SIS/PDGF-B expression in benign and malignant human breast lesions

Northern blots with poly(A)-selected RNAs were prepared from four primary human breast carcinomas and hybridized with a SIS/PDGF-B gene probe. High expression of a normal-sized 3.7 kb SIS/PDGF-B transcript was observed in three samples. These three carcinomas were all T3 (> 5 cm) lesions and were histologically infiltrating ductal carcinomas accompanied by moderate to marked desmoplasia. Furthermore in situ hybridization with photobiotinylated probes was performed and demonstrated that the SIS/PDGF-B expression was localized within the epithelial cells of malignant as well as benign lesions. It is possible that SIS/PDGFB expression within the epithelial cell components of nonmalignant as well as malignant breast lesions may be in part responsible for the stromal reaction.