COX-2 and c-kit expression in canine gliomas

Gliomas are among the most common primary neural tumours of dogs. Cyclooxygenase-2 (COX-2) and c-kit overexpression are associated with increased aggressiveness of gliomas and decreased survival in human beings. COX-2 is the inducible form of cyclooxygenase, which catalyzes prostaglandin formation and may increase tumour proliferation and angiogenesis. C-kit is a tyrosine kinase receptor involved in normal cell physiology; c-kit is upregulated in some canine tumours. In this retrospective study, 20 canine gliomas were identified: 11 (55%) oligodendrogliomas, including 1 anaplastic variant; 1 (5%) oligoastrocytoma; and 8 (40%) astrocytomas, of which 2 were glioblastoma multiforme. None of the gliomas expressed COX-2. None of the gliomas were immunoreactive for c-kit, although all three high-grade tumours had intramural vascular expression. Consequently, COX-2 inhibitors would likely be ineffective against canine gliomas. C-kit inhibitors may have an anti-angiogenic effect in high-grade gliomas, but would likely be ineffective in low- and medium-grade tumours.