Expression of Somatostatin Receptor (SSTR) Subtypes (SSTR-1, 2A, 3, 4 and 5) in Neuroendocrine Tumors Using Real-time RT-PCR Method and Immunohistochemistry.

Molecule targeting therapy using somatostatin (SS) analogues has become a widely accepted modality to treat neuroendocrine tumors (NETs), particularly gastrointestinal (GI) and pancreatic endocrine tumors. On the other hand, little is known about the expression of somatostatin receptor (SSTR) subtypes in neuroendocrine carcinomas (NECs). We investigated the expression of SSTR subtypes (SSTR-1, 2A, 3, 4 and 5) using real-time reverse transcription polymerase chain reaction (RT-PCR) method and immunohistochemistry in 32 neuroendocrine neoplasms (9 NET G1, 2 NET G2, 18 NECs G3 and 3 mixed NEC G3) of various primary sites. Expression of more than two SSTR subtypes was detected in all neuroendocrine neoplasms examined. Expression of SSTR-2A mRNA was significantly higher than other subtypes. In addition, mRNA expression of SSTR-3 and SSTR-5 was significantly low or below the detection level except for gastroduodenal NET G1. No significant difference of the expression of SSTR subtypes was observed between the NET and NEC groups. The expression of protein and mRNA was generally well correlated. In conclusion, NECs would be a good candidate for molecule targeting therapy using SS analogues, and the expression of SSTR-2A can be useful as a biomarker of neuroendocrine differentiation. We have demonstrated that NEC G3 small cell type shows a different expression profile of SSTR subtypes compared with NET and NEC non-small cell type.

Squamous cell carcinoma with sarcomatous feature (so-called carcinosarcoma) of stomach probably metastasized from esophageal tumor: a case report with quick-freezing and deep-etching method.

A squamous cell carcinoma (SCC) with sarcomatous features (so-called carcinosarcoma) of stomach is reported in a 72-year-old man. The gastric submucosal tumor (12 x 11 x 6 cm) consisted of carcinoma cells and sarcomatous spindle cells, which were immunohistochemically recognized to contain high molecular weight cytokeratin. These histological and immunohistochemical results indicated that carcinoma cells and spindle tumor cells had cytokeratin similar to that of stratified squamous epithelium. These features were consistent with so-called carcinosarcoma of esophagus. A combined type of tumor consisting of polypoid and shallow ulcerative lesions (5.5 cm in diameter) was demonstrated by the biopsy to have SCC on the polypoid surface area. Therefore, the gastric tumor was thought to have metastasized from the esophageal tumor. The quick-freezing and deep-etching (QF-DE) method demonstrated that many spindle tumor cells in the gastric tumor had abundant intermediate filaments, which were evenly distributed in more peripheral cytoplasm along the cell membrane. This feature was similar to that of the control SCC. Intramembranous protein particles in the cell membrane of the tumor cells were markedly decreased as compared with those of control SCC. These ultrastructures by QF-DE method could be used for the pathological diagnosis of so-called carcinosarcomas of esophagus.