Discovery and identification of alpha-defensins as low abundant, tumor-derived serum markers in colorectal cancer.
OBJECTIVE
Although colorectal cancer is one of the best characterized tumors with regard to the multistep genetic progression, it remains one of the most frequent and deadly neoplasms in Western countries. This is mainly due to the fact that, up to now, no clinically relevant serum markers could be established in an early routine diagnostic procedure.


METHODS
We comparatively analyzed microdissected normal and tumorous colonic epithelium by ProteinChip technology to detect proteins specific for the tumor directly in the tissue. Immunohistochemistry (IHC) was used for the in situ localization of the discovered proteins, and an ELISA was performed to quantify these proteins in serum.


RESULTS
By this approach, we found and identified alpha-defensins 1-3 (HNP1-3) to be more highly expressed in the tumor than in normal epithelium. These findings could be confirmed by IHC. Detection of these peptides in the corresponding serum samples was subsequently performed with ELISA, resulting in an average sensitivity of 69% and specificity of 100% for the recognition of colorectal cancer when using the HNP1-3 level in the serum of the patients.


CONCLUSIONS
The direct analysis of microdissected tissue for the discovery of tumor-specific markers followed by the specific detection of these markers in serum by antibody-based methods proved to be a successful strategy in this study. Therefore, we can conclude that these promising markers would not have been found in serum without the information gained through the analysis of microdissected tissue by ProteinChip technology.
Melle
Christian
C
Core Unit Chip Application, Institute of Human Genetics and Anthrology, Jena, Germany.
Ernst
Günther
G
Schimmel
Bettina
B
Bleul
Annett
A
Thieme
Heike
H
Kaufmann
Roland
R
Mothes
Henning
H
Settmacher
Utz
U
Claussen
Uwe
U
Halbhuber
Karl-Jürgen
KJ
Von Eggeling
Ferdinand
F
D000236:Adenoma / Q000378:metabolism* / Q000473:pathology*; D000595:Amino Acid Sequence; D014408:Biomarkers, Tumor / Q000097:blood / Q000378:metabolism*; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000473:pathology*; D042241:Early Diagnosis; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000378:metabolism / Q000473:pathology; D042282:Microdissection; D008969:Molecular Sequence Data; D040081:Protein Array Analysis; D023084:alpha-Defensins / Q000097:blood / Q000235:genetics / Q000378:metabolism*
D014408:Biomarkers, Tumor; D023084:alpha-Defensins; C406413:human neutrophil peptide 1; C406416:human neutrophil peptide 2; C406427:human neutrophil peptide 3