The molecular biology of pituitary tumors: a personal perspective.

Oncogenes and tumor suppressor genes involved in most common cancers are not involved in the great majority of pituitary adenomas. Similarly, there is little evidence to suggest that the mutations involved in genetic syndromes associated with pituitary tumors (such as the gsp, MEN1, PKAR1A or AIP mutations) are common in sporadic tumors. A novel pituitary tumor transforming gene (PTTG, securin) has been identified which is over-expressed in most tumors--but it is unclear as to its causal role in oncogenesis. Cell signaling abnormalities have been identified in pituitary tumors but their genetic basis is unknown. However, both the Akt pathway and the MAPK pathway are over-expressed in many pituitary tumors, which results in the inhibition of cell cycle inhibitors. These pathways share a common root in the tyrosine kinase receptor, and a change to these receptors or their relationship to membrane matrix-related proteins may be an early event in tumorigenesis.