title: Targeting elongation factor-2 kinase (eEF-2K) induces apoptosis in human pancreatic cancer cells.
abstract: Pancreatic cancer (PaCa) is one of the most aggressive, apoptosis-resistant and currently incurable cancers with a poor survival rate. Eukaryotic elongation factor-2 kinase (eEF-2K) is an atypical kinase, whose role in PaCa survival is not yet known. Here, we show that eEF-2K is overexpressed in PaCa cells and its down-regulation induces apoptotic cell death. Rottlerin (ROT), a polyphenolic compound initially identified as a PKC-δ inhibitor, induces apoptosis and autophagy in a variety of cancer cells including PaCa cells. We demonstrated that ROT induces intrinsic apoptosis, with dissipation of mitochondrial membrane potential (ΔΨm), and stimulates extrinsic apoptosis with concomitant induction of TNF-related apoptosis inducing ligand (TRAIL) receptors, DR4 and DR5, with caspase-8 activation, in PANC-1 and MIAPaCa-2 cells. Notably, while none of these effects were dependent on PKC-δ inhibition, ROT down-regulates eEF-2K at mRNA level, and induce eEF-2K protein degradation through ubiquitin-proteasome pathway. Down-regulation of eEF-2K recapitulates the events observed after ROT treatment, while its over-expression suppressed the ROT-induced apoptosis. Furthermore, eEF-2K regulates the expression of tissue transglutaminase (TG2), an enzyme previously implicated in proliferation, drug resistance and survival of cancer cells. Inhibition of eEF-2K/TG2 axis leads to caspase-independent apoptosis which is associated with induction of apoptosis-inducing factor (AIF). Collectively, these results indicate, for the first time, that the down-regulation of eEF-2K leads to induction of intrinsic, extrinsic as well as AIF-dependent apoptosis in PaCa cells, suggesting that eEF-2K may represent an attractive therapeutic target for the future anticancer agents in PaCa.
authors.affiliation: Department of Experimental Therapeutics, Unit 422, The University of Texas, M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX, 77030, USA.
authors.forename: Ahmed A
authors.initials: AA
authors.lastname: Ashour
authors.forename: Abdel-Aziz H
authors.initials: AA
authors.lastname: Abdel-Aziz
authors.forename: Ahmed M
authors.initials: AM
authors.lastname: Mansour
authors.forename: S Neslihan
authors.initials: SN
authors.lastname: Alpay
authors.forename: Longfei
authors.initials: L
authors.lastname: Huo
authors.forename: Bulent
authors.initials: B
authors.lastname: Ozpolat
mesh_terms: D000098:Acetophenones / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D051033:Apoptosis Inducing Factor / Q000235:genetics / Q000378:metabolism; D001578:Benzopyrans / Q000494:pharmacology; D045744:Cell Line, Tumor; D054736:Elongation Factor 2 Kinase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D010190:Pancreatic Neoplasms / Q000188:drug therapy / Q000201:enzymology* / Q000235:genetics / Q000503:physiopathology; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D000098:Acetophenones; D000970:Antineoplastic Agents; D051033:Apoptosis Inducing Factor; D001578:Benzopyrans; C085746:rottlerin; D054736:Elongation Factor 2 Kinase