The effectiveness of the long acting
somatostatin analogues like
octreotide and
lanreotide depends on the expression of specific
somatostatin receptors on the target cells. The immunohistochemical method performed on surgically removed
tumors searches the expression of receptors at the level of receptor
protein and gives us insight into receptor's cellular localization. The aim of study was to assess the presence of all the 5 subtypes of
SSTR 1-5 (including 2A and 2B SSTR
isoforms) in surgically treated human
neuroendocrine tumors (NETs) to establish which receptor subtype is the dominant form of
somatostatin receptor in particular
tumor and thus to be able to predict which
somatostatin analog will be effective in NETs treatment. 18 samples of
neuroendocrine tumors (surgically excised
tumors or biopsies) were immunostained with specific
antibodies. Expression of SSTR was scored semiquantitatively. Only strong or moderate immunostaining was considered as positive reaction. The summarized expression pattern of SSTR in the investigated
neuroendocrine tumors in our material was:
SSTR 1> SSTR 5> SSTR 3> SSTR 2A> SSTR 2B. The receptors were distributed mainly in the area of cells cytoplasm with a few specimens showing only membranous or mixed: membranous--cytoplasmic localization. The observed pattern suggests that apart from
octreotide and
lanreotide, newly synthesized multiligand analogs such as
SOM 230, KE 108 or
SSTR 1 and SSTR 5 selective analogs could be effective in NETs treatment.