Micro-invasion of Epidermis caused by Substituted Anisoles

Abstract

ONE of the earliest morphological lesions to be observed in tumours of the epidermis is the protrusion of pseudopods through defective areas in the basement membrane—a phenomenon termed micro-invasion¹. Such lesions have been found in the early stages of experimental tumours induced by the local application of the carcinogen dimethylbenzanthracene to the cheek pouch epithelium of hamsters, whereas non-carcinogenic irritants failed to produce them². It therefore seems from these findings that micro-invasion may serve as an early sign of a neoplastic change in the epithelial cells and hence might be interpreted as an indication of the carcinogenicity of substances which produce it. Since our initial report of basal cell pseudopods caused by applications of 4-hydroxyanisole and 3-hydroxyanisole to guinea-pig epidermis³, we have investigated a number of related substances (Fig. 1). Some of these, notably 7C-phenyl-4-hydroxy-anisole and butylated hydroxyanisole (BHA), have been shown to cause micro-invasion.