Human papillomaviruses in 91 oral cancers from Indian betel quid chewers--high prevalence and multiplicity of infections.

India has one of the world's highest incidences of oral cancer. The habit of chewing betel quid is widespread and is suspected to play a role in the etiology of this disease. Studies in many other countries have also pointed to a role for human papilloma-viruses (HPVs) in the etiology of some oral cancers. In this study we analyzed biopsies from 91 Indian oral cancer patients, most of whom were betel quid chewers, by PCR amplification and direct DNA sequencing. HPV DNA was detected in 74% of these lesions, of which 41% had multiple HPV infections. Among the lesions from different oral sites, lesions of the tongue had the highest rate (9 of 11) of HPV infection. These HPV prevalences are among the highest ever reported in oral cancers. As to individual HPV types, prevalences of HPV-6, HPV-11, HPV-16 and HPV-18 were 13%, 20%, 42% and 47%, respectively. No additional known or novel HPV types were detected. To understand the unexpectedly high prevalences of the "low-risk" types HPV-6 and HPV-11, we compared the subtypes and variants that were found in oral cancers against those from benign genital warts from the same patient population but found no differences. The high prevalence of HPV in the oral cancers of these Indian patients suggests that viral infection is an important etiological component, with betel quid probably causing additional mutagenic steps in the carcinogenic process.

Expression of galactoside-specific endogenous lectins and their ligands in human oral squamous cell carcinoma.

Human endogenous lectins have a wide spectrum of biological functions. The present study analyses the expression of beta-galactoside specific and N-acetyl-D-galactosamine specific endogenous lectins in oral squamous cell carcinomas using biotinylated neoglycoproteins. The expression pattern of beta-galactosyl-containing glycoconjugates or ligands of beta-galactoside specific lectins in these tissues was also studied using an endogenous biotinylated lectin, the human 14-kDa lectin. For comparison a galactoside specific plant lectin from mistletoe, Viscum album was also employed. The results demonstrate that oral squamous cell carcinomas mainly express accessible binding sites for lactosylated neoglycoprotein (90%) while few carcinomas expressed mild amount of N-acetyl-D-galactosamine specific binding sites (40%). There was no difference in the binding patterns of these probes between well and less differentiated carcinomas. Expression of these neoglycoprotein binding sites were mostly concentrated in immature basaloid cells, indicating a possible association with cell proliferation. The binding pattern of D-galactosyl specific lectins (human 14-kDa and mistletoe lectins) showed conspicuous differences. This feature emphasizes the caution that needs to be exercised in interpreting the biological significance of results attained using plant lectins on human tissue.