RECURRENT CHROMOSOMAL IMBALANCES DETECTED IN BIOPSY MATERIAL FROM ORAL PREMALIGNANT AND MALIGNANT LESIONS BY COMBINED TISSUE MICRODISSECTION, UNIVERSAL DNA AMPLIFICATION, AND COMPARATIVE GENOMIC HYBRIDIZATION

Biopsies routinely performed for the histopathological diagnosis of or al epithelial lesions before treatment were screened for chromosomal i mbalances by comparative genomic hybridization, Comparative genomic hy bridization was performed on 12 oral premalignant lesions (OPLs; dyspl asias and carcinomas in situ) and 14 oral squamous cell carcinomas (OS CCs), Eight biopsies displayed areas of different histopathological ap pearance, so that OPLs and OSCCs from the same patient were analyzed. To avoid contamination with nonneoplastic cells, defined cell populati ons were isolated by micromanipulation with a glass needle. Before com parative genomic hybridization analysis, universal DNA amplification w as performed using the DOP-polymerase chain reaction protocol. In the 14 OSCCs examined, the average number of chromosomal imbalances was :s ignificantly higher than in the 12 OPLs (mean +/- SEM: 11.9 +/- 1.9 ve rsus 3.2 +/- 1.2; P = 0.003), The DNA copy number changes identified i n more than one OPL were gains on 8q (3 of 12) and 16p (2 of 12), as w ell as losses on 3p (5 of 12); 5q (4 of 12); 139 (3 of 12); and 4q, 8p , and 9p (2 of 12 each). In more than 30% of OSCCs, gains of chromosom al material were identified on 20q (8 of 14); 8q, 11q, 22q (7 of 14 ea ch); 3q, 15q, and 17p (6 of 14 each); and 14q, 17q, and 20p (5 of 14 e ach), and losses were identified on 3p and 4q (9 of 14 each), 5q (7 of 14), 15q (6 of 14), and 2q and 9p (5 of 14 each). These results were validated by positive and negative control comparative genomic hybridi zation experiments and microsatellite analysis for the detection of al lelic loss. The vast majority of genomic alterations found in OPLs wer e again identified in OSCCs from the same biopsy, supporting the hypot hesis that multiple lesions in the same patient are clonally related. In summary, we show that comprehensive information on the genomic alte rations in oral epithelial lesions can be obtained from small biopsies . Such data may identify prognostic indicators that could eventually a ssist in designing therapeutic strategies.