Objective    To study the inhibitory effect and its mechanism of sodium butyrate on human laryngeal carcinoma in nude mice.     Methods    Human laryngeal carcinoma cell line Hep-2 was seeded in the subcutaneous layer of 12 nude mice to built laryngeal carcinoma xenograft model. Then they were randomly and equally divided into 2 groups. Sodium butyrate was given in experimental group while phosphatic-buffered saline (PBS) was used in control group for 4 weeks. Tumor size and body weight of the mice were measured at regular time-intervals. The tumor

heart

liver

lungs

spleen and kidneys were removed at the end of treatment. Tumor sections were examined by electronic microscopy. TUNEL method and immunohistochemical S-P method were used for detecting the expression of Ki-67 nuclear antigen and survivin protein. The heart

liver

lung

spleen and kidney sections were examined after HE staining for assessment of toxicity.     Results    In experimental group

the volume of tumors was reduced

the area of necrosis in tumors was widened

the apoptotic rate was increased obviously and the expression level of Ki-67 nuclear antigen and survivin protein was decreased as compared with control group. During treatment

all the nude mice grew well and there were no toxic reactions. At the end of treatment

there were no abnormal changes in heart

liver

lung

spleen and kidney sections examined under light microscope.     Conclusion    Sodium butyrate can significantly inhibit the growth of human laryngeal carcinoma xenograft in nude mice. Its mechanism may be related to the apoptosis in tumor cells by inhibiting the expression of survivin protein and Ki-67 nuclear antigen. There is no toxicity to heart

liver

lungs

spleen and kidneys at a treatment dose of sodium butyrate.