Overexpression of RGC-32 in colon cancer and other tumors.
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.
Fosbrink
Matthew
M
Program in Toxicology, University of Maryland at Baltimore, Baltimore, MD 21201, USA.
Cudrici
Cornelia
C
Niculescu
Florin
F
Badea
Tudor C
TC
David
Stefan
S
Shamsuddin
Abulkalam
A
Shin
Moon L
ML
Rus
Horea
H
D000230:Adenocarcinoma / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000032:analysis*; D015152:Blotting, Northern; D015153:Blotting, Western; D002277:Carcinoma / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000096:biosynthesis*; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D019394:Ki-67 Antigen / Q000378:metabolism; D009124:Muscle Proteins / Q000096:biosynthesis*; D009369:Neoplasms / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000096:biosynthesis*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D015854:Up-Regulation
D014408:Biomarkers, Tumor; D018797:Cell Cycle Proteins; D019394:Ki-67 Antigen; D009124:Muscle Proteins; D009419:Nerve Tissue Proteins; C115049:RGCC protein, human; D012333:RNA, Messenger