P53 gene mutations in pituitary carcinomas.

Area of Science:

• Endocrinology
• Oncology
• Molecular Biology

Background:

• p53 overexpression is observed in pituitary tumors.
• Genetic mutations in the p53 gene have not been previously identified in pituitary adenomas or carcinomas.

Purpose of the Study:

• To investigate the presence of p53 gene mutations in pituitary adenomas and carcinomas.
• To correlate p53 gene mutations with p53 protein expression levels.

Main Methods:

• Immunohistochemistry to detect p53 protein expression.
• Polymerase chain reaction amplification and sequencing of p53 exons 5-8 to identify genetic mutations.
• Analysis of pituitary adenomas, pituitary carcinomas, lung carcinomas, and breast carcinoma cell lines.

Main Results:

• p53 gene mutations were identified in two of six pituitary carcinomas.
• These mutations were associated with high p53 protein overexpression (60% and 90%).
• All eight pituitary adenomas were negative for p53 mutations and showed low p53 protein expression (15%).

Conclusions:

• p53 gene mutations are present in a subset of pituitary carcinomas.
• High p53 protein overexpression is often associated with p53 gene mutations in pituitary carcinomas.