Nuclear changes induced in NIH/3T3 cells by transfection and tumorigenesis

Abstract

Discriminants such as nuclear phenotypes, nuclear areas and perimeters, multinucleation, nuclear fusion and micronucleation were investigated in NIH/3T3 cells transfected with the whole genomic DNA of T24 and MCF-7 cells and with the ras oncogene of T24 cells, and primary cultures of tumours induced in nude mice by injection of transfected cells. The observations were carried out in cell preparations stained with 0.025% toluidine blue solution at pH 4.0. An increase in chromatin condensation involving euchromatin areas was detected in transfected cells and in cells derived from tumours. The pattern of condensation varied with the type of DNA transfected to the recipient cells. Based upon the enhanced expression of nuclear phenotypes exhibiting clumps of condensed chromatin in tumour-derived cells, it was concluded that chromatin condensation is associated with cell transformation, which is also manifested by multinucleation, nuclear fusion and micronucleation.