Role of Tumor Collagenase Stimulating Factor in Breast Cancer Invasion and Metastasis.

Abstract

Abstract : Tumor Collagenase Stimulating Factor (TCSF) is a 58 kDa glycoprotein identified in the plasma membrane of cancer cells which induces fibroblasts to produce Matrix Metalloproteinases (MMPs). Using immunohistochemical techniques, we have characterized the cellular localization of TCSF as compared to gelatinase A in human breast tumor tissue. Antibodies to TCSF reacted strongly with noninvasive and invasive cancer cells with intense staining of the plasma membrane. Normal appearing breast ducts also stained positively with anti-TCSF antibody. To distinguish between cells producing TCSF and gelatinase A, we performed in situ hybridization (ISH) using specific radiolabeled RNA antisense probes. TCSF mRNAs were detected in both noninvasive and invasive ductal cancer cells and in premalignant breast lesions, but not in normal mammary ducts. Gelatinase A mRNA was expressed by peritumoral fibroblasts, but not by cancer cells. The discrepancy between immunolocalization and ISH data suggests a long half-life for TCSF protein in cells. Human TCSF has been expressed as a fusion protein with glutathione-S-transferase in the prokaryotic pGEX vector. The 28 kDa noglycosylated fusion protein was biologically inactive. In contrast, CHO cells transfected with human TCSF cDNA produced TCSF that was post-translationally processed to a 58 kDa biologically active protein which stimulated fibroblast production of MMPs, but not TIMP-1.