Regulation of Promoter-CAT Stress Genes in HepG2 Cells by Suspensions of Particles from Ambient Air

Abstract

A panel of HepG2-derived cell lines (CAT-Tox [L] assay, Xenometrix), harboring stress genes consisting of a sequence for chloramphenicol acetyltransferase (CAT) under the transcriptional regulation from mammalian promoters and response elements, was exposed for 18-24 hr to aqueous suspensions of urban dusts (SRM-1648, SRM-1649, EHC-93) or PM2.5 particles (particulate matter < 2.5 fim). Expression of CAT protein was measured by enzymelinked immunosorbent assay. Induction of the CAT genes was verified with benzo[a]pyrene (CYPlAl, cytochrome P450 1A1 promoter; GSTYa, glutathione transferase subunit Ya promoter; XRE, xenobiotic response element), cadmium sulfate, and copper sulfate (HMTIIa, metallothionein ria promoter; HSP70, heat shock protein 70 promoter). The urban dust suspensions were active on CYPlAl, GSTYa, and XRE cell lines. SRM-1648 and SRM-1649 were twice as potent as EHC-93 per unit mass in inducing the xenobiotic-dependent responses, which correlated with contents in polycyclic aromatic hydrocarbons. These three reference particles, as well as six PM2.5 preparations collected on hivol filters in the Great Lakes basin, were also found to induce HMTIIa and HSP70, the magnitude of the responses correlating closely with the amount of soluble copper in the particulate preparations. The results indicate that bioavailable chemical species in the unfractionated particles can directly and quantitatively induce xenobiotic, metal, and stress-dependent responses in a target cell model, resulting in patterns of gene induction consistent with the chemical compositions of the environmental materials. We propose that cell culture models could be helpful for toxicodynamic inferences in adjunct to environmental monitoring and exposure assessments.

Effects of ambient air particles on the endothelin system in human pulmonary epithelial cells (A549)

“…This shows that fractionating particles may not be the ideal approach for delineating the effect of particle composition on biological potency. A better strategy may be to use whole particles and then analyze the data using principal component analysis against particle composition (Vincent et al, 1997).…”

“…The TiO 2 was washed in methanol and phosphate-buffered saline (PBS) to remove organics (Vincent et al,1997). The urban dust preparation EHC-93 refers to material collected in Ottawa, Ontario, Canada (Vincent et al, 1997).…”

“…The TiO 2 was washed in methanol and phosphate-buffered saline (PBS) to remove organics (Vincent et al,1997). The urban dust preparation EHC-93 refers to material collected in Ottawa, Ontario, Canada (Vincent et al, 1997). Briefly, this urban particulate material was recovered from bag-house filters of the single-pass air purification system of the Environmental Health Centre in Ottawa and was mechanically sieved (36 µm) to obtain finely dispersed particles.…”

“…The characterization of material EHC-93 has been described previously (Vincent et al 1997). The urban dust is composed mainly of particles with a median physical diameter of 0.4 µm, and solubility in water is ∼15-20%.…”

Concentration Distribution and Bioaccessibility of Trace Elements in Nano and Fine Urban Airborne Particulate Matter: Influence of Particle Size

“…The EHC samples have been used in lung, heart, and allergy studies (Vincent et al 1997(Vincent et al , 2001Kooter et al 2003;Steerenberg et al 2003). For example, inhalation toxicology of urban ambient PM has been investigated in detail using bulk EHC-93 sample (Vincent et al 2001), and lung damage has been observed after instillation with EHC particles (Prieditis and Adamson 2002;Kooter et al 2003).…”