[Preliminary study of p16 gene expression in pituitary adenomas].

Background & Objective: The inactivation and low expression of tumor suppressor gene p16 has been found to play an important role in the tumorigenesis of a wide variety of human tumors, but its association with human pituitary adenomas was not clear. This study was conducted to investigate the relationship between p16 gene expression and clinicopathologic features including invasiveness and recurrence in pituitary adenoma patients.

Methods: The p16 mRNA and p16 protein expression levels were examined using reverse transcription polymerase chain reaction (RT-PCR) and Western Blot analysis respectively in 70 pituitary adenomas and 10 normal brain tissues.

Results: Fifty-two of 70 (74.3%) tumor samples presented loss or low p16 mRNA and p16 protein. The invasive and recurrent adenomas had higher loss expression rates than noninvasive and nonrecurrent group respectively; however, there was no significant difference (P >0.05). Moreover, the mean diameter of adenomas without p16 expression was obviously larger than that of p16-positive tumors (22.1+/-7.2 mm versus 8.1+/-4.5 mm, P< 0.01). There was no association between p16 expression and other clinicopathologic features of pituitary adenomas.

Conclusion: These findings suggested that p16 down-regulation may play an important role in the initial tumorigenesis, growth, and biological behavior of pituitary adenomas.