Download Human Liver Stem Cells for Assessing AhR

Temporal and Dose-dependent AhR-Mediated Gene Expression Analysis
in Human Liver Adult Stem Cells
S Kim1,2,3, E Dere1,2, LD Burgoon1,2, CC Chang2,4 & TR Zacharewski1,2,3.
1Department
3Center
of Biochemistry & Molecular Biology, 2National Food Safety & Toxicology Center,
for Integrative Toxicology, 4Department of Pediatrics & Human Development, Michigan
State University, East Lansing, MI, 48824
Time course and dose-response studies with the human liver cell line, HL1-1, which possesses
stem cell characteristics were conducted to assess gene expression responses elicited by
2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). For the dose-response study, cells were treated for
12 hrs with 0.001, 0.01, 0.1, 1, 10 or 100 nM TCDD or DMSO vehicle control. The time course
study was conducted by treating cells with 10 nM TCDD or vehicle for 1, 2, 4, 8, 12, 24 or 48 hrs.
TCDD-elicited changes in gene expression were monitored using human cDNA microarrays
consisting of 7,844 genes. Empirical Bayes analysis identified 251 genes that were differentially
expressed at one or more time points.
Most of those genes also exhibited dose-dependent
responses. Dose- and time- dependent induction of CYP1B1, ALDH1A3 and SLC7A5 gene
expressions were confirmed by qRT-PCR. Comparisons of the HL1-1 temporal responses with
human HepG2 and mouse Hepa1c1c7 hepatoma cell lines identified 75 genes and 18 orthologs
common to HL1-1 cells, respectively. Further comparison of temporal gene expression in HL1-1
with hepatic tissue from immature ovariectomized C57BL/6 mice treated with 30 g/kg TCDD
identified 32 commonly regulated orthologous genes, primarily associated with signal
transduction and transcriptional regulation. Metabolism and transport related genes were also
commonly regulated between all comparisons. This comparative model analysis further
elucidates species-specific toxicity and susceptibility mediated by AhR-mediated gene
expression, thus supporting high throughput screening assay development and more
appropriate risk assessment while decreasing the uncertainties associated with extrapolation
between species.
Supported by NIGMS grant R21 GM075838.