title: An ShRNA Based Genetic Screen Identified Sesn2 as a Potential Tumor Suppressor in Lung Cancer via Suppression of Akt-mTOR-p70S6K Signaling.
abstract: BACKGROUND
  Lung cancer is emerging rapidly as the leading death cause in Chinese cancer patients. The causal factors for Chinese lung cancer development remain largely unclear. Here we employed an shRNA library-based loss-of-function screen in a genome-wide and unbiased manner to interrogate potential tumor suppressor candidates in the immortalized human lung epithelial cell line BEAS-2B.
  
  
  RESULTS
  Soft agar assays were conducted for screening BEAS-2B cells infected with the retroviral shRNA library with the acquired feature of anchorage-independent growth, large (>0.5mm in diameter) and well-separated colonies were isolated for proliferation. PCRs were performed to amplify the integrated shRNA fragment from individual genomic DNA extracted from each colony, and each PCR product is submitted for DNA sequencing to reveal the integrated shRNA and its target gene. A total of 6 candidate transformation suppressors including INPP4B, Sesn2, TIAR, ACRC, Nup210, LMTK3 were identified. We validated Sesn2 as the candidate of lung cancer tumor suppressor. Knockdown of Sesn2 by an shRNA targeting 3' UTR of Sesn2 transcript potently stimulated the proliferation and malignant transformation of lung bronchial epithelial cell BEAS-2B via activation of Akt-mTOR-p70S6K signaling, whereas ectopic expression of Sens2 re-suppressed the malignant transformation elicited by the Sesn2 shRNA. Moreover, knockdown of Sesn2 in BEAS-2B cells promoted the BEAS-2B cell-transplanted xenograft tumor growth in nude mice. Lastly, DNA sequencing indicated mutations of Sesn2 gene are rare, the protein levels of Sesn2 of 77 Chinese lung cancer patients varies greatly compared to their adjacent normal tissues, and the low expression level of Sesn2 associates with the poor survival in these examined patients by Kaplan Meier analysis.
  
  
  CONCLUSIONS
  Our shRNA-based screen has demonstrated Sesn2 is a potential tumor suppressor in lung epithelial cells. The expression level of Sesn2 may serve as a prognostic marker for Chinese lung cancer patients in the clinic.
authors.affiliation: The Laboratory of Medical Genetics, Harbin Medical University, Harbin, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Xu
authors.affiliation: The Laboratory of Medical Genetics, Harbin Medical University, Harbin, China.
authors.forename: Huiying
authors.initials: H
authors.lastname: Sun
authors.affiliation: The Laboratory of Medical Genetics, Harbin Medical University, Harbin, China.
authors.forename: Haiyuan
authors.initials: H
authors.lastname: Zhang
authors.affiliation: The Laboratory of Medical Genetics, Harbin Medical University, Harbin, China.
authors.forename: Jiawei
authors.initials: J
authors.lastname: Liu
authors.affiliation: The Laboratory of Medical Genetics, Harbin Medical University, Harbin, China.
authors.forename: Fangfang
authors.initials: F
authors.lastname: Fan
authors.affiliation: The Laboratory of Medical Genetics, Harbin Medical University, Harbin, China.
authors.forename: Yilan
authors.initials: Y
authors.lastname: Li
authors.affiliation: The Laboratory of Medical Genetics, Harbin Medical University, Harbin, China.
authors.forename: Xuelian
authors.initials: X
authors.lastname: Ning
authors.affiliation: The Laboratory of Medical Genetics, Harbin Medical University, Harbin, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Sun
authors.affiliation: The Tumor Hospital, Harbin Medical University, Harbin, China.
authors.forename: Shaochun
authors.initials: S
authors.lastname: Dai
authors.affiliation: The Tumor Hospital, Harbin Medical University, Harbin, China.
authors.forename: Baogang
authors.initials: B
authors.lastname: Liu
authors.affiliation: The Fourth Affiliated Hospital, Harbin Medical University, Harbin, China.
authors.forename: Min
authors.initials: M
authors.lastname: Gao
authors.affiliation: The Laboratory of Medical Genetics, Harbin Medical University, Harbin, China.
authors.forename: Songbin
authors.initials: S
authors.lastname: Fu
authors.affiliation: The Laboratory of Medical Genetics, Harbin Medical University, Harbin, China.
authors.forename: Chunshui
authors.initials: C
authors.lastname: Zhou
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002465:Cell Movement; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D004195:Disease Models, Animal; D004847:Epithelial Cells / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D016147:Genes, Tumor Suppressor; D064593:Heterografts; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics* / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism*; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*; D000084622:Sestrins
chemical_list: D009687:Nuclear Proteins; D051057:Proto-Oncogene Proteins c-akt; D034741:RNA, Small Interfering; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D058570:TOR Serine-Threonine Kinases; C465398:SESN2 protein, human; D000084622:Sestrins