Evidence for Oldenlandia diffusa-evoked cancer cell apoptosis through superoxide burst and caspase activation.
OBJECTIVE
Oldenlandia diffusa (Bai Hua She She Cao) is one of the herbs most commonly used in traditional Chinese medicine for treating cancer. Various studies using the herb alone or in combination with other therapy plans have evidenced the effectiveness of the herb in the management of cancers of different tissue origin. However, the mechanisms underlying its anti-cancer activity are unknown. In the present study, we attempted to investigate the apoptotic activity of crude extracts of the herb as well as the possible molecular pathways.


METHODS
We incubated human promyelocytic leukemia cell line HL60 cells with ethanol or aqueous extracts of the herb, and determined the levels of intracellular superoxide at 2 and 4 hours as well as caspase activity at 3, 6 and 8 hours using photospectrometry. Cancer cell survival and apoptosis were quantified at 24 hours by using MTT and flow cytometry analyses respectively.


RESULTS
We found that it dose-dependently inhibited the cancer cell growth in MTT assay. Flow cytometry analysis revealed that it elicited significant production of sub-G(1) population of the cells, indicating the extract-evoked cell apoptotic death. The LD(50) of the ethanol extract was estimated to be approximately 320 microg/ml. Moreover, treatment of the cancer cells with the ethanol component markedly increased the production of superoxide within few hours. Significant elevation in the protease activities of caspases-2 and -3 were detected at as early as 3 and 6 hours respectively.


CONCLUSIONS
Our results show that the ethanol extract of the herb effectively evokes cancer cell apoptosis, possibly through burst-mediated caspase activation.
Yadav
Sanjiv Kumar
SK
Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597.
Lee
Shao Chin
SC
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D053143:Caspase 2 / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D020169:Caspases / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D018922:HL-60 Cells; D006801:Humans; D032067:Oldenlandia / Q000737:chemistry*; D013482:Superoxide Dismutase / Q000378:metabolism*
D000972:Antineoplastic Agents, Phytogenic; D004365:Drugs, Chinese Herbal; D013482:Superoxide Dismutase; D053143:Caspase 2; D053148:Caspase 3; D020169:Caspases