title: Haptoglobin-beta chain defined by monoclonal antibody RM2 as a novel serum marker for prostate cancer.
abstract: In our previous study, monoclonal antibody RM2, established toward the glycosyl epitope, reflected grade of malignancy of prostate cancer cells whereas RM2 reactivity to benign glands was negative or weak. RM2 reactivity was also detected in stroma, suggesting the glycoprotein RM2 recognizes could be released into the bloodstream. Then, we explored RM2 reactivity to sera of early prostate cancer. We compared RM2 reactivity to sera between 62 patients with early prostate cancer and 43 subjects with benign prostatic disease, and examined RM2 reactivity before and after radical prostatectomy in 15 patients by Western blotting. We also examined RM2 reactivity to sera of the other urogenital cancers. RM2 reactivity was significantly enhanced on a serum glycoprotein with molecular mass approximately 40 kDa, hereby termed GPX, in the patients with early prostate cancer when compared with those with benign prostatic disease (p < 0.0001). Setting an appropriate cutoff level, RM2 reactivity to GPX for detection of prostate cancer had sensitivity of 87% and specificity of 84%, respectively. Furthermore, the level of RM2 reactivity significantly decreased after radical prostatectomy (p = 0.006). However, increased RM2 reactivity to GPX was also observed in the other urogenital cancers. The proteomics approach identified GPX as haptoglobin-beta chain and RM2 showed preferential reactivity toward haptoglobin-beta chain derived from prostate cancer when compared with polyclonal anti-haptoglobin antibody. Haptoglobin-beta chain defined by RM2 is a novel serum marker that may be useful for detection of early prostate cancer when coupled with prostate-specific antigen because it is not specific to prostate cancer.
authors.affiliation: Department of Urology, Tohoku University, Graduate School of Medicine, Aoba-ku, Sendai, Japan. ssaito@uro.med.tohoku.ac.jp
authors.forename: Seiichi
authors.initials: S
authors.lastname: Saito
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Murayama
authors.forename: Yuzhuo
authors.initials: Y
authors.lastname: Pan
authors.forename: Takenobu
authors.initials: T
authors.lastname: Taima
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Fujimura
authors.forename: Kimie
authors.initials: K
authors.lastname: Murayama
authors.forename: Martin
authors.initials: M
authors.lastname: Sadilek
authors.forename: Shin
authors.initials: S
authors.lastname: Egawa
authors.forename: Seiji
authors.initials: S
authors.lastname: Ueno
authors.forename: Akihiro
authors.initials: A
authors.lastname: Ito
authors.forename: Shigeto
authors.initials: S
authors.lastname: Ishidoya
authors.forename: Haruo
authors.initials: H
authors.lastname: Nakagawa
authors.forename: Masanori
authors.initials: M
authors.lastname: Kato
authors.forename: Makoto
authors.initials: M
authors.lastname: Satoh
authors.forename: Mareyuki
authors.initials: M
authors.lastname: Endoh
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Arai
mesh_terms: D000368:Aged; D000911:Antibodies, Monoclonal / Q000097:blood; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000097:blood* / Q000276:immunology; D014408:Biomarkers, Tumor / Q000097:blood* / Q000276:immunology; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D006242:Haptoglobins / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000097:blood; D011468:Prostatectomy; D011470:Prostatic Hyperplasia / Q000097:blood / Q000276:immunology; D011471:Prostatic Neoplasms / Q000097:blood* / Q000276:immunology* / Q000601:surgery; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D000911:Antibodies, Monoclonal; D015295:Antigens, Tumor-Associated, Carbohydrate; D014408:Biomarkers, Tumor; C485359:HP protein, human; D006242:Haptoglobins; C500697:RM2 antigen, human; D017430:Prostate-Specific Antigen