The effect of alpha-v integrin inhibition on the malignant characteristics of medulloblastoma.
OBJECTIVE
Hypoxia induces an aggressive phenotype in some brain tumors in part due to hypoxia-inducible factor-1α (HIF-1α) and integrin expression. The importance of hypoxia in medulloblastoma is unclear and the interaction of HIF-1α and c-Myc in medulloblastoma has not been explored. The objective of this study was to determine if hypoxia induces an aggressive phenotype in human medulloblastoma cells that constitutively express high (D283 Med) or low (DAOY) levels of c-Myc and to determine if blocking α(v) integrins with the monoclonal antibody intetumumab inhibits hypoxia-induced cellular stress responses.


METHODS
Cells were grown at 21% and 1% O(2) and in the presence or absence of intetumumab. Measures of malignancy evaluated included cell proliferation, cell migration, and expression of vascular endothelial growth factor (VEGF), α(v) integrins, HIF-1α, and c-Myc.


RESULTS
Both cell lines robustly expressed α(v) integrins. Hypoxic DAOY cells showed significantly increased proliferation compared with normoxic controls (p < 0.05), whereas D283 Med cells did not. Both cell lines exhibited a dose-dependent decrease in proliferation when treated with intetumumab (p < 0.05). Hypoxia did not increase DAOY migration, but intetumumab significantly inhibited migration at both oxygen conditions (p < 0.05). Intetumumab significantly decreased VEGF levels in DAOY cells at both oxygen conditions (p < 0.05) and in normoxic D283 cells (p < 0.01). Neither cell line demonstrated increased HIF-1α expression in response to hypoxia. However, hypoxic D283 Med cells grown in the presence of intetumumab demonstrated significantly decreased c-Myc expression (p < 0.05).


CONCLUSIONS
Hypoxia did not clearly induce a more aggressive phenotype in medulloblastoma cells. Despite this result, intetumumab decreased medulloblastoma cell proliferation and migration and variably decreased VEGF and c-Myc expression in hypoxic conditions. Targeting α(v) integrins represents a promising potential adjuvant modality in the treatment of medulloblastoma, particularly subtypes that metastasize and overexpress VEGF and c-Myc.
Department of Neurological Surgery, Oregon Health & Science University, Portland, OR, USA.
Eric M
EM
Thompson
Nathaniel L
NL
Whitney
Y Jeffrey
YJ
Wu
Edward A
EA
Neuwelt
D000911:Antibodies, Monoclonal / Q000627:therapeutic use; D061067:Antibodies, Monoclonal, Humanized; D015153:Blotting, Western; D002448:Cell Adhesion / Q000187:drug effects; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002528:Cerebellar Neoplasms / Q000188:drug therapy* / Q000473:pathology*; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D000860:Hypoxia / Q000473:pathology; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000502:physiology; D039482:Integrin alpha5 / Q000187:drug effects*; D008527:Medulloblastoma / Q000188:drug therapy* / Q000473:pathology*; D010641:Phenotype; D016271:Proto-Oncogene Proteins c-myc / Q000096:biosynthesis / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis / Q000235:genetics
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D039482:Integrin alpha5; D016271:Proto-Oncogene Proteins c-myc; D042461:Vascular Endothelial Growth Factor A; C486839:intetumumab