title: Elongation factor-2 kinase regulates TG2/β1 integrin/Src/uPAR pathway and epithelial-mesenchymal transition mediating pancreatic cancer cells invasion.
abstract: Pancreatic ductal adenocarcinoma is one of the lethal cancers with extensive local tumour invasion, metastasis, early systemic dissemination and poorest prognosis. Thus, understanding the mechanisms regulating invasion/metastasis and epithelial-mesenchymal transition (EMT), is the key for developing effective therapeutic strategies for pancreatic cancer (PaCa). Eukaryotic elongation factor-2 kinase (eEF-2K) is an atypical kinase that we found to be highly up-regulated in PaCa cells. However, its role in PaCa invasion/progression remains unknown. Here, we investigated the role of eEF-2K in cellular invasion, and we found that down-regulation of eEF-2K, by siRNA or rottlerin, displays impairment of PaCa cells invasion/migration, with significant decreases in the expression of tissue transglutaminase (TG2), the multifunctional enzyme implicated in regulation of cell attachment, motility and survival. These events were associated with reductions in β1 integrin/uPAR/MMP-2 expressions as well as decrease in Src activity. Furthermore, inhibition of eEF-2K/TG2 axis suppresses the EMT, as demonstrated by the modulation of the zinc finger transcription factors, ZEB1/Snail, and the tight junction proteins, claudins. Importantly, while eEF-2K silencing recapitulates the rottlerin-induced inhibition of invasion and correlated events, eEF-2K overexpression, by lentivirus-based expression system, suppresses such rottlerin effects and potentiates PaCa cells invasion/migration capability. Collectively, our results show, for the first time, that eEF-2K is involved in regulation of the invasive phenotype of PaCa cells through promoting a new signalling pathway, which is mediated by TG2/β1 integrin/Src/uPAR/MMP-2, and the induction of EMT biomarkers which enhance cancer cell motility and metastatic potential. Thus, eEF-2K could represent a novel potential therapeutic target in pancreatic cancer.
authors.affiliation: Department of Experimental Therapeutics, The University of Texas, M.D. Anderson Cancer Center, Houston, TX, USA; Department of Pharmacology and Toxicology, Faculty of Pharmacy, Al-Azhar University, Cairo, Egypt.
authors.forename: Ahmed A
authors.initials: AA
authors.lastname: Ashour
authors.forename: Nilgun
authors.initials: N
authors.lastname: Gurbuz
authors.forename: Sultan Neslihan
authors.initials: SN
authors.lastname: Alpay
authors.forename: Abdel-Aziz H
authors.initials: AA
authors.lastname: Abdel-Aziz
authors.forename: Ahmed M
authors.initials: AM
authors.lastname: Mansour
authors.forename: Longfei
authors.initials: L
authors.lastname: Huo
authors.forename: Bulent
authors.initials: B
authors.lastname: Ozpolat
mesh_terms: D000098:Acetophenones / Q000008:administration & dosage; D001578:Benzopyrans / Q000008:administration & dosage; D045744:Cell Line, Tumor; D054736:Elongation Factor 2 Kinase / Q000235:genetics* / Q000378:metabolism; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics; D019204:GTP-Binding Proteins; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D019012:Integrin beta1 / Q000096:biosynthesis* / Q000235:genetics; D009361:Neoplasm Invasiveness / Q000235:genetics; D010190:Pancreatic Neoplasms / Q000235:genetics* / Q000473:pathology; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D034741:RNA, Small Interfering; D055293:Receptors, Urokinase Plasminogen Activator / Q000096:biosynthesis* / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics; D011503:Transglutaminases / Q000096:biosynthesis*; D019061:src-Family Kinases / Q000096:biosynthesis / Q000235:genetics
chemical_list: D000098:Acetophenones; D001578:Benzopyrans; D019012:Integrin beta1; D034741:RNA, Small Interfering; D055293:Receptors, Urokinase Plasminogen Activator; C085746:rottlerin; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D019061:src-Family Kinases; D054736:Elongation Factor 2 Kinase; D019204:GTP-Binding Proteins
keywords: Ca2+/calmodulin-dependent kinase III; EMT; MMP-2; Src; eEF-2K; integrin; pancreatic ductal adenocarcinoma; rottlerin; tissue transglutaminase; uPAR