Release of cytokeratin-18 and -19 fragments (TPS and CYFRA 21-1) into the extracellular space during apoptosis.
Serum fragments of cytokeratins-18 and -19 (measured as TPS and CYFRA 21-1, respectively) have traditionally been considered as markers of tumor proliferation, although the evidence is scarce for a causative relationship between proliferation and levels of TPS and CYFRA 21-1. We examined whether apoptosis might produce TPS and CYFRA 21-1 fragments. MCF-7 breast cancer cells were treated with mitomycin C or agonistic anti-CD95 antibody, and levels of TPS and CYFRA 21-1 in tissue culture supernatants were compared with the frequency of cells exhibiting the following markers of cell death: intracellular cytokeratin-18 cleavage, surface staining with annexin-V, propidium iodide uptake, DNA fragmentation. Twenty-four hours after inducing apoptosis, levels of TPS and CYFRA 21-1 were elevated > or = 4-fold in culture supernatants. Elevations in TPS and CYFRA 21-1 coincided with apoptosis measured by the first three cell death markers but preceded DNA fragmentation. These mitomycin C- and CD95-mediated elevations were completely inhibited by co-incubation with the caspase inhibitors Z-VAD.fmk and Z-IETD.fmk, respectively. We conclude that TPS and CYFRA 21-1 can be abundantly released into the extracellular space during the intermediate stage of epithelial cell apoptosis.
Sheard
Michael A
MA
Laboratory of Apoptosis Research, Masaryk Memorial Cancer Institute, Zluty Kopec 7, 656 53 Brno, Czech Republic. sheard@mou.cz
Vojtesek
Borek
B
Simickova
Marta
M
Valik
Dalibor
D
D000951:Antigens, Neoplasm / Q000378:metabolism*; D017209:Apoptosis / Q000502:physiology*; D014408:Biomarkers, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology; D020169:Caspases / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism; D005260:Female; D006801:Humans; D053539:Keratin-19; D007633:Keratins / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism*; D012995:Solubility; D014407:Tumor Cells, Cultured
D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D053539:Keratin-19; D010446:Peptide Fragments; D010455:Peptides; C102012:antigen CYFRA21.1; C089984:tissue polypeptide specific antigen; D007633:Keratins; D020169:Caspases