Technology to Unmask Accessible Tumor Vascular Targets

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DESCRIPTION (provided by applicant): This grant application proposes to apply innovative, (either a well tested set or well-tested sets) yet reasonably well tested set of technologies to define the proteome of the vascular endothelial cell surface with emphasis on discovering protein differences between normal and tumor blood vessels. Much anticancer research has focused on the development of tumor cell-targeted drug therapies that are quite effective in destroying tumors cells grown in a culture dish but not when injected into the patient?s blood stream because various barriers prevent access to the cancer cells inside the tumor. An attractive alternative strategy for solid tumor therapy is to target the inherently accessible endothelial cells that line tumor blood vessels essential for tumor growth. This vascular targeting strategy is distinct from current anti-angiogenesis therapies because the goal is not preventing tumor blood vessel growth but rather tumor-specific destruction. A new addition to the vascular targeting strategy apparent from our recent work is the utility of a vesicular transport pathway (caveolae) discovered in endothelium for selectively overcoming this key cell barrier to permit delivery inside the tissue. Direct discovery of tumor vascular targets is now feasible because of novel technology that we have developed to facilitate the molecular mapping of the endothelial cell surface and its caveolae as they exist natively in tissue. Here, we will attempt the first in-depth antibody and proteomic analysis of the luminal endothelial cell surface and its caveolae in rat lung tumors using new tissue subfractionation techniques, comparative one- and two-dimensional gel electrophoresis, and mass spectrometric analysis. Data is provided that demonstrates the utility of this new approach in uncovering novel accessible tumor-induced targets expressed in multiple rat, mouse, rabbit, monkey and human tumors. Antibodies specific for such candidate targets will be generated to establish the degree of specificity for the tumor, endothelium, and caveolae as well as to test tumor immunotargeting in vivo. This work is likely to yield tumor-specific vascular targets that facilitate tumor-directed pharmaco delivery, overcome the endothelial cell barrier and, ultimately, provide improved localized tumor therapy with little damage to bystander organs. Discovery of tumor vascular targets may be useful in improving both the early detection and treatment of solid tumors in humans.