P-89 Function and regulation of insulin-like growth factor binding protein-2 and -3 in ovarian cancer cell models

for 8 days by pair-feeding. On the 9th day, half of the rats in each group were sacrificed after 16 hours fasting (F) and the other half were sacrificed after 16 hours fasting followed by 6hr re-feeding (R). First, we measured plasma concentrations of insulin and glucocorticoid that are main hormones to regulate IGFBP-1 transcription. Plasma insulin concentrations were higher in the re-fed groups than in the fasted groups but did not differ among the three dietary groups. Plasma corticosterone concentrations were not affected by protein-deprivation or antioxidant intake. In contrast, liver TBARS concentrations, which reflect the magnitude of oxidative stress, were significantly higher in the protein-deprived groups than in the control groups, and returned to the control level in antioxidant-fed groups. As we previously reported, hepatic IGFBP-1 mRNA significantly increased by 16 hours fasting. Six hours re-feeding in the 20C group decreased hepatic IGFBP-1 mRNA levels by 74%; however, this repression was not observed in the 0C group. Interestingly, feeding-dependent suppression of IGFBP-1 mRNA was restored by intake of the antioxidants even in the 0C group. These results demonstrated that oxidative stress attenuates the effects of feeding on reduction of hepatic IGFBP-1 mRNA in proteindeprived rats, probably caused by impairment of insulin signals.