Myoepithelial-specific CD44 shedding contributes to the anti-invasive and antiangiogenic phenotype of myoepithelial cells.
Myoepithelial cells surround incipient ductal carcinomas of the breast and exert anti-invasive and antiangiogenic effects in vitro through the elaboration of suppressor molecules. This study examines one putative molecule, solubilized CD44 produced by myoepithelial shedding of membrane CD44. Studies with different human myoepithelial cell lines demonstrate that myoepithelial cells express and shed both the 85-kDa standard (CD44s) and the 130-kDa epithelial (CD44v8-10) isoforms, findings further confirmed by the use of isoform-specific antibodies. PMA pretreatment enhances CD44 shedding detected by two different methods at different time points: a reduction in surface CD44 at 2 h by flow cytometry and a marked decrease in both total cellular CD44 and plasma membrane CD44 at 12 h by Western blot. This shedding is both specific for CD44 and specific for myoepithelial cells. This shedding is inhibited by the chymotrypsin inhibitors chymostatin and alpha(1)-antichymotrypsin but not by general metallo-, cysteine, or other serine proteinase inhibitors. Myoepithelial-cell-conditioned medium and affinity-purified solubilized CD44 from this conditioned medium block hyaluronan adhesion and migration of both human carcinoma cell lines and human umbilical vein endothelial cells.
Alpaugh
M L
ML
Department of Pathology, UCLA School of Medicine, Los Angeles, California 90024, USA.
Lee
M C
MC
Nguyen
M
M
Deato
M
M
Dishakjian
L
L
Barsky
S H
SH
D015703:Antigens, CD / Q000502:physiology; D001943:Breast Neoplasms; D002277:Carcinoma; D017077:Culture Media, Conditioned; D004847:Epithelial Cells / Q000166:cytology / Q000502:physiology; D005260:Female; D006801:Humans; D018960:Hyaluronan Receptors / Q000187:drug effects / Q000502:physiology*; D009361:Neoplasm Invasiveness / Q000517:prevention & control*; D009389:Neovascularization, Pathologic / Q000517:prevention & control*; D011480:Protease Inhibitors / Q000494:pharmacology; D020033:Protein Isoforms / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014415:Tunicamycin / Q000494:pharmacology
D015703:Antigens, CD; D017077:Culture Media, Conditioned; D018960:Hyaluronan Receptors; D011480:Protease Inhibitors; D020033:Protein Isoforms; D019715:Tissue Inhibitor of Metalloproteinase-1; D014415:Tunicamycin; D013755:Tetradecanoylphorbol Acetate