Image cytometric DNA analysis of 9-10 dimethyl 1-2 benzanthracene induced submandibular salivary gland lesions in albino rats

ABSTRACT

The unclear DNA content of rat subm and ibular salivary gl and [SMSG] lesions was determined using CAS 200 image cytometer. Squamous metaplasia, epithelial hyperplasia and dysplasia as well as epidermoid cysts were induced at eight weeks after implantation of 5 mg 9-10 dimethyl 1-2 benzanthracene [DMBA] in the rat SMSG. The production of well differentiated, moderately differentiated and undifferentiated squamous cell carcinomas [SCC] were demonstrated in 75% of the animals 16, 20 and 24 weeks after AMBA implantation. Interestingly, two cases of carcinosarcoma were also revealed at 24 weeks after treatment. The nuclear DNA content of the hyperplastic and dysplastic epithelium showed a diploid distribution pattern. Multiple stem lines peaks with variable DNA content were also evident in DNA histograms of the dysplastic epithelium. The nuclear DNA pattern of SCC cells showed marked DNA abnormalities with tetraploid and aneuploid modes. An increase in the DNA index of the induced cells was observed during DMBA carcinogenesis reaching its highest value [2.34] in the carcinosarcomas. It can be concluded that the variations in the nuclear DNA content occurring during DMBA carcinogenesis are correlated to the degree of cell differentiation and using image analysis provide better sensitivity for detecting aneuploid DNA content and lead to a more accurate and objective measure of tumor proliferative activity. The role of induced aneuploidy in DMBA carcinogenesis was also evaluated