Transplantation and chromosomal analysis of cell lines derived from mesotheliomas induced in rats with erionite and UICC chrysotile asbestos.

The histological lesions, chromosomal characteristics and transplantability of 6 erionite-induced and 7 UICC chrysotile-induced rat mesotheliomas are compared. The tumours were of 4 types: tubulopapillary, fibrosarcomatous, mixed fibrosarcomatous and tubulopapillary, and mixed fibrosarcomatous and chondrosarcomatous. Cell lines derived from these tumours displayed heterogeneous chromosome anomalies, but none were unique either to chrysotile or erionite treatment. Six of 7 erionite-induced and 4 of 6 UICC chrysotile-induced tumours had various anomalies of chromosome No. 1. When 7 cell lines were transplanted into syngeneic rats, all produced tumours that were pathologically similar to the original tumour, regardless of the route of injection. Cytogenetically, the cell lines derived from tumours after intrapleural transplantation resembled the injected cell line. The cytogenetic analysis of the cell lines derived from the tumours after subcutaneous transplantation is in progress. The induction period for transplanted tumours was 28-80 days.

Metaphase and anaphase analysis of V79 cells exposed to erionite, UICC chrysotile and UICC crocidolite.

The cytogenetic effects of erionite treatment of V79 cells were compared with those of UICC crocidolite and UICC chrysotile treatment. A significant reduction in diploid cells with an accompanying increase in aneuploid and polyploid cells was observed with all three treatments. In the erionite-treated cultures, an increase in aneuploidy was observed at all dose levels ranging from 10 to 100 micrograms/ml, whereas in the crocidolite- and chrysotile-treated cultures, significant increases in aneuploidy were observed at all dose levels except the low dose, 10 micrograms/ml. Chromatid aberrations were observed in cultures treated with crocidolite and chrysotile and were especially pronounced at dose 100 micrograms/ml of chrysotile. The clastogenic effect of erionite was weaker but statistically significant at dose 100 micrograms/ml. An extrapolation of these cytogenetic changes over dose in number of fibers suggests that erionite was more reactive than the other two minerals in producing aneuploidy. The number of fibers required to produce a similar degree of cytogenetic effects was several orders of magnitude higher for chrysotile and crocidolite than erionite. These results correlate with the higher tumorigenic potency of erionite. In general, fewer cells treated with erionite entered anaphase than those treated with the other two minerals. As a result, abnormal anaphases representing chromosomal mis-segregation were observed only in the chrysotile- and crocidolite-treated cultures. To our knowledge, this is the first report on cytogenetic effects of erionite.