INDUCTION OF SQUAMOUS METAPLASIA IN ORGAN-CULTURES OF HAMSTER TRACHEA BY NATURALLY-OCCURRING AND SYNTHETIC-FIBERS

  • 1 January 1983
    • journal article
    • research article
    • Vol. 43  (10) , 4906-4912
Abstract
Asbestos exhibits many properties of classical tumor promoters. These characteristics include the ability to stimulate proliferation and inhibit normal differentiation of cells. In organ cultures of trachea, crocidolite and amosite asbestos stimulate squamous metaplasia, a pathological process in which a rapidly proliferating squamous epithelium replaces the normal epithelium. The induction of metaplasia may depend upon the fibrous nature of asbestos. Accordingly, several naturally occurring and synthetic fibrous materials and their nonfibrous analogs were assessed for their ability to induce metaplastic changes in tracheal mucosa of the Syrian hamster. Exposure to both crocidolite asbestos and fiberglass resulted in significant increases (P < 0.05) in squamous metaplasia over a range of dosages (1.0, 4.0, 16.0 mg/ml). Attapulgite (palygorskite) and both long- and short-fiber preparations of chrysotile asbestos had similar but less marked effects. Nonfibrous analogs of each material (riebeckite, antigorite, and glass particles) failed to produce metaplasia. Asbestos, and fibrous materials in general, appear to stimulate squamous metaplasia because of their fibrous geometry.