title: ISL-1 is overexpressed in non-Hodgkin lymphoma and promotes lymphoma cell proliferation by forming a p-STAT3/p-c-Jun/ISL-1 complex.
abstract: BACKGROUND
  Insulin enhancer binding protein-1 (ISL-1), a LIM-homeodomain transcription factor, is essential for the heart, motor neuron and pancreas development. Recently, ISL-1 has been found in some types of human cancers. However, how ISL-1 exerts the role in tumor development is not clear.
  
  
  RESULTS
  The expression of ISL-1 was assessed in 211 human lymphoma samples and 23 normal lymph node samples. Immunohistochemistry results demonstrated a markedly higher expression of ISL-1 in 75% of non-Hodgkin lymphoma (NHL) samples compared with that in normal lymph nodes or Hodgkin lymphoma (HL) samples. CCK-8 analysis, cell cycle assay and xenograft model were performed to characterize the association between ISL-1 expression level and biological functions in NHL. The results showed that ISL-1 overexpression obviously promoted NHL cells proliferation, changed the cell cycle distribution in vitro and significantly enhanced xenografted lymphoma development in vivo. Real-time PCR, Western blot, luciferase assay and ChIP assay were used to explore the potential regulatory targets of ISL-1 and the results demonstrated that ISL-1 activated the c-Myc expression in NHL by direct binding to a conserved binding site on the c-Myc enhancer. Further results revealed that ISL-1 could be positively regulated by the c-Jun N-terminal kinase (JNK) and the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathways. Both the JNK and JAK/STAT signaling inhibitors could significantly suppressed the growth of NHL cells through the down-regulation of ISL-1 as demonstrated by CCK-8 and Western blot assays. Bioinformatic analysis and luciferase assay exhibited that ISL-1 was a novel target of p-STAT3 and p-c-jun. ChIP, Co-IP and ChIP-re-IP analysis revealed that ISL-1 could participate with p-STAT3 and p-c-Jun to form a p-STAT3/p-c-Jun/ISL-1 transcriptional complex that binds directly on the ISL-1 promoter, demonstrating a positive feedback regulatory mechanism for ISL-1 expression in NHL.
  
  
  CONCLUSIONS
  Our results provide the first evidence that ISL-1 is tightly linked to NHL proliferation and development by promoting c-Myc transcription, and its aberrant expression was regulated by p-STAT3/p-c-Jun/ISL-1 complex activation.
authors: Qiao
authors: Q
authors: Zhang
authors: Zhe
authors: Z
authors: Yang
authors: Zhuqing
authors: Z
authors: Jia
authors: Cuiling
authors: C
authors: Liu
authors: Chen
authors: C
authors: Guo
authors: Huafei
authors: H
authors: Lu
authors: Ping
authors: P
authors: Chen
authors: Kangtao
authors: K
authors: Ma
authors: Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education of China, Peking University, 38 Xueyuan Road, 100191 Beijing, China. wwp@bjmu.edu.cn.
authors: Weiping
authors: W
authors: Wang
authors: Chunyan
authors: C
authors: Zhou
mesh_terms: D001483:Base Sequence; D002453:Cell Cycle; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D015536:Down-Regulation; D055785:Gene Knockdown Techniques; D006801:Humans; D007150:Immunohistochemistry; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D053612:Janus Kinases / Q000378:metabolism; D060850:LIM-Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D008228:Lymphoma, Non-Hodgkin / Q000378:metabolism* / Q000473:pathology*; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism*; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D015854:Up-Regulation; D023041:Xenograft Model Antitumor Assays
chemical_list: D060850:LIM-Homeodomain Proteins; D016755:Proto-Oncogene Proteins c-jun; D016271:Proto-Oncogene Proteins c-myc; D050796:STAT3 Transcription Factor; D014157:Transcription Factors; C063843:insulin gene enhancer binding protein Isl-1; D053612:Janus Kinases; D048031:JNK Mitogen-Activated Protein Kinases