Dillenia suffruticosa dichloromethane root extract induced apoptosis towards MDA-MB-231 triple-negative breast cancer cells

Jhi Biau Foo, Latifah Saiful Yazan, Yin Sim Tor, Agustono Wibowo, Norsharina Ismail, Nurdin Armania, Yoke Kqueen Cheah, Rasedee Abdullah

Dillenia suffruticosa is traditionally used for treatment of cancerous growth including breast cancer in Malaysia. Dillenia suffruticosa is a well-known medicinal plant in Malaysia for the treatment of cancer. Nevertheless, no study has been reported the cytotoxicity of this plant towards MDA-MB-231 triple-negative breast cancer cells. The present study was designed to investigate the mode of cell death and signaling pathways of MDA-MB-231 cells treated with dichloromethane Dillenia suffruticosa root extract (DCM-DS). Extraction of Dillenia suffruticosa root was performed by the use of sequential solvent procedure. The cytotoxicity of DCM-DS was determined by using MTT assay. The mode of cell death was evaluated by using an inverted light microscope and flow cytometry analysis using Annexin-V/PI. Cell cycle analysis and measurement of reactive oxygen species level were performed by using flow cytometry. The cells were treated with DCM-DS and antioxidants α-tocopherol or ascorbic acid to evaluate the involvement of ROS in the cytotoxicity of DCM-DS. Effect of DCM-DS on the expression of antioxidant, apoptotic, growth, survival genes and proteins were analysed by using GeXP-based multiplex system and Western blot, respectively. The cytotoxicity of compounds isolated from DCM-DS was evaluated towards MDA-MB-231 cells using MTT assay. DCM-DS induced apoptosis, G2/M phase cell cycle arrest and oxidative stress in MDA-MB-231 cells. The induction of apoptosis in MDA-MB-231 cells by DCM-DS is possibly due to the activation of pro-apoptotic JNK1 and down-regulation of anti-apoptotic ERK1, which in turn down-regulates anti-apoptotic BCL-2 to increase the BAX/BCL-2 ratio to initiate the mitochondrial apoptotic pathway. The cell cycle arrest in DCM-DS-treated MDA-MB-231 cells is possibly via p53-independent but p21-dependent pathway. A total of 3 triterpene compounds were isolated from DCM-DS. Betulinic acid appears to be the most major and most cytotoxic compound in DCM-DS. The data suggest the potential application of DCM-DS in the treatment of triple-negative breast cancer.