title: Mitogen- and stress-activated Kinase 1 mediates Epstein-Barr virus latent membrane protein 1-promoted cell transformation in nasopharyngeal carcinoma through its induction of Fra-1 and c-Jun genes.
abstract: BACKGROUND
  Mitogen- and Stress-Activated Kinase 1 (MSK1) is a nuclear kinase that serves as active link between extracellular signals and the primary response of gene expression. However, the involvement of MSK1 in malignant transformation and cancer development is not well understood. In this study, we aimed to explore the role of MSK1 in Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1)-promoted carcinogenesis of nasopharyngeal carcinoma (NPC).
  
  
  METHODS
  The level of MSK1 phosphorylation at Thr581 was detected by the immunohistochemical analysis in NPC tissues and normal nasopharynx tissues, and its correlation with LMP1 was analyzed in NPC tissues and cell lines. Using MSK1 inhibitor H89 or small interfering RNA (siRNA)-MSK1, the effects of MSK1 on LMP1-promoted CNE1 cell proliferation and transformation were evaluated by CCK-8 assay, flow cytometry and focus-forming assay respectively. Furthermore, the regulatory role of MSK1-mediated histone H3 phosphorylation at Ser10 on the promoter activity and expression of Fra-1 or c-Jun was determined by reporter gene assay and western blotting analysis.
  
  
  RESULTS
  Immunohistochemical analysis revealed that the level of MSK1 phosphorylation at Thr581 was significantly higher in the poorly differentiated NPC tissues than that in normal nasopharynx tissues (P < 0.001). Moreover, high level of phosphorylated MSK1 was positively correlated with the expression of LMP1 in NPC tissues (r = 0.393, P = 0.002) and cell lines. MSK1 inhibitor H89 or knockdown of MSK1 by siRNA dramatically suppressed LMP1-promoted CNE1 cell proliferation, which was associated with the induction of cell cycle arrest at G0/G1 phase. In addition, the anchorage-independent growth promoted by LMP1 was blocked in MSK1 knockdown cells. When the activity or expression of MSK1 was inhibited, LMP1-induced promoter activities of Fra-1 and c-Jun as well as their protein levels were greatly reduced. It was found that only H3 WT, but not mutant H3 S10A, dramatically increased LMP1 induction of Fra-1 and c-Jun genes compared with mock cells.
  
  
  CONCLUSIONS
  Increased MSK1 activity is critically important for LMP1-promoted cell proliferation and transformation in NPC, which may be correlated with its induction of Fra-1 and c-Jun through phosphorylation of histone H3 at Ser10.
authors.affiliation: Department of Pathophysiology, Guangdong Medical College, Dongguan, Guangdong, 523808, China. libinbin1022@126.com.|Key Laboratory for Medical Diagnostics of Guangdong Province, Sino-American Cancer Research Institute, Guangdong Medical College, Dongguan, Guangdong, 523808, China. libinbin1022@126.com.
authors.forename: Binbin
authors.initials: B
authors.lastname: Li
authors.affiliation: Key Laboratory for Medical Diagnostics of Guangdong Province, Sino-American Cancer Research Institute, Guangdong Medical College, Dongguan, Guangdong, 523808, China. 565458630@qq.com.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Wan
authors.affiliation: Key Laboratory for Medical Diagnostics of Guangdong Province, Sino-American Cancer Research Institute, Guangdong Medical College, Dongguan, Guangdong, 523808, China. huang.glen@gmail.com.
authors.forename: Guoliang
authors.initials: G
authors.lastname: Huang
authors.affiliation: Key Laboratory for Medical Diagnostics of Guangdong Province, Sino-American Cancer Research Institute, Guangdong Medical College, Dongguan, Guangdong, 523808, China. zn_huang@yahoo.com.
authors.forename: Zunnan
authors.initials: Z
authors.lastname: Huang
authors.affiliation: Department of Pathophysiology, Guangdong Medical College, Dongguan, Guangdong, 523808, China. Zhangxn_2006@126.com.
authors.forename: Xiangning
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Pathophysiology, Guangdong Medical College, Dongguan, Guangdong, 523808, China. 26312526@qq.com.
authors.forename: Dan
authors.initials: D
authors.lastname: Liao
authors.affiliation: Department of Pathophysiology, Guangdong Medical College, Dongguan, Guangdong, 523808, China. 1149276516@qq.com.
authors.forename: Shengqun
authors.initials: S
authors.lastname: Luo
authors.affiliation: Department of Pathophysiology, Guangdong Medical College, Dongguan, Guangdong, 523808, China. zhiweihe688@yahoo.com.|Key Laboratory for Medical Diagnostics of Guangdong Province, Sino-American Cancer Research Institute, Guangdong Medical College, Dongguan, Guangdong, 523808, China. zhiweihe688@yahoo.com.
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: He
mesh_terms: D000328:Adult; D002277:Carcinoma; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic; D044127:Epigenesis, Genetic; D048049:Extracellular Signal-Regulated MAP Kinases; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006657:Histones / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000473:pathology / Q000821:virology; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics* / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics* / Q000378:metabolism; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000502:physiology*; D015533:Transcriptional Activation; D014763:Viral Matrix Proteins / Q000502:physiology*; D000099169:Fos-Related Antigen 1
chemical_list: D048049:Extracellular Signal-Regulated MAP Kinases; D006657:Histones; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D038744:Ribosomal Protein S6 Kinases, 90-kDa; D014763:Viral Matrix Proteins; D000099169:Fos-Related Antigen 1; C037662:EBV-associated membrane antigen, Epstein-Barr virus; C116919:mitogen and stress-activated protein kinase 1