Investigation of aloe-emodin and Aloe vera gel extract on apoptosis dependent pathways in leukemia and lymphoma cell lines

Background and Aims: The present study was designed to evaluate the mechanism of cytotoxic effects of aloe-emodin relative to Aloe vera gel extract (AVG) on chronic myelogenous leukemia K562 and Burkitt's lymphoma P3HR-1 cell lines. Methods: Cytotoxicity tests were assessed by tetrazolium bromide (MTT) assay. Annexin V-FITC/PI labelling was used for apoptosis/necrosis evaluation and western blotting for apoptotic molecules measurement. Results: It was shown that, AE has cytotoxic activity againts K562 and P3HR-1 cells with an [IC.sub.50] value of 60.9 [micro]M and 28 [micro]M, respectively. AVG was found cytotoxic on K562 cells with an [IC.sub.50] value of 243.2 [micro]g/mL and ineffective on P3HR-1 cells. The ratio of apoptotic cells (46.7%) was high in only K562 cells after AVG treatment. The percentage of apoptotic cells (K562=34.1, P3HR-1=38.8) was higher than necrotic cells (K562=11.9, P3HR-1=16.6) after AE treatment. The main apoptosis pathway in both cell lines was found to be through caspase-3 and caspase-9 activations after AE treatment, caspase-8 was also activated in K562 cells but suppressed in P3HR-1 cells. Likewise caspase-9 was activated in K562 cells after AVG treatment. Conclusion: These results suggest that AE and AVG realized cell death activating apoptotic mechanisms in K562 and P3HR-1cells through extrinsic and intrinsic pathways. Keywords: Aloe vera, aloe-emodin, cytotoxicity, leukemia, lymphoma, apoptosis, caspases