Piperlongumine, chemical from Indian pepper plant inhibits enzyme in cancer cells

UT Southwestern Medical Center scientists have uncovered the chemical process behind anti-cancer properties of a spicy Indian pepper plant called the long pepper, whose suspected medicinal properties date back thousands of years. The study is published in the Journal of Biological Chemistry.

Dr. Westover’s lab used X-ray crystallography to create this molecular model of piperlongumine.
Credit: UT Southwestern

The secret lies in a chemical called Piperlongumine (PL), which has shown activity against many cancers including prostate, breast, lung, colon, lymphoma, leukemia, primary brain tumors, and gastric cancer.

Using x-ray crystallography, researchers were able to create molecular structures that show how the chemical is transformed after being ingested. Piperlongumine (PL) converts to hPiperlongumine (hPL), an active drug that silences a gene called GSTP1. The GSTP1 gene produces a detoxification enzyme Glutathione S-Transferase Pi 1 that is often overly abundant in tumors.

“We are hopeful that our structure will enable additional drug development efforts to improve the potency of PL for use in a wide range of cancer therapies,” said Dr. Kenneth Westover, Assistant Professor of Biochemistry and Radiation Oncology. “This research is a spectacular demonstration of the power of x-ray crystallography.”

Dr. Westover, a member of the Harold C. Simmons Comprehensive Cancer Center, used cutting edge technologies in UT Southwestern’s Structural Biology Core (SBC) – the University’s world-renowned facility for X-ray crystallography, to better understand the anticancer properties of Piperlongumine (PL). X-ray crystallography allows scientists to determine molecular structures that reveal how molecules interact with targets – in this case how Piperlongumine (PL) interacts with GSTP1. Viewing the structures helps in developing drugs for those targets.

Citation: Harshbarger, Wayne, Sudershan Gondi, Scott B. Ficarro, John Hunter, Durga Udayakumar, Deepak Gurbani, William Singer, Yan Liu, Lianbo Li, Jarrod A. Marto and Kenneth D. Westover. “Structural and Biochemical Analyses Reveal the Mechanism of Glutathione S-Transferase Pi 1 Inhibition by the Anti-cancer Compound Piperlongumine.” Journal of Biological Chemistry (2016): jbc-M116.
DOI: 10.1074/jbc.M116.750299
Research funding: V Foundation for Cancer Research, Welch Foundation, and Cancer Prevention and Research Institute of Texas.
Adapted from press release by UT Southwestern Medical Center.