(a) Map of 10p12 covering the region homozygously deleted in the HSC-6 cell line. Bacterial artificial chromosomes (BACs) spotted on the array are shown by horizontal bars: white bars, BACs with log 2 ratio<−2 indicating homozygous deletion; black bars, BACs with log 2 ratio >−2 in HSC-6 cells. The minimum homozygously deleted region in HSC-6 cells, as determined by genomic PCR, is indicated as a horizontal white closed arrow. Eight genes located around this region, which are homozygously deleted (six genes) or retained (two genes) detected by genomic PCR in the HSC-6 cell line, are indicated as white or black bars, respectively, that show positions and directions of transcription. (b) Images from genomic PCR experiments showing GAPDH, the functional control and eight genes that were harbored around the homozygous deletion at 10p12 using 18 oral squamous-cell carcinoma (OSCC) cell lines including HSC-6. DW, distilled water; PLC, normal peripheral lymphocytes. The arrowhead indicates the cell line having the homozygous deletion at 10p12 (HSC-6). (c) Expression of PRTFDC1, c10orf63, THNSL1, GPR158, MYO3A and GAD2 in OSCC cell lines, and control RT7 and primary culture of normal oral epithelial cells, detected by RT–PCR. DW, distilled water. Arrowhead indicates the cell line (HSC-6) with the homozygous deletion shown in (b). Note that eight (OM-1, OM-2, NA, ZA, Ca9-22, HSC-2, HSC-3 and KON) of the 18 cell lines without a homozygous deletion of PRTFDC1 showed almost complete silencing of this gene and one line (HOC-313) showed decreased expression compared with normal controls. (d) Representative results of RT–PCR analysis to reveal PRTFDC1 expression in NA, HSC-2 and ZA cells with or without treatment with 5-aza-dCyd (5 or 10 μ M) for 5 days and/or TSA (100 ng/ml) for 24 h.