[Detection of DNA amplifications and deletions in oral squamous cell carcinoma cell lines by comparative genomic hybridization (CGH)]

Comparative genomic hybridization (CGH) has recently developed for surveying DNA sequence copy number in tumors. The purpose of this study is to find and map chromosomal regions with amplifications and deletions in oral cancers by CGH. The results were further compared to those obtained by Southern hybridization and fluorescence in situ hybridization to investigate the mechanism of CGH identifying the amplification of oncogenes. DNAs extracted from 17 oral squamous cell carcinoma cell lines were labeled with biotin and hybridized to a normal metaphase spread together with digoxigenin-labeled normal reference DNA. The relative intensities of tumor DNA (detected using FITC) and normal DNA (detected with rhodamine) were measured by fluorescence imaging analysis system. Recurrent loci for amplification were observed on 8q22-q26, 3q25-q27, 7p12, 11q13, 13q33, 14q, 15q and 20q13. Deletions were seen on 3p, 18q21, 5q21-q22, 7q31 and 8p. There was a strong concordance for amplification detected by the CGH and Southern hybridization methods. These results indicated that these loci may contain previously unknown genes. Thus, CGH provides a useful approach for rapid identification of putative oncogenes as well as finding specific genetic markers for oral cancers.