Genomic alterations associated with malignancy in head and neck cancer

Comparative genomic hybridization (CGH) was performed on 50 primary head and neck squamous cell carcinomas (HNSCC) to discover molecular genetic alterations underlying the progression of these tumors.

In CGH, equal amounts of differently labeled tumor deoxyribonucleic acid (DNA) and normal reference DNA were hybridized simultaneously to normal metaphase chromosomes. They were visualized by different fluorochromes, and the signal intensities were quantitated separately as gray levels along the single chromosomes. The over- and underrepresented DNA segments were determined by computation of ratio images and average ratio profiles.

Prevalent changes observed in more than 50% of the HNSCC included deletions of chromosomes 1p, 4, 5q, 6q, 8p, 9p, 11, 13q, 18q, and 21q and DNA overrepresentations of 11q13 as well as 3q, 8q, 16p, 17q, 19, 20q, and 22q. The calculation of ratio profiles of tumor subgroups revealed that well differentiated carcinomas (G1) were defined by the deletions of chromosomes 3p, 5q, and 9p together with the overrepresentation of 3q, suggesting the association with early tumor development. Accordingly, the undifferentiated tumors (G3) were characterized by additional deletions of chromosomes 4q, 8p, 11q, 13q, 18q, 21q, and overrepresentations of 1p, 11q13, 19, and 22q.

Our data indicate that the CGH patterns of chromosomal imbalances may help to define the malignant potential of head and neck squamous cell carcinomas.