title: Tumor suppressor gene RBM5 delivered by attenuated Salmonella inhibits lung adenocarcinoma through diverse apoptotic signaling pathways.
abstract: BACKGROUND
  RBM5 (RNA-binding motif protein 5, also named H37/LUCA-15) gene from chromosome 3p21.3 has been demonstrated to be a tumor suppressor. Current researches in vitro confirm that RBM5 can suppress the growth of lung adenocarcinoma cells by inducing apoptosis. There is still no effective model in vivo, however, that thoroughly investigates the effect and molecular mechanism of RBM5 on lung adenocarcinoma.
  
  
  METHODS
  We established the transplanted tumor model on BALB/c nude mice using the A549 cell line. The mice were treated with the recombinant plasmids carried by attenuated Salmonella to induce the overexpression of RBM5 in tumor tissues. RBM5 overexpression was confirmed by immunohistochemistry staining. H&E staining was performed to observe the histological performance on plasmids-treated A549 xenografts. Apoptosis was assessed by TUNEL staining with a TUNEL detection kit. Apoptosis-regulated genes were detected by Western blot.
  
  
  RESULTS
  We successful established the lung adenocarcinoma animal model in vivo. The growth of tumor xenografts was significantly retarded on the mice treated with pcDNA3.1-RBM5 carried by attenuated Salmonella compared to that on mice treated with pcDNA3.1. Overexpression of RBM5 enhanced the apoptosis in tumor xenografts. Furthermore, the expression of Bcl-2 protein was decreased significantly, while the expression of BAX, TNF-α, cleaved caspase-3, cleaved caspase-8, cleaved caspase-9 and cleaved PARP proteins was significantly increased in the pcDNA3.1-RBM5-treated mice as compared to that in the control mice.
  
  
  CONCLUSIONS
  In this study, we established a novel animal model to determine RBM5 function in vivo, and concluded that RBM5 inhibited tumor growth in mice by inducing apoptosis. The study suggests that although RBM5's involvement in the death receptor-mediated apoptotic pathway is still to be investigated, RBM5-mediated growth suppression, at least in part, employs regulation of the mitochondrial apoptotic pathways.
authors.affiliation: Department of Respiratory Medicine, Second Affiliated Hospital of Jilin University, 18 Ziqiang Street, Changchun, Jilin 130041, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Shao
authors.forename: Baoxue
authors.initials: B
authors.lastname: Yang
authors.forename: Lijing
authors.initials: L
authors.lastname: Zhao
authors.forename: Song
authors.initials: S
authors.lastname: Wang
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.forename: Ke
authors.initials: K
authors.lastname: Wang
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D020169:Caspases / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D049109:Cell Proliferation; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005822:Genetic Vectors; D006801:Humans; D007124:Immunoenzyme Techniques; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008928:Mitochondria / Q000378:metabolism / Q000473:pathology; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D012485:Salmonella typhi / Q000235:genetics*; D015398:Signal Transduction; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C473448:RBM5 protein, human; D016601:RNA-Binding Proteins; D014409:Tumor Necrosis Factor-alpha; D025521:Tumor Suppressor Proteins; D051028:bcl-2-Associated X Protein; D020169:Caspases