Analysis of individual and combined estrogenic effects of bisphenol, nonylphenol and diethylstilbestrol in immature rats with mathematical models

BACKGROUND@#Traditional toxicological studies focus on individual compounds. However, this single-compound approach neglects the fact that the mixture exposed to human may act additively or synergistically to induce greater toxicity than the single compounds exposure due to their similarities in the mode of action and targets. Mixture effects can occur even when all mixture components are present at levels that individually do not produce observable effects. So the individual chemical effect thresholds do not necessarily protect against combination effects, an understanding of the rules governing the interactive effects in mixtures is needed. The aim of the study was to test and analyze the individual and combined estrogenic effects of a mixture of three endocrine disrupting chemicals (EDCs), bisphenol A (BPA), nonylphenol (NP) and diethylstilbestrol (DES) in immature rats with mathematical models.@*METHOD@#In the present study, the data of individual estrogenic effects of BPA, NP and DES were obtained in uterotrophic bioassay respectively, the reference points for BPA, NP and DES were derived from the dose-response ralationship by using the traditional no observed adverse effect (NOAEL) or lowest observed adverse effect level (LOAEL) methods, and the benchmark dose (BMD) method. Then LOAEL values and the benchmark dose lower confidence limit (BMDL) of single EDCs as the dose design basis for the study of the combined action pattern. Mixed prediction models, the 3 × 2 factorial design model and the concentration addition (CA) model, were employed to analyze the combined estrogenic effect of the three EDCs.@*RESULTS@#From the dose-response relationship of estrogenic effects of BPA, NP and DES in the model of the prepuberty rats, the BMDL(NOAEL) of the estrogenic effects of BPA, NP and DES were 90(120) mg/kg body weight, 6 mg/kg body weight and 0.10(0.25) μg/kg body weight, and the LOAEL of the the estrogenic effects of three EDCs were 240 mg/kg body weight, 15 mg/kg body weight and 0.50 μg/kg body weight, respectively. At BMDL doses based on the CA concept and the factorial analysis, the mode of combined effects of the three EDCs were dose addition. Mixtures in LOAEL doses, NP and DES combined effects on rat uterine/body weight ratio indicates antagonistic based on the CA concept but additive based on the factorial analysis. Combined effects of other mixtures are all additive by using the two models.@*CONCLUSION@#Our results showed that CA model provide more accurate results than the factorial analysis, the mode of combined effects of the three EDCs were dose addition, except mixtures in LOAEL doses, NP and DES combined effects indicates antagonistic effects based on the CA model but additive based on the factorial analysis. In particular, BPA and NP produced combination effects that are larger than the effect of each mixture component applied separately at BMDL doses, which show that additivity is important in the assessment of chemicals with estrogenic effects. The use of BMDL as point of departure in risk assessment may lead to underestimation of risk, and a more balanced approach should be considered in risk assessment.

Potential Antitumor Activity of SIM-89 in Non-Small Cell Lung Cancer Cells

PURPOSE: c-Met and its ligand, hepatocyte growth factor (HGF), play a critical role in oncogenesis and metastatic progression. The aim of this study was to identify inhibited enzymogram and to test the antitumor activity of SIM-89 (a c-Met receptor tyrosine kinase inhibitor) in non-small cell lung cancer. MATERIALS AND METHODS: Z′-LYTE kinase assay was employed to screen the kinase enzymogram, and mechanism of action (MOA) analysis was used to identify the inhibited kinases. Cell proliferation was then analyzed by CCK8 assay, and cell migration was determined by transwell assay. The gene expression and the phosphorylation of c-Met were examined by realtime-PCR and western blotting, respectively. Finally, the secretion of HGF was detected by ELISA assay. RESULTS: c-Met, activated protein kinase (AMPK), and tyrosine kinase A (TRKA) were inhibited by SIM-89 with the IC₅₀ values of 297 nmol/L, 1.31 µmol/L, and 150.2 nmol/L, respectively. SIM-89 exerted adenosine triphosphate (ATP) competitive inhibition on c-Met. Moreover, the expressions of STAT1, JAK1, and c-Met in H460 cells were decreased by SIM-89 treatment, and c-Met phosphorylation was suppressed in A549, H441, H1299, and B16F10 cells by the treatment. In addition, SIM-89 treatment significantly decreased the level of HGF, which accounted for the activation of c-Met receptor tyrosine kinase. Finally, we showed cell proliferation inhibition and cell migration suppression in H460 and H1299 cells after SIM-89 treatment. CONCLUSION: In conclusion, SIM-89 inhibits tumor cell proliferation, migration and HGF autocrine, suggesting it's potential antitumor activity.