Chromosomal aberrations determined by Comparative Genomic Hybridization in Oral Cancer

Objective: To elucidate the genetic alterations in 20 surgically removed fresh frozen oral squamous cell carcinoma (OSCC) cases using the CGH technique. Method: Twenty frozen tissue specimens of OSCC from the Malaysian Oral Cancer Data and Tumour Bank System (MOCDTBS) coordinated by OCRCC-UM were included in this study. A macrodissection technique for the frozen tissue sample was used to obtain ≥70% epithelial tumor cells. High molecular weight genomic DNA was extracted from samples and from whole blood of a healthy donor using a DNA extraction kit (Qiagen's QIAamp DNA Mini kit). Hybridization and detection of differentially labeled test and reference DNAs to commercially prepared normal metaphase chromosomes was performed using nick translation method. Image acquisition was done using epifluorescence microscope (Olympus, BX61) equipped with 100-W mercury lamp and CCD camera (cool-1300QS, ASI) controlled by an image analysis system (Applied Spectral Imaging, US). Results: CGH analysis revealed gains and/or losses in DNA sequence copy number in all tumors. Gains in DNA sequence copy number were detected frequently for chromosome arms 1p22-33 (8/20), 1q32-42 (8/20), 3p13-14 (6/20), 8q21.1-qter (8/20) and 10q22-qter (7/20), and losses in chromosome arms 7q11.2-21 (7/20), 14q11.2-13 (7/20), 15q11.2-21 (10/20), 18q12-23 (11/20), 19q (6/20) and 21q (10/20). Conclusion: All samples showed both losses and gains of DNA at parts of chromosomes. The study revealed losses of chromosomes 18q12-23 indicative of genes which may be involved in the development of OSCCs in a manner similar to their role in the development of other carcinomas, including colon and pancreatic cancers.

This study was supported by University Malaya IPPP. PS282/2007B and University of Malaya Scholarship program.