Heparan sulfate sulfatase SULF2 regulates PDGFRα signaling and growth in human and mouse malignant glioma
Joanna J. Phillips, … , David H. Rowitch, Zena Werb
Joanna J. Phillips, … , David H. Rowitch, Zena Werb
Published February 1, 2012
Citation Information: J Clin Invest. 2012;122(3):911-922. https://doi.org/10.1172/JCI58215.
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Research Article Neuroscience

Heparan sulfate sulfatase SULF2 regulates PDGFRα signaling and growth in human and mouse malignant glioma

Abstract

Glioblastoma (GBM), a uniformly lethal brain cancer, is characterized by diffuse invasion and abnormal activation of multiple receptor tyrosine kinase (RTK) signaling pathways, presenting a major challenge to effective therapy. The activation of many RTK pathways is regulated by extracellular heparan sulfate proteoglycans (HSPG), suggesting these molecules may be effective targets in the tumor microenvironment. In this study, we demonstrated that the extracellular sulfatase, SULF2, an enzyme that regulates multiple HSPG-dependent RTK signaling pathways, was expressed in primary human GBM tumors and cell lines. Knockdown of SULF2 in human GBM cell lines and generation of gliomas from Sulf2–/– tumorigenic neurospheres resulted in decreased growth in vivo in mice. We found a striking SULF2 dependence in activity of PDGFRα, a major signaling pathway in GBM. Ablation of SULF2 resulted in decreased PDGFRα phosphorylation and decreased downstream MAPK signaling activity. Interestingly, in a survey of SULF2 levels in different subtypes of GBM, the proneural subtype, characterized by aberrations in PDGFRα, demonstrated the strongest SULF2 expression. Therefore, in addition to its potential as an upstream target for therapy of GBM, SULF2 may help identify a subset of GBMs that are more dependent on exogenous growth factor–mediated signaling. Our results suggest the bioavailability of growth factors from the microenvironment is a significant contributor to tumor growth in a major subset of human GBM.

Authors

Joanna J. Phillips, Emmanuelle Huillard, Aaron E. Robinson, Anna Ward, David H. Lum, Mei-Yin Polley, Steven D. Rosen, David H. Rowitch, Zena Werb

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Figure 2

SULF2 confers a growth advantage to human GBM cells in vitro and in vivo.

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SULF2 confers a growth advantage to human GBM cells in vitro and in vivo...
(A) Knockdown of SULF2 in U251 cells by 2 different shRNA constructs; SULF2 is decreased by 83% with shRNA SULF2-A and 55% with SULF2-B compared with the scrambled shRNA control. (B) In vitro growth of EGFP-positive SULF2-A shRNA (shSULF2-A) and scrambled shRNA control (shControl) cells demonstrated a selective growth advantage of SULF2-expressing cells over cells with SULF2 knockdown, as demonstrated by a decreased ratio of GFP-positive to total cells over time. *P < 0.01; n = 3. (C and D) Decreased growth and cell viability of SULF2-A shRNA cells versus scrambled shRNA control cells, as determined by counting live cells over time (*P < 0.00005; n = 3) (C) and by the colorimetric MTT viability assay, viable cell number normalized to control, day 5 after plating (*P < 0.00005; n = 5 independent experiments) (D). (E) Overexpression of mSulf2 in cells with SULF2 knockdown and in scrambled shRNA control cells. (F) Restoration of control growth with overexpression of mSulf2 in SULF2-A shRNA–containing cells (n = 3). (G) Mean tumor volume (mm3); subcutaneous flank transplant (11 days, *P < 0.05; n = 10 mice per group). (B, C, D, F, and G) Results are depicted as mean ± SEM.