Correlation of Mutagenic, Carcinogenic and Cocarcinogenic Effects of Chemical Substances.
Interim scientific rept.,
EIDGENOESSISCHE TECHNISCHE HOCHSCHULE ZURICH (SWITZERLAND)
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In the first year, optimal culture conditions for in vivo transformed cells and for normal granulation tissue cells were determined. In addition, selective growth condition for in vivo transformed cells compared. The influences of media, sera, pH and pO2 on growth of freshly isolated cells derived from fibrosarcoma or from, a 4 day old granuloma tissue were investigated. The low pO2 found in vivo 30-40 mmHg stimulated in vitro growth of transformed as well as normal cells in culture. The stimulus was much higher in tumor cells 2-5 fold increase than in normal cells 1. 2-1. 4 fold. With a selected set of growth modifying chemicals TPA, dexamethasome Vitamin E, glutathion, insulin this stimulus could not be further enhanced. Optimal conditions for growth of transformed cells in living hosts nude mice and rats were investigated. It was found, that species, strain, and inoculum size influenced growth of tumor cells. Futhermore it was observed that co-injection of normal cells shortened the lag time. The in vitro handling of transformed cell did not affected their growth in nude mice. Selective growth conditions for transformed cells were evaluated with 14 tumor cell population grew out of tumors. In vitro, growth in Ca depleted medium and anchorage independent growth in the soft agar were the most reliable conditions. In the second year, we started to analyze freshly isolated cells exposed in vivo in the granulation tissue to the established genotoxic agent N-methyl-N-nitro-N-nitrosoguanidine MNNG at a dose which induces a high yield of mutations and which gives rise to fibrosarcona development at the site of injection.