Insulin-like growth factor II in two human colon-carcinoma cell lines: gene structure and expression, and protein secretion.
Abnormal expression and structural modification of the IGF-II gene in correlation with high IGF-II production have recently been described in human colorectal tumors in comparison with normal adjacent tissues. Here, we have studied IGF-II in 2 human colon-carcinoma cell lines, HT29 and COLO 320DM. RFLP analyses revealed no apparent alteration at the IGF-II locus in these 2 cell lines. HT29 cells weakly expressed IGF-II mRNA in comparison with the high over-expression previously observed in some colorectal tumors, and only the 4.8-kb mRNA species was present. In addition, the serum-free medium conditioned by HT29 cells contained high IGF-II levels (approx. 900 ng/10(8) cells), as measured in a specific IGF-II radioimmunoassay (RIA). After chromatography on Bio-Gel P-60, we observed that 64% of the total IGF-II secreted by HT29 cells were present as a high-molecular-weight form of about 17 kDa. In contrast, no detectable expression of the IGF-II gene was observed in COLO 320DM cells, and low IGF-II levels were secreted by these cells in the serum-free medium, with only 9% total IGF-II represented by the large species.
Lambert
S
S
Laboratory of Molecular Oncology, University of Liege, Sart Tilman, Belgium.
Carlisi
A
A
Collette
J
J
Franchimont
P
P
Gol-Winkler
R
R
D002277:Carcinoma / Q000737:chemistry*; D002460:Cell Line; D003110:Colonic Neoplasms / Q000737:chemistry*; D003470:Culture Media; D015870:Gene Expression; D006801:Humans; D007335:Insulin-Like Growth Factor II / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D014407:Tumor Cells, Cultured
D003470:Culture Media; D012333:RNA, Messenger; D007335:Insulin-Like Growth Factor II