Amplification and overexpression of genes in 17p11.2∼p12 in osteosarcoma

We summarize and briefly discuss recent findings with respect to the amplification and overexpression of candidate oncogenes in 17p11.2∼p12 in high-grade osteosarcomas. Amplification of this region occurrs in about 25% of cases. The amplification profiles are often complex and suggest the involvement of more than one oncogene. The 17p11.2∼p12 region harbors many low-copy repeats (LCRs). We propose LCR-mediated repeated duplication by mitotic nonallelic homologous recombination as mechanism for the generation of the amplifications in this region. Genes PMP22 and COPS3 and three expressed sequence tags from within 17p11.2∼p12 have been found to be frequently overexpressed and consistently overexpressed after amplification, which identifies them as candidate oncogenes in this region. Overexpression of COPS3 has been linked to TP53 protein degradation and, being equivalent to TP53 mutation, the induction of genomic instability, which frequently occurrs in high-grade osteosarcoma. These findings may serve as a framework for future work aimed to identify the causative oncogenes in 17p11.2∼p12, to clarify the mechanism of their amplification, and to determine their importance in osteosarcoma tumorigenesis.