Hypoxia Inducible Factor-1a a Novel Molecular Target for 2-Aminopyrrole Derivative: Biological and Molecular Modeling Study

Hypoxia-inducible factor-1α (HIF-1α) is a well-known transcriptional regulator that me-diates a broad spectrum of cellular responses to hypoxia, including angiogenesis, extra-cellular matrix remodeling, and metabolic reprogramming. These activities can be achieved by up-regulation of numerous genes, such as vascular endothelial growth fac-tors, fibroblast growth factors, and platelet-derived growth factors, which are involved in the growth regulation of normal tissues and solid tumors. Of note, HIF-1α-mediated regu-lation of the solid tumor’s microenvironment effectively modulates tumor sensitivity to anticancer therapies and thereby can contribute to disease progression. We show here that a 2-aminopyrrole derivative (2-amino-1-benzamido-5-(2-(naphthalene-2-yl)-2-oxoethylidene)-4-oxo-4,5-dihydro-1-H-pyrrole-3-carboxamide – 2-ANPC), previously shown as a potent microtubule-targeting agent, effectively down-regulates HIF-1α expression in a broad spectrum of cancer cell lines, including breast, lung, and prostate cancer. The downregulation of HIF-1α expression in 2-ANPC-treated cancer cells was due to en-hanced proteasome-mediated degradation, whereas the proteasome inhibitor MG-132 ef-fectively reversed this downregulation. 2-ANPC’s potency to down-regulate HIF-1α was also shown in vivo by using the 4T1 breast cancer syngraft model. Important, this 2-aminopyrrole derivative also down-regulated the expression of vascular endothelial growth factor receptors 1 and 3 (VEGFR1 and 3) in 4T1 tumors, which correlated with de-creased tumor weight and size. As expected, an increase of apoptotic (i.e., cleaved caspa-se-3-positive) cells was detected in 4T1 tumors treated with 2-aminopyrrole derivative. Lastly, using various computational tools, we identified four potential binding sites for 2-ANPC to interact with HIF-1α, HIF-1β, and the p300 complex. Collectively, we show here, for the first time, that HIF-1α is a novel molecular target for the 2-aminopyrrole de-rivative (2-ANPC), thereby illustrating it as a potential scaffold for the development of po-tent chemotherapeutic agents with anti-angiogenic activity.