The MDM2 SNP309 G allele is not preferentially amplified in bone and soft tissue tumors.

[well-differentiated liposarcoma]

The transcriptional enhancer region in intron 1 of the proto-oncogene MDM 2 contains a polymorphic site (SNP 309 ) that may harbor a G or a T nucleotide . Previous studies have shown that the G allele confers a higher affinity for the Sp 1 transcription factor , resulting in an increased transcriptional activity of MDM 2 . A constitutional G allele has also been associated with earlier onset of various cancer types , and studies of sarcomas have shown an enrichment of the G allele in tumors with MDM 2 amplification , notably atypical lipomatous tumor (also known as well-differentiated liposarcoma ). In the present study , we analyzed the SNP 309 genotype in blood samples and tumor tissue from 57 patients with bone or soft tissue tumors showing amplification of MDM 2 . We did not observe any constitutional enrichment of the G allele . More importantly , there was no preferential amplification of the G allele in tumor tissue from TG heterozygotes . The expression levels of MDM 2 messenger RNA were not higher in tumors with amplification of the G allele than in tumors with amplification of the T allele . Thus , we could not find any evidence for a selective advantage of the SNP 309 G allele in bone and soft tissue tumors with MDM 2 amplification .