoblastoid cell lines (Jasril et al., 2003). Nordamnacanthal has also been reported to exhibit antiviral, antimicrobial and cytotoxic properties (Ali et al., 2000). The mechanisms on how the bioactive agents of this anthraquinone exert their cytotoxicity are still unknown. It could be due to the prominent chemical feature of quinones with ability to undergo redox cycling to generate reactive oxygen species which eventually cause damage to the tumor cell (Kalyanaraman et al., 1991; Schreiber et al., 1987). Figure 1: Chemical structure of nordamnacanthal (Rajendran et al., 2004) Apoptosis or programmed cell death is genetically regulated as important to balance the proliferation and maintain the correct number of cells during development and pathological condition (Thompson 1995; Wyllie et al., 1980). This mode of cell death involves the removal of cells from tissues in a systematic and deliberate manner, without the inflammatory reaction (Kerr et al., 1972). There are two major pathways involve in apoptosis and have been O O OH CHO OH