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Anti-VEGFR2 driven nuclear translocation of VEGFR2 and acquired malignant hallmarks are mutation dependent in
Adarsh Shankar1, Meenu Jain1, Mei Jing Lim1
1Tumor Angiogenesis Lab, Cancer Center, Augusta University, 1410 Laney Walker Blvd, CN3124A, Augusta, GA 30912, USA.
Objective:
Anti-angiogenic therapies (AATs), targeting VEGF-VEGFR pathways, are being used as an adjuvant to normalize glioblastoma (GBM) vasculature. Unexpectedly, clinical trials have witnessed transient therapeutic effect followed by aggressive tumor recurrence. In pre-clinical studies, targeting VEGFR2 with vatalanib, increased GBM growth under hypoxic microenvironment. There is limited understanding of these unanticipated results. Here, we investigated tumor cell associated phenotypes in response to VEGFR2 blockade.
Methods:
Human U251 cells were orthotopically implanted in mice (day 0) and were treated with vehicle or vatalanib on day 8. Tumor specimens were collected for immunohistochemistry and protein array. Nuclear translocation of VEGFR2 was analyzed through IHC and western blot. In vitro studies were performed in U251 (p53 and EGFR mutated) and U87 (p53 and EGFR wildtype) cells following vehicle or vatalanib treatments under normoxia (21% O2) and hypoxia (1% O2). Proliferation, cell cycle and apoptosis assays were done to analyze tumor cell phenotypes after treatments.
Results:
Vatalanib treated animals displayed distinct patterns of VEGFR2 translocation into nuclear compartment of U251 tumor cells. In vitro studies suggest that vatalanib significantly induced nuclear translocation of VEGFR2, characterized in chromatin bound fraction, especially in U251 tumor cells grown under normoxia and hypoxia. Anti-VEGFR2 driven nuclear translocation of VEGFR2 was associated with increased cell cycle and proliferation, decreased apoptosis, and displayed increased invasiveness in U251 compared to U87 cells.
Conclusions:
Study suggests that AAT- induced molecular and phenotypic alterations in tumor cells are associated with mutation status and are responsible for aggressive tumor growth. Therefore, mutation status of the tumor in GBM patients should be taken in to consideration before applying targeted therapy to overcome unwanted effects.
Insights
Targeting VEGFR2 with vatalanib unexpectedly increased glioblastoma growth by inducing nuclear translocation of VEGFR2, leading to aggressive tumor phenotypes. Tumor mutation status is critical for effective anti-angiogenic therapy.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Research
Background:
- Anti-angiogenic therapies (AATs) targeting VEGF-VEGFR pathways are used for glioblastoma (GBM).
- Clinical trials show transient effects and aggressive tumor recurrence after AATs.
- Pre-clinical studies indicate VEGFR2 blockade can enhance GBM growth, particularly in hypoxia.
Purpose of the Study:
- Investigate tumor cell phenotypes in response to VEGFR2 blockade.
- Understand the molecular mechanisms behind unexpected GBM recurrence after anti-angiogenic therapy.
- Determine the role of VEGFR2 nuclear translocation in tumor cell behavior.
Main Methods:
- Orthotopic implantation of human U251 GBM cells in mice, followed by vatalanib treatment.
- Immunohistochemistry and western blot to analyze VEGFR2 nuclear translocation.
- In vitro studies on U251 and U87 cells under normoxia and hypoxia to assess proliferation, cell cycle, and apoptosis.
Main Results:
- Vatalanib induced VEGFR2 nuclear translocation in U251 tumor cells, particularly under normoxia and hypoxia.
- Nuclear VEGFR2 translocation correlated with increased cell cycle, proliferation, and invasiveness.
- U251 cells (mutated p53/EGFR) showed greater phenotypic alterations than U87 cells (wildtype p53/EGFR).
Conclusions:
- AAT-induced alterations in tumor cells, linked to mutation status, drive aggressive tumor growth.
- Tumor mutation status is a critical factor to consider before applying targeted therapies like AATs.
- Targeting VEGFR2 may lead to paradoxical effects, necessitating personalized treatment strategies for GBM.
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