Detection of micro invasion during progression in preneoplastic human breast xenograft model

Xenografted MCF10AT cell lines develop regions resembling human proliferative breast disease including atypical hyperplasia and carcinoma in situ (CIS). The lesions are truly preneoplastic because progression to invasive carcinoma occurs. Sporadic, stepwise progression produces xenografts in which relatively normal ducts, hyperplastic ducts, CIS, and invasive carcinoma may coexist. However, early invasive events are difficult to discern. A silver stain that identifies basement membrane due to the content of glycoprotein was used to define areas of invasiveness. The method confirms the progressive nature of the xenograft model, identifies micro invasive fronts, and allows definitive classification of lesion components.