Osteopontin mediates glioblastoma-associated macrophage infiltration and is a potential therapeutic target
Jun Wei, … , Shulin Li, Amy B. Heimberger
Jun Wei, … , Shulin Li, Amy B. Heimberger
Published January 2, 2019; First published October 11, 2018
Citation Information: J Clin Invest. 2019;129(1):137-149. https://doi.org/10.1172/JCI121266.
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Categories: Research Article Immunology

Osteopontin mediates glioblastoma-associated macrophage infiltration and is a potential therapeutic target

Abstract

Glioblastoma is highly enriched with macrophages, and osteopontin (OPN) expression levels correlate with glioma grade and the degree of macrophage infiltration; thus, we studied whether OPN plays a crucial role in immune modulation. Quantitative PCR, immunoblotting, and ELISA were used to determine OPN expression. Knockdown of OPN was achieved using complementary siRNA, shRNA, and CRISPR/Cas9 techniques, followed by a series of in vitro functional migration and immunological assays. OPN gene–deficient mice were used to examine the roles of non-tumor-derived OPN on survival of mice harboring intracranial gliomas. Patients with mesenchymal glioblastoma multiforme (GBM) show high OPN expression, a negative survival prognosticator. OPN is a potent chemokine for macrophages, and its blockade significantly impaired the ability of glioma cells to recruit macrophages. Integrin αvβ5 (ITGαvβ5) is highly expressed on glioblastoma-infiltrating macrophages and constitutes a major OPN receptor. OPN maintains the M2 macrophage gene signature and phenotype. Both tumor-derived and host-derived OPN were critical for glioma development. OPN deficiency in either innate immune or glioma cells resulted in a marked reduction in M2 macrophages and elevated T cell effector activity infiltrating the glioma. Furthermore, OPN deficiency in the glioma cells sensitized them to direct CD8+ T cell cytotoxicity. Systemic administration in mice of 4-1BB–OPN bispecific aptamers was efficacious, increasing median survival time by 68% (P < 0.05). OPN is thus an important chemokine for recruiting macrophages to glioblastoma, mediates crosstalk between tumor cells and the innate immune system, and has the potential to be exploited as a therapeutic target.

Authors

Jun Wei, Anantha Marisetty, Brett Schrand, Konrad Gabrusiewicz, Yuuri Hashimoto, Martina Ott, Zacharia Grami, Ling-Yuan Kong, Xiaoyang Ling, Hillary Caruso, Shouhao Zhou, Y. Alan Wang, Gregory N. Fuller, Jason Huse, Eli Gilboa, Nannan Kang, Xingxu Huang, Roel Verhaak, Shulin Li, Amy B. Heimberger

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Figure 2

OPN expression in either the tumor or host impacts survival in a murine model of glioma.

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OPN expression in either the tumor or host impacts survival in a murine ...
(A) Experimental schema to clarify the significance of OPN expression in glioma progression in various cellular contexts. Either WT or Opn–/– background (KO) mice were intracranially implanted with GL261 cells that were transfected with either a non-targeting shRNA (NT control) or shRNA specific to OPN (OPN shRNA). (B) The median survival time was markedly increased in mice implanted with GL261 glioma cells transfected with OPN shRNA relative to GL261 controls (NT control) (n = 9 for GL261 OPN shRNA group, and n = 10 for NT group; P = 0.0027). (C) The median survival time of mice bearing intracranial GL261 tumors was also extended in the Opn–/– background (n = 10 per group; P = 0.0141). (D) There was no significant difference in survival if both glioma and host OPN expression was knocked out (P = 1). P values were calculated based on the log-rank test with Bonferroni’s correction. (E) Kaplan-Meier curves demonstrating survival of all groups for comparison. Data are representative of 2 independent experiments.