A heterometallic ruthenium–gold complex displays antiproliferative, antimigratory, and antiangiogenic properties and inhibits metastasis and angiogenesis-associated proteases in renal cancer

Heterobimetallic compounds are designed to harness chemotherapeutic traits of distinct metal species into a single molecule. The ruthenium-gold (Ru-Au) family of compounds based on Au-N-heterocyclic carbene (NHC) fragments [Cl(2)(p-cymene)Ru(μ-dppm)Au(NHC)]ClO(4) was conceived to combine the known antiproliferative and cytotoxic properties of Au-NHC-based compounds and the antimigratory, antimetastatic and antiangiogenic characteristic of specific Ru-based compounds. Following recent studies of the anticancer efficacies of these Ru–Au-NHC complexes with promising potential as chemotherapeutics against colorectal, and renal cancers in vitro, we report here on the mechanism of a selected compound, [Cl(2)(p-cymene)Ru(μ-dppm)Au(IMes)]ClO(4) (RANCE-1, 1). The studies were carried out in vitro using a human clear cell renal carcinoma cell line (Caki-1). These studies indicate that bimetallic compound RANCE-1 (1) is significantly more cytotoxic than the Ru (2) or Au (3) monometallic derivatives. RANCE-1 significantly inhibits migration, invasion and angiogenesis, which are essential for metastasis. RANCE-1 was found to disturb pericellular proteolysis by inhibiting cathepsins, and the metalloproteases MMP and ADAM which play key roles in the etiopathogenesis of cancer. RANCE-1 also inhibits the mitochondrial protein TrxR that is often overexpressed in cancer cells and facilitates apoptosis evasion. We found that while Auranofin perturbed migration and invasion to similar degrees as RANCE-1 (1) in Caki-1 renal cancer cells, RANCE-1 (1) inhibited antiangiogenic formation and VEGF expression. We found that Auranofin and RANCE-1 (1) have distinct proteolytic profiles. In summary, RANCE-1 constitutes a very promising candidate for further preclinical evaluations in renal cancer.