Effect of the dithiocarbamate pesticide zineb and its commercial formulation, the azzurro: V. Abnormalities induced in the spindle apparatus of transformed and non-transformed mammalian cell lines

Abstract

Abnormalities induced in the mitotic spindle by zineb and azzurro (1.0–25.0 μg/ml, 24 h) were evaluated in Chinese hamster ovary (CHO) and HeLa cells, and in non-transformed human fibroblasts (NTHF). Spindles were stained with FITC-conjugated anti-β tubulin. Treatment with 10.0 μg/ml of zineb induced complete inhibition of cell viability in NTHF cells while 10.0 μg/ml of azzurro decreased cell growth down to 62%. Higher doses of both compounds induced cell death. In HeLa and CHO cells, 15.0 μg/ml of zineb and 10.0–15.0 μg/ml of azzurro decreased viability, whereas 25.0 μg/ml of both compounds was cytotoxic. A significantly decreased mitotic index (MI) was observed in NTHF treated with 5.0 μg/ml zineb or azzurro, whereas 10.0 μg/ml of both chemicals were necessary to induce the same phenomenon in HeLa and CHO cells. Treatment with 1.0–5.0 μg/ml of zineb or azzurro induced a dose-dependent increase of degenerated spindles in NTHF and the number of degenerated or multipolar spindles in HeLa and CHO cells increased in a dose-dependent manner with 1.0–10.0 μg/ml zineb and azzurro. Although zineb and azzurro were able to induce mitotic spindle abnormalities in all cell types, non-transformed cells were less resistant than immortalized cells.