PTEN is not altered in sporadic vestibular schwannomas.

ABSTRACT

AIMS: To investigate the role of the tumour suppressor gene PTEN in the tumorigenesis and growth of sporadic vestibular schwannomas, and to characterize the cellular distribution of the PTEN protein in relation to the MIB-1 proliferation index in these tumour. METHODS AND RESULTS: Immunoexpression of the PTEN protein was observed within the neoplastic Schwann cells in 21 out of 30 sporadic schwannomas examined (70%). PTEN expression was consistently stronger in Antoni A areas than in Antoni B areas. High levels of PTEN immmunoexpression in schwannomas were associated with an increased MIB-1 labelling index. Occasionally, vascular endothelial cells also showed PTEN immunoreaction. By polymerase chain reaction-single strand conformation polymorphism screening, no mutations were found in the complete protein coding region of the PTEN gene. CONCLUSIONS: The PTEN tumour suppressor gene is expressed in the majority of sporadic schwannomas. The maintained expression of the PTEN protein, together with the lack of detectable mutations in this gene, suggests that the function of the PTEN tumour suppressor gene is not altered in sporadic vestibular schwannomas.