Small molecule inhibitors of ATP7A as novel theraphies for cancer

Abstract

Recent studies suggest that trace element copper (Cu) plays a key role in cancer progression. Cu dependent signaling pathways in cancer cells are poorly understood and are being actively investigated. In a recently published PNAS paper, we demonstrated that ATP7A copper transporter promotes breast and lung tumor growth and spread in mice by activating pro cancerous enzyme, lysyl oxidase (LOX). Therefore, we propose that blocking ATP7A using small molecule inhibitors could be a powerful approach in blocking cancer progression. We screened for inhibitors of ATP7A using a structure based virtual screen of ATP7A interacting drug like compounds, resulting in identification of our lead compound, MKV3. We used microscale thermophoresis and standard enzyme activity assays to measure the binding affinity of MKV3 to ATP7A and test the effect of MKV3 on ATP7A dependent LOX and tyrosinase enzymes. In vitro scratch and tumorigenesis assays were performed to test the effect of MKV3 on cancer cell migration and tumor growth. Microscale thermophoresis experiments revealed that MKV3 binds to ATP7A with nanomolar affinity and is a potent inhibitor of ATP7A dependent LOX activity and cell migration of 4T1 breast, LLC and A549 lung cancer cells. Moreover, MKV3 inhibited ATP7A dependent tyrosinase activity in B16 melanoma cells and suppressed B16 tumorigenesis in vivo. In summary, these studies have identified a novel first in class high affinity inhibitor of ATP7A and provide a framework to design MKV3 derivative s with improved therapeutic efficacy in mouse models of cancer. Our findings have the potential for a sustained and powerful impact in cancer therapy.