The objective of the current study was to explore initial transcriptional changes in a bronchial epithelial cell line exposed to “sub-lethal” concentrations of the commonly used resin monomer 2-hydroxy-ethylmethacrylate (HEMA). Altered gene regulation may be interpreted as a cellular adaptation to the exposure condition, yielding a valuable tool to identify cellular interactions with the monomer.
The BEAS-2B human bronchial epithelial cell line grown in LHC-9 medium was used as a model system. Cell cultures were exposed to HEMA (0-8 mM). After 24 h exposure, the cell viability was measured by the MTT assay. Total RNA from control cells and cells exposed to 2 mM HEMA for 4 h were isolated using the RNeasy kit (Qiagen). mRNA expression profiles (transcriptomics) were performed by the Genomics Core Facility at Oslo University Hospital HF using Illumina bead array. Analysis was performed using the J-express software and differential expression between samples was calculated using rank product. Western blotting was used to measure protein levels of the altered genes.
Exposure to HEMA concentrations below 4 mM for 24 h did not reduce cell viability as measured by the MTT assay. HEMA exposure significantly increased transcription of 25 genes, including genes coding for proteins associated with antioxidant defense (e.g. Heme Oxygenase 1 (HMOX1), Thioredoxin Reductase 1 (TXRND1) and Glutamate-Cysteine Ligase, Catalytic subunit (GCLC)) and Hsp70 family proteins. Western blotting revealed increased protein levels that were in line with the transcriptional changes.
The current study shows that HEMA exposure lead to cellular stress at concentrations that are not cytotoxic according to the MTT assay. The upregulated levels of antioxidant enzymes indicate increased oxidative load and the increased level of Hsp70 family proteins suggest increased protein misfolding.
This abstract is based on research that was funded entirely or partially by an outside source: Norwegian Directorate of Health, Oslo, Norway
Jan Tore Samuelsen (Presenter), NIOM
Håkon Valen, NIOM
Bergitte Olderbø, NIOM
Rune Becher, NIOM