Matrigel㤠invasion and migration of capillary endothelial cells are blocked by Tunicamycin a glycosylation inhibitor

Abstract

Angiogenesis is a hall mark of breast tumor growth, progression and metastasis, and requires a critical balance between pro‐ and anti‐angiogenic factors. Our laboratory has been studying the key issue(s) of protein N‐glycosylation to regulate angiogenesis and the capillary invasion. We have observed that (i) eFactor VIIIC (a Mr 270 kDa asparagine‐linked glycoprotein) expression precedes capillary endothelial cell proliferation; and (ii) the presence of anti‐Factor VIIIC monoclonal antibody makes cells less invasive. The role of eFactor VIIIC N‐glycans on tissue invasion was then tested in cells treated with tunicamycin. Considerable inhibition of Matrigel™ invasion raised a question of matrix metalloproteinases (MMPs) and analyzed after treating cells with tunicamycin (1μg/ml). The expression of MMP‐9, MMP‐2 and TIMP‐2 was quantified by western blotting. MMP‐9 and MMP‐2 were down‐regulated but TIMP‐2 was upregulated. This was supported by QRT‐PCR and gelatin zymography. To verify the effect in vivo we have used Matrigel™ implants in nude mice and observed reduced number of blood vessels following tunicamycin treatment. Quantitative assessment of paraffin sections of the plugs histologically or immunohistochemically for CD34 and CD144 confirmed reduced microvessel density as well. Cell migration was also inhibited. We conclude that tunicamycin targets tissue invasion and cell migration, and eliminate breast tumor growth. Supported by NIH U54‐CA096297 and Komen for the Cure BCTR06582 (DKB), and NIH/NCRR/RCMI G12‐RR03035 (KB).