Shed membrane vesicles and selective localization of gelatinases and MMP-9/TIMP-1 complexes.

Fisiopatologia. — Membrane vesicles, shed from in vitro cultured human breast carcinomas cells, inhibit lymphocytes proliferation.

Membrane vesicles are released by the cells of the two human breast carcinoma cell lines 8701-BC and MCF-7. Vesicles express on their surface HLA Class I molecules and tumor associated antigens and they appear to have a strong, dose dependent, inhibitory effect on thymidine incorporation by periferal lymphocytes. Inhibition is evident on both PhA stimulated or non stimulated lymphocytes. The inhibitory effect is visible after three days of culture. Vesicle addition does not cause cytotoxic effects since inhibited lymphocytes are still capable to exclude Trypan blue. No apoptoptic cells were observed.

Shedding of Membrane Vesicles Mediates Fibroblast Growth Factor-2 Release from Cells

Fibroblast growth factor-2 (FGF-2), a polypeptide with regulatory activity on cell growth and differentiation, lacks a conventional secretory signal sequence, and its mechanism of release from cells remains unclear. We characterized the role of extracellular vesicle shedding in FGF-2 release. Viable cells released membrane vesicles in the presence of serum. However, in serum-free medium vesicle shedding was dramatically down-regulated, and the cells did not release FGF-2 activity into their conditioned medium. Addition of serum to serum-starved cells rapidly induced intracellular FGF-2 clustering under the plasma membrane and into granules that colocalized with patches of the cell membrane …

Urokinase Plasminogen Activator and Gelatinases Are Associated with Membrane Vesicles Shed by Human HT1080 Fibrosarcoma Cells

Membrane vesicles are shed by tumor cells both in vivo and in vitro. Although their functions are not well understood, it has been proposed that they may play multiple roles in tumor progression. We characterized membrane vesicles from human HT1080 fibrosarcoma cell cultures for the presence of proteinases involved in tumor invasion. By gelatin zymography and Western blotting, these vesicles showed major bands corresponding to the zymogen and active forms of gelatinase B (MMP-9) and gelatinase A (MMP-2) and to the MMP-9. tissue inhibitor of metalloproteinase 1 complex. Both gelatinases appeared to be associated with the vesicle membrane. HT1080 cell vesicles also showed a strong, plasminoge…