Overexpression of RGC-32 in colon cancer and other tumors

Exp Mol Pathol. 2005 Apr;78(2):116-22. doi: 10.1016/j.yexmp.2004.11.001. Epub 2005 Jan 5.


Tumors often exhibit deregulation of the cell cycle and overexpression of cyclins and cyclin-dependent kinases (CDKs). Response gene to complement (RGC)-32 is a substrate and regulator of CDC2 and its overexpression induces cell cycle activation. We investigated RGC-32 mRNA and protein expression in tumors with special emphasis in colon carcinoma. By using an expression array technique we found that 19% of tumor tissues showed increased RGC-32 mRNA expression over the levels of corresponding normal tissues. On the other hand, an increased RGC-32 protein was found in 70% of colon adenocarcinoma samples tested. In colon carcinomas, two major patterns of RGC-32 immunoreactivity were seen: staining of malignant epithelial cells only in some tumors and RGC-32 reactivity of both malignant epithelia as well as cells in the interstitium in others. Colonic epithelium obtained from normal individuals was consistently negative for RGC-32 protein. Overexpression of RGC-32 protein was found in other tumors including prostate, bladder, breast, lung, and other digestive tract tumors. RGC-32 expression was present in the same malignant epithelial cells that also expressed the proliferation marker Ki-67. Our data suggest that RGC-32 overexpression might be part of the deregulation of the cell cycle that is required for the growth of tumor cells.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenocarcinoma / metabolism
  • Biomarkers, Tumor / analysis*
  • Blotting, Northern
  • Blotting, Western
  • Carcinoma / metabolism
  • Cell Cycle Proteins / biosynthesis*
  • Cell Line, Tumor
  • Colonic Neoplasms / metabolism*
  • Humans
  • Immunohistochemistry
  • Immunoprecipitation
  • Ki-67 Antigen / metabolism
  • Muscle Proteins / biosynthesis*
  • Neoplasms / metabolism*
  • Nerve Tissue Proteins / biosynthesis*
  • Polymerase Chain Reaction
  • RNA, Messenger / analysis
  • Up-Regulation


  • Biomarkers, Tumor
  • Cell Cycle Proteins
  • Ki-67 Antigen
  • Muscle Proteins
  • Nerve Tissue Proteins
  • RGC32 protein, human
  • RNA, Messenger