Gene discovery in oral squamous cell carcinoma through the Head and Neck Cancer Genome Anatomy Project: confirmation by microarray analysis

Abstract

The near completion of the human genome project and the recent development of novel, highly sensitive high-throughput techniques have now afforded the unique opportunity to perform a comprehensive molecular characterization of normal, precancerous, and malignant cells, including those derived from squamous carcinomas of the head and neck (HNSCC). As part of these efforts, representative cDNA libraries from patient sets, comprising of normal and malignant squamous epithelium, were generated and contributed to the Head and Neck Cancer Genome Anatomy Project (HN-CGAP). Initial analysis of the sequence information indicated the existence of many novel genes in these libraries [Oral Oncol 36 (2000) 474]. In this study, we surveyed the available sequence information using bioinformatic tools and identified a number of known genes that were differentially expressed in normal and malignant epithelium. Furthermore, this effort resulted in the identification of 168 novel genes. Comparison of these clones to the human genome identified clusters in loci that were not previously recognized as being altered in HNSCC. To begin addressing which of these novel genes are frequently expressed in HNSCC, their DNA was used to construct an oral-cancer-specific microarray, which was used to hybridize alpha-(33)P dCTP labeled cDNA derived from five HNSCC patient sets. Initial assessment demonstrated 10 clones to be highly expressed (>2-fold) in the normal squamous epithelium, while 14 were highly represented in the malignant counterpart, in three of the five patient sets, thus suggesting that a subset of these newly discovered transcripts might be highly expressed in this tumor type. These efforts, together with other multi-institutional genomic and proteomic initiatives are expected to contribute to the complete understanding of the molecular pathogenesis of HNSCCs, thus helping to identify new markers for the early detection of preneoplastic lesions and novel targets for pharmacological intervention in this disease.