Loss of IGFBP-3 expression was detected by Western blotting in both cell lines without changes in transcriptional activity, and ELISA showed significantly lower amounts of secreted IGFBP-3 in the culture media of the mutant cell lines than in that of the parental line. Despite the loss of IGFBP-3 expression, IGFR signalling
activity remained unchanged. Forced expression of IGFBP-3 by adenovirus-mediated transfection or recombinant IGFBP-3 slightly increased the growth-inhibitory and apoptotic effects of EGFR-TKIs, whereas suppression of IGFBP-3 did not affect sensitivity to find more EGFR-TKI. Serum IGFBP-3 levels measured by ELISA before and after the development of EGFR-TKI resistance in 20 patients showed no significant changes (1815.3 +/- 94.6 ng/mL before treatment vs. 1778.9 +/- 87.8 ng/mL after EGFR-TKI resistance). In summary, although IGFBP-3 downregulation is associated with the acquisition of resistance to EGFR-TKIs regardless of the mechanism, its effect on resistance was not significant, indicating that IGFBP-3 may not play an important role in resistance to EGFR-TKIs and serum IGFBP-3 Sapanisertib order level
is not a reliable indicator of resistance.”
“Objective: Intravenous (IV) midazolam is the preferred cytochrome P450 (CYP) 3A probe for phenotyping, with systemic clearance (CL) estimating hepatic CYP3A activity. A limited sampling strategy was conducted to determine whether partial area under the concentration-time curves (AUCs) could reliably estimate midazolam systemic CL during conditions of CYP3A baseline activity, inhibition, and induction/activation. Methods: Midazolam plasma concentrations during CYP3A baseline (n = 93), inhibition (n = 40), and induction/activation (n = 33) were obtained from 7 studies in healthy
adults. Noncompartmental analysis determined observed CL (CLobs) and partial AUCs. Linear regression equations were derived from partial AUCs to estimate CL (CLpred) during CYP3A baseline, inhibition, and induction/activation. Preestablished criterion for linear regression analysis was r(2) bigger than = 0.9. CLpred was compared with CLobs, and ATR activation relative bias and precision were assessed using percent mean prediction error and percent mean absolute error. Results: During CYP3A baseline and inhibition, all evaluated partial AUCs failed to meet criterion of r(2) bigger than = 0.9 and/or percent mean absolute error smaller than 15%. During CYP3A induction/activation, equations derived from partial AUCs from 0 to 1 hour (AUC(0-1)), 0 to 2 hours (AUC(0-2)), and 0 to 4 hours (AUC(0-4)) were acceptable, with good precision and minimal bias. These equations provided the same conclusions regarding equivalency testing compared with intense sampling. Conclusions: During CYP3A induction/activation, but not baseline or inhibition, midazolam partial AUC(0-1), AUC(0-2), and AUC(0-4) reliably estimated systemic CL and consequently hepatic CYP3A activity in healthy adults.