Problematic divergencies between clinical and immunocytochemical findings in prolactinomas

Höfler, Heinz; Walter, Gerhard; Leb, G.; Auer, L. M.; Cianci, Gianguido C.; Tscherne, G; Urdí, W.; Warnkroß, H; Schneider, Gyula

doi:10.1515/9783110853858-010

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“…However, a more feasible explanation would seem to be stalk compression and impaired delivery of PRL-inhibiting factor, resulting in an unrestrained release of PRL from the normal gland, as other authors have suggested. 18 Two GH/PRL tumours showed normal levels of PRL in the blood flow, a feature that has been previously reported by others. 19 In accordance with these observations, most of the pituitary tumours with high levels of SNAP-25 protein expression are PRL-cell adenomas.…”

Section: Discussionsupporting

confidence: 76%

Immunocytochemical analysis of the synaptic proteins SNAP‐25 and Rab3A in human pituitary adenomas. Overexpression of SNAP‐25 in the mammosomatotroph lineages

Majó

Ferrer²,

Marsal

et al. 1997

J. Pathol.

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SNAP‐25 and Rab3A were originally identified as synaptic proteins involved in neuronal membrane traffic. Recently, both proteins have been detected in several mammalian endocrine cell types and have been proposed as essential components of the exocytotic pathway in neuroendocrine cells. In this study, the expression of SNAP‐25 and Rab3A was analysed in biopsied human anterior pituitary tumours (21 cases) by immunocytochemical methods. No differences in Rab3A immunoreactivity were observed between tumour and normal pituitary cells. Strong SNAP‐25 immunoreactivity was detected in tumour cells of prolactinomas (n=3). Several growth hormone (GH)/prolactin (PRL) tumours also displayed intense SNAP‐25 immunolabelling (n=3), whereas the remaining GH‐secreting adenomas (n=4) exhibited moderate to weak SNAP‐25 immunoreactivity. In contrast, SNAP‐25 near‐background immunostaining was observed in tumour cells of adrenocorticotrophic hormone (ACTH)‐secreting tumours (n=4) and non‐secreting tumours (n=7), as well as in normal pituitary cells. Since SNAP‐25 and Rab3A have been shown to be involved in exocytotic events in rodent endocrine cells, overexpression of SNAP‐25 protein in PRL and GH/PRL tumour cells might be implicated in the mechanism of exocytosis of the neoplastic human mammosomatotroph lineages. © 1997 John Wiley & Sons, Ltd.

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Section: Discussionsupporting

confidence: 76%