Introduction. Neuroendocrine neoplasms (NENs) are neoplasms that most commonly arise from gastrointestinal tract, pancreas, and lung. HES1 is a downstream target of Notch signaling pathway. The current literature about HES1 expression in NENs is sparse and inconsistent. Methods. In this study, we evaluated HES1 expression by immunohistochemistry in a total of 32 cases of NENs, including 13 well-differentiated neuroendocrine tumors from gastrointestinal tract, 10 cases of well-differentiated neuroendocrine tumors of pancreas, 9 cases from lung, including 4 cases of typical carcinoid, 1 case of atypical carcinoid, and 4 cases of neuroendocrine carcinoma. The intensity of the stain was scored from - to +++, and the distribution of the staining of HES1 was evaluated. Results. HES1 demonstrates uniform robust (+++) nuclear staining pattern in the tumor cells of all the NENs (32/32), regardless of the origin of the system and the grade of the tumor. Conclusions. HES1 is uniformly expressed in NENs with robust nuclear expression pattern. Our finding suggests that NOTCH1 or HES1 inhibitor is a potential therapeutic choice for neuroendocrine neoplasms.
Keywords: HES1; Notch; gastrointestinal; lung; neuroendocrine neoplasm; pancreas.