Etiology and Pathogenesis > Somatostatin  

Abstract

Differential Expression of sst₁, sst_2A, and sst₃ Somatostatin Receptor Proteins in Low-Grade and High-Grade Astrocytomas

Christian Mawrin, MD,^{a, b} Solveig Schulz, MD,^a Steffen U. Pauli, MD,^a Tim Treuheit, MD,^a Sabine Diete, MD,^a Knut Dietzmann, MD,^a Raimund Firsching, MD,^a Stefan Schulz, MD,^a and Volker Höllt, MD^a

^aFrom the Departments of Neuropathology (CM, KD), Obstetrics and Gynecology (SS), Neurosurgery (SUP, RF), Neurology (TT, SD), Pharmacology and Toxicology (SS, VH), and Psychiatry (CM), Otto-von-Guericke-University, Magdeburg, Germany. ^bCorrespondence to: Christian Mawrin, MD, Department of Neuropathology, Otto-von-Guericke-University, Leipziger Strasse 44, D-39120 Magdeburg, Germany. E-mail: christian.mawrin@medizin.uni-magdeburg.de. Manuscript Received by the Society May 6, 2003. Revised Manuscript Received September 1, 2003. Manuscript Accepted September 15, 2003.

We have previously reported that sst_2A somatostatin receptors are frequently overexpressed in human meningiomas. 
Initial clinical observations suggest that somatostatin analogues may also be of value for imaging and treatment of other human intracranial tumors, including astrocytomas. 
However, contradictory results have been reported regarding the expression of somatostatin receptors in low-grade and high-grade astrocytomas. 
Therefore, we determined the precise pattern of somatostatin receptor protein expression in 8 diffuse astrocytoma (DA), 10 anaplastic astrocytomas (AA), and 32 glioblastoma multiforme (GBM) using immunohistochemistry and Western blot analysis. 
sst₁ and sst_2A somatostatin receptors were not present in DA and only occasionally detected in AA. 
In GBM, sst₁ was present in 66%, and sst_2A was found in 44% of the tumors. 
sst₃ receptors were present in 38% of DA, 40% of AA, and 84% of GBM. 
Thus, loss of differentiation was significantly associated with increased expression of sst₁, sst_2A, and sst₃ somatostatin receptors. 
In contrast, sst₄ and sst₅ receptors were found in 80% and 25% of all cases, respectively, in a manner independent of histological grade. 
No significant correlation was found between somatostatin receptor expression and the proliferation rate of the tumors as determined by MIB-1 immunostaining. 
Furthermore, the presence or absence of the 5 somatostatin receptor subtypes did not significantly influence survival time in 14 GBM patients.

Keywords: Astrocytoma, Immunohistochemistry, Somatostatin receptor.

© Copyright 2004 American Association of Neuropathologists, Inc.