Cytokeratin-18 is a useful serum biomarker for early determination of response of breast carcinomas to chemotherapy.
OBJECTIVE
With a widening arsenal of cancer therapies available, it is important to develop therapy-specific predictive markers and methods to rapidly assess treatment efficacy. We here evaluated the use of cytokeratin-18 (CK18) as a serum biomarker for monitoring chemotherapy-induced cell death in breast cancer.


METHODS
Different molecular forms of CK18 (caspase cleaved and total) were assessed by specific ELISA assays. Drug-induced release of CK18 was examined from breast carcinoma cells and tissue. CK18 protein composition was examined in serum. CK18 levels were determined in serum from 61 breast cancer patients during docetaxel or cyclophosphamide/epirubicin/5-fluorouracil (CEF) therapy.


RESULTS
Caspase-cleaved CK18 molecules were released from monolayer cultures and tumor organ cultures to the extracellular compartment. CK18 was present in complexes with other cytokeratins in serum. Such CK18 protein complexes are remarkably stable, leading to favorable performance of CK18 biomarker assays for clinical investigations. Docetaxel induced increased levels of caspase-cleaved CK18 in serum from breast cancer patients, indicating apoptosis. CEF therapy led to increases predominantly in uncleaved CK18, indicating induction of necrotic cell death in many tumors. The increase in total CK18 at 24 h of the first treatment cycle correlated to the clinical response to CEF therapy (P < 0.0001).


CONCLUSIONS
Induction of necrotic cell death may explain the clinical efficacy of anthracycline-based therapy for breast carcinomas with defective apoptosis pathways. We suggest that CK18 biomarkers are useful for early prediction of the response to CEF therapy in breast cancer and may be useful biomarkers for clinical trials.
Olofsson
Maria Hägg
MH
Cancer Center Karolinska, Department of Oncology and Pathology, Karolinska Institute and Hospital, Stockholm, Sweden.
Ueno
Takayuki
T
Pan
Yang
Y
Xu
Ren
R
Cai
Feng
F
van der Kuip
Heiko
H
Muerdter
Thomas E
TE
Sonnenberg
Maike
M
Aulitzky
Walter E
WE
Schwarz
Stephan
S
Andersson
Elina
E
Shoshan
Maria C
MC
Havelka
Aleksandra Mandic
AM
Toi
Masakazu
M
Linder
Stig
S
D000970:Antineoplastic Agents / Q000494:pharmacology*; D014408:Biomarkers, Tumor; D001943:Breast Neoplasms / Q000097:blood / Q000188:drug therapy* / Q000235:genetics*; D045744:Cell Line, Tumor; D000077143:Docetaxel; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D053538:Keratin-18 / Q000097:blood* / Q000235:genetics*; D008957:Models, Genetic; D009336:Necrosis; D009362:Neoplasm Metastasis; D015203:Reproducibility of Results; D043823:Taxoids / Q000494:pharmacology; D013997:Time Factors; D016896:Treatment Outcome
D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; D053538:Keratin-18; D043823:Taxoids; D000077143:Docetaxel