Haptoglobin-β chain defined by monoclonal antibody RM2 as a novel serum marker for prostate cancer

Seiichi Saito, Yasuko Murayama, Yuzhuo Pan, Takenobu Taima, Tsutomu Fujimura, Kimie Murayama, Martin Sadilek, Shin Egawa, Seiji Ueno, Akihiro Ito, Shigeto Ishidoya, Haruo Nakagawa, Masanori Kato, Makoto Satoh, Mareyuki Endoh, Yoichi Arai

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)


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 ∼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-β chain and RM2 showed preferential reactivity toward haptoglobin-β chain derived from prostate cancer when compared with polyclonal anti-haptoglobin antibody. Haptoglobin-β 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.

Original languageEnglish
Pages (from-to)633-640
Number of pages8
JournalInternational Journal of Cancer
Issue number3
Publication statusPublished - 2008 Aug 1


  • Haptoglobin
  • Prostate cancer
  • RM2
  • Serum marker


Dive into the research topics of 'Haptoglobin-β chain defined by monoclonal antibody RM2 as a novel serum marker for prostate cancer'. Together they form a unique fingerprint.

Cite this