Tumor-Associated Macrophages in Glioblastoma Multiforme—A Suitable Target for Somatostatin Receptor-Based Imaging and Therapy?

Please always quote using this URN: urn:nbn:de:bvb:20-opus-125498
  • Background Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults. Tumor-associated macrophages (TAM) have been shown to promote malignant growth and to correlate with poor prognosis. [1,4,7,10-tetraazacyclododecane-NN′,N″,N′″-tetraacetic acid]-d-Phe1,Tyr3-octreotate (DOTATATE) labeled with Gallium-68 selectively binds to somatostatin receptor 2A (SSTR2A) which is specifically expressed and up-regulated in activated macrophages. On the other hand, the role of SSTR2A expression on the cell surface of glioma cells has notBackground Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults. Tumor-associated macrophages (TAM) have been shown to promote malignant growth and to correlate with poor prognosis. [1,4,7,10-tetraazacyclododecane-NN′,N″,N′″-tetraacetic acid]-d-Phe1,Tyr3-octreotate (DOTATATE) labeled with Gallium-68 selectively binds to somatostatin receptor 2A (SSTR2A) which is specifically expressed and up-regulated in activated macrophages. On the other hand, the role of SSTR2A expression on the cell surface of glioma cells has not been fully elucidated yet. The aim of this study was to non-invasively assess SSTR2A expression of both glioma cells as well as macrophages in GBM. Methods 15 samples of patient-derived GBM were stained immunohistochemically for macrophage infiltration (CD68), proliferative activity (Ki67) as well as expression of SSTR2A. Anti-CD45 staining was performed to distinguish between resident microglia and tumor-infiltrating macrophages. In a subcohort, positron emission tomography (PET) imaging using \(^{68}Ga-DOTATATE\) was performed and the semiquantitatively evaluated tracer uptake was compared to the results of immunohistochemistry. Results The amount of microglia/macrophages ranged from <10% to >50% in the tumor samples with the vast majority being resident microglial cells. A strong SSTR2A immunostaining was observed in endothelial cells of proliferating vessels, in neurons and neuropile. Only faint immunostaining was identified on isolated microglial and tumor cells. Somatostatin receptor imaging revealed areas of increased tracer accumulation in every patient. However, retention of the tracer did not correlate with immunohistochemical staining patterns. Conclusion SSTR2A seems not to be overexpressed in GBM samples tested, neither on the cell surface of resident microglia or infiltrating macrophages, nor on the surface of tumor cells. These data suggest that somatostatin receptor directed imaging and treatment strategies are less promising in GBM.show moreshow less

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Metadaten
Author: Constantin Lapa, Thomas Linsenmann, Katharina Lückerath, Samuel Samnick, Ken Herrmann, Carolin Stoffer, Ralf-Ingo Ernestus, Andreas K. Buck, Mario Löhr, Camelia-Maria Monoranu
URN:urn:nbn:de:bvb:20-opus-125498
Document Type:Journal article
Faculties:Medizinische Fakultät / Klinik und Poliklinik für Nuklearmedizin
Language:English
Parent Title (English):PLoS One
Year of Completion:2015
Volume:10
Issue:3
Pagenumber:e0122269
Source:PLoS ONE 10(3): e0122269. doi:10.1371/journal.pone.0122269
DOI:https://doi.org/10.1371/journal.pone.0122269
Dewey Decimal Classification:6 Technik, Medizin, angewandte Wissenschaften / 61 Medizin und Gesundheit / 610 Medizin und Gesundheit
Tag:glioblastoma multiforme; glioma; immunostaining; macrophages; magnetic resonance imaging; microglial cells; positron emission tomography; somatostatin
Release Date:2016/01/28
Collections:Open-Access-Publikationsfonds / Förderzeitraum 2015
Licence (German):License LogoCC BY: Creative-Commons-Lizenz: Namensnennung