EXPRESSION OF A BREAST-CANCER-ASSOCIATED PROTEIN (PS2) IN HUMAN NEUROENDOCRINE TUMORS

pS2 protein expression has been demonstrated in a range of malignant t issues in an oestrogen-independent pathway. Recently, it has been demo nstrated that pS2, in prostate cancer, is closely associated with neur o-endocrine differentiation, In the present study, we have analyzed, b y immunohistochemistry along with microwave antigen retrieval, the exp ression of pS2 protein in a retrospective series of 236 human primary neuro-endocrine tumours and attempted to correlate this with the clini copathologic features of patients and the presence of oestrogen recept or (ER), pS2 immunoreactivity was detected in 42% of small-cell lung c arcinomas, 36% of lung carcinoids, 33% of phaeochromocytomas, 38% of c arotid-body tumours, 31% of pancreatic neuro-endocrine tumours, 60% of stomach carcinoids, 55% of ileal carcinoids, 23% of appendiceal carci noids and 86% of rectal carcinoids respectively in more than 10% tumou r cells, No pituitary tumours displayed pS2 immunoreactivity, pS2 tran script was also detected in lung carcinoid and carotid-body tumours by Northern-blot analysis, There was a statistically higher incidence of pS2 expression in carcinoid tumours of the ileum and rectum than in t hose of the appendix. No association was observed between pS2 expressi on and the occurrence of the carcinoid syndrome; nor was any correlati on observed between the occurrence of pS2 immunoreactivity and that of ER, Our results suggest that the expression of the pS2 protein in a w ide spectrum of neuro-endocrine tumours may be implicated in the patho genesis and progression of some neuro-endocrine tumours in an oestroge n-independent pathway. (C) 1997 Wiley-Liss, Inc.