Identification of the decay-accelerating factor CD55 as a peanut agglutinin-binding protein and its alteration in non-small cell lung cancers.
OBJECTIVE
Peanut agglutinin (PNA) recognizes tumor-associated carbohydrates. In this study, we aimed to identify the core protein harboring PNA-binding sugars in the human lung and to explore the relationship with the pathology of primary non-small cell lung cancers (NSCLC).


METHODS
PNA lectin blotting was used to detect PNA-binding proteins in the microsomal fraction of lung tissue from 24 patients with NSCLC. The 55- to 65-kDa core peptide PNA-binding protein was characterized by enzymatic treatment and identified by immunoprecipitation and affinity chromatography. The expression level and increase in size of the 55- to 65-kDa PNA-binding protein/decay-accelerating factor (DAF) were compared between normal and tumor regions of the tumor tissue by Western blotting and quantitative PCR.


RESULTS
The 55- to 65-kDa PNA-binding protein was observed in human lung. This was a glycosylphosphatidylinositol-anchored membrane protein carrying O-linked carbohydrates. This core protein was identified as DAF, one of the complementary regulatory proteins. DAF was enlarged to 65 to 75 kDa in NSCLC tumor lesions due to sialylation in the sugar moiety. At the transcription level, DAF levels were significantly lower in tumor regions, suggesting its down-regulation in NSCLC cells.


CONCLUSIONS
DAF was identified as a new PNA-binding protein in the human lung. The down-regulation and heavy sialylation of DAF was associated with pathology in NSCLC, and these alterations make this protein a potential marker for NSCLC.
Higuchi
Mitsunori
M
Department of Surgery I, Fukushima Medical University School of Medicine, and Fukushima Red Cross Hospital, Fukushima, Japan.
Endo
Yuichi
Y
Suzuki
Hiroyuki
H
Osuka
Fumihiko
F
Shio
Yutaka
Y
Fujiu
Koichi
K
Kanno
Ryuzo
R
Oishi
Akio
A
Fujita
Teizo
T
Gotoh
Mitsukazu
M
D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis*; D015153:Blotting, Western; D018958:CD55 Antigens / Q000378:metabolism*; D002289:Carcinoma, Non-Small-Cell Lung / Q000378:metabolism* / Q000473:pathology; D002846:Chromatography, Affinity; D005260:Female; D006801:Humans; D047468:Immunoprecipitation; D008175:Lung Neoplasms / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011975:Receptors, Mitogen / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D014408:Biomarkers, Tumor; D018958:CD55 Antigens; D011975:Receptors, Mitogen; C038223:peanut agglutinin receptor