1.Conformation-activity relationship on novel 4-pyridylmethylthio derivatives with antiangiogenic activity.
Honda T;Tajima H;Kaneko Y;Ban M;Inaba T;Takeno Y;Okamoto K;Aono H Bioorg Med Chem Lett. 2008 May 1;18(9):2939-43. doi: 10.1016/j.bmcl.2008.03.068. Epub 2008 Mar 29.
We found 4-pyridylmethylthio derivative 1 to be very effective in using antiangiogenesis activity to prevent proliferation of HUVECs (Human Umbilical Vein Endothelial Cells), which was induced by vascular endothelial growth factor (VEGF). Compound 1 was equally effective in inhibiting VEGF receptor2 tyrosine kinase (KDR, IC(50)=26nM). We deduced that the inhibition was the result of binding the catalytic domain of VEGF receptor2 tyrosine kinase in a similar fashion to both phthalazine derivative PTK787 2 and anthranylamide derivative AAL993 3. In this report, we will describe the conformational analyses, from ab initio MO calculation and X-ray crystallographic analyses, of compound 1 and the analogs, which include non-active 9, all in comparison with 2 and 3. The conformation-activity relationships suggest that a nonbonded intramolecular interaction between the sulfur and the carbonyl oxygen of 1 was very important in inhibiting KDR.
2.Advances in the structural biology, design and clinical development of VEGF-R kinase inhibitors for the treatment of angiogenesis.
Manley PW;Bold G;Brüggen J;Fendrich G;Furet P;Mestan J;Schnell C;Stolz B;Meyer T;Meyhack B;Stark W;Strauss A;Wood J Biochim Biophys Acta. 2004 Mar 11;1697(1-2):17-27.
Initial studies with angiogenesis inhibitors showed little clinical benefit. However, recently reported clinical studies in colorectal cancer have shown that bevacizumab, a vascular endothelial growth factor (VEGF) monoclonal antibody, in combination with cytotoxic therapy has positive effects on patient survival. Furthermore, the VEGF receptor kinase (VEGF-R) tyrosine kinase inhibitor, vatalanib, has also shown encouraging results in colorectal cancer, with molecular resonance imaging providing evidence that the anti-tumor efficacy was indeed the result of anti-angiogenic activity. Both of these agents are progressing in phase III trials. This proof of concept has stimulated the desire for second-generation VEGF-R inhibitors having an improved profile. Structural biology insight regarding the binding mode of protein kinase inhibitors is valuable for the design of molecules possessing superior selectivity, efficacy and tolerability. Towards this goal, we have developed a new series of VEGF-R2 kinase inhibitors, based upon an anthranilic acid amide scaffold. An X-ray crystal structure of a representative compound, AAL993 (ZK260253), in complex with the catalytic domain of diphosphorylated VEGF-R2 has revealed that this molecule binds to an inactive conformation of the protein.
3.Suppression of hypoxia-induced HIF-1alpha accumulation by VEGFR inhibitors: Different profiles of AAL993 versus SU5416 and KRN633.
Ban HS;Uno M;Nakamura H Cancer Lett. 2010 Oct 1;296(1):17-26. doi: 10.1016/j.canlet.2010.03.010. Epub 2010 Apr 7.
The hypoxia-inducible factor (HIF) is a heterodimeric basic helix-loop-helix transcriptional factor and the activated HIF plays pivotal roles in various pathological conditions, including inflammation and cancer. HIF-1alpha overexpression has been observed in many common human cancers, including brain, breast, colon, lung, ovary, and prostate, and HIF-mediated genes, such as vascular endothelial growth factor (VEGF), inducible nitric oxide synthase (iNOS), and insulin-like growth factor (IGF)-1, are associated with tumor angiogenesis, metastasis, and invasion. Therefore, the pro-oncogenic protein HIF is a novel target of cancer therapy. We examined the effects of VEGFR inhibitors, AAL993, SU5416, and KRN633, on suppression of HIF-1alpha accumulation under the hypoxic condition. We found that VEGFR tyrosine kinase inhibitors, AAL993, SU5416, and KRN633, possess dual functions: inhibition of VEGFR signaling and HIF-1alpha expression under the hypoxic condition. The detailed mechanistic study indicated that SU5416 and KRN633 suppressed HIF-1alpha expression through inhibition of both Akt and ERK phosphorylation signaling pathways, whereas AAL993 suppressed HIF-1alpha expression through ERK inhibition without affecting Akt phosphorylation.