Utilization of cytokeratin-based biomarkers for pharmacodynamic studies

Abstract

Cytokeratin (CK)18 is a useful serum biomarker for the determination of cell death of epithelial-derived tumors (carcinomas). ELISAs are available for caspase-cleaved CK18 (M30) released from apoptotic cells, or total CK18 (M65) released by cells undergoing cell death by any cause. These assays have been demonstrated to have prognostic or predictive utility in various types of carcinomas. Encouraging data have been reported by different investigators with regard to the potential use of CK18 as a serum efficacy biomarker for monitoring therapy efficiency in carcinoma patients. The ratio of caspase-cleaved to total CK18 can be determined conveniently in serum or plasma using commercially available ELISA kits (M30-Apoptosense and M65 ELISA, Peviva AB, Bromma, Sweden). M30:M65 ratios potentially provide information as to whether tumor cells undergo apoptosis or necrosis. However, as discussed in this review, M30:M65 ratios should be interpreted with caution and, preferably, only be applied to samples that contain significant levels of CK18. We conclude that M30 and M65 biomarkers provide both quantitative and qualitative information on carcinoma cell death.

Cytokeratin 8: The Dominant Type II Intermediate Filament Protein in Lung Cancer

“…Tumor markers targeting single type I CKs in the systemic circulation have been evaluated: e.g., CK18 as a traditional TPS, caspase-cleaved CK19 as Cyfra 21-1, and the recently developed caspase-cleaved CK18 (M30) as well as total CK18 (M65) (Kramer et al, 2004;Linder et al, 2010). While circulating type II CKs had not been reported as tumor markers targeting single CK origin, we observed that serum levels of a type II CK8 were significantly associated with tumor progression and shortened survival in patients with NSCLC.…”

“…Type I CK18 is also a good substrate for caspases as discussed earlier in this chapter. ELISAs are now available for assay of CK18 that is cleaved at Asp396 by caspases, which can be detected using M30 and M5 monoclonal antibodies (referred to as M30), and for assay of total CK18, which can be detected using M5 and M6 monoclonal antibodies (referred to as M65) (Kramer et al, 2004;Linder et al, 2010). M30-recognized circulating CK18 is released from apoptotic cells, whereas M65-recognized CK18 reflects cell death by any cause.…”

“…M30-recognized circulating CK18 is released from apoptotic cells, whereas M65-recognized CK18 reflects cell death by any cause. The ratio of caspase-cleaved to total CK18, calculated using M30-and M65-ELISAs, may provide potentially useful information regarding the mode of tumor cell death (Linder et al, 2010). The usefulness of M30 for tumor monitoring has been demonstrated by Koelink et al They determined caspase-cleaved CK18 and total CK18 levels in the plasma of 49 colorectal cancer patients, before and after surgical resection.…”

Cytokeratin 18 (CK18) and CK18 Fragments for Detection of Minimal Residual Disease in Colon Cancer Patients

“…The broad spectrum TPA test measures CKs 8, 18, and 19 concentrations, while TPS and CYFRA 21-1 assays are more specific and determine CK18 and CK 19 levels, respectively (Linder, 2007). More recently, the ratio of caspase-cleaved (M30) to total CK18 (M65), which can be assessed in the serum or plasma using commercially available enzyme-linked immunosorbent assay (ELISA) kits, has been evaluated as a biomarker for monitoring therapy efficacy in carcinoma patients (Linder et al, 2010).…”

“…Although the levels of CKs in serum of cancer patients have been widely used for monitoring progression of tumor growth and effectiveness of treatment, the mechanisms of the release of CK fragments from cells is not clear (Linder et al, 2010). Studies in patients have shown that the release of CKs by tumors is a complex process, which seems to be not simply correlated to the number of proliferating cells or to the tumor mass but may also be dependent on the rate of cell damage (Oehr et al, 1997).…”