A Soluble Bis-Chelated Gold(I) Diphosphine Compound with Strong Anticancer Activity and Low Toxicity

Gold-containing compounds have shown anticancer potential, but their clinical applications have been severely limited by poor stability and high toxicity in vivo. Here, we report a novel soluble bis-chelated gold(I)–diphosphine compound (GC20) with strong anticancer activity and low toxicity. GC20 shows strong antiproliferation potency against a broad spectrum of cancer cell lines including cisplatin-resistant cancer cells (IC50 ≈ 0.5 μM) and significantly reduces tumor growth in several tumor xenografts in mouse models at doses as low as 2 mg/kg. Studies of its mechanism revealed that GC20 specifically inhibits the enzymatic activity of thioredoxin reductase by binding to selenocysteine residue, without targeting other well-known selenol and thiol groups contained in biomolecules. Remarkably, in animal studies GC20 was shown to be well tolerated even at the high dose of 8 mg/kg. Our results strongly suggest that GC20 represents a promising candidate for the development of novel anticancer drugs.