studymainsource: Mouse liver studytype: Single Dose Toxicity assaytype: ex vivo strain: C57Bl6 compound: dimethylsulfoxide dose: 0.5 doseunit: % doseduration: 24 durationunit: h dosefrequency: once vehicle: DMSO route: medium
After a recovery period of 40-42h, the Dulbecco's Modified Eagle's (Gibco BRL, Breda, The Netherlands) culture medium was replaced by culture medium containing either one of the 21 compounds or a vehicle control (0.5% of DMSO, PBS, EtOH). Seventeen chemicals were obtained through Sigma-Aldrich, TCDD through Cerilliant, DMBA through ICN, E2 through Steraloids Inc. and PhB through Brocacef Intramuraal bv. A dose causing minimal cytotoxicity after 24h of exposure thus resulting in ±80% viability, was established by the MTT assay (Mosmann, 1983). Next, cells were treated with an IC20-24h dose of di(2-ethylhexyl)phthalate(DEHP),4-Acetylaminofluorene(4AAF),Curcumin(Cur),Phenobarbital(PhB),Reserpine(Res),7,12-Dimethylbenzanthracene (DMBA),Resorcinol(Resorcinol),Para-cresidine(pCres),Phenacetin(Phen),Diclofenac(diclo),Wy 14643(Wy),Tributyltinoxide(TBTO),Benzo[a]pyrene(BaP),8-Hydroxyquinoline [AKA 8-quinolinol](8HQ),17-b-estradiol(E2),ampicillin(AmpC),cisplatin(CisPl),Aflatoxin B1(AFB1),Cyclosporin A(CsA),2,3,7,8-Tetrachlorodibenzo-p-dioxin(TCDD),Quercetin(Que) for 24 or 48 h before being harvested. Independent biological experiments (at least in triplicate) with hepatocytes from different mice were obtained for every time point.
PMH were isolated from adult male C57BL/6 mice using a perfusion method and cultured between a collagen-collagen sandwich formation in two six wells plates as described before.
At the end of treatment the medium was removed and PMH were harvested in Qiazol (QIAGEN Benelux B.V., Venlo, The Netherlands). Total RNA was isolated using a miRNeasy Mini Kit (QIAGEN Benelux B.V., Venlo, The Netherlands) according to the manufacturer’s protocol and followed by DNase I (Qiagen, Inc) treatment. Following purification, RNA concentrations were measured by means of a NanoDrop® ND-1000 spectrophotometer (Thermo Scientific, Wilmington, USA) at 260 and 280 nm. RNA quality and integrity were assessed by using automated gel electrophoresis on an Agilent 2100 Bioanalyzer system (Agilent Technologies Netherlands B.V., Amstelveen, The Netherlands). Only RNA samples which showed clear 18S and 28S peaks and with an RNA integrity number (RIN) higher than 8 were used. Samples were stored at -80ºC until RNA hybridization.
High-density oligonucleotide GeneChips from Affymetrix were used to measure gene expression levels (Mouse Genome 430 2.0 array (45101 probes)). Targets for these arrays were prepared from 250 ng of total RNA by means of the GeneChip 3’ IVT Express Kit according to the Affymetrix protocol (Affymetrix UK Ltd, High Wycombe, UK).
Amplified, biotinylated and fragmented targets were then hybridized on to the arrays.
After hybridization, arrays were washed and stained using an Affymetrix fluidics station and scanned by use of an Affymetrix GeneArray scanner. A total of 189 RNA samples was prepared and analyzed on GeneChip arrays (treated and control samples from each time point were at least in triplicate). Normalization quality controls, including scaling factors, average intensities, present calls, background intensities, noise, and raw Q values, appeared to be within acceptable limits for all chips. Hybridization controls BioB, BioC, BioD, and CreX were called present on all chips and yielded the expected increases in intensities.
All raw datasets from generated CEL files were first imported into R2.11.0 and run through an in-house quality control pipeline (available through ArrayAnalysis.org (Eijssen et al, 2013)) and then used for statistical analysis. R package is freely available for academic use from the Comprehensive R Archive Network (http://www.cran.r-project.org/). The probe sets were re-annotated by use of custom Cell Definition Files (CDF) (version 12.1.0. http://brainarray.mbni.med.umich.edu/Brainarray/Database/CustomCDF/12.1.0/entrezg.asp). This resulted in a list of 16,331 unique gene IDs. After re-annotation, data were normalized by Robust Multichip Average (RMA) normalization and log2 transformed using the R package “affy”. Low expression genes were filtered out by using a log[intensity cutoff] >5. This cutoff was based on the 1st quartile of the distribution of average intensities of all reporters.