Discovery of Artemisinins as Microsomal Prostaglandins Synthase-2 Inhibitors for the Treatment of Colorectal Cancer via Chemoproteomics.

Colorectal cancer remains the second leading cause of cancer-related mortalities worldwide. While artemisinin (ART), a key active compound from the traditional Chinese medicinal herb Artemisia annua , has been recognized for its antiproliferative activity against colon cancer cells, its underlying molecular underpinnings remain elusive. Whereas promiscuity of heme-dependent alkylating of macromolecules, mainly proteins, has been seen pivotal as a universal and primary mode of action of ART in cancer cells, accumulating evidence suggests the existence of unique targets and mechanisms of actions contingent on cell or tissue specificities. Here, we employed photoaffinity probes to identify the specific targets responsible for ART's anti-colon cancer actions. Upon validation, microsomal prostaglandins synthase-2 emerged as a specific and reversible target of ART in HCT116 colorectal cancer cells, whose inhibition resulted in reduced cellular prostaglandin E 2 biosynthesis and cell growth. Our discovery opens new opportunities for pharmacological treatment of colon cancer.