H-ras and c-fos exhibit similar expression patterns during most stages of oral oncogenesis

H-ras and c-fos oncogenes interact in signalling pathways but their level and time course of expression during oral cancer development are unclear. The present study used an animal model for the simultaneous investigation of H-Ras and c-Fos expression in sequential stages of oral oncogenesis.

Three experimental groups of Syrian golden hamsters (A, B and C; 10 animals each) and one control group (7 animals) were used. The buccal pouches of hamsters in groups A, B and C were treated with 0.5% of the carcinogen 9,10-dimethyl-1,2-benzanthracene and were excised at 10, 14 and 19 weeks, respectively. The biopsies, which included tissue stages ranging from normal oral mucosa to moderately differentiated carcinoma, were studied immunohistochemically.

A reduction in both H-Ras and c-Fos expression was observed from group A to B and from hyperplasias to early tumour stages, while a simultaneous increase was noted from group B to C and from well-differentiated to moderately-differentiated carcinomas. The H-ras/c-fos expression ratio had a value of approximately (1.09 +/- 0.21) in five out of seven studied tissue stages.

H-Ras and c-Fos exhibit a similar expression pattern throughout most stages of oral carcinogenesis, an observation supported by the known molecular pathway connecting H-ras signalling with subsequent c-fos gene transcription.