Spatial and temporal expression pattern of somatostatin receptor 2 in mouse / 生物工程学报

Somatostatin (SST) is an inhibitory polypeptide hormone that plays an important role in a variety of biological processes. Somatostatin receptor 2 (SSTR2) is the most widely expressed somatostatin receptor. However, the specific cell types expressing Sstr2 in the tissues have not been investigated. In this study, we detected the expression pattern of SSTR2 protein in mouse at different development stages, including the embryonic 15.5 days and the postnatal 1, 7, 15 days as well as 3 and 6 months, by multicolour immunofluorescence analyses. We found that Sstr2 was expressed in some specific cells types of several tissues, including the neuronal cells and astrocytes in the brain, the mesenchymal cells, the hematopoietic cells, the early hematopoietic stem cells, and the B cells in the bone marrow, the macrophages, the type Ⅱ alveolar epithelial cells, and the airway ciliated cells in the lung, the epithelial cells and the neuronal cells in the intestine, the hair follicle cells, the gastric epithelial cells, the hematopoietic stem cells and the nerve fibre in the spleen, and the tubular epithelial cells in the kidney. This study identified the specific cell types expressing Sstr2 in mouse at different developmental stages, providing new insights into the physiological function of SST and SSTR2 in several cell types.

Establishment and application of a drug screening model targeting somatostatin receptor 2 / 中国药理学通报

Aim To establish a cell model to detect the activity of somatostatin (SST) by targeting somatostatin receptor 2 (SSTR2), and to provide a simple and stable evaluation method for the drug screening of SSTR2 agonists and somatostatin analogues (SSTA). Methods The target gene of SSTR2 was integrated into the pEGFP-N3 vector, and the recombinant plasmid was constructed and transfected into HEK293 cells. After G418 screening, positive clone was selected and the stable cell lines were obtained by expanding culture. The stable cell lines were identified by fluorescence cell imaging, Western blot and qPCR. A calcium flow detection system was established to optimize cell number, fluorescence dye concentration and incubation time. Finally, the screening model was used to detect the different batches of the marketed somatostatin preparation Stilamin. Results SSTR2 stable cell lines were successfully constructed, and the receptors were mainly distributed on the cell membrane. The optimal conditions for calcium flow detection were determined as follows; 30 000 cells/Well, Fluo-4/AM indicator concentration was 3 p,mol • L -1 ~5 u,mol • L-1 , incubation time was 45 min. Under this condition, EC50 value of Stilamin in different batches was stable. Conclusions SSTR2 overexpressed stable cell lines are successfully constructed and calcium flow detection method is optimized to provide a simple and stable model for the screening of somatostatin receptor agonists.

SSTR2A Protein Expression in Neuroendocrine Neoplasms of the Colorectum

BACKGROUND: Expression studies of somatostatin receptor type 2A (SSTR2A) in neuroendocrine neoplasms (NENs) led to the development of clinically relevant diagnostic and therapeutic strategies. However, most of these strategies used in-house-developed antibodies and were focused on lung tumors. We evaluated commercially available SSTR2A antibodies in NENs of the colorectum to observe their subcellular localization and distribution within the resected tumor. METHODS: The immunohistochemistry of 77 NENs located in the colorectum were studied using a commercially available antibody against SSTR2A. RESULTS: Most neuroendocrine tumors (NET) grade (G)1 and G2 expressed the SSTR2A in the cytoplasm with apical or luminal localization. However, all neuroendocrine carcinomas (NEC) G3 were negative for SSTR2A. CONCLUSIONS: Our data indicate that SSTR2A immunohistochemistry shows cytoplasmic staining with distinct subcellular localization in most NET G1 in the colorectum using a commercially available antibody. Low or no expression of SSTR2A in NET G2 and NEC G3 raises the possibility that SSTR2A may correlate with histologic differentiation and proliferative activity. Further validation studies in large case series are needed.