PTEN MMAC1/TEP1 INVOLVEMENT IN PRIMARY PROSTATE CANCERS/

The PTEN/MMAC1/TEP1 gene, located at 10q23.3, is a tumor suppressor ge ne responsible for the familial cancer syndromes Cowden disease and Ba nnayan-Zonana syndrome, and is commonly somatically mutated in several types of cancers. Mutations of the PTEN gene have been found in prost ate cancer cell lines and LOH at 10q22-24 in prostate tumors have also been described with a high frequency. To determine the role of this g ene in prostate tumorigenesis, we therefore analysed 22 primary tumors for loss of heterozygosity (LOH) within the 10q22-23 region such that tumors hemizygous at those loci may be examined for somatic PTEN muta tions. Losses of heterozygosity of at least one locus was found in 12 (55%) of the 22 tumors DNAs. Among these, six tumors exhibited allele loss in the interval between D10S1765 and D10S541 wherein lies the PTE N gene. We searched the entire coding region of PTEN for somatic mutat ions in these six tumors. One somatic mutation (17%), a 1 bp deletion, was detected in exon 7 of the gene, in ode tumor, indicating that som atic mutations of the PTEN gene may occur in primary prostate tumors.