Characterization of malignant rat keratinocytes in culture following the induction of oral squamous cell carcinomas in vivo.

An in model of oral epithelial carcinogenesis in rats has been established successfully in cell culture. Oral carcinomas of the tongue and palate were induced in Sprague-Dawley male rats by painting their palates three times weekly for 7 – 8 months with 0.5% (w/v) 4-nitroquinoline--oxide. Oral keratinocytes from malignant and untreated control tissues were cultivated using 3T3 fibroblast support. Both the normal and mahgnant cells stained positively with an anti-human keratin polydonal antibody but mahgnant keratinocytes were heterogeneous with regard to cell size, shape and intercellular packing, unlike the regular organization of the normal cultures. Mahgnant keratinocyte cultures differed markedly from their normal counterparts by an increase in their growth rate, the capacity for serial cultivation to the 25th passage (to date) and independence of 3T3 fibroblast support. In contrast, cultures established from healthy tissue showed signs of senescence usually by passage 4 and were totally reliant on 3T3 fibroblast support for growth. Malignant keratinocytes expressed anchorage independence when cultured in a semi-solid medium and gave rise to tumour formation in athymic mice. The development of this specialized cell culture system substantially increases the potential of the rat 4NQO model to investigate the pathogenesis of oral squamous cell carcinomas. [ABSTRACT FROM PUBLISHER]