Insulin-like growth factor (IGF)-binding protein-6 inhibits IGF-II-induced but not basal proliferation and adhesion of LIM 1215 colon cancer cells.
IGF-II is an autocrine growth factor for many colon cancer cells. This study aimed to determine the role of IGF-II in proliferation and adhesion of LIM 1215 colon cancer cells. RT-PCR demonstrated expression of IGF-I and IGF-II mRNA. Addition of IGF-I or -II increased monolayer proliferation in a dose-dependent manner. Although addition of IGFBP-6 had no effect on basal proliferation, coincubation of IGFBP-6 decreased IGF-II but not IGF-I-induced proliferation. Colony formation in agar was increased by IGF-II, an effect inhibited by coincubation with IGFBP-6. IGFBP-6 alone significantly decreased colony formation. Preincubation of cells with IGF-II increased adhesion to type IV collagen, fibronectin and laminin. IGFBP-6 had no effect on basal cell adhesion but completely inhibited the effects of IGF-II. LIM 1215 colon cancer cells are therefore IGF-responsive but IGF-II is not a major autocrine factor for these cells in monolayer, suggesting heterogeneity between colon carcinoma cell lines with respect to the role of the IGF system.
Leng
S L
SL
Department of Medicine, University of Melbourne, Austin and Repatriation Medical Centre, Heidelberg, Vic. 3084, Australia.
Leeding
K S
KS
Whitehead
R H
RH
Bach
L A
LA
D019898:Autocrine Communication; D002448:Cell Adhesion / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D003110:Colonic Neoplasms / Q000473:pathology*; D005109:Extracellular Matrix / Q000378:metabolism; D006801:Humans; D018976:Insulin-Like Growth Factor Binding Protein 6 / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000235:genetics; D007335:Insulin-Like Growth Factor II / Q000037:antagonists & inhibitors* / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D014407:Tumor Cells, Cultured
D018976:Insulin-Like Growth Factor Binding Protein 6; D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II