title: Protrusion-localized STAT3 mRNA promotes metastasis of highly metastatic hepatocellular carcinoma cells in vitro.
abstract: OBJECTIVE
  Recent evidence shows that localization of mRNAs and their protein products at cellular protrusions plays a decisive function in the metastasis of cancer cells. The aim of this study was to identify the variety of proteins encoded by protrusion-localized mRNAs and their roles in the metastasis and invasion of liver cancer cells.
  
  
  METHODS
  Highly metastatic hepatocellular carcinoma cell line HCCLM3 and non-metastatic hepatocellular carcinoma cell line SMMC-7721 were examined. Cell protrusions (Ps) were separated from cell bodies (CB) using a Boyden chamber assay; total mRNA population in CB and Ps fractions was analyzed using high-throughput direct RNA sequencing. The localization of STAT3 mRNA and protein at Ps was confirmed using RT-qPCR, RNA FISH, and immunofluorescence assays. Cell migration capacity and invasiveness of HCCLM3 cells were evaluated using MTT, wound healing migration and in vitro invasion assays. The interaction between Stat3 and growth factor receptors was explored with co-immunoprecipitation assays.
  
  
  RESULTS
  In HCCLM3 cells, 793 mRNAs were identified as being localized in the Ps fraction according to a cut-off value (Ps/CB ratio) >1.6. The Ps-localized mRNAs could be divided into 4 functional groups, and were all closely related to the invasive and metastatic properties. STAT3 mRNA accumulated in the Ps of HCCLM3 cells compared with non-metastatic SMMC-7721 cells. Treatment of HCCLM3 cells with siRNAs against STAT3 mRNA drastically decreased the cell migration and invasion. Moreover, Ps-localized Stat3 was found to interact with pseudopod-enriched platelet-derived growth factor receptor tyrosine kinase (PDGFRTK) in a growth factor-dependent manner.
  
  
  CONCLUSIONS
  This study reveals STAT3 mRNA localization at the Ps of metastatic hepatocellular carcinoma HCCLM3 cells by combining application of genome-wide and gene specific description and functional analysis.
authors.affiliation: Department of Chemistry, Tsinghua University, Beijing 100084, China.|The Ministry-Province Jointly Constructed Base for State Key Lab-Shenzhen Key Laboratory of Chemical Biology, the Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.|Key Laboratory of Laboratory Medicine, Ministry of Education of China, Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou 325035, China.
authors.forename: Yan-Hong
authors.initials: YH
authors.lastname: Liu
authors.affiliation: Hebi Polytechnic, Hebi 458030, China.
authors.forename: Jia-Lu
authors.initials: JL
authors.lastname: Jin
authors.affiliation: Key Laboratory of Laboratory Medicine, Ministry of Education of China, Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou 325035, China.
authors.forename: Yu-Zhe
authors.initials: YZ
authors.lastname: Wang
authors.affiliation: The Ministry-Province Jointly Constructed Base for State Key Lab-Shenzhen Key Laboratory of Chemical Biology, the Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Tan
authors.affiliation: Key Laboratory of Laboratory Medicine, Ministry of Education of China, Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou 325035, China.
authors.forename: Ying-Ying
authors.initials: YY
authors.lastname: Zhou
authors.affiliation: Key Laboratory of Laboratory Medicine, Ministry of Education of China, Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou 325035, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Peng
authors.affiliation: Key Laboratory of Laboratory Medicine, Ministry of Education of China, Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou 325035, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Li
authors.affiliation: Key Laboratory of Laboratory Medicine, Ministry of Education of China, Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou 325035, China.
authors.forename: Wan-Dong
authors.initials: WD
authors.lastname: Liang
authors.affiliation: Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Québec, H3C 3J7, Canada.
authors.forename: Pascal
authors.initials: P
authors.lastname: Chartrand
authors.affiliation: Department of Chemistry, Tsinghua University, Beijing 100084, China.|The Ministry-Province Jointly Constructed Base for State Key Lab-Shenzhen Key Laboratory of Chemical Biology, the Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.|Department of Pharmacology and Pharmaceutical Sciences, School of Medicine, Tsinghua University, Beijing 100084, China.
authors.forename: Yu-Yang
authors.initials: YY
authors.lastname: Jiang
authors.affiliation: Shenzhen Kivita Innovative Drug Discovery Institute; Shenzhen Technology and Engineering for Personalized Cancer Diagnostics and Therapeutics, Shenzhen 518055, China.|Key Laboratory of Laboratory Medicine, Ministry of Education of China, Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou 325035, China.
authors.forename: Zhi-Fa
authors.initials: ZF
authors.lastname: Shen
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D002465:Cell Movement; D006801:Humans; D008099:Liver / Q000378:metabolism / Q000473:pathology*; D008113:Liver Neoplasms / Q000235:genetics* / Q000473:pathology; D009361:Neoplasm Invasiveness / Q000235:genetics / Q000473:pathology; D009362:Neoplasm Metastasis / Q000235:genetics / Q000473:pathology; D012333:RNA, Messenger / Q000032:analysis* / Q000235:genetics*; D050796:STAT3 Transcription Factor / Q000235:genetics*
chemical_list: D012333:RNA, Messenger; D050796:STAT3 Transcription Factor