Flt-1, a receptor for vascular endothelial growth factor, is known to display dysregulated expression in both tumor vasculature and tumor cells per se, suggesting that the flt-1 promoter might be a useful candidate to achieve tumor-specific transgene expression.
The VEGF receptors, kinase domain region (KDR) and Fms-like-tyrosine kinase (Flt-1), also were upregulated in the tumor vasculature of glioblastoma multiforme, anaplastic oligodendrogliomas, and ependymomas with necrosis, whereas the astrocytomas grade II, anaplastic astrocytomas, and oligodendroglioma tumors tended to express a weak to nondetectable signal.
KDR and Flt-1 were expressed in the tumor vasculature, with particularly high levels seen in coiled young proliferating vessels, especially those in the cyst wall.