STUDIES ON THE DETECTION OF DIFFERENTIALL Y EXPRESSED GENES IN HEAD AND NECK-CANCER

Background: Carcinogenesis is generally considered a multistage proces s based on many alterations of the genetic substance. These alteration s lead to many qualitative and quantitative changes in gene expression with subsequent malignant transformation of the cell. Only a few of t hese genetic alterations are identified yet. Methods: The differential display reverse transcriptase polymerase chain reaction was employed to detect differentially expressed genes in head and neck cancer. The mRNA expression of cultivated keratinocytes of the upper aerodigestive tract was compared to the one of cultivated squamous cell carcinoma c ells of the larynx, hypopharynx, and floor of the mouth. Results: A to tal of 116 differentially expressed gene fragments were identified. Th ey were either solely expressed by the malignant cells or the keratino cytes or in just one carcinoma cell entity. Forty-three of the 116 DNA fragments were sequenced successfully. In four cases the specific dif ferential expression was confirmed by Northern blot hybridisation in c omparison to keratinocytes, normal mucosa, and 3 benign tumors from th e head and neck region. A gene bank search revealed in three cases a h omology of less than 20% to already known human, animal, bacterial or viral gene sequences and in one case a homology of 98% with a human ge ne sequence. Conclusions: The detected for squamous cell carcinoma of the head and neck specific genes or gene fragments are the basis for f urther investigations to better understand carcinogenesis.