Augmented expression of endothelin-1, endothelin-3 and the endothelin-B receptor in breast carcinoma

Aims: Endothelins (ETs) are peptides expressed in many tumours which may st imulate angiogenesis and desmoplasia. Because ETs have not been extensively studied mammary neoplasia, we assessed ET protein and mRNA expression and receptor mRNA expression in normal and neoplastic breast tissues. Methods and results: Tissues from five normal breasts, six fibroadenomas, s even ductal carcinomas in situ (DCIS) and 25 invasive carcinomas were stain ed with anti-ET-1 and anti-ET-3 antibodies and analysed using a grading sys tem. ET-1, ET-3, ETA and ETB mRNA expression was assessed by quantitative R T-PCR from eight carcinomas and five normals. Weak staining for ET-1 and ET -3 was detected in all normals. Moderate to strong staining was seen in 72% and 64% of carcinomas for ET-1 and ET-3, respectively. Most fibroadenomas showed weak positivity for ET-1 (83%) and ET-3 (67%). ET-1 and ET-3 mRNA le vels were upregulated in carcinomas compared with normal breast. No ETA mRN A was not detected in any tissue. ETB mRNA was detected in normal breast an d was increased in carcinomas. Conclusion: These results suggest that the ET system is altered in breast c arcinomas and this may be of importance in the progression from in-situ to invasive carcinoma.