Etiology and Pathogenesis > Insulin-like Growth Factors · Invasion

Meeting Abstract

Pseudopalisading Cells In Glioblastoma Are Hypoxic And Could Represent A Rapidly Migrating Population

Daniel J. Brat, Amilcar Castellano-Sanchez, Stephen B. Hunter, Marcia Pecot, Cynthia Cohen, Elizabeth H. Hammond, Balveen Kaur, and Erwin G. Van Meir

Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA (DJB, AC-S, SBH, MP, CC); Department of Pathology, LDS Hospital, Salt Lake City, UT (EHH); Departments of Neurosurgery and Hematology/Oncology and Winship Cancer Center, Emory University School of Medicine, Atlanta, GA (BK, EGVM); USA

Pseudopalisading (PsP) cells are hypercellular zones surrounding foci of necrosis in glioblastoma (GBM).
Their emergence is tightly linked with aggressive biologic behavior, yet their pathogenesis is poorly understood.
By immunohistochemistry (IHC) for Mib-1 performed on surgically resected GBM specimens, we have shown that proliferation indices in PsPs are 5%–50% lower than in adjacent astrocytoma.
IHC for cleaved (activated) caspase-3 demonstrated 9%–20X more apoptotic cells in PsPs than adjacent tumor; total caspase-3 levels were similar.
CD68+ macrophages and LCA+ lymphocytes accounted for <2% of cells in PsPs and adjacent tumor.
PSPs have increased nuclear hypoxia inducible factor 1apha (HIF-1alpha) by IHC and human GBM cell lines (2024, WT11, LN229) grown in hypoxia (1% O2) show increased HIF-1alpha protein by Western blot.
Migration experiments, performed in modified Boyden chambers using 2024, WT11, and LN229 cells, demonstrated a 17%–60% increase in cell migration after 24 hours in hypoxia compared to normoxia (20% O2).
Hypoxic cells showed a stellate morphology and expressed proteins associated with increased migration, including increased total gelatinase activity by gelatin zymography, modestly increased cellular urokinase receptor (uPAR), and increased secreted urokinase-type plasminogen activator (uPA).
In situ zymography performed on GBM tissue sections showed gelatinase activity corresponding to regions of PsPs.
In order to evaluate potential sources of hypoxia and mechanisms of PsP formation in GBMs, we performed morphometric analysis of 234 complete PsPs in 85 pretreatment GBMs.
Both blood vessels and thrombosis were more frequently present within PsPs with larger internal widths.
Among PsPs <100 μm wide, 28% had vessels and 6% had thrombosis; among PsPs >500 μm, 100% had vessels and 36% had thrombosis.
Narrow (<100 μm) PsPs commonly contained fibrillar, nonnecrotic centers (77%), while wide PsPs (>500 μm) had necrotic centers (95%) and peripheral fibrillar zones.
Taken together, this evidence suggests that PsP cells are less proliferative and more apoptotic than adjacent astrocytoma.
PsPs may represent different stages and histologic samplings of glioblastoma cells migrating away from hypoxia, perhaps in some instances from a central vaso-occlusive event.

Copyright © 2003 by the Society for Neuro-Oncology