SOMATOSTATIN RECEPTOR SUBTYPE GENE-EXPRESSION IN HUMAN AND RODENT TUMORS

Somatostatin (SRIF) analogues display anti-tumor properties believed t o be mediated by specific cell surface somatostatin receptors (SSTR). SSTR subtypes have unique pharmacological properties, including specif ic GTP-binding protein coupling, ion channel regulation, and cAMP inhi bition; therefore, identification of isotypes expressed in tumor cells facilitates current efforts to design potent antitumor SRIF analogues . Human and rodent solid, transplantable tumors and tumor cell lines w ere examined for gene expression of SSTR1, SSTR2 and SSTR3 by reverse transcription of tumor mRNA and subsequent amplification of cDNA by th e polymerase chain reaction, using SSTR subtype-specific oligonucleoti de primers. SSTR2 mRNA transcripts were observed in all of the tumor c ell lines examined. SSTR1 gene expression was seen in several human an d rat tumor types, and SSTR3 gene expression observed in two rodent tu mor types. SSTR mRNA-positive tumors are expected to possess membrane- bound receptors which could potentially interact with anti-tumor SRIF analogues.