Effect Of Artemisinin On Astrocytoma

Brain tumor is a mass of cells growing abnormally in the brain. Malignant brain tumor grows rapidly and is life threatening. More than two hundred thousands people are diagnosed each year with brain tumors. Chemotherapy involves the use of drugs to kill cancer cells. These drugs have very toxic side effects although they are effective for many types of cancers. However, current chemotherapy is not an effective treatment for brain tumors, mostly because standard drugs cannot pass through the blood-brain barrier. It has been recently suggested that artemisinin (Qing Hao Su), which has been used since antiquity to treat malaria, has anti-cancer effect. Artemisinin reacts with iron to form free radicals that kill malaria parasites. Because the rapidly growing cancer cells require more iron than normal cells, it had been speculated that they would be more susceptible to the killing effect of the drug. It had been reported that artemisinin strongly affect the growing of a number of cancer cell lines. Since artemisinin is highly permeable to blood-brain barrier to reach the brain tissue, we reasoned that there may be a possibility of using it to treat brain tumor. This project designed experiments to test the anti-cancer effect of artemisinin in vitro and in vivo. After incubation for 24 hours with dihydroartemisinin, an analog of artemisinin, it effectively killed human astrocytoma cells, the most commontype of brain tumor cell. The effect shown strong dosage dependence with EC50 of 48 micromole, similar to Temozolomide, a recent FDA approved drug for brain tumor. The same treatment had considerably less effect on normal non-cancer human fibroblast cells. Specific staining with TUNEL assay shown astrocytoma cells were undergoing apoptosis after treatment with artemisinin. The effect is poorly reversible after drug withdrawal, suggesting a strong interaction between artemisinin and its binding site of the target protein. Because the effects of many anti-cancer drugs are cell cycle dependent, we studied the effects of artemisinin while controlling the cells growth in certain phase of the cell cycle. Increased susceptibility in mitosis phase was observed, suggesting the effect of artemisinin on DNA proliferation.The effect of artemisinin on chloride channel was investigated in order to explore the mechanism of cancer selectivity. Whole cell current recordings were made by patch clamp technique. Studies were performed on human astrocytoma cells, with human non-cancer fibroblast cells used as control. The result displayed a hyperpolarizing activated chloride current was expressed only in astrocytoma cell and inhibited by the extra-cellular application of artemisinin. Western blot using specific antibody against C1C-2, a chloride channel known to be important in astrocytoma, demonstrated decreased protein expression level after artemisinin treatment.Finally, brain tumor animal model was generated to investigate whether systemic application of artemisinin can affect the tumor grown in brain. Intracerebral implantation if astrocytoma cells in to mice caused both functional and morphological alterations. Ten days after implantation, six out of ten mice shown abnormal spiky activities in EEG, indicating local damaged in the brain. Histology studies on the brain slides provided further evidence that the morphology of the hippocampus had been altered by introducing astrocytoma. I.P injection of artemisinin did not cause any observable change in the control animal. But in the brain tumor implanted animals it caused apoptosis as shown in TUNEL staining, indicating the drug can pass through blood brain barrier to affect on the tumor cells in vivo. Since artemisinin is a very safe drug that causes no known sideeffects even at high dosage, the results of this study support the possibility that artemisinin to be developed as a new-drug for the treatment of brain tumor.