Alterations in Galectin-3 Expression and Distribution Correlate with Breast Cancer Progression: Functional Analysis of Galectin-3 in Breast Epithelial-Endothelial Interactions

• Published in: The American journal of pathology Vol. 165; no. 6; pp. 1931 - 1941
• Main Authors: Shekhar, Malathy P.V, Nangia-Makker, Pratima, Tait, Larry, Miller, Fred, Raz, Avraham
• Format: Journal Article
• Language: English
• Published: Bethesda, MD ASIP 01.12.2004; American Society for Investigative Pathology
• Subjects: Animals; Biological and medical sciences; Breast Neoplasms - metabolism; Breast Neoplasms - pathology; Carcinoma, Intraductal, Noninfiltrating - metabolism; Carcinoma, Intraductal, Noninfiltrating - pathology; Cells, Cultured; Coculture Techniques; Disease Progression; Endothelial Cells - metabolism; Endothelial Cells - pathology; Epithelial Cells - metabolism; Epithelial Cells - pathology; Female; Galectin 3 - genetics; Galectin 3 - metabolism; Gynecology. Andrology. Obstetrics; Humans; Investigative techniques, diagnostic techniques (general aspects); Mammary gland diseases; Medical sciences; Mice; Mice, Nude; Neoplasm Invasiveness - pathology; Original Research Paper; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Peptide Hydrolases; RNA, Messenger - genetics; RNA, Messenger - metabolism; Stromal Cells - metabolism; Stromal Cells - pathology; Transplantation, Heterologous; Tumors; Umbilical Veins - metabolism; Umbilical Veins - pathology; Mammary gland diseases; Anatomic pathology; Endothelial cell; Interaction; Distribution; Tumor progression; Breast; Galectin 3; Functional analysis; Breast cancer; Mammary gland; Malignant tumor
• ISSN: 0002-9440; 1525-2191
• DOI: 10.1016/S0002-9440(10)63245-2

To define the role of galectin-3 in breast cancer progression, we have used a novel three-dimensional co-culture system that recapitulates in vivo reciprocal functional breast epithelial-endothelial cell-cell and cell-matrix interactions, and examined the expression of galectin-3 mRNA and protein in human breast tumors and xenografts. Galectin-3 is required for the stabilization of epithelial-endothelial interaction networks because immunoneutralization with galectin-3 antibodies abolishes the interactions in a dose-dependent manner. Co-culture of epithelial cells with endothelial cells results in increase in levels of secreted galectin-3 and presence of proteolytically processed form of galectin-3 in the conditioned media. In contrast, intracellular galectin-3 predominantly exists in the intact form. This difference in sensitivity to proteolytic processing of secreted versus intracellular galectin-3 probably arises from differences in accessibility of protease-sensitive sites, levels, and/or type of activated protease(s), and may be indicative of different functional roles for intact and processed galectin-3. To determine whether the proteolytically cleaved galectin-3 retains its ability to bind to endothelial cells, binding assays were performed with the full-length and matrix metallopeoteinase-2-cleaved recombinant galectin-3. Although a dose-dependent increase in binding to human umbilical vein endothelial cells was observed with both full-length and cleaved galectin-3, proteolytically cleaved galectin-3 displayed approximately 20-fold higher affinity for human umbilical vein endothelial cells as compared to the full-length protein. Examination of galectin-3 expression in breast tumors and xenografts revealed elevated levels of galectin-3 mRNA and protein in the luminal epithelial cells of normal and benign ducts, down-regulation in early grades of ductal carcinoma in situ (DCIS), and re-expression in peripheral tumor cells as DCIS lesions progressed to comedo-DCIS and invasive carcinomas. These data suggest that galectin-3 expression is associated with specific morphological precursor subtypes of breast cancer and undergoes a transitional shift in expression from luminal to peripheral cells as tumors progressed to comedo-DCIS or invasive carcinomas. Such a localized expression of galectin-3 in cancer cells proximal to the stroma could lead to increased invasive potential by inducing novel or better interactions with the stromal counterparts.