Cytotoxic and genotoxic effects of styrene-7,8-oxide in neuroadrenergic Pc 12 cells

• Published in: Carcinogenesis (New York) 1992-03, Vol.13 (3), p.417-424
• Main Authors: Dypbukt, Jeannette M., Costa, Lucio G., Manzo, Luigi, Orrenius, Sten, Nicotera, Pierluigi
• Format: Article
• Language: English
• Subjects: Adrenal Gland Neoplasms; Animals; Biological and medical sciences; Calcium - metabolism; Cell Differentiation - drug effects; Chemical mutagenesis; DNA Damage; DNA Repair; DNA, Single-Stranded - drug effects; Epoxy Compounds - toxicity; Glutathione - analogs & derivatives; Glutathione - metabolism; Glutathione Disulfide; L-Lactate Dehydrogenase - metabolism; Medical sciences; Pheochromocytoma; Rats; Toxicology; Tumor Cells, Cultured
• ISSN: 0143-3334; 1460-2180
• DOI: 10.1093/carcin/13.3.417

Exposure of Pc 12 cells to styrene-7,8-oxide (SO) (0.5–1 mM) caused a rapid increase in cytosolic Ca2+, depletion of intracellular glutathione and ATP, DNA damage and loss of cell viability. Lower SO concentrations (≤ 100 μM), did not cause loss of cell viabifity or affect cell growth rate. However, at 30 and 100 μM, SO stimulated the formation of alkali-sensitive, DNA single-strand breaks (SSB). DNA SSB were fully repaired when cells exposed to 30 μM SO were subsequently incubated for 3 h in fresh medium, whereas DNA repair was only partial after exposure to 100 μM SO. When cells exposed to 30 or 100 μM SO were incubated with the inhibitors of repair synthesis 1-β-D-arabinofuranosyl-cytosine (AraC) and hydroxyurea (HU), SSB accumulated, indicating the involvement of the excision-repair system in the removal of DNA lesions. A SO adduct with guanine at the N7 position was detected in the DNA extracted from treated cells. SO did not induce the formation of double-strand breaks, interstrand cross-links, or DNA-protein cross-links. Although cells exposed to 30 or 100 μM SO underwent normal cell division, latent DNA damage was retained for up to 14 subsequent replicative cycles. In addition, SO-treated cells partially lost their normal ability to differentiate in response to nerve growth factor (NGF) stimulation. NGF failed to induce differentiation in cells that had replicated for 20 generations after exposure to 100 μM SO. Spontaneous differentiation stimulated by high-density culture was also inhibited in SO-treated cells. These results indicate that non lethal concentrations of SO can cause modifications that compromise the ability of Pc 12 cells to respond to NGF and differentiate.