Design and synthesis of small molecule agonists of EphA2 receptor

Abstract

Ligand-independent activation of EphA2 receptor kinase promotes cancer metastasis and invasion. Activating EphA2 receptor tyrosine kinase with small molecule agonist is a novel strategy to treat EphA2 overexpressing cancer. In this study, we performed a lead optimization of a small molecule Doxazosin that was identified as an EphA2 receptor agonist. 33 new analogs were developed and evaluated; a structure-activity relationship was summarized based on the EphA2 activation of these derivatives. Two new derivative compounds 24 and 27 showed much improved activity compared to Doxazosin. Compound 24 possesses a bulky amide moiety, and compound 27 has a dimeric structure that is very different to the parental compound. Compound 27 with a twelve-carbon linker of the dimer activated the kinase and induced receptor internalization and cell death with the best potency. Another dimer with a six-carbon linker has significantly reduced potency compared to the dimer with a longer linker, suggesting that the length of the linker is critical for the activity of the dimeric agonist. To explore the receptor binding characteristics of the new molecules, we applied a docking study to examine how the small molecule binds to the EphA2 receptor. The results reveal that compounds 24 and 27 form more hydrogen bonds to EphA2 than Doxazosin, suggesting that they may have higher binding affinity to the receptor.

Adaptive RSK‐EphA2‐GPRC5A signaling switch triggers chemotherapy resistance in ovarian cancer

“…Frequently overexpressed in OC, EphA2 associates with high tumor grade, advanced stage, and poor clinical outcome (Thaker et al, 2004). It has been recognized as a putative target to block HGSC progression, although currently developed molecular-targeted therapies lack proof for specificity and efficacy (Landen et al, 2005b;Petty et al, 2018). In adhesion-dependent signaling, EphA2 cooperates with integrins, the transmembrane receptors that link the ECM to cell cytoskeleton (Hamidi & Ivaska, 2018).…”

EphA2 receptor is a key player in the metastatic onset of Ewing sarcoma

“…These results highlight the need for additional studies to ascertain the contribution of CCL2 in the metastatic process using humanized models and suggest the potential role of the immune system in metastatic progression. These findings suggest targeting of EphA2 and EphA2-mediated events as novel targets for ES therapy, opening an opportunity to test EphA2 small molecule agonists 41 alone or in combination with either antiangiogenic agents or targeted therapy against EGFR-related components overexpressed in the most aggressive forms of ES.…”

A quantitative LC–MS/MS method for determination of a small molecule agonist of EphA2 in mouse plasma and brain tissue

“…Compound 27 and internal standard (ISTD) prazosin were synthesized and purified according to the published procedure (Figure ; Petty et al, ). HPLC‐grade acetonitrile and ACS‐grade ethyl acetate were purchased from BDH chemicals (Carle Place, NY) and LC/MS‐grade formic acid was from Fisher Scientific (Waltham, MA, USA).…”

“…However, the potency of doxazosin as an agonist of EphA2 is not good enough for clinical application in cancer treatment. Further structural optimization of doxazosin led to the discovery of a new EphA2 agonist compound 27 with enhanced affinity, specificity and potency (Petty et al, ). In order to investigate the compound with in vivo animal models for its targeting effect to EphA2 and therapeutic efficacy, a pre‐clinical pharmacokinetic study is urgently needed.…”