title: EB-virus latent membrane protein 1 potentiates the stemness of nasopharyngeal carcinoma via preferential activation of PI3K/AKT pathway by a positive feedback loop.
abstract: Our previous study reported that Epstein-Barr virus(EBV)-encoded latent membrane protein 1 (LMP1) could induce development of CD44(+/High) stem-like cells in nasopharyngeal carcinoma (NPC). However, the molecular mechanisms that underlie modulation of cancer stem cells (CSCs) in NPC remain unclear. Here, we show that LMP1 induced CSC-like properties through promotion of the expression of epithelial-mesenchymal transition-like cellular markers and through alterations in differentiation markers. Furthermore, LMP1 activated and triggered phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) pathway, which subsequently stimulated expression of CSC markers, development of side population and tumor sphere formation. This suggests that PI3K/AKT pathway has an important role in the induction and maintenance of CSC properties in NPC. Similarly, PI3K/AKT pathway was also activated by phosphorylase in LMP1-induced CD44(+/High) cells. In addition, LMP1 greatly increased expression of miR-21 and downregulated expression of the miR-21 target, PTEN. Overexpression of miR-21 by transfection of miR-21 mimics into LMP1-transformed cells led to phosphorylase-mediated activation of the PI3K/AKT pathway and induction of CSCs. On the contrary, phosphorylation of the PI3K/AKT pathway and the expression of CSC were reversed by an miR-21 inhibitor. The specific inhibitor (Ly294002) of PI3K/AKT pathway significantly decreased expression of miR-21 and CSC markers and upregulated the expression of PTEN, which indicates that miR-21 and PTEN are the downstream effectors of PI3K/AKT and that expression of these two effectors are related to the development of NPC CSCs. Taken together, our novel findings indicate that LMP1, PI3K/AKT, miR-21 and PTEN constitute a positive feedback loop and have a key role in LMP1-induced CSCs in NPC.
authors.affiliation: Department of Experimental Research, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou China.|Department of Cancer Chemotherapy, Gaozhou People's Hospital, Gaozhou, China.
authors.forename: C-F
authors.initials: CF
authors.lastname: Yang
authors.affiliation: Department of Cancer Chemotherapy, Zengcheng People's Hospital (BoJi-Affiliated Hospital of Sun Yat-Sen University), Zengcheng, China.
authors.forename: G-D
authors.initials: GD
authors.lastname: Yang
authors.affiliation: Department of Nuclear Medicine, The Second People's Hospital of Shenzhen, Shenzhen, China.
authors.forename: T-J
authors.initials: TJ
authors.lastname: Huang
authors.affiliation: Second College of Clinical Medicine, Southern Medical University, Guangzhou, China.
authors.forename: R
authors.initials: R
authors.lastname: Li
authors.affiliation: School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, China.
authors.forename: Q-Q
authors.initials: QQ
authors.lastname: Chu
authors.affiliation: Department of Experimental Research, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou China.
authors.forename: L
authors.initials: L
authors.lastname: Xu
authors.affiliation: Department of Cancer Chemotherapy, Gaozhou People's Hospital, Gaozhou, China.
authors.forename: M-S
authors.initials: MS
authors.lastname: Wang
authors.affiliation: Department of Cancer Chemotherapy, Gaozhou People's Hospital, Gaozhou, China.
authors.forename: M-D
authors.initials: MD
authors.lastname: Cai
authors.affiliation: Department of Cancer Chemotherapy, Gaozhou People's Hospital, Gaozhou, China.
authors.forename: L
authors.initials: L
authors.lastname: Zhong
authors.affiliation: Department of Cancer Chemotherapy, Gaozhou People's Hospital, Gaozhou, China.
authors.forename: H-J
authors.initials: HJ
authors.lastname: Wei
authors.affiliation: Department of Pharmacy, Sun Yat-Sen University Cancer Center, Guangzhou, China.
authors.forename: H-B
authors.initials: HB
authors.lastname: Huang
authors.affiliation: Department of Pathology, Saint Barnabas Medical Center, Livingston, NJ, USA.
authors.forename: J-L
authors.initials: JL
authors.lastname: Huang
authors.affiliation: Department of Experimental Research, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou China.|Department of Nasopharyngeal Carcinoma, Sun Yat-Sen University Cancer Center, Guangzhou, China.
authors.forename: C-N
authors.initials: CN
authors.lastname: Qian
authors.affiliation: Department of Experimental Research, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou China.
authors.forename: B-J
authors.initials: BJ
authors.lastname: Huang
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D002460:Cell Line; D045744:Cell Line, Tumor; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D015151:Immunoblotting; D008297:Male; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D035683:MicroRNAs / Q000235:genetics; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D014411:Neoplastic Stem Cells / Q000378:metabolism*; D051059:PTEN Phosphohydrolase / Q000235:genetics / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D014183:Transplantation, Heterologous; D014763:Viral Matrix Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C037662:EBV-associated membrane antigen, Epstein-Barr virus; C524940:MIRN21 microRNA, human; D035683:MicroRNAs; D014763:Viral Matrix Proteins; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human