title: Inhibition of eEF-2 kinase sensitizes human nasopharyngeal carcinoma cells to lapatinib-induced apoptosis through the Src and Erk pathways.
abstract: Previous studies have reported that eEF-2 kinase is associated with tumour cell sensitivity to certain therapies. In the present study, we investigated the relationship between eEF-2 kinase and lapatinib, a dual inhibitor of EGFR and HER-2, in nasopharyngeal carcinoma (NPC) cells.
  
  
  
  The effect of treatment on the growth and proliferation of NPC cells was measured by three methods: cell counting, crystal violet staining and colony counting. Apoptosis was evaluated by flow cytometry to determine Annexin V-APC/7-AAD and cleaved PARP levels, and the results were further confirmed by Western blot analysis. The expression of eEF-2 kinase and the impacts of different treatments on different signalling pathways were analysed by Western blot analysis.
  
  
  
  The expression of eEF-2 kinase was significantly associated with NPC cell sensitivity to lapatinib. Therefore, suppression of this kinase could increase the cytocidal effect of lapatinib, as well as reduce cell viability and colony formation. Furthermore, inhibition of eEF-2 kinase, by either RNA interference (eEF-2 kinase siRNA or shRNA) or pharmacological inhibition (NH125), enhanced lapatinib-induced apoptosis of NPC cells. The results also showed that lapatinib combined with NH125 had a synergistic effect in NPC cells. In addition, mechanistic analyses revealed that downregulation of the ERK1/2 and Src pathways, but not the AKT pathway, was involved in this sensitizing effect.
  
  
  
  The results of this study suggest that targeting eEF-2 kinase may improve the efficacy of therapeutic interventions such as lapatinib in NPC cells.
authors.affiliation: Department of Medical Oncology, The Fifth Affiliated Hospital of Sun-Yat-Sen University, 52 Mei Hua Road East, Zhu Hai, 519000, Guangdong Province, People's Republic of China.
authors.forename: Lin
authors.initials: L
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Oncology in South China; Collaborative Innovation Center for Cancer Medicine; Department of nasopharyngeal carcinoma, Sun Yat-sen University Cancer Center, Guangzhou, China.
authors.forename: PeiYu
authors.initials: P
authors.lastname: Huang
authors.affiliation: Department of Medical Oncology, The Fifth Affiliated Hospital of Sun-Yat-Sen University, 52 Mei Hua Road East, Zhu Hai, 519000, Guangdong Province, People's Republic of China.
authors.forename: ZhiHui
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Medical Oncology, The Fifth Affiliated Hospital of Sun-Yat-Sen University, 52 Mei Hua Road East, Zhu Hai, 519000, Guangdong Province, People's Republic of China.
authors.forename: Nan
authors.initials: N
authors.lastname: Chen
authors.affiliation: Department of Surgical Oncology, The Fifth Affiliated Hospital of Sun-Yat-Sen University, Zhu Hai, China.
authors.forename: Con
authors.initials: C
authors.lastname: Tang
authors.affiliation: Department of Medical Oncology, The Fifth Affiliated Hospital of Sun-Yat-Sen University, 52 Mei Hua Road East, Zhu Hai, 519000, Guangdong Province, People's Republic of China.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Lin
authors.affiliation: Department of Medical Oncology, The Fifth Affiliated Hospital of Sun-Yat-Sen University, 52 Mei Hua Road East, Zhu Hai, 519000, Guangdong Province, People's Republic of China. pengpjian@163.com.
authors.forename: PeiJian
authors.initials: P
authors.lastname: Peng
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D002277:Carcinoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D019008:Drug Resistance, Neoplasm; D004357:Drug Synergism; D054736:Elongation Factor 2 Kinase / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D020868:Gene Silencing; D006801:Humans; D000077341:Lapatinib; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011799:Quinazolines / Q000494:pharmacology*; D034622:RNA Interference; D015398:Signal Transduction / Q000187:drug effects*; D019061:src-Family Kinases / Q000378:metabolism*
chemical_list: D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D000077341:Lapatinib; D019061:src-Family Kinases; D054736:Elongation Factor 2 Kinase; D048049:Extracellular Signal-Regulated MAP Kinases
keywords: Lapatinib; Nasopharyngeal carcinoma; Src/Erk signalling pathway; Synergistic effect; eEF-2 kinase