BACKGROUNDFragile histidine triad (FHIT) is a candidate tumor suppressor gene. Aberrant expression of FHIT has been observed in multiple carcinomas induced by environmental carcinogens, especially in lung cancer. In this study, the expression of FHIT protein in lung cancer progression tissue microarray was detected and their roles in oncogenesis and progression of lung cancer were discussed.

METHODSThe expression of FHIT protein in tissue microarray with 270 cores was detected by SP immunohistochemistry method, in which there were 89 cases of primary lung cancer, 12 cases of lymph node metastasis of lung cancer, 12 cases of precancerous lesion and 10 cases of normal lung tissue, and the clinicopathological features of lung cancer were analyzed.

RESULTSThe expression of FHIT was localized in the cytoplasm. Loss of FHIT expression in primary cancers, precancerous lesion and lymph node metastasis of lung cancer was 46.1%, 41.7% and 50.0% respectively, while 0 in 10 cases of normal tissues. A significant difference of FHIT expression was observed among four groups (P < 0.05). Loss of FHIT expression in precancerous lesion, primary lung cancer and lymph node metastasis of lung cancer was significantly higher than that in normal lung tissue (P < 0.05). The difference among precancerous lesion, primary lung cancer and lymph node metastasis of lung cancer groups was not statistically significant (P > 0.05). Loss of FHIT expression was related to tumor histologicol types, degree of cell differentiation and the smoking history of patients (P < 0.05), but not to sex, age, gross appearance types, TNM stages, or lymph node metastasis (P > 0.05).

CONCLUSIONSThe protein expression level of FHIT is reduced in primary cancers and precancerous tissues, especially in most squamous cell carcinomas, poorly differentiated group and the patients with a smoking history. These results indicate that loss of FHIT expression might correlate with carcinogenesis, development of lung cancer and the carcinogenesis induced by smoking.