Loss of epithelial blood group substance A in oral carcinomas

Oral cancer

In the U.S. oral cancer accounts for 2.1% of all cancers and 1% of cancer deaths. Two to three times as many males as females are affected. Blacks have more intra-oral cancer than whites, and their incidence and mortality rates have increased in recent years. The etiologic process very likely involves several factors. The major etiologic agents are tobacco (all types) and alcoholic beverages. Herpes simplex virus, human papilloma virus, and Candida have been implicated. Host factors include poor state of dentition, nutritional aberrations, cirrhosis of liver, lichen planus, and immunologic impairmant. Cellular changes include amplification of some oncogenes, alterations in antigen expression, production of gamma-glutamyl transpeptidase, and disturbance of keratin and involucrin production. Experimentally, cancer is readily produced on the hamster cheek pouch and rat oral mucosa. Unlike oral cancer in humans, most experimental lesions are exophytic, and they rarely metastasize.

Loss of epithelial cell surface carbohydrates during experimental oral carcinogenesis in the rat

Cell surface glycoconjugates were investigated in a rat model of oral chemical carcinogenesis. The lectins Griffonia simplicifolia (GS-I-B4; specific for alpha-D-galactosyl end groups) and Ulex europeus (UEA-I; specific for alpha-L-fucosyl groups) were examined microspectrofluorimetrically in the oral epithelium of rats painted with the carcinogen 4-nitroquinoline N-oxide (4NQO) and compared with those treated with solvent alone. After labelling with GS-I-B4, the fluorescent intensity of the basal and parabasal epithelial cells was significantly less after 9 months of 4NQO treatment and in overt squamous cell carcinomas compared to controls. The fluorescent activity of the spinous epithelial cells in the non-invasive tissues treated with 4NQO and in the well differentiated (sites of keratin elaboration) malignant epithelium of squamous cell carcinomas was unchanged after labelling with UEA-I. UEA-I failed to stain undifferentiated (areas lacking keratin) malignant epithelium. The findings indicate that alpha-D-galactosyl residues are diminished on the membranes of premalignant and malignant rat epithelial cells. The expression of alpha-L-fucosyl groups, however, remains unchanged in premalignant rat oral epithelium and is closely correlated to the presence of keratin in the malignant epithelium of squamous cell carcinomas.