Novel DNA amplification on chromosomes 2p25.3 and 7q11.23 in cholangiocarcinoma identified by arbitrarily primed polymerase chain reaction

Purpose: To detect and characterize amplified DNA sequences in cholangiocarcinoma (CCA). Patients and methods: We extracted DNA from tumor and corresponding normal tissues of 30 patients with CCA and amplified with 30 random ten-mer arbitrary primers by the arbitrarily primed polymerase chain reaction (AP-PCR) technique. Results: Our results showed gains of genomic sequences at high frequency. Using the AX-11 arbitrary primer, we determined an amplified DNA fragment occurred frequently in the tumors analyzed. The DNA fragment was isolated and identified as two sequences mapped to chromosomes 2p25.3 and 7q11.23. Specific primers were designed employing these sequences and used for detecting amplification by real-time quantitative PCR. The amplification of the DNA sequences on chromosomes 2p25.3 and 7q11.23 was detected in 10 (33%) and 6 (20%) cases, respectively. Thirteen (43%) cases showed amplification on both or one of the chromosomes. In addition, amplification of the DNA on chromosome 2p25.3 was predominantly observed in poorly differentiated tumors. Conclusions: Our findings suggest that the novel amplified DNA on chromosomal regions at 2p25.3 and 7q11.23 might be involved in the development and progression of CCA.