RESUMEN
BACKGROUND: Melastoma malabathricum (MM) is a traditional plant used in the Borneo region. The cytotoxic effects of methanol extracts from MM leaves have been reported in a number of human cancer cell lines. However, the mode of cell death by MM has not been investigated. OBJECTIVE: We investigated the cytotoxic effects of MM in both human breast and lung cancer cell lines, MCF-7 and A549, respectively, and defined the mode of cell death. MATERIALS AND METHODS: Cell viability was measured using the 3-(4-, 5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Annexin-V/propidium iodide (PI) and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining was done to determine the mode of cell death. RESULTS: The MTT assay revealed that MM extract had an IC50 of >400 µg/ml on both cell lines at 24 h posttreatment. Flow cytometric and fluorescence microscopy analysis of Annexin-V/PI stained MM-treated cells revealed that the majority of the cells underwent secondary necrosis/late apoptosis. TUNEL assay showed that little to no DNA nicks were present in MM-treated cells, suggesting that cells have undergone secondary necrosis, not late apoptosis, at that time point. CONCLUSION: MCF-7 and A549 cells undergoes secondary necrosis 24 h post-treatment with MM extract. MM leaf extract could be a potential source for a novel anti-tumor agent for cancer therapy. SUMMARY: Melastoma malabathricum (MM) extract was toxic on human breast and lung cancer cell linesMajority of MM-treated cells died by either secondary necrosis or late apoptosis at 24 h post-treatmentTerminal deoxynucleotidyl transferase dUTP nick-end labeling assay confirmed that MM-treated cells underwent secondary necrosis, not late apoptosis. Abbreviations used: DMSO: Dimethyl sulfoxide; MM: Melastoma malabathricum; MTT: 3-(4-, 5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide; PI: Propidium iodide; TUNEL: Terminal deoxynucleotidyl transferase dUTP nick-end labeling.
