Release of cytokeratin‐18 and ‐19 fragments (TPS and CYFRA 21‐1) into the extracellular space during apoptosis

Abstract

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.

Serum CYFRA 21-1 (cytokeratin-19 fragments) is a useful tumour marker for detecting disease relapse and assessing treatment efficacy in breast cancer

“…It has been well demonstrated that breast cancer cells express fragments of cytokeratin-19 (Moll et al, 1982;Brotheric et al, 1998;Sheard et al, 2002), which is one of the various kinds of cytokeratins comprising the intermediate filaments of the cytoskeleton (Moll et al, 1982). Serum fragments of cytokeratin-19 can be detected using anti-CYFRA 21-1 antibody (Pujol et al, 1993).…”

“…Most of the epitopes that are detectable by clinically useful tumour markers such as CEA, CA 15-3, CA 19-9, and alpha-fetoprotein are glycoproteins shed from the cell surface. CYFRA 21-1 is unique in that its epitope is a polypeptide, which is most likely released following cell death (Stieber et al, 1993;Sheard et al, 2002). Elevated levels of serum CYRFA 21-1 titres have been observed in various malignancies, especially in lung cancer (Molina et al, 1994).…”

Methods and biomarkers for the diagnosis and prognosis of cancer and other diseases: Towards personalized medicine

“…The development of these tools has kept close pace with the rapid progress in basic science and applied clinical research (Table 1). In addition, laboratories have benefited Table 1 Novel biochemical markers for the ex vivo-monitoring of cell death -correlates with severity of hepatic coma -strongly correlates with biochemical marker levels for liver damage: serum hepatocyte growth factor, aspartate aminotransferase (AST), lactic dehydrogenase (LDH), and alkaline phosphatase (ALP) -negatively correlates with serum alpha-fetoprotein (AFP) and total plasma bilirubin levels Cytochrome c Neuronal damage Ahlemeyer et al (2002), Satchell et al (2005) -detected in cerebrospinal fluid -associated with inflicted traumatic brain injury, observed more frequently in female patients -detected in extracellular space upon staurosporine-induced neuronal cell death, may mediate bystander effect under these experimental conditions Caspase-1 Neuronal damage Satchell et al (2005) -detected in cerebrospinal fluid -associated with traumatic brain injury 7 -detected in extracellular space Cowan et al (2005) -participate in degradation of excess extracellular matrix during remodeling in development and disease (in vitro data) Malignancies of epithelial origin, prostate-, breast, other cancers Kramer et al (2004), Sheard et al (2002) -detected in serum and plasma -cytosolic pool of soluble full-length cytokeratin-18 released during necrosis; apoptosis is associated with significant release of caspase-cleaved cytokeratin-18 fragments, mainly the 13 kDa fragment (TSP) Malignancies of epithelial origin, prostate-, breast, other cancers Sheard et al (2002) -detected in serum and plasma, culture supernatants -∼30 kDa fragment of cytokeratin-19, called also "water-soluble cytokeratin-19 fragment" or CYFRA 21-1, is an indicator in vivo apoptotic cell death -generation of CYFRA 21-1 during apoptosis, can be inhibited by caspase inhibitors A u t h o r ' s p e r s o n a l c o p y from the commercial availability of a wide range of reagents and kits, high-throughput strategies for screening, and highly focused training programs in medicine, laboratory sciences, clinical chemistry, pathology, and imaging. These advances have raised the expectations of investigators, technologists, trainees, and the consuming public for levels of specificity and sensitivity that bring high predictive value to a diagnostic test.…”

“…The apoptotic form of cell death, on the contrary, is a much more orderly and tightly regulated sequence of biochemical events (Brouckaert et al, 2005;Lavrik et al, 2005;Philchenkov et al, 2004). Apoptosis results in the extracellular release of a limited number of proteins including: cytochrome c (Ahlemeyer et al, 2002;Barczyk et al, 2005;Renz et al, 2001a;Satchell et al, 2005), some caspases (Cowan et al, 2005;Satchell et al, 2005), cleaved cytokeratin-18 and -19 (Sheard et al, 2002) (Table 1), and possibly a few other proteins. The apoptotic cascade can be triggered by a variety of signaling mechanisms, the death-receptor pathway (Los et al, 1995;Muzio et al, 1996) and the mitochondrial pathway (Cecconi et al, 1998;Los et al, 1999) being the most common.…”

Serum cytokeratin 18 as a biomarker for gastric cancer

“…CK18 may be a useful indicator of gastric cancer, because it is an accepted marker of cell death [14]. Several types of cell death such as apoptosis, necrosis, and autophagy have been described as a part of the ongoing disease process.…”