Arsenic trioxide induces apoptosis of oesophageal carcinoma in vitro

The arsenic compounds in traditional Chinese medicine have been recorded to have therapeutic effects on the treatment of psoriasis, syphilis, rheumato sis and a number of malignant tumours. Recent studies showed that arsenic t rioxide can induce clinical remission in patients with acute promyelocytic leukemia, including those who have relapsed after retinoic acid treatment. However, the mechanism of how arsenic trioxide targets tumour cells is not clearly understood. We have examined the effects of arsenic trioxide on oes ophageal carcinoma cell line EC8712. Our results demonstrated that the grow th and survival of tumour cells were markedly inhibited by arsenic trioxide . The half dose effect (ED50) was at the concentration of 1 mu M. Electron microscopic study demonstrated that EC8712 tumour cells treated with arseni c trioxide display a typical morphological appearance of apoptosis, includi ng chromatin condensation and fragmentation of the nuclei. In contrast, no apoptotic features were observed in tumour cells without arsenic trioxide t reatment. TUNEL assay also showed the biological features of apoptosis in c ells treated with arsenic trioxide. Flow cytometry analyses showed that apo ptotic peak was identified in arsenic trioxide treated cells but not in the control. Apoptotic cells in arsenic trioxide treated group account for 35% of total cell populations after three days treatment at a dose of 3 mu M. In short, our results suggested that the anticancer effect of arsenic triox ide is due, at least in part, to the induction of apoptosis in cancer cells .