CHARACTERIZATION OF A RAT ORAL SQUAMOUS-CELL CARCINOMA CELL-LINE UHG-RAC-'93 INDUCED BY 4-NITROQUINOLINE-1-OXIDE IN-VIVO

This study describes several characteristics of a cell line, UHG-RaC ' 93 derived from rat oral squamous cell carcinoma induced by the carcin ogen 4-nitroquinoline-1-oxide (4NQO), The cell Line was established fr om explant cultures without support of fibroblast feeder cells and con tinued for > 30 passages, UHG-RaC '93 had a high mitotic rate with a p opulation doubling time of 25 h and a high rate of squame production, The first passage had a low colony-forming efficiency in agarose gel, whereas later passages did not grow at all in semi-solid medium, Pheno type selection was furthermore apparent from a gradual increase of the trypsin-detachment time, Cytogenetic analysis showed that UHG-RaC '93 was hypotetraploid with an average of 74 chromosomes, Abnormalities c ompared to the normal karyotype were assessed and consisted mainly of breakpoints at (1)(q5?3), (3)(p1), (3)(q11q23), (11)(p?11), (13)(p13) and a derivative (12)t(12;13)(q10;q10). The karyotype remained stable for at least 26 passages, The expression of typical epithelioid marker s like cytokeratins and desmoglein corresponded with normal rat oral k eratinocytes, However expression of alpha 6 beta 4-integrin was altere d, Squame production, immunophenotype and anchorage dependency indicat ed that UHG-RaC '93 had the same features of a well-differentiated car cinoma with a low degree of agressiveness as the original tumour. The stable karyotype of this cell line provides a basis for further analys is of the effect of 4NQO on the genotype, phenotype and behaviour of r at oral keratinocytes.