AW464 (NSC 706704) is a novel
benzothiazole substituted
quinol compound active against colon, renal and certain
breast cancer cell lines. NCI COMPARE analysis indicates possible interaction with
thioredoxin/
thioredoxin reductase, which is upregulated under
hypoxia. Through activity on HIF1alpha,
VEGF levels are regulated and angiogenesis controlled. A
thioredoxin inhibitor could therefore exhibit enhanced hypoxic toxicity and indirect antiangiogenic effects. In vitro experiments were performed on colorectal and
breast cancer cell lines under both normoxic and hypoxic conditions and results compared against those obtained with normal cell lines, fibroblasts and keratinocytes. Antiangiogenic effects were studied using both large and microvessel cells. Indirect antiangiogenic effects (production of angiogenic
growth factors) were studied via ELISA. We show that AW464 exerts antiproliferative effects on tumour cell lines as well as endothelial cells with an IC(50) of approximately 0.5 microM. Fibroblasts are however resistant. Proliferating, rather than quiescent, endothelial cells are sensitive to the
drug indicating potential antiangiogenic rather than antivascular action. Endothelial differentiation is also inhibited in vitro.
Hypoxia (1% O(2) for 48 h) sensitises colorectal cells to lower
drug concentrations, and in HT29s greater inhibition of
VEGF is observed under such conditions. In contrast, bFGF levels are unaffected, suggesting possible involvement of HIF1alpha. Thus, AW464 is a promising chemotherapeutic
drug that may have enhanced potency under hypoxic conditions and also additional antiangiogenic activity.