Induction of Preneoplastic Lesions by Sodium Arsenite in Human Fetal Respiratory Epithelia in Organ-Culture

The effects of sodium arsenite (As) and N-methyl-Nʹnitro-N-nitrosoguanidine (MNNG) on epithelia of human fetal trachea and bronchiolar epithelia of human fetal lung were studied by using organ-cultured explants. In epithelium of human fetal trachea, 34 mu M MNNG induced hyperplasia, metaplasia, and dysplasia; 1 mu M As induced hyperplasia; and 3-9 mu M As induced hyperplasia and cellular atypia. In glandular epithelium of human fetal trachea, 34 mu M MNNG induced hyperplasia and metaplasia; 1 mu M As did not induce obvious changes; and 3-9 mu M As induced hyperplasia and epidermoid metaplasia with nuclear atypia. In bronchiolar epithelium of human fetal lung, the induction of dysplasia was observed for 1 mu M As. Arsenic-induced preneoplastic lesions support the conclusion of epidemiological studies that arsenic is carcinogenic 60 human lung.