Frequent expression of MAGE1 tumor antigens in bronchial epithelium of smokers without lung cancer

Abstract

Melanoma antigens (MAGE) are frequently expressed in lung cancer and are promising targets of anti-cancer immunotherapy. Our preliminary data suggested that MAGE may be expressed during early lung carcinogenesis, raising the possibility of targeting MAGE as a lung cancer prevention strategy. The purpose of this study was to investigate MAGE activation patterns in the airways of chronic smokers without lung cancer. MAGE-A1, -A3 and -B2 gene expression was determined in bronchial brush cells from chronic former smokers without lung cancer by reverse transcription-PCR(RT-PCR). The results were correlated with clinical parameters. The 123 subjects had a median age of 57 years, a median of 40 pack-years smoking history, and had quit smoking for at least one year prior to enrollment. Among the subjects, 31(25%), 38 (31%), and 46 (37%) had detectable MAGE-A1, -A3 and -B2 expression, respectively, in their bronchial brush samples. Expression of MAGE-A1 and -B2 positively correlated with pack-years smoking history (P=0.03 and 0.03, respectively). The frequency of expression did not decrease despite a prolonged smoking cessation period. In conclusion, MAGE-A1, -A3 and -B2 genes are frequently expressed in the bronchial epithelial cells of chronic smokers without lung cancer, suggesting that chronic exposure to cigarette smoke activates these genes even before the malignant transformation of bronchial cells in susceptible individuals. Once activated, the expression persists despite long-term smoking cessation. These data support the targeting of MAGE as a novel lung cancer prevention strategy.