Untersuchung des Einflusses von GPNMB auf das Wachstum von malignen Gliomen
Immunologie
Klinische Neurologie; Neurochirurgie und Neuroradiologie
Molekulare Biologie und Physiologie von Nerven- und Gliazellen
Zusammenfassung der Projektergebnisse
Glioblastoma (GBM) is the most aggressive brain tumor in adults. It is strongly infiltrated by microglia and peripheral monocytes that have been shown to support tumor growth. The aim of this project was divided into two major aims. 1) To perform an RNA-Seq experiment with freshly-isolated CD11b+ glioblastomaassociated microglia/monocytes (GAMs) sorted from human GBM specimens in order to get further knowledge of these cells and their activation state and to compare these gene expression pattern to our data from mouse GAMs. 2) To investigate the function and the expression pattern in the tumor of two genes, GPNMB/Osteoactivin and SPP1/Osteopontin, that we have identified as upregulated in human and mouse GAMs. Aim 1): We were able to perform RNA sequencing from CD11b+ cells isolated from eight human GBM and eight non-tumor brain samples and found 334 significantly regulated genes in GAMs samples in comparison to the control samples. In comparison to human control microglia human GAMs upregulated genes associated with mitotic cell cycle, cell migration, cell adhesion, and extracellular matrix organization. The comparison to murine GAMs showed that both cell populations share a significant fraction of upregulated transcripts compared with their respective controls, these genes were mostly related to mitotic cell cycle. However, in contrast to murine cells, human GAMs did not upregulate genes associated to immune activation. Aim 2): We analyzed TCGA glioblastoma datasets and performed stainings of human and mouse GBM samples and found that Iba1+ GAMs are the major source of both GPNMB and SPP1 in both human and mouse glioblastomas. In addition, we found that both GPNMB and SPP1 are expressed by Iba1-cells in a subset of tumors. Overexpression of Gpnmb in tumor cells in PDGF-driven RCAS tumors in vivo did not result in a difference in survival compared to control animals. So far, we were unable to acquire Gpnmb-/- mice, in order to investigate the effect of loss of host-derived GPNMB on glioblastoma growth and the tumor microenvironment. In turn, we were able to investigate tumor growth in Spp1-/- mice. We found that loss of microenvironment-derived SPP1/Osteopontin enhanced tumor progression. This was accompanied by a significant increase of CD11b+/CD45low microglia but not of CD11b+/CD45high macrophages/monocytes in tumors in OPN-/- mice. However, we did not detect an altered expression of selected pro- and antiinflammatory marker genes in freshly sorted CD11b+ cells. Our findings provide new insights into the biology of human glioblastoma-associated microglia/monocytes. The dataset of regulated genes in human GAMs is a valuable contribution to the scientific research field investigating glioblastoma-associated microglia/monocytes. We are further analyzing the dataset for additional potential target genes that can be manipulated for potential therapeutic applications. Our finding on SPP1/Osteopontin in glioblastoma is contrary to the findings of different studies investigating the role of tumor cell-derived Osteopontin, however it is in line with several other studies investiating the role of loss of microenvironment-derived Osteopontin in other solid cancers. We are continuing our work on GPNMB and hope to be able to study the function of microenvironment-derived GPNMB on tumor growth with the help of GPNMB-/- mice in the near future.
Projektbezogene Publikationen (Auswahl)
- Human glioblastoma-associated microglia/monocytes express a distinct RNA profile compared to human control and murine samples. Glia. 2016 Aug;64(8):1416-36
Szulzewsky F, Arora S, de Witte L, Ulas T, Markovic D, Schultze JL, Holland EC, Synowitz M, Wolf SA, Kettenmann H
(Siehe online unter https://doi.org/10.1002/glia.23014) - Genetic driver mutations define the expression signature and microenvironmental composition of high-grade gliomas. Glia. 2017 Dec;65(12):1914-1926
Herting CJ, Chen Z, Pitter KL, Szulzewsky F, Kaffes I, Kaluzova M, Park JC, Cimino PJ, Brennan C, Wang B, Hambardzumyan D
(Siehe online unter https://doi.org/10.1002/glia.23203) - Mutant IDH1 regulates the tumor-associated immune system in gliomas. Genes Dev. 2017 Apr 15;31(8):774-786
Amankulor NM, Kim Y, Arora S, Kargl J, Szulzewsky F, Hanke M, Margineantu DH, Rao A, Bolouri H, Delrow J, Hockenbery D, Houghton AM, Holland EC
(Siehe online unter https://doi.org/10.1101/gad.294991.116) - Loss of host-derived osteopontin creates a glioblastoma-promoting microenvironment. Neuro Oncol. 2018 Feb 19;20(3):355-366
Szulzewsky F, Schwendinger N, Güneykaya D, Cimino PJ, Hambardzumyan D, Synowitz M, Holland EC, Kettenmann H
(Siehe online unter https://doi.org/10.1093/neuonc/nox165)
