Molecular analysis of the somatostatin receptor subtype 2 in human glioma cells

Gliomas constantly overexpress the receptor subtype SST2 for the inhibitory peptide somatostatin. Since somatostatin or metabolically stable agonists like octreotide have an antiproliferative and antisecretory potential for t he treatment of SST2-expressing tumors, we evaluated the molecular integrit y of SST2 in gliomas on the DNA, mRNA and protein levels. Sequencing of abo ut 1800 bases from the SST2 gene in nine gliomas and five control samples r evealed no mutations, but polymorphisms were detected in the 5'-region irre spective of the malignancy of the sample. Gliomas and the human glioma cell line U343 expressed mRNA for the receptor splice variant SST2A with a size of about 4.2 kb. A novel antibody generated against an extracellular part of the SST2 amino acid sequence strongly reacted with an 75-kDa protein in membranes from glioma or meningioma cells and-much weaker-normal rat astroc ytes. The receptor could be immunostained on the surface of intact glioma c ells or (weaker) astrocytes at the light and electron microscopic level. Th ese results show that the somatostatin receptor SST2 is non-mutated in glio mas and has similar molecular properties as in non-malignant cells. (C) 199 9 Elsevier Science B.V. All rights reserved.