DIFFERENTIALLY EXPRESSED GENES IN HEAD AND NECK-CANCER

Carcinogenesis is considered a multistep process. To further elucidate involved genetic changes, the differential display method was applied to compare gene expression of head and neck carcinoma cells and norma l keratinocytes from the upper aerodigestive tract, Total RNA was extr acted from cultured squamous carcinoma cells and keratinocytes. mRNA w as reverse transcribed into cDNA, amplified by PCR, and separated on a gel. Currently three DNA transcripts were identified with a length of 191 to 336 base pairs (bp) that were either expressed only by the ker atinocytes or by the malignant cells. Differentially expressed DNA fra gments of the carcinoma cells sind the keratinocytes were cloned and s equenced. it gene bank database search identified one fragment express ed by the carcinoma cells as an unknown gene, another one found in the keratinocytes as probably at part of the human cell attachment domain , and the third one with homology to the mRNA of the human epidermal g rowth factor receptor (EGFR), Northern blot analysis confirmed the dif ferential expression in the malignant cells or the keratinocytes. Diff erential display seems to confirm the well-known overexpression and up -regulation of the EGFR, the differential expression of the cell attac hment domain may play a role as a cofactor in carcinogenesis of head a nd neck cancer, and the third unknown fragment is still under investig ation to elucidate the role in carcinogenesis.