VISUALIZATION OF INT2 AND HSTI AMPLIFICATION IN ORAL SQUAMOUS-CELL CARCINOMAS

Oral squamous cell carcinoma (OSCC) develops along a multistep genetic pathway including loss of tumor suppressor genes and alteration of on cogenes. We characterized seven OSCC cell lines by classical and molec ular cytogenetic analysis and fresh tumor and adjacent oral mucosa cor responding to three of the cell lines by molecular cytogenetics. We ob served homogeneously staining regions (hsrs) in four of the seven cell lines, at 11q13 in three and at 11q23 and in an unidentified marker c hromosome in the fourth. Amplification of band 11q13 occurs in 30-60% of head and neck squamous cell carcinomas. To determine whether INT2 a nd HST1, both located in band 11q13, are amplified in the tissues and cell lines and to confirm the chromosomal location(s) of the amplifica tion, we used dual-color fluorescence in situ hybridization (FISH) wit h DNA probes for these genes and the chromosome 11 centromere. We repo rt chromosomal localization of INT2/HST1 amplification in OSCC. Coampl ification of INT2 and HST1 was detected in the hsrs in cultured tumor cells from the four hsr-containing tumors and in directly harvested tu mor cells, which were available from only two of these tumors. Amplifi cation was not present in tumors lacking hsrs or adjacent oral mucosa corresponding to any of the seven tumors. The observation of amplifica tion in fresh tumor cells suggests that the amplification was present in the patients, may play a key role in the development and/or progres sion of OSCC, and is not due to karyotypic evolution in vitro, The abs ence of amplification in the adjacent mucosa suggests that 11q13 ampli fication is a relatively late event in OSCC tumorigenesis. (C) 1995 Wi ley-Liss, Inc.