STROMAL EXPRESSION OF C-ETS1 TRANSCRIPTION FACTOR CORRELATES WITH TUMOR INVASION

The stroma reaction has an important role in tumor growth, invasion, a nd metastasis. In various invasive human carcinomas, as well as in a m ouse model for tumor invasion, transcripts encoding the transcription factor c-Ets1 were detected within stromal fibroblasts, whereas they w ere absent in epithelial tumor cells. This expression of c-Ets1 was of ten increased in fibroblasts directly adjacent to neoplastic cells. En dothelial cells of stromal capillaries were also positive for c-Ets1 e xpression. In contrast, fibroblasts of corresponding noninvasive lesio ns and of normal tissues were consistently negative. In cultured human fibroblasts stimulated by basic fibroblast growth factor and tumor ne crosis factor alpha, the expression of c-Ets1 correlated with the accu mulation of transcripts for potential target genes, collagenase-1 and stromelysin-1. The same correlation was observed in some of the invasi ve carcinomas investigated. These results suggest that c-Ets1 particip ates in the regulation of tumor invasion in vivo.