INVITRO TRANSFORMATION OF NEWBORN HAMSTER CELLS INDUCED BY SODIUM-NITRITE

Abstract

The in vitro carcinogenicity of sodium nitrite was examined. Addition of a high concentration of sodium nitrite (50 mM or 100 mM) to mass cultures of newborn hamster cells for 24 h resulted in morphological transformation of the cells. The shortest time required for morphological transformation after treatment was 21 days. Two of 5 transformed cultures produced progressively growing tumors when injected into young adult hamsters. These tumors were diagnosed as fibrosarcomas. In 2 control cultures of the same experimental groups, transformed cells appeared 10 wk or more later than those in treated cultures. The chromosomes were analyzed at several stages of transformation. In the early stages of transformation, chromosome number varied widely from near diploid to tetraploid, but later they became near diploid. Morphological alteration caused by sodium nitrite was also seen in a short-term assay, in which hamster embryonic cells (1 .times. 104 cells/60 mm dish) were treated and morphology was observed 8 days after treatment.