Aneuploidy and consistent structural chromosome changes associated with transformation of Syrian hamster embryo cells.

To gain a better understanding of the role of specific numerical and structural chromosome changes in the multistage process of transformation of Syrian hamster embryo (SHE) cells, we analyzed seven benzo(a)pyrene (BP)-induced immortal SHE cell lines, and one spontaneously immortalized cell line. In addition, we analyzed chromosome changes in early passage tumor-derived cell lines induced by injection of four immortalized cell lines into neonate hamsters. Of particular interest was the observation of a deletion in the short arm of chromosome 2 in four of the seven BP-immortalized cell lines. Other types of alterations in chromosome 2 were observed in two other cell lines. Loss of one copy of chromosome 16 was also observed in more than 90 to 100% of the cells in three of seven BP-immortalized cell lines. In contrast, the only chromosome alteration seen in the spontaneously immortalized cell line was a deletion in the short arm of chromosome 20. Genetic instability, as indicated by increased numerical or structural chromosome changes, was observed in all tumor-derived cell lines compared to the immortal cell line from which they originated. These results, along with previous reports in the literature, suggest that alterations in specific chromosomes, like chromosome 2, may be involved in transformation of SHE cells.

Establishment of immortalized alveolar type II epithelial cell lines from adult rats.

We developed methodology to isolate and culture rat alveolar Type II cells under conditions that preserved their proliferative capacity, and applied lipofection to introduce an immortalizing gene into the cells. Briefly, the alveolar Type II cells were isolated from male F344 rats using airway perfusion with a pronase solution followed by incubation for 30 min at 37 degrees C. Cells obtained by pronase digestion were predominantly epithelial in morphology and were positive for Papanicolaou and alkaline phosphatase staining. These cells could be maintained on an extracellular matrix of fibronectin and Type IV collagen in a low serum, insulin-supplemented Ham's F12 growth medium for four to five passages. Rat alveolar epithelial cells obtained by this method were transformed with the SV40-T antigen gene and two immortalized cell lines (RLE-6T and RLE-6TN) were obtained. The RLE-6T line exhibits positive nuclear immunostaining for the SV40-T antigen and the RLE-6TN line does not. PCR analysis of genomic DNA from the RLE-6T and RLE-6TN cells demonstrated the T-antigen gene was present only in the RLE-6T line indicating the RLE-6TN line is likely derived from a spontaneous transformant. After more than 50 population doublings, the RLE-6T cells stained positive for cytokeratin, possessed alkaline phosphatase activity, and contained lipid-containing inclusion bodies (phosphine 3R staining); all characteristics of alveolar Type II cells. The RLE-6TN cells exhibited similar characteristics except they did not express alkaline phosphatase activity. Early passage RLE-6T and 6TN cells showed a near diploid chromosome number.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential effects of mineral dusts on the in vitro activation of alveolar macrophage eicosanoid and cytokine release.

We investigated the in vitro effects of the pneumotoxic agents, silica and asbestos, and the relatively innocuous materials, aluminium oxide (Al(2)O(3)) and titanium dioxide (TiO(2)), on alveolar macrophages (AM) using endpoints reflecting the cytotoxic and AM activating properties of the dusts. Rat AM were exposed in vitro (24 hr) to 10-1000 mug/ml of the dusts. AM conditioned media was analysed for lactate dehydrogenase (cytotoxicity), beta-glucuronidase (lysosomal enzyme), leukotriene B4 (LTB4), prostaglandin E(2) (PGE(2)), tumour necrosis factor alpha (TNF) and interleukin-1 (IL-1). AM LTB4 and TNF release were increased by silica and asbestos but not by Al(2)O(3) or TiO(2). IL-1 release was not affected, and changes in PGE(2) release were minimal, after dust exposure. Cytotoxic activity was not consistently associated with LTB4, TNF or beta-glucuronidase release. The ability of silica and asbestos, but not Al(2)O(3) and TiO(2), to activate AM to release the pro-inflammatory mediators, LTB4 and TNF, may be responsible, at least in part, for the greater inflammation and pneumotoxicity associated with silica and asbestos exposure. These findings suggest that assessment of AM mediator secretion in vitro can provide information to understand better the potential of a material to cause respiratory toxicity.