The mechanisms by which cancer cell-intrinsic CYP monooxygenases promote tumor progression are largely unknown. CYP3A4 was unexpectedly associated with breast cancer mitochondria and synthesized arachidonic acid (AA)-derived epoxyeicosatrienoic acids (EETs), which promoted the electron transport chain/respiration and inhibited AMPKα. CYP3A4 knockdown activated AMPKα, promoted autophagy, and prevented mammary tumor formation. The diabetes drug metformin inhibited CYP3A4-mediated EET biosynthesis and depleted cancer cell-intrinsic EETs. Metformin bound to the active-site heme of CYP3A4 in a co-crystal structure, establishing CYP3A4 as a biguanide target. Structure-based design led to discovery of N1-hexyl-N5-benzyl-biguanide (HBB), which bound to the CYP3A4 heme with higher affinity than metformin. HBB potently and specifically inhibited CYP3A4 AA epoxygenase activity. HBB also inhibited growth of established ER+ mammary tumors and suppressed intratumoral mTOR. CYP3A4 AA epoxygenase inhibition by biguanides thus demonstrates convergence between eicosanoid activity in mitochondria and biguanide action in cancer, opening a new avenue for cancer drug discovery. Guo et al. discover inhibition of CYP3A4 AA epoxygenase by biguanides, thereby demonstrating convergence between eicosanoid activity in mitochondria and biguanide action in cancer, opening a new avenue for cancer drug discovery.
Bibliographical noteFunding Information:
R01-CA113570 , Susan G. Komen Foundation grant KG090861 , Randy Shaver Foundation and Community Fund, Minnesota Partnership for Biotechnology and Medical Genomics , University of Minnesota (UMN) Medical School Research Renewal Program to D.A.P. and Dr. Carol Lange, the Fairview Foundation Dr. Barbara Bowers Fund, and the State of Minnesota through the Translational Product Development Fund (TPDF with R.J.S.) to D.A.P. The Walther Prize for Cancer Research to D.G.T and D.A.P. We also acknowledge Masonic Cancer Center NIH grant P30-CA077598 (Dr. Douglas Yee, P.I.) for Analytical Biochemistry core support and the National Center for Advancing Translational Sciences of the NIH Award numbers UL1TR000114 and UL1TR000135 (Dr. Bruce R. Blazar, P.I.; Sundeep Kohsla, P.I.). Instituto Nacional de Cancerologica de Mexico , Patronato del Instituto Nacional de Cancerologia , Consejo Nacional de Ciencia y Tecnología , grant 280148 for visiting student support. Support is acknowledged of grants R01 ES025767 to I.F.S., R01 GM057353 to T.L.P. and NIH MIRA award R35 GM118145 to S.G.S., NIH MIRA R35 GM118030 to J.D.L., R01 CA157971 to A.K., F31 CA177119 to E.A.H., NIH GM110790 to W.M.A., P30ES013508 to I.A.B. and P30CA016520 (Dr. Chi V. Dang, P.I.), 5R01-GM037922 and 5P01-DK038226 to J.H.C., and NIH U01 HL117664 to K.G. Students J.A. and William Marrero Ortiz were supported by LSSURP grant R25 HL088728 to Dr. Colin Campbell. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH. E.A. acknowledges support of UMN Department of Medicinal Chemistry and the UMN Supercomputing Institute for Advanced Computational Research (MSI). Support is acknowledged of Fashion Footwear Charitable Foundation of New York/QVC Presents Shoes on Sale (to D.G.T.) and the National Research Fund of Korea grant 2015R15A2009124 (to Y.K.B.). Support is acknowledged of the Robert A. Welch Foundation ( I-0011 ) and the Dr. Ralph and Marian Falk Medical Research Trust to J.R.F. Support is acknowledged of the Center for Translational Medicine of the UMN . We acknowledge gifts from patients and their families and Epsilon Sigma Alpha Foundation, Beta Sigma Chapter to the UMN Foundation and Minnesota International Medicine. We thank Drs. Carol Lange, Douglas Yee, Bruce Hammock, Martin Brand, Chi Dang, Phillip A. Sharp, Jeffrey Miller, Margot Cleary, Deepali Sachdev, George Sledge, Ze'ev Ronai, Beth Levine, Aditi Das, Tom Makris, Matthew Vander Heiden, Henry Wong, Peter Villalta, Jeffry P. Jones, Ranjana Mitra, and David Donner for helpful discussions and Drs. Daniel Weisdorf, Philip McGlave, Peter Igarashi, Tucker LeBien, and Bruce Blazar for their support. We thank Robin Bliss, Lia Coicou, Natalie Pascutoi, William Marrero Ortiz, Monique Morgan, Michael Maher, Christian Torres, Diego Hinojosa, Julia Nguyen, Margaret Mysz, and Dr. Kathryn J. Chavez for expert assistance. We thank Dr. Stephen C. Schmechel, Jonathan Henriksen, and Colleen Forster for pathology core laboratory support. We thank Drs. Christophe Morisseau and Sung Hee Hwang for t-AUCB and Dr. John Imig for EET C22. We thank Michael Franklin for help with editing of the manuscript. Mitochondrial image credit for graphical abstract is: Extender_01/stock.adobe. com. Figure 7 credit: Courtesy: ChemDraw by PerkinElmer Informatics. D.G.T. is a consultant for Resonant Therapeutics. D.G.T. has received compensation from Resonant Therapeutics as a consultant. K.G. is a consultant for Fera Pharmaceuticals LLC. The University of Minnesota has a use patent application for HBB in ER + HER2 − breast cancer and EET-C22, the 14,15-EET agonist analog, is covered by a patent jointly owned by the Medical College of Wisconsin and the University of Texas Southwestern Medical Center.
- breast cancer
- cytochrome P450
- electron transport chain
- epoxyeicosatrienoic acid