Jerena Manoharan

Enalapril and ASS inhibit tumor growth in a transgenic mouse model of islet cell tumors

Accumulating evidence suggests a role for angiotensin-converting enzymes involving the angiotensin II-receptor 1 (AT1-R) and the cyclooxygenase pathway in carcinogenesis. The effects of ASS and enalapril were assessed in vitro and in a transgenic mouse model of pancreatic neuroendocrine neoplasms (pNENs). The effects of enalapril and ASS on proliferation and expression of the AGTR1A and its target gene vascular endothelial growth factor (Vegfa) were assessed in the neuroendocrine cell line BON1. Rip1-Tag2 mice were treated daily with either 0.6 mg/kg bodyweight of enalapril i.p., 20 mg/kg bodyweight of ASS i.p., or a vehicle in a prevention (weeks 5-12) and a survival group (week 5 till death). Tumor surface, weight of pancreatic glands, immunostaining for AT1-R and nuclear factor kappa beta (NFKB), and mice survival were analyzed. In addition, sections from human specimens of 20 insulinomas, ten gastrinomas, and 12 non-functional pNENs were evaluated for AT1-R and NFKB (NFKB1) expression and grouped according to the current WHO classification. Proliferation was significantly inhibited by enalapril and ASS in BON1 cells, with the combination being the most effective. Treatment with enalapril and ASS led to significant downregulation of known target genes Vegf and Rela at RNA level. Tumor growth was significantly inhibited by enalapril and ASS in the prevention group displayed by a reduction of tumor size (84%/67%) and number (30%/45%). Furthermore, daily treatment with enalapril and ASS prolonged the overall median survival compared with vehicle-treated Rip1-Tag2 (107 days) mice by 9 and 17 days (P=0.016 and P=0.013). The AT1-R and the inflammatory transcription factor NFKB were abolished completely upon enalapril and ASS treatment. AT1-R and NFKB expressions were observed in 80% of human pNENs. Enalapril and ASS may provide an approach for chemoprevention and treatment of pNENs.

The future: diagnostic and imaging advances in MEN1 therapeutic approaches and management strategies

Prospective randomized data are lacking, but current clinical expert guidelines recommend annual screening examinations, including laboratory assessments and various imaging modalities (e.g. CT, MRI, scintigraphy and EUS) for patients with multiple endocrine neoplasia type 1 (MEN1). Routine screening is proposed to detect and localize neuroendocrine manifestations as early as possible. The goal is timely intervention to improve quality of life and to increase life expectancy by preventing the development of life-threatening hormonal syndromes and/or metastatic disease. In recent years, some studies compared different and new imaging methods regarding their sensitivity and utility in MEN1 patients. This present article reviews the proposed diagnostic tools for MEN1 screening as well as potential future perspectives.

An unusual phenotype of MEN1 syndrome with a SI-NEN associated with a deletion of the MEN1 gene.

Summary We report about a young female who developed an unusual and an aggressive phenotype of the MEN1 syndrome characterized by the development of a pHPT, malignant non-functioning pancreatic and duodenal neuroendocrine neoplasias, a pituitary adenoma, a non-functioning adrenal adenoma and also a malignant jejunal NET at the age of 37 years. Initial Sanger sequencing could not detect a germline mutation of the MEN1 gene, but next generation sequencing and MPLA revealed a deletion of the MEN1 gene ranging between 7.6 and 25.9 kb. Small intestine neuroendocrine neoplasias (SI-NENs) are currently not considered to be a part of the phenotype of the MEN1-syndrome. In our patient the SI-NENs were detected during follow-up imaging on Ga68-Dotatoc PET/CT and could be completely resected. Although SI-NENs are extremely rare, these tumors should also be considered in MEN1 patients. Whether an aggressive phenotype or the occurrence of SI-NENs in MEN1 are more likely associated with large deletions of the gene warrants further investigation. Learning points Our patient presents an extraordinary course of disease. Although SI-NENs are extremely rare, these tumors should also be considered in MEN1 patients, besides the typical MEN1 associated tumors. This case reports indicate that in some cases conventional mutation analysis of MEN1 patients should be supplemented by the search for larger gene deletions with modern techniques, if no germline mutation could be identified by Sanger sequencing.

Chemoprevention with Enalapril and Aspirin in Men1(+/T) Knockout Mouse Model

Pancreatic neuroendocrine neoplasias (pNEN) are the most common cause of death in adult patients with multiple endocrine neoplasia type 1 (MEN1). So far, only few chemopreventive strategies (e.g., with somatostatin analogues) have been evaluated for MEN1 associated pNENs. In this experimental study on 75 Men1(+/T) knockout mice, the effect of aspirin (n = 25) and an inhibitor of angiotensin-I converting enzyme (enalapril, n = 25) compared to controls (n = 25) were evaluated as single chemopreventive strategies for pNENs after 6, 9, 12, 15, and 18 months. After each study period, mice were sacrificed and the resected pancreata were evaluated by histopathological analysis, immunostaining, and real-time PCR. PNEN size and number was measured. Aspirin and enalapril lead to a pNEN size reduction of 80% (167,518 vs. 838,876 µm2, p < 0.001) and 79% (174,758 vs. 838,876 µm2, p < 0.001) compared to controls. Furthermore, aspirin and enalapril treatment resulted in a significant reduction of the number of pNENs by 33%, (p = 0.04) and 41% (p = 0.002) respectively. The apoptosis marker caspase 3 revealed a higher positive expression in pNEN of treated Men1(+/T) mice. Immunostaining of VEGF in pNEN detected a downregulation of its expression in treated Men1(+/T) mice compared to the control group. REL A transcript was significantly downregulated in 18-months treated enalapril Men1(+/T) mice, but not in aspirin-treated Men1(+/T) mice. There was no significant difference in the Ki-67 index. Using a transgenic mouse model that imitates human MEN1, this study provides first evidence that aspirin and enalapril are effective chemopreventive agents that aid in the progression of pNENs.