BACKGROUND: : Previously, we have observed that highly unsaturated dietary (n-3) fatty acids inhibit cell proliferation in conjunction with stimulation of insulin-like growth factor-binding protein (IGFBP)-6 secretion in Caco-2 cells, a human colon carcinoma cell line. METHODS: : To test the converse hypothesis that inhibition of endogenous IGFBP-6 secretion stimulates Caco-2 cell proliferation, cells were transfected with the antisense IGFBP-6 expression construct or pcDNA3 vector only, and single colonies resistant to G418 sulfate were isolated. RESULTS: : Our initial studies indicated that three antisense clones grew faster and produced less IGFBP-6 than two pcDNA3 clones, so antisense IGFBP-6 #5 and pcDNA3 #8 were selected for further detailed analysis. Both the control and antisense clones grew in serum-free medium reaching a plateau density at day eight. However, the antisense clone grew at a rate faster than that of the control and reached a final density that was 31 +/- 3% higher than the control. Northern blot, ligand blot and immunoblot analyses revealed that accumulation of IGFBP-6 mRNA and concentrations of IGFBP-6 peptide produced by the antisense clone were decreased by 80-90% compared to the control. The doubling times of the antisense and control clones were 21.9 +/- 0.4 and 24.8 +/- 0.3 h (P < 0.05), respectively. Exogenous IGF-I and IGF-II (0.2-200 nmol/L) stimulated proliferation of both the control and antisense clones in a dose-dependent manner, but the relative potency and efficacy of IGF-II was higher in the antisense clone compared to the control. These results indicate that suppression of IGFBP-6 secretion correlates with an increase in the basal rate of Caco-2 cell growth. CONCLUSIONS: : Our findings are consistent with the hypothesis that IGFBP-6 inhibits cell growth by binding to endogenously produced IGF-II, thereby preventing IGF-II from interacting with the IGF-I receptor to stimulate cellular proliferation by an autocrine mechanism. Copyright 2002 Blackwell Publishing Asia Pty Ltd
BACKGROUND: : Previously, we have observed that highly unsaturated dietary (n-3) fatty acids inhibit cell proliferation in conjunction with stimulation of insulin-like growth factor-binding protein (IGFBP)-6 secretion in Caco-2 cells, a humancolon carcinoma cell line. METHODS: : To test the converse hypothesis that inhibition of endogenous IGFBP-6 secretion stimulates Caco-2 cell proliferation, cells were transfected with the antisense IGFBP-6 expression construct or pcDNA3 vector only, and single colonies resistant to G418 sulfate were isolated. RESULTS: : Our initial studies indicated that three antisense clones grew faster and produced less IGFBP-6 than two pcDNA3 clones, so antisense IGFBP-6 #5 and pcDNA3 #8 were selected for further detailed analysis. Both the control and antisense clones grew in serum-free medium reaching a plateau density at day eight. However, the antisense clone grew at a rate faster than that of the control and reached a final density that was 31 +/- 3% higher than the control. Northern blot, ligand blot and immunoblot analyses revealed that accumulation of IGFBP-6 mRNA and concentrations of IGFBP-6 peptide produced by the antisense clone were decreased by 80-90% compared to the control. The doubling times of the antisense and control clones were 21.9 +/- 0.4 and 24.8 +/- 0.3 h (P < 0.05), respectively. Exogenous IGF-I and IGF-II (0.2-200 nmol/L) stimulated proliferation of both the control and antisense clones in a dose-dependent manner, but the relative potency and efficacy of IGF-II was higher in the antisense clone compared to the control. These results indicate that suppression of IGFBP-6 secretion correlates with an increase in the basal rate of Caco-2 cell growth. CONCLUSIONS: : Our findings are consistent with the hypothesis that IGFBP-6 inhibits cell growth by binding to endogenously produced IGF-II, thereby preventing IGF-II from interacting with the IGF-I receptor to stimulate cellular proliferation by an autocrine mechanism. Copyright 2002 Blackwell Publishing Asia Pty Ltd
Authors: Rajaraman Durai; Wenxuan Yang; Sharmila Gupta; Alexander M Seifalian; Marc C Winslet Journal: Int J Colorectal Dis Date: 2005-01-14 Impact factor: 2.571
Authors: Richard A Dean; Georgina S Butler; Yamina Hamma-Kourbali; Jean Delbé; David R Brigstock; José Courty; Christopher M Overall Journal: Mol Cell Biol Date: 2007-10-01 Impact factor: 4.272