Direct comparison of the hepatoma cell lines HepG2 and HepaRG has previously been performed by only evaluating a limited set of genes or proteins. In this study, we examined the whole-genome gene expression of both cell lines before and after exposure to the genotoxic (GTX) carcinogens aflatoxin B1 and benzo[a]pyrene and the nongenotoxic (NGTX) carcinogens cyclosporin A, 17beta-estradiol, and 2,3,7,8-tetrachlorodibenzo-para-dioxin for 12 and 48 h. Before exposure, this analysis revealed an extensive network of genes and pathways, which were regulated differentially for each cell line. The comparison of the basal gene expression between HepG2, HepaRG, primary human hepatocytes (PHH), and liver clearly showed that HepaRG resembles PHH and liver the most. After exposure to the GTX and NGTX carcinogens, for both cell lines, common pathways were found that are important in carcinogenesis, for example, cell cycle regulation and apoptosis. However, also clear differences between exposed HepG2 and HepaRG were observed, and these are related to common metabolic processes, immune response, and transcription processes. Furthermore, HepG2 performs better in discriminating between GTX and NGTX carcinogens. In conclusion, these results have shown that HepaRG is a more suited in vitro liver model for biological interpretations of the effects of exposure to chemicals, whereas HepG2 is a more promising in vitro liver model for classification studies using the toxicogenomics approach. Although, it should be noted that only five carcinogens were used in this study.

Chronic oxidative stress and systemic inflammation contribute to the pathology of several chronic diseases, one among which is chronic obstructive pulmonary disease (COPD). In addition, increased oxidative stress and inflammation have been observed to be negatively associated with telomere length (TL). Our aim was to investigate the TL in COPD patients in relation to pulmonary and extrapulmonary disease severity. Furthermore, based on experimental evidence suggesting the effects of oxidative stress on telomere shortening, we studied the association of TL with the antioxidant enzyme superoxide dismutase (SOD). One hundred and two COPD patients with moderate to severe COPD were studied and compared with 19 healthy age-matched controls. Patients were characterized by elevated levels of inflammatory markers (CRP, sTNF-receptors) and lower SOD-activity than the controls (p<0.001), irrespective of the SOD genotype. TL was negatively associated with age (p<0.01) and was significantly shorter in COPD patients than controls (p<0.05). Within the patient group age-adjusted TL variability could not be explained by lung function and smoking history but a modest association was found with the percentage of fat mass (p<0.05). These data provide evidence for a relationship between a disturbed oxidant/antioxidant balance and telomere shortening and indicate that preservation of fat mass may be protective in delaying telomere shortening in COPD patients.

An experimental and computational approach to categorizing UVCBs according to chemical and biological similarities.

Consumption of fruits and vegetables has been associated with a decrease in cancer incidence and cardiovascular disease, presumably caused by antioxidants. We designed a human intervention study to assess antioxidative and possible anti-genotoxic properties of fruit-borne antioxidants. We hypothesized that individuals bearing genetic polymorphisms for genes related to quercetin metabolism, benzo[a]pyrene metabolism, oxidative stress and DNA repair differ in their response to DNA protective effects of increased antioxidant intake. In the present study, 168 healthy volunteers consumed a blueberry/apple juice that provided 97 mg quercetin and 16 mg ascorbic acid a day. After a 4-week intervention period, plasma concentrations of quercetin and ascorbic acid and trolox equivalent antioxidant capacity (TEAC) were significantly increased. Further, we found 20% protection (P < 0.01) against ex vivo H(2)O(2)-provoked oxidative DNA damage, measured by comet assay. However, the level of ex vivo induced benzo[a]pyrene-diol-epoxide (BPDE)-DNA adducts was 28% increased upon intervention (P < 0.01). Statistical analysis of 34 biologically relevant genetic polymorphisms revealed that six significantly influenced the outcome of the intervention. Lymphocytes from individuals bearing variant genotype for Cyp1B1 5 seemed to benefit more than wild-types from DNA damage-protecting effects upon intervention. Variants for COMT tended to benefit less or even experienced detrimental effects from intervention. With respect to GSTT1, the effect is ambiguous; variants respond better in terms of intervention-related increase in TEAC, but wild-types benefit more from its protecting effects against oxidative DNA damage. We conclude that genotyping for relevant polymorphisms enables selecting subgroups among the general population that benefit more of DNA damage-modulating effects of micronutrients.

One of the most challenging areas in regulatory science is assessment of the substances known as UVCB (unknown or variable composition, complex reaction products and biological materials). Because the inherent complexity and variability of UVCBs present considerable challenges for establishing sufficient substance similarity based on chemical characteristics or other data, we hypothesized that new approach methodologies (NAMs), including in vitro test-derived biological activity signatures to characterize substance similarity, could be used to support grouping of UVCBs. We tested 141 petroleum substances as representative UVCBs in a compendium of 15 human cell types representing a variety of tissues. Petroleum substances were assayed in dilution series to derive point of departure estimates for each cell type and phenotype. Extensive quality control measures were taken to ensure that only high-confidence in vitro data were used to determine whether current groupings of these petroleum substances, based largely on the manufacturing process and physico-chemical properties, are justifiable. We found that bioactivity data-based groupings of petroleum substances were generally consistent with the manufacturing class-based categories. We also showed that these data, especially bioactivity from human induced pluripotent stem cell (iPSC)-derived and primary cells, can be used to rank substances in a manner highly concordant with their expected in vivo hazard potential based on their chemical compositional profile. Overall, this study demonstrates that NAMs can be used to inform groupings of UVCBs, to assist in identification of representative substances in each group for testing when needed, and to fill data gaps by read-across.