EPITHELIAL-STROMAL INTERACTIONS MODULATING PENETRATION OF MATRIGEL MEMBRANES BY HPV 16-IMMORTALIZED KERATINOCYTES

The role of epithelial-stromal interactions in the progression of huma n papillomavirus-associated squamous intraepithelial lesions to invasi ve cervical cancer is poorly understood. Using the Matrigel artificial basement membrane assay as a model of keratinocyte invasion, the effe cts of selected growth factors on penetration of human papillomavirus 16-immortalized keratinocytes through Matrigel were studied. Also stud ied in this model were the effects of conditioned media from fibroblas t lines derived from normal cervical tissues (normal fibroblasts) and adjacent cervical cancer biopsies (tumor-associated fibroblasts) and f rom primary keratinocytes. Addition of basic fibroblast growth factor, transforming growth factor-alpha, and hepatocyte growth factor/scatte r factor or conditioned media from tumor-associated fibroblasts to the Matrigel resulted in near-doubling of penetration of human papillomav irus 16-immortalized keratinocytes, whereas transforming growth factor -beta, platelet derived growth factor-B, or conditioned media from pri mary keratinocytes decreased penetration 10-fold. Antibodies to basic fibroblast growth factor abrogated the stimulatory effects of conditio ned media from tumor-associated fibroblasts on keratinocyte penetratio n, whereas antibodies to transforming growth factor-beta abrogated the inhibitory effects of conditioned media from normal fibroblasts on ke ratinocyte penetration. S1 nuclease protection and enzyme-linked immun osorbent assay showed increased expression of transforming growth fact or-beta and decreased expression of basic fibroblast growth factor in normal compared with tumor-associated fibroblasts. Messenger RNA in si tu hybridization of five cervical cancer biopsies demonstrated basic f ibroblast growth factor expression in stromal cells surrounding nests of invading keratinocytes. Epithelial-stromal interactions mediated by growth factors such as transforming growth factor-beta and basic fibr oblast growth factor modulate penetration of human papillomavirus 16-i mmortalized keratinocytes through Matrigel in vitro and these interact ions may also be operative in vivo.