THROMBOSPONDIN-1 AND THROMBOSPONDIN-2 MESSENGER-RNA EXPRESSION IN NORMAL, BENIGN, AND NEOPLASTIC HUMAN BREAST TISSUES - CORRELATION WITH PROGNOSTIC FACTORS, TUMOR ANGIOGENESIS, AND FIBROBLASTIC DESMOPLASIA

Thrombospondin-1 (TSP1) is a M(r) 450,000 extracellular matrix glycopr otein that modulates tumor growth, angiogenesis, and metastasis, Of th e five structurally different TSPs described to date, only TSP2 is sim ilar to TSP1 in terms of its molecular architecture, and TSP2 also mod ulates angiogenesis. Angiogenesis plays a relevant role in the biologi cal aggressiveness of breast cancer, and TSP1 is present in the tumor stroma (termed desmoplasia) of invasive human breast ductal carcinoma not otherwise specified (NOS), The present study was designed to ident ify and quantify TSP1 and TSP2 mRNAs in normal, benign, and neoplastic human breast tissues using the reverse transcriptase PCR technique, W e found that TSP2, like TSP1, was expressed in human breast tissues, a nd that TSP1 and TSP2 mRNA expression in invasive breast carcinoma NOS was significantly increased compared to that observed in normal and b enign tissues, The expression of TSP1 and TSP2 in invasive breast duct al carcinoma NOS did not significantly correlate with any of the progn ostic factors studied (tumor size, lymph node status, morphology, and hormone receptor status), However, when our study population was divid ed according to the quantity of tumor stroma, TSP1 (and possibly TSP2) mRNA expression and microvessel counts in desmoplastic-rich stroma of breast carcinoma NOS were significantly increased compared to those o bserved in desmoplastic-poor stromata.