Growing vascular endothelial cells express somatostatin subtype 2 receptors

We hypothesized that non-proliferating (quiescent) human vascular endotheli al cells would not express somatostatin receptor subtype 2 (sst 2) and that this receptor would be expressed when the endothelial cells begin to grow. To test this hypothesis, placental veins were harvested from 6 human place ntas and 2 mm vein disks were cultured in 0.3% fibrin gels. Morphometric an alysis confirmed that 50-75% of cultured vein disks developed radial capill ary growth within 15 days. Sst 2 gene expression was determined by reverse transcription-polymerase chain reaction (RT-PCR) analysis of the RNA from v eins before culture and from tissue-matched vein disks that exhibited an an giogenic response. The sst 2 gene was expressed in the proliferating angiog enic sprouts of human vascular endothelium. The presence of sst 2 receptors on proliferating angiogenic vessels was confirmed by immunohistochemical s taining and in vivo scintigraphy. These results suggest that sst 2 may be a unique target for antiangiogenic therapy with sst 2 preferring somatostati n analogues conjugated to radioisotopes or cytotoxic agents. (C) 2001 Cance r Research Campaign.