Galactosyltransferase associated with tumor in patients with ovarian cancer: factors involved in elevation of serum galactosyltransferase.

The serum level of beta1,4-galactosyltransferase (beta1,4-GalT) is increased in both malignancy and benign diseases. Galactosyltransferase associated with tumor (GAT) is one of the soluble forms of beta1,4-GalT, and is a marker of ovarian cancer with a high specificity. GAT and normal soluble beta1,4-GalT are both derived from the same membrane-bound form of the enzyme. This study investigated the mechanism of GAT elevation in patients with ovarian cancer. The serum levels of GAT and normal beta1,4-GalT were measured using specific monoclonal antibodies. In addition, nude mice bearing human ovarian cancer were used to assess the kinetics of tumor-derived enzymes. GAT and normal beta1,4-GalT were both detected in ovarian cancer patients, but only GAT reflected the tumor status. In tumor-bearing nude mice, both soluble forms of beta1,4-GalT were released from tumor cells, but the half-life of GAT was far shorter than that of normal beta1,4-GalT. Addition of serum from healthy women to colostrum (which has a high GAT content) reduced the GAT level, while adding patient serum caused a significantly smaller reduction of GAT. Addition of the serum from mouse which includes no human beta1,4-GalT to colostrum also reduced the GAT level with no significant change of total soluble beta1,4-GalT. These findings indicate that human serum contains certain factors that decrease the GAT level, but these factors are inhibited in ovarian cancer patients so that a high GAT level persists. It seems that the decrease of GAT occurs as a result of conversion into normal beta1,4-GalT.
AuthorsEiko Saitoh, Daisuke Aoki, Nobuyuki Susumu, Yasuhiro Udagawa, Shiro Nozawa
JournalInternational journal of oncology (Int J Oncol) Vol. 23 Issue 2 Pg. 303-10 (Aug 2003) ISSN: 1019-6439 [Print] Greece
PMID12851678 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)
Chemical References
  • Biomarkers, Tumor
  • RNA, Messenger
  • Galactosyltransferases
  • N-Acetyllactosamine Synthase
  • Animals
  • Biomarkers, Tumor (blood, genetics)
  • Blotting, Northern
  • Colostrum (enzymology)
  • Female
  • Galactosyltransferases (blood, genetics)
  • Humans
  • Immunoenzyme Techniques
  • Mice
  • Mice, Inbred BALB C
  • Mice, Nude
  • Middle Aged
  • N-Acetyllactosamine Synthase (blood, genetics)
  • Neoplasms, Experimental (enzymology)
  • Ovarian Neoplasms (enzymology)
  • RNA, Messenger (metabolism)
  • Tumor Cells, Cultured

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