Alterations in Gene Expression in Human Mesothelial Cells Correlate with Mineral Pathogenicity

Human mesothelial cells (LP9/TERT-1) were exposed to low and high (15 and 75 m2/cm2 dish) equal surface area concentrations of crocidolite asbestos, nonfibrous talc, fine titanium dioxide (TiO2), or glass beads for 8 or 24 h. RNA was then isolated for Affymetrix microarrays, GeneSifter analysis and QRT-PCR. Gene changes by asbestos were concentration- and time-dependent. At low nontoxic concentrations, asbestos caused significant changes in mRNA expression of 29 genes at 8 h and 205 genes at 24 h, whereas changes in mRNA levels of 236 genes occurred in cells exposed to high concentrations of asbestos for 8 h. Human primary pleural mesothelial cells also showed the same patterns of increased gene expression by asbestos. Nonfibrous talc at low concentrations in LP9/TERT-1 mesothelial cells caused increased expression of 1 gene Activating Transcription Factor 3 (ATF3) at 8 h and no changes at 24 h, whereas expression levels of 30 genes were elevated at 8 h at high talc concentrations. Fine TiO2 or glass beads caused no changes in gene expression. In human ovarian epithelial (IOSE) cells, asbestos at high concentrations elevated expression of 2 genes (NR4A2, MIP2) at 8 h and 16 genes at 24 h that were distinct from those elevated in mesothelial cells. Since ATF3 was the most highly expressed gene by asbestos, its functional importance in cytokine production by LP9/TERT-1 cells was assessed using siRNA approaches. Results reveal that ATF3 modulates production of inflammatory cytokines (IL-1, IL-13, G-CSF) and growth factors (VEGF and PDGF-BB) in human mesothelial cells.

57

Shukla A, MacPherson MB, Hillegass J, Ramos-Nino ME, Alexeeva V, Vacek PM, Bond JP, Pass HI, Steele C, Mossman BT