Sstr2A immunohistochemical expression in human meningiomas: Is there a correlation with the histological grade, proliferation or microvessel density?

Abstract

Abstract. Somatostatin anti-proliferative and anti-angiogenic activities, together with the expression of somatostatin receptors (sstrs), account for the use of somatostatin analogues in the treatment of human tumours. In the present study, sstr2A immunohistochemical expression was analyzed in grade II and III meningiomas and was compared with that revealed in grade I meningiomas. Thirty-five formalin-fixed paraffinembedded meningiomas, comprising 13 grade I, 19 grade II and 3 grade III tumours, according to the WHO 2007 classification, were submitted to immunohistochemical assays for sstr2A. Moreover, in the same cohort of tumours, the immunoexpression of CD105, a specific marker for neoangiogenesis, as well as the Ki-67 labelling index (LI), reflecting the proliferative activity of the meningiomas, were recorded. Sstr2A immunoreaction was evidenced in 26/35 cases and was localized at the cytoplasm and the plasma membrane in 12 and in 14 cases, respectively. Specifically, a positive staining was found in 7/13 grade I, in 16/19 grade II and in 3/3 grade III tumours, thus demonstrating that sstr2A is frequently expressed in high grade meningiomas. A significantly higher microvessel density (MVD), assessed by CD105 immunostaining and Ki-67 LI were evidenced in high grade meningiomas. A significant correlation was recorded between sstr2A expression and a high MVD of the meningiomas. The existence of a correlation between sstr2A expression and the entity of neo-angiogenesis provides the basis for the use of somatostatin analogue-based therapies in the treatment of meningiomas.

Peptide Receptor Radionuclide Therapy in Patients with Inoperable Meningiomas: Our Experience and Review of the Literature

“…Namely, meningiomas have been uniformly found to be positive for sstr, the receptor density reaching even more than 400 fmol/mg protein. 47 Moreover, a prominent expression of subtype 2 sstr also in endothelial cells of peritumoral blood vessels, 43 suggesting that PPRT may exert its action also through an antiangiogenic effect, and a correlation between sstr2A expression and the entity of neo-angiogenesis 48 have been demonstrated in meningiomas.…”

Differential efficacy of SSTR1, -2, and -5 agonists in the inhibition of C6 glioma growth in nude mice

“…A wide series of solid or hematological malignancies have been demonstrated to variably express SSTRs (54). As far as brain tumors, different SSTR subtypes have also been detected in both meningiomas (4,10) and gliomas (17), where receptor distribution correlated with scintigraphic imaging and in vitro response to SST analogs (16). Moreover, SST and analogs showed antineoplastic activity in a variety of experimental tumor models in vivo, inhibiting the growth of transplantable tumors and improving the survival of tumor-bearing animals.…”

Increased 68Ga-DOTATATE Uptake in PET Imaging Discriminates Meningioma and Tumor-Free Tissue

“…To enable a comparability with the literature (17,18), SSTR2 expression was classified according to a 4-scaled staining score as follows: positive immunostaining of 0%-25%, 26%-50%, 51%-75%, and 76%-100% of the respective tissue translated to a corresponding staining score of grade 1 (no/weak), grade 2 (mild/modest), grade 3 (moderate), and grade 4 (strong). In cases for which the scoring of tissue samples was discordant between the 2 neuropathologists, the senior neuropathologist cast the tie-breaking vote.…”