Loss of heterozygosity at APC and MCC genes of oral cancer and leukoplakia tissues from Indian tobacco chewers

Background: Loss of heterozygosity (LOH) at tumor suppressor genes, such as adenomatous polyposis coli (APC) and mutated in colon cancer (MCC) genes, is one of the early events in carcinogenesis of oral tissue in Caucasian and Chinese patients. We wanted to check whether it is also true in Indian oral pre-cancer and cancer patients. Methods: Loss of heterozygosity at APC and MCC genes was investigated in 57 and 40 unrelated primary oral leukoplakia (a pre-cancerous lesion) and squamous cell carcinomas (SCC), respectively, by polymerase chain reaction. Results: In these samples, most of the leukoplakia patients had tobacco smoking habit whereas majority of cancer patients had tobacco chewing habit. LOH at APC gene was observed in 4 of 16 (25%) and 1 of 29 (3%) informative tumor and leukoplakia DNAs from tobacco chewers, respectively. LOH at MCC gene was not detected either in tumor or in leukoplakia DNAs. Conclusion: This infrequent LOH at APC gene of pre-cancer and cancer tissues suggests that it may not be an early event in oral carcinogenesis in these patients.