EXPRESSION OF THE SOMATOSTATIN GENE IN HUMAN ASTROCYTOMA CELL-LINES

Somatostatin (somatotropin release-inhibiting hormone; SRIH) has been demonstrated in neurons of the central nervous system (CNS) as well as in endocrine cells of the pancreas and gastrointestinal tract and can suppress various immune functions including lymphocyte proliferation, immunoglobulin synthesis, and cytokine production. Since astrocytes p ossess antigen-presenting activity and can secrete a wide array of imm unoregulatory and inflammatory cytokines, we studied SRIH gene express ion in both astrocyte cell lines and mitogen-stimulated peripheral blo od mononuclear leukocytes from healthy donors, We now report by means of a complementary DNA-based reverse transcription PCR that differenti al levels of SRIH mRNA were expressed in 9 of 11 human astrocytoma cel l lines tested but were undetectable in activated peripheral blood mon onuclear leukocytes as well as in a variety of human lymphocyte and mo nocyte cell lines. The synthesis and secretion of SRIH protein by astr ocytoma cells that expressed SRIH transcripts were confirmed by specif ic radioimmunoassay of cell culture fluids. These findings support the notion that SRIH gene expression occurs in human astrocytoma cells bu t not in mature lymphoid cells of the immune system.