We synthesized a novel synthetic chemical library and used it in a forward chemical genetics screen designed to identify small molecule inhibitors of endothelial morphogenesis. This screen resulted in the identification of structurally-related small molecules that inhibited endothelial cell proliferation, migration, the ability to form tubule-like structures in matrigel, as well as neo- angiogenesis visualized using a dorsal skin fold vascular window chamber. Biochemical analysis revealed that the novel small molecules inhibited ENOX1, a plasma membrane- associated enzyme that exhibits protein disulfide-thiol interchange activity. While ENOX activity is important for cellular proliferation, the molecular mechanisms are not well understood. shRNA-mediated inhibition of ENOX activity in HUVECs inhibited endothelial cell migration and formation of tubule-like structures in matrigel, reproducing the effects of the small molecule inhibitors. Small molecule inhibition of ENOX1 was associated with a significant increase in endothelial cell apoptosis induced by ionizing radiation. Colony formation assays demonstrated that these small molecules increased the radiation sensitivity of endothelial cells. In contrast, the radiation sensitivity of tumor epithelial cells was unaffected by the small molecules. Administration of a small molecule ENOX1 inhibitor prior to fractionated X-irradiation produced a statistically significant decrease in the number and density of CD34 expressing Lewis Lung Carcinoma (LLC) tumor-associated microvasculature. Use of LLC and human HT29 colon carcinoma tumor models demonstrated that the small molecule ENOX1 inhibitors coupled with fractionated X-irradiation produced a statistically significant increase in tumor growth delay compared to irradiation alone. No evidence of acute toxicity was observed over a 30 day interval when mice received a bolus injection of 120 mg/kg. These preliminary data support the hypothesis that ENOX1 represents a rationale molecular target for increasing the ability of ionizing radiation to control tumor growth. The short term goal of this application is to valid this hypothesis. The long term goal is to develop these small molecule inhibitors into a radiation sensitizer that exhibits clinical efficacy.

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A forward chemical genetics screen identifies small molecule inhibitors of endothelial morphogenesis. Biochemical analysis revealed that these novel small molecules inhibited the enzyme ENOX1, increased the radiation sensitivity of endothelial cells, increased radiation- mediated suppression of tumor-associated vasculature, thereby suppressing tumor growth. These preliminary data support the hypothesis that ENOX1 represents a rationale molecular target for increasing the ability of ionizing radiation to control tumor growth.

National Institute of Health (NIH)
National Cancer Institute (NCI)
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Radiation Therapeutics and Biology Study Section (RTB)
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Bernhard, Eric J
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Vanderbilt University Medical Center
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Franks, Lirit N; Ford, Benjamin M; Madadi, Nikhil R et al. (2014) Characterization of the intrinsic activity for a novel class of cannabinoid receptor ligands: Indole quinuclidine analogs. Eur J Pharmacol 737:140-8
Penthala, Narsimha Reddy; Madadi, Nikhil Reddy; Janganati, Venumadhav et al. (2014) L-Proline catalyzed one-step synthesis of 4,5-diaryl-2H-1,2,3-triazoles from heteroaryl cyanostilbenes via [3+2] cycloaddition of azide. Tetrahedron Lett 55:5562-5565
Sekhar, Konjeti R; Benamar, Mouadh; Venkateswaran, Amudhan et al. (2014) Targeting nucleophosmin 1 represents a rational strategy for radiation sensitization. Int J Radiat Oncol Biol Phys 89:1106-14
Venkateswaran, Amudhan; Sekhar, Konjeti R; Levic, Daniel S et al. (2014) The NADH oxidase ENOX1, a critical mediator of endothelial cell radiosensitization, is crucial for vascular development. Cancer Res 74:38-43
Madadi, Nikhil Reddy; Penthala, Narsimha Reddy; Janganati, Venumadhav et al. (2014) Synthesis and anti-proliferative activity of aromatic substituted 5-((1-benzyl-1H-indol-3-yl)methylene)-1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione analogs against human tumor cell lines. Bioorg Med Chem Lett 24:601-3
Penthala, Narsimha Reddy; Sonar, Vijayakumar N; Horn, Jamie et al. (2013) Synthesis and evaluation of a series of benzothiophene acrylonitrile analogs as anticancer agents. Medchemcomm 4:1073-1078
Penthala, Narsimha Reddy; Ponugoti, Purushothama Rao; Kasam, Vinod et al. (2013) 5-((1-Aroyl-1H-indol-3-yl)methylene)-2-thioxodihydropyrimidine-4,6(1H,5H)-diones as potential anticancer agents with anti-inflammatory properties. Bioorg Med Chem Lett 23:1442-6
Madadi, Nikhil Reddy; Penthala, Narsimha Reddy; Brents, Lisa K et al. (2013) Evaluation of (Z)-2-((1-benzyl-1H-indol-3-yl)methylene)-quinuclidin-3-one analogues as novel, high affinity ligands for CB1 and CB2 cannabinoid receptors. Bioorg Med Chem Lett 23:2019-21
Penthala, Narsimha Reddy; Yerramreddy, Thirupathi Reddy; Crooks, Peter A (2011) Synthesis and in vitro screening of novel N-benzyl aplysinopsin analogs as potential anticancer agents. Bioorg Med Chem Lett 21:1411-3
Sekhar, Konjeti R; Reddy, Yerramreddy Thirupathi; Reddy, Penthala Narsimha et al. (2011) The novel chemical entity YTR107 inhibits recruitment of nucleophosmin to sites of DNA damage, suppressing repair of DNA double-strand breaks and enhancing radiosensitization. Clin Cancer Res 17:6490-9

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