title: Localization of thymosin beta-4 in tumors.
abstract: Overexpression of thymosin beta-4 has been linked to malignant progression but the localization of this polypeptide within tumors is incompletely known. We therefore examined breast cancers for thymosin beta-4 using immunofluorescence. Reactive cells were identified with monoclonal cell marker antibodies. A very heterogeneous staining pattern for thymosin beta-4 was observed. Thus, while leukocytes and macrophages showed intense reactivity for this polypeptide, cancer cells, and endothelial cells showed a much more variable reactivity. A similar heterogeneous staining was observed also in colorectal carcinomas. The degree of staining of breast cancer cells for thymosin beta-4 correlated neither to histological grade nor to endothelial cell staining. However, there was a tendency toward correlation (P = 0.07) between staining of endothelial cells and histological grade. Treatment of cultured breast cancer cells (SK-BR-3) with 1-4 microg thymosin beta-4/mL significantly increased cell numbers, as determined by MTT-assays. These data reveal an unexpected cellular heterogeneity of thymosin beta-4 expression in breast and colonic carcinomas and suggest that local release of this polypeptide in the tumor microenvironment may modulate tumor behavior.
authors.affiliation: Anatomy and Cell Biology, IBHV, Faculty of Life Sciences, University of Copenhagen, Gronnegaardsvej 7, DK-1870 Frederiksberg C, Denmark. lail@life.ku.dk
authors.forename: Lars-Inge
authors.initials: LI
authors.lastname: Larsson
authors.forename: Susanne
authors.initials: S
authors.lastname: Holck
mesh_terms: D001943:Breast Neoplasms / Q000473:pathology*; D002467:Cell Nucleus / Q000473:pathology; D015179:Colorectal Neoplasms / Q000473:pathology*; D003593:Cytoplasm / Q000473:pathology; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D007633:Keratins / Q000032:analysis; D007962:Leukocytes / Q000166:cytology / Q000473:pathology; D013947:Thymosin / Q000032:analysis*; D000099201:Thymosin beta(4)
chemical_list: D007633:Keratins; D013947:Thymosin; D000099201:Thymosin beta(4)