Expression of the PTEN tumour suppressor protein during human development.

The tumour suppressor gene PTEN, localized to 10q23.3, is the susceptibility gene for Cowden syndrome (CS) and Bannayan-Riley-Ruvalcaba (BRR) syndrome, two hamartoma syndromes with an increased risk of breast and thyroid tumours. Somatic mutations have been found in a variety of human tumours. Functional studies have revealed that PTEN plays a fundamental role in cellular growth, death, adhesion and migration. RNA in situ hybridization using the pten coding region in mouse embryos showed ubiquitous transcription, providing evidence that pten could play a versatile role throughout murine development. Nothing is known regarding the pattern of PTEN expression during human development. Here, we present the pattern of PTEN expression during human development using a specific monoclonal antibody and examine the relationship of the temporal and spatial expression pattern to the clinical manifestations of CS and BRR, the somatic genetic data in sporadic cancers, the murine knockout models and the RNA expression data in mouse embryos. We observed mainly high-level PTEN expression in tissues (e.g. skin, thyroid and central nervous system) known to be involved in CS and BRR. In addition, we identified tissues (e.g. peripheral nervous system, autonomomic nervous system and upper gastrointestinal tract) with high PTEN expression not commonly known to play a role in these syndromes nor in sporadic tumorigenesis in those organs. This knowledge may help in identifying roles for PTEN which, as of today, are unknown or even unsuspected.