Expression of somatostatin receptor and effects of somatostatin analog on pancreatic endocrine tumors.
OBJECTIVE
Somatostatin analogs have been administered to patients with pancreatic endocrine tumors in an attempt to inhibit hormone hypersecretion and prevent tumor growth. It is speculated that their efficacy is correlated with the expression of specific subtypes of somatostatin receptors. The aim of this study was to immunohistochemically evaluate the expression of somatostatin receptor subtypes in human pancreatic endocrine tumors, and to determine whether the expression of these subtypes is correlated with the effectiveness of the somatostatin analogs.


METHODS
Somatostatin receptor subtypes 1, 2, and 3 (sst 1, 2, and 3) were immunohistochemically investigated in seven pancreatic endocrine tumors: four insulinomas, one VIPoma, and two nonfunctioning tumors associated with multiple endocrine neoplasia type I, using paraffin sections. Three of the four patients with insulinoma were given an octreotide injection.


RESULTS
Cells were homogeneously stained in the tumor region. More than 85% of the specimens expressed sst 1, 2, and 3. There was no difference among the immunohistochemical stainings of somatostatin receptor subtypes according to most tumor characteristics; however, the expression of sst 2 was extremely positive, and the expression of sst 3 was moderately positive in the specimen from a patient in whom the octreotide injection had proven very effective.


CONCLUSIONS
These findings indicate that the efficacy of octreotide may be correlated with the density of sst 2 and 3 in an immunohistological study using paraffin sections.
Department of Breast and Endocrine Surgery, Aichi Medical University, Nagakute-cho, Aichi-gun, Japan.
Yasushi
Y
Oda
Yuji
Y
Tanaka
Takayoshi
T
Naruse
Ryuichiro
R
Sasanabe
Mari
M
Tsubamoto
Hiroomi
H
Funahashi
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007340:Insulinoma / Q000188:drug therapy / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D018761:Multiple Endocrine Neoplasia Type 1 / Q000188:drug therapy / Q000378:metabolism; D015282:Octreotide / Q000627:therapeutic use*; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000378:metabolism*; D017481:Receptors, Somatostatin / Q000378:metabolism*; D003969:Vipoma / Q000188:drug therapy / Q000378:metabolism
D018931:Antineoplastic Agents, Hormonal; D017481:Receptors, Somatostatin; C103631:somatostatin receptor 3; C093733:somatostatin receptor 2; D015282:Octreotide