title: Matrix metalloproteinase-26 is expressed in human endometrium but not in endometrial carcinoma.
abstract: BACKGROUND
  The human matrix metalloproteinase (MMP)-26, also called matrilysin-2 or endometase, has been isolated as a matrilysin (MMP-7) homolog. Matrix metalloproteinase-26 was expressed in tissue samples from the placenta and endometrial tumors and its expression may be related to the development of endometrial carcinomas.
  
  
  METHODS
  Total RNAs were isolated from 5 endometrial carcinoma cell lines, 36 normal endometrial tissue samples, 4 hyperplasia tissue samples, and from 24 endometrial carcinoma tissue samples. Reverse transcription-polymerase chain reation (RT-PCR) was performed to detect MMP-26 mRNA expression. To identify MMP-26 mRNA localization and protein expression, we performed in situ RT-PCR and immunohistochemistry, respectively.
  
  
  RESULTS
  Reverse transcription-polymerase chain reaction analysis revealed that MMP-26 mRNA was expressed in 24 of 36 normal human endometrial tissue samples. However, MMP-26 mRNA expression was not detected in endometrial carcinoma cell lines nor in endometrial carcinoma tissue samples except for one case. Western blot analysis showed similar results. In situ RT-PCR analysis revealed that MMP-26 expression was localized in the epithelial glandular cells but faint expression was observed in the stromal cells. Subsequently, we separated endometrial tissues into epithelial glandular and stromal cells. Using RT-PCR, the purified epithelial glandular cells exhibited MMP-26 mRNA expression but the purified stromal cells did not. Immunohistochemical analyses revealed that MMP-26 protein expression is also limited to endometrial epithelial glandular cells but not to cancer cells. Therefore, MMP-26 expression is limited to normal epithelial glandular cells.
  
  
  CONCLUSIONS
  We found a significant difference in MMP-26 expression in normal and malignant endometrial tissue samples, although its function is still unknown. These data suggest that MMP-26 may be a candidate for a new tumor marker for endometrial carcinomas.
authors.affiliation: Department of Obstetrics and Gynecology, Tokyo Medical University, 6-7-1 Nishishinjuku Shinjuku-ku, Tokyo 160-0023, Japan. isaka@tokyo-med.ac.jp
authors.forename: Keiichi
authors.initials: K
authors.lastname: Isaka
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Nishi
authors.forename: Hiromi
authors.initials: H
authors.lastname: Nakai
authors.forename: Toshihide
authors.initials: T
authors.lastname: Nakada
authors.forename: Yin
authors.initials: Y
authors.lastname: Feng Li
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Ebihara
authors.forename: Masaomi
authors.initials: M
authors.lastname: Takayama
mesh_terms: D015153:Blotting, Western; D017931:DNA Primers / Q000737:chemistry; D004714:Endometrial Hyperplasia / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology; D016889:Endometrial Neoplasms / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology; D004717:Endometrium / Q000166:cytology / Q000201:enzymology*; D004789:Enzyme Activation; D005260:Female; D006801:Humans; D015151:Immunoblotting; D007124:Immunoenzyme Techniques; D020782:Matrix Metalloproteinases / Q000235:genetics / Q000378:metabolism*; D053505:Matrix Metalloproteinases, Secreted; D012333:RNA, Messenger / Q000378:metabolism; D012334:RNA, Neoplasm / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017154:Stromal Cells / Q000201:enzymology; D014407:Tumor Cells, Cultured
chemical_list: D017931:DNA Primers; D012333:RNA, Messenger; D012334:RNA, Neoplasm; C410599:MMP26 protein, human; D020782:Matrix Metalloproteinases; D053505:Matrix Metalloproteinases, Secreted