Immunohistochemical analysis of the p53 family members in human craniopharyngiomas

Abstract

Craniopharyngiomas are intracranial tumors that usually arise in the site around the sella turcica. They are composed of distinctive sheets of epithelial cells showing adamantinomatous or squamous-papillary histologic types. Because little is known about the tumorigenesis of craniopharyngiomas, we retrieved samples from 15 tumor cases to investigate the functional significance of the p53 family of transcription factors, which are known to be expressed in various human epithelia. Immunohistochemical analysis of these cases demonstrated similar expression profiles of p53 family members in the two histologic types of the tumor; i.e., strong nuclear expression of p63 was observed in all cell layers, and moderate to intense nuclear expression of p73 was observed in the basal cell layers. In contrast to p63 and p73, the reactivity of an archetypal tumor suppressor, p53, was occasional and weak in the two histologic types. Because p63 was widely expressed in the tumors, reverse transcription-polymerase chain reaction (RT-PCR) analysis was conducted to elucidate which spliced variant of p63 was expressed. The results showed that deltaNp63, lacking a terminal transactivation domain of p63, was the dominant isoform. Together with the reported evidence that the deltaNp63 isoform is highly expressed in human squamous-cell carcinomas, these data suggest that the cellular architecture characteristic of the expression of p53 family members may be required for the histogenesis of craniopharyngiomas, where deltaNp63 has a possible role in maintaining proliferative activity of the tumor cells, like squamous-cell carcinomas in other tissues.