title: Zinc chelation induces rapid depletion of the X-linked inhibitor of apoptosis and sensitizes prostate cancer cells to TRAIL-mediated apoptosis.
abstract: The X-linked inhibitor of apoptosis (XIAP), the most potent member of the inhibitor of apoptosis protein (IAP) family of endogenous caspase inhibitors, blocks the initiation and execution phases of the apoptotic cascade. As such, XIAP represents an attractive target for treating apoptosis-resistant forms of cancer. Here, we demonstrate that treatment with the membrane-permeable zinc chelator, N,N,N',N',-tetrakis(2-pyridylmethyl) ethylenediamine (TPEN) induces a rapid depletion of XIAP at the post-translational level in human PC-3 prostate cancer cells and several non-prostate cell lines. The depletion of XIAP is selective, as TPEN has no effect on the expression of other zinc-binding members of the IAP family, including cIAP1, cIAP2 and survivin. The downregulation of XIAP in TPEN-treated cells occurs via proteasome- and caspase-independent mechanisms and is completely prevented by the serine protease inhibitor, Pefabloc. Finally, our studies demonstrate that TPEN promotes activation of caspases-3 and -9 and sensitizes PC-3 prostate cancer cells to TRAIL-mediated apoptosis. Taken together, our findings indicate that zinc-chelating agents may be used to sensitize malignant cells to established cytotoxic agents via downregulation of XIAP.
authors.affiliation: Department of Surgical Oncology, Division of Urology, Fox Chase Cancer Center, Philadelphia, PA 19111, USA.
authors.forename: P
authors.initials: P
authors.lastname: Makhov
authors.forename: K
authors.initials: K
authors.lastname: Golovine
authors.forename: R G
authors.initials: RG
authors.lastname: Uzzo
authors.forename: J
authors.initials: J
authors.lastname: Rothman
authors.forename: P L
authors.initials: PL
authors.lastname: Crispen
authors.forename: T
authors.initials: T
authors.lastname: Shaw
authors.forename: B J
authors.initials: BJ
authors.lastname: Scoll
authors.forename: V M
authors.initials: VM
authors.lastname: Kolenko
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D002614:Chelating Agents / Q000494:pharmacology*; D003300:Copper / Q000494:pharmacology; D004354:Drug Screening Assays, Antitumor; D004789:Enzyme Activation / Q000187:drug effects; D005021:Ethylamines / Q000494:pharmacology; D006801:Humans; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008954:Models, Biological; D011471:Prostatic Neoplasms / Q000201:enzymology / Q000473:pathology*; D011480:Protease Inhibitors / Q000494:pharmacology; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011725:Pyridines; D011743:Pyrimidines / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000378:metabolism; D013450:Sulfones / Q000494:pharmacology; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000494:pharmacology*; D051636:X-Linked Inhibitor of Apoptosis Protein / Q000737:chemistry / Q000172:deficiency*; D015032:Zinc / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D002614:Chelating Agents; D005021:Ethylamines; C511824:N,N,N',N'-tetrakis(2-pyridylmethyl)ethane-1,2-diamine; D011480:Protease Inhibitors; D011725:Pyridines; D011743:Pyrimidines; D034741:RNA, Small Interfering; D013450:Sulfones; D053221:TNF-Related Apoptosis-Inducing Ligand; D051636:X-Linked Inhibitor of Apoptosis Protein; C002010:4-(2-aminoethyl)benzenesulfonylfluoride; D003300:Copper; D020169:Caspases; D046988:Proteasome Endopeptidase Complex; D015032:Zinc