Article
The influence of EPI-X4, a novel albumin-derived peptide ligand for CXCR4, on SDF-1-induced proliferation and migration in glioblastoma multiforme
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Authors
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Elvira Dietrich
- Experimentelle Anästhesiologie, Universitätsklinikum Ulm, Germany
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Haouraa Mostafa
- Experimentelle Anästhesiologie, Universitätsklinikum Ulm, Germany
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Andrej Pala
- Neurochirurgie, Universitätsklinikum Ulm und Bezirkskrankenhaus Günzburg, Germany
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Onofrio Zirafi
- Institut für Molekulare Virologie, Universität Ulm, Germany
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Jan Münch
- Institut für Molekulare Virologie, Universität Ulm, Germany
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E. Marion Schneider
- Experimentelle Anästhesiologie, Universitätsklinikum Ulm, Germany
| Published: | June 8, 2016 |
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Outline
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Objective: In glioblastoma multiforme (GBM), the most common and highly malignant brain tumor, CXCR4 and its physiological ligand CXCL12 (SDF-1) are known to play an essential role in tumor dissemination and proliferation. Therefore, novel receptor antagonists may be crucial to influence dissemination of GBM in the brain, especially after surgery. In previous studies, a high affinity CXCR4 antagonist, AMD3100, has been investigated but turned out to have serious side effects in peripheral tissues and in brain as well. A natural peptide ligand for CXCR4 called EPI-X4, an endogenous fragment from albumine, has been demonstrated to affect certain functions of the receptor in hematopoietic cells. So far, the effect on GBM has not been studied.
Method: A total of 9 permanent cell lines were established from primary tumor tissues. Cells were characterized for various expression antigens in addition to CXCL12 and CXCR4. Results on CXCR4 and CXCL12 were confirmed by mRNA expression analysis. Functional assays for proliferation and migration were performed in the presence and absence of exogenous CXCL12, EPI-X4, and AMD3100, using chemiluminescence based assays for proliferation (Promega), and IBIDI®-based chemotaxis assays.
Results: Flow cytometry and qPCR demonstrate the presence of CXCR4 at different quantitative levels in all cell lines investigated, implying an autocrine role by CXCL12. We also found that stimulation with recombinant CXCL12 further stimulated CXCR4 dependent proliferation in a subgroup of cell lines. Migration and proliferation assays gave evidence for impaired dissemination when tumor cells were pre-incubated with EPI-X4. This effect was most prominent in those cell lines which were responsive to exogenous CXCL12. The binding of EPI-X4 to the GBM surface was also confirmed by immunogold-labelling using a peptide-specific antibody.
Conclusions: Endogenous and exogenous CXCL12 plays a unique role in GBM as exemplified here in novel GBM cell lines generated. The endogenous, albumin-derived peptide EPI-X4 is a promising candidate to influence dissemination of defined GBM. Association of CXCL12 production to tumor progression as well as recruitment and activation of immune cells are of potential relevance for individualized therapeutic approaches. The novel endogenous peptide, EPI-X4 may modulate the chemokine receptor to address the different pathways induced by CXCL12 in greater detail.
