Supplementary Material for: A Critical Evaluation of sst3 and sst5 Immunohistochemistry in Human Pituitary Adenomas
Körner M.
Waser B.
Christ E.
Beck J.
Reubi J.C.
10.6084/m9.figshare.4996175.v1
https://karger.figshare.com/articles/journal_contribution/Supplementary_Material_for_A_Critical_Evaluation_of_sst3_and_sst5_Immunohistochemistry_in_Human_Pituitary_Adenomas/4996175
<p><b><i>Background:</i></b> Somatostatin receptor (sst) overexpression
in neuroendocrine tumors allows sst-targeted tumor imaging and therapy
with long-acting, cold, or radioactive somatostatin analogs. sst2 has
been most important, owing to its wide overexpression and high affinity
for somatostatin analogs, but other sst subtypes become of increasing
clinical interest due to drug development. Immunohistochemistry is the
preferred method to detect sst in resected tumor tissues. While it is
established for sst2 using the antibody UMB-1, there is less experience
for other sst subtypes. <b><i>Methods:</i></b> sst3 and sst5
immunohistochemistry using the antibodies UMB-5 and UMB-4 was evaluated
in 60 pituitary adenomas and compared with in vitro sst autoradiography
(ARG), the in vitro gold standard method to assess sst. <b><i>Results:</i></b>
UMB-4 immunohistochemistry for sst5 yielded membranous staining of
tumor cells. It correlated fairly well with ARG, results matching in 80%
of tumors. UMB-5 immunohistochemistry for sst3 showed not only a
membranous, but also cytoplasmic background staining. Agreement with ARG
was limited. All tumors showed UMB-5 staining, while only 57% were
positive by ARG. In comparison, UMB-1 staining levels showed a highly
significant correlation with autoradiographic sst2 density levels (<i>R</i><sup>2</sup> = 0.797). Not only tumor cells, but also intratumoral blood vessels were immunohistochemically positive for sst2, 3, and 5. <b><i>Conclusion:</i></b>
UMB-1 immunohistochemistry for sst2 is excellent. sst3
immunohistochemistry using UMB-5 is not yet optimal, with suspected
limited specificity, and should be applied with caution. UMB-4
immunohistochemistry for sst5 appears to be equivalent to sst5-ARG and
suitable for diagnostic applications.</p>
2017-05-11 12:35:23
Pituitary adenoma
Somatostatin receptor
sst2
sst3
sst5
Immunohistochemistry
Receptor autoradiography