Arsenic Trioxide Induced Differentiation and Apoptosis in Human Nasopharyngeal Carcinoma Xenografts in BALB/C Nude Mice

摘要

Objective: To study the effect of arsenic trioxide (As_2O_3) on human poorly differentiated na-sopharyngeal cancer cell line, CSNE-1, in vivo and its possible mechanism of action. Methods: CSNE-1 cells were established as xenografts in BALB/C nude mice. The tumor-bearing mice were treated with As_2O_3 at the dose of 5 mg/kg every day. The tumor growth was observed by tumor-growth curve. Morphologic changes were studied under light microscopy and electron microscopy. TUNEL was used to detect apoptosis. The expression of PCNA, p53, Bcl-2 and Bax were determined by immunohistochemistry. Results: The cell growth and proliferate activity were significantly inhibited by As_2O_3 at the dose of 5 mg/kg every day. Morphologic changes such as the formation of keratinization of tumor cells, decreased ratio of nuclear/cytoplasm, increased organelle and plasmic fibril in cytoplasm were identified. Cytodesma, desmo-somes and micro-process were seen under light microscopy and transmission electron microscopy, which revealed that the cancer cells underwent differentiation. In addition, remarkable cell apoptosis were observed by TUNEL assay. Over expression of p53 and Bax was detected in the As_2O_3 treatment group when compared with control group. Conclusion: As_2O_3 inhibited proliferation of human poorly differentiated nasopharyngeal cancer cell CSNE-1 by inducing differentiation and apoptosis, which may be related to the up-regulation of p53 and Bax expression.