Abstract: BACKGROUND ＆ AIM: To study the correlation between the level of Cap43 expression and histological pattern in hunman lung cancer. MATERIALS AND METHODS: The method of immunohistochemistry was used to detect Cap43 expression in 79 lung cancer specimens and western blot was used to detect its expression in 28 fresh lung cancer specimens and their surrounding normal controls.The results were semiquantitatively analyzed by image analysis systems. RESULTS: Immunohistochemistry staining revealed the distribution of Cap43 was mainly in cell cytoplasm.However,parts of the proteins were in the nucleus. Cap43 expression in lung cancer was obviously higher than normal controls (P<0.05). It was also found that Cap43 expression in patient with adenocarcinoma was higher than those with squamous cell carcinoma(P<0.01). Western blot also showed high expression of cap43 in lung cancer. Cap43 expression in mucoid adenocarcinoma was significantly higher than the other pathological types of lung cancer. (P<0.01).It was shown that the less the lung cancer differentiated, the higher the Cap43 expression was(P<0.05). Two detection methods together demonstrated Cap43 expression in normal controls and small cell lung cancers was very low. The positive rate of western blot(82.14％) was higer than immunohistochemistry(69.62％),but the two detection methods were not significantly different(P>0.05). CONCLUSION: Cap43 was highly expressed in non_small cell lung cancer and the level of expression was closely correlated with the histological pattern of tumor.

Key words: lung cancer, Cap43, semiquantitative analysis