THE PTEN TUMOR-SUPPRESSOR GENE AND MALIGNANT-MELANOMA

A candidate tumour suppressor gene, PTEN, has recently been identified within chromosome 10q23, the locus of the Cowden syndrome/Lhermitte-D uclos disease susceptibility gene. Cowden disease is an autosomal domi nant cancer predisposition syndrome associated with tumours of the bre ast, thyroid and, less frequently, malignant melanoma. Based on the id entification of mutations in sporadic breast, brain and prostate tumou rs, we decided to examine the potential role of PTEN in sporadic malig nant melanoma. Frozen tissue from primary cutaneous melanomas (n = 23) and metastases (n = 17) were microdissected, and microsatellite marke rs D10S541 and D10S547, flanking the gene on both sides, were used to search for loss of heterozygosity (LOH) in the PTEN gene locus. To ide ntify mutations within the putative tumour suppressor gene, we perform ed single strand conformation polymorphism (SSCP) analysis using intro nic primers to amplify exons 5, 6, 7 and 8 of the PTEN gene. No LOH wa s detected using the polymorphic markers D10S541 and D105547. SSCP ana lysis revealed no aberrant bands in the tumour specimen. Our results s uggest that the PTEN gene does not play a major role in the initiation and progression of melanoma. (C) 1998 Lippincott Williams & Wilkins.