Human mitochondrial peptide deformylase, a new anticancer target of actinonin-based antibiotics
Mona D. Lee, … , Francis M. Sirotnak, David A. Scheinberg
Mona D. Lee, … , Francis M. Sirotnak, David A. Scheinberg
Published October 15, 2004
Citation Information: J Clin Invest. 2004;114(8):1107-1116. https://doi.org/10.1172/JCI22269.
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Article Oncology

Human mitochondrial peptide deformylase, a new anticancer target of actinonin-based antibiotics

Abstract

Peptide deformylase activity was thought to be limited to ribosomal protein synthesis in prokaryotes, where new peptides are initiated with an N-formylated methionine. We describe here a new human peptide deformylase (Homo sapiens PDF, or HsPDF) that is localized to the mitochondria. HsPDF is capable of removing formyl groups from N-terminal methionines of newly synthesized mitochondrial proteins, an activity previously not thought to be necessary in mammalian cells. We show that actinonin, a peptidomimetic antibiotic that inhibits HsPDF, also inhibits the proliferation of 16 human cancer cell lines. We designed and synthesized 33 chemical analogs of actinonin; all of the molecules with potent activity against HsPDF also inhibited tumor cell growth, and vice versa, confirming target specificity. Small interfering RNA inhibition of HsPDF protein expression was also antiproliferative. Actinonin treatment of cells led to a tumor-specific mitochondrial membrane depolarization and ATP depletion in a time- and dose-dependent manner; removal of actinonin led to a recovery of the membrane potential consistent with indirect effects on the electron transport chain. In animal models, oral or parenteral actinonin was well tolerated and inhibited human prostate cancer and lung cancer growth. We conclude that HsPDF is a new human mitochondrial enzyme that may provide a novel selective target for anticancer therapy by use of actinonin-based antibiotics.

Authors

Mona D. Lee, Yuhong She, Michael J. Soskis, Christopher P. Borella, Jeffrey R. Gardner, Paula A. Hayes, Benzon M. Dy, Mark L. Heaney, Mark R. Philips, William G. Bornmann, Francis M. Sirotnak, David A. Scheinberg

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Figure 5

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siRNAs designed to target HsPDF inhibit protein expression and tumor cel...
siRNAs designed to target HsPDF inhibit protein expression and tumor cell proliferation. (A) siRNAs were designed to target HsPDF. The 2 siRNA sequences that were effective were HsPDF 581–601 and HsPDF 659–679. The numbers refer to the nucleotide number relative to the start codon of human Pdf mRNA. (B) HeLa cells stably expressing HsPDF-YFP fusion protein were transfected with 100 nM of control or HsPDF-specific siRNAs. Mean peak fluorescence determined 48 hours after transfection shows that the target-specific siRNAs significantly reduced protein expression (*P < 0.001). (C) HeLa cells were transfected with 100 nM of control or HsPDF-specific siRNAs. Cell proliferation was determined by tritiated thymidine incorporation over a period of 3 days following transfection. The control siRNA group (filled circles) showed no significant changes (P > 0.05) in cell proliferation when compared with the no-siRNA control group (open circles). siRNA HsPDF 581–601 (upright triangles) and siRNA HsPDF 659–679 (inverted triangles) caused significant decreases (**P < 0.05) in cell proliferation 1 and 2 days after transfection. (D) HeLa cells were transfected with 10, 20, 50, and 100 nM of control or HsPDF-specific siRNAs. Cell proliferation was determined by tritiated thymidine incorporation 2 days after transfection. The HsPDF-specific siRNAs significantly inhibited cell proliferation (*P < 0.001) at all 4 doses when compared with both the no-siRNA group and the corresponding dose of control siRNA, while significant inhibition ( P < 0.001) was seen only at the higher doses (50 and 100 nM) of the control group.