title: p53 deficiency linked to B cell translocation gene 2 (BTG2) loss enhances metastatic potential by promoting tumor growth in primary and metastatic sites in patient-derived xenograft (PDX) models of triple-negative breast cancer.
abstract: BACKGROUND
  Despite advances in early diagnosis and treatment of cancer patients, metastasis remains the major cause of mortality. TP53 is one of the most frequently mutated genes in human cancer, and these alterations can occur during the early stages of oncogenesis or as later events as tumors progress to more aggressive forms. Previous studies have suggested that p53 plays a role in cellular pathways that govern metastasis. To investigate how p53 deficiency contributes to late-stage tumor growth and metastasis, we developed paired isogenic patient-derived xenograft (PDX) models of triple-negative breast cancer (TNBC) differing only in p53 status for longitudinal analysis.
  
  
  METHODS
  Patient-derived isogenic human tumor lines differing only in p53 status were implanted into mouse mammary glands. Tumor growth and metastasis were monitored with bioluminescence imaging, and circulating tumor cells (CTCs) were quantified by flow cytometry. RNA-Seq was performed on p53-deficient and p53 wild-type tumors, and functional validation of a lead candidate gene was performed in vivo.
  
  
  RESULTS
  Isogenic p53 wild-type and p53-deficient tumors metastasized out of mammary glands and colonized distant sites with similar frequency. However, p53-deficient tumors metastasized earlier than p53 wild-type tumors and grew faster in both primary and metastatic sites as a result of increased proliferation and decreased apoptosis. In addition, greater numbers of CTCs were detected in the blood of mice engrafted with p53-deficient tumors. However, when normalized to tumor mass, the number of CTCs isolated from mice bearing parental and p53-deficient tumors was not significantly different. Gene expression profiling followed by functional validation identified B cell translocation gene 2 (BTG2), a downstream effector of p53, as a negative regulator of tumor growth both at primary and metastatic sites. BTG2 expression status correlated with survival of TNBC patients.
  
  
  CONCLUSIONS
  Using paired isogenic PDX-derived metastatic TNBC cells, loss of p53 promoted tumor growth and consequently increased tumor cell shedding into the blood, thus enhancing metastasis. Loss of BTG2 expression in p53-deficient tumors contributed to this metastatic potential by enhancing tumor growth in primary and metastatic sites. Furthermore, clinical data support conclusions generated from PDX models and indicate that BTG2 expression is a candidate prognostic biomarker for TNBC.
authors.affiliation: Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA. epowell1@mdanderson.org.|Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA. epowell1@mdanderson.org.
authors.forename: Emily
authors.initials: E
authors.lastname: Powell
authors.affiliation: Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA. JShao@mdanderson.org.
authors.forename: Jiansu
authors.initials: J
authors.lastname: Shao
authors.affiliation: Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA. yuanyuan0116@gmail.com.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Yuan
authors.affiliation: Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA. HChen8@mdanderson.org.
authors.forename: Hsiang-Chun
authors.initials: HC
authors.lastname: Chen
authors.affiliation: Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA. SCai1@mdanderson.org.
authors.forename: Shirong
authors.initials: S
authors.lastname: Cai
authors.affiliation: Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA. GVEcheverria@mdanderson.org.
authors.forename: Gloria V
authors.initials: GV
authors.lastname: Echeverria
authors.affiliation: Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA. nipunmistry@gmail.com.
authors.forename: Nipun
authors.initials: N
authors.lastname: Mistry
authors.affiliation: Center for Pharmacogenomics, Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA. keithforestdecker@gmail.com.
authors.forename: Keith F
authors.initials: KF
authors.lastname: Decker
authors.affiliation: Center for Pharmacogenomics, Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA. chris.schlosberg@gmail.com.
authors.forename: Christopher
authors.initials: C
authors.lastname: Schlosberg
authors.affiliation: Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA. kimdo@mdanderson.org.
authors.forename: Kim-Anh
authors.initials: KA
authors.lastname: Do
authors.affiliation: Center for Pharmacogenomics, Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA. JEDWARDS@DOM.wustl.edu.
authors.forename: John R
authors.initials: JR
authors.lastname: Edwards
authors.affiliation: Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA. HLiang1@mdanderson.org.
authors.forename: Han
authors.initials: H
authors.lastname: Liang
authors.affiliation: Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA. dpiwnica-worms@mdanderson.org.|Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA. dpiwnica-worms@mdanderson.org.
authors.forename: David
authors.initials: D
authors.lastname: Piwnica-Worms
authors.affiliation: Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA. hpiwnica-worms@mdanderson.org.
authors.forename: Helen
authors.initials: H
authors.lastname: Piwnica-Worms
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000235:genetics*; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D017874:Immediate-Early Proteins / Q000096:biosynthesis* / Q000235:genetics; D051379:Mice; D009362:Neoplasm Metastasis; D009360:Neoplastic Cells, Circulating / Q000473:pathology; D064726:Triple Negative Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*; D025521:Tumor Suppressor Proteins / Q000096:biosynthesis* / Q000235:genetics; D023041:Xenograft Model Antitumor Assays
chemical_list: D017874:Immediate-Early Proteins; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; C070114:BTG2 protein, human
references.citation: Nature. 2015 Feb 19;518(7539):422-6
references.pmid: 25470049
references.citation: Proc Natl Acad Sci U S A. 1992 Aug 15;89(16):7491-5
references.pmid: 1323840
references.citation: BMC Cancer. 2006;6:276
references.pmid: 17150101
references.citation: Mol Carcinog. 2000 Feb;27(2):57-64
references.pmid: 10657898
references.citation: Int J Cancer. 2013 Mar 1;132(5):1227-31
references.pmid: 22886769
references.citation: Cancer Res. 2011 Sep 1;71(17):5635-45
references.pmid: 21737487
references.citation: Cancer Res. 2013 Aug 1;73(15):4885-97
references.pmid: 23737486
references.citation: Proc Natl Acad Sci U S A. 2010 Oct 19;107(42):18115-20
references.pmid: 20921380
references.citation: Semin Cancer Biol. 2010 Jun;20(3):161-8
references.pmid: 20470890
references.citation: Nat Methods. 2005 Aug;2(8):607-14
references.pmid: 16094386
references.citation: Plant Physiol. 1991 Feb;95(2):498-503
references.pmid: 16668012
references.citation: J Clin Oncol. 2009 Mar 10;27(8):1160-7
references.pmid: 19204204
references.citation: J Cell Physiol. 2001 May;187(2):155-65
references.pmid: 11267995
references.citation: Proc Natl Acad Sci U S A. 2005 Sep 20;102(38):13550-5
references.pmid: 16141321
references.citation: Nature. 2010 Apr 15;464(7291):999-1005
references.pmid: 20393555
references.citation: Nat Med. 1995 Oct;1(10):1029-34
references.pmid: 7489358
references.citation: Genes Dev. 2003 May 15;17(10):1253-70
references.pmid: 12756227
references.citation: Proc Natl Acad Sci U S A. 2004 Apr 6;101(14):4966-71
references.pmid: 15051869
references.citation: J Cell Biol. 2011 Jan 24;192(2):209-18
references.pmid: 21263025
references.citation: Cell Mol Life Sci. 1999 Jan;55(1):48-63
references.pmid: 10065151
references.citation: Cold Spring Harb Perspect Biol. 2011 Jan;3(1):a003228
references.pmid: 20980442
references.citation: Nat Med. 2011;17(11):1514-20
references.pmid: 22019887
references.citation: Genes Dev. 2006 Jan 15;20(2):236-52
references.pmid: 16418486
references.citation: Oncogene. 2011 Jul 7;30(27):3084-95
references.pmid: 21339742
references.citation: Genes Chromosomes Cancer. 1995 Sep;14(1):71-5
references.pmid: 8527388
references.citation: Cell Rep. 2013 Sep 26;4(6):1116-30
references.pmid: 24055055
references.citation: Cancer Discov. 2014 Apr;4(4):405-14
references.pmid: 24658082
references.citation: Cancer Res. 2010 Jul 15;70(14):5649-69
references.pmid: 20610625
references.citation: Cancer Res. 2014 Dec 15;74(24):7406-17
references.pmid: 25339353
references.citation: Cell. 2014 Aug 28;158(5):1110-22
references.pmid: 25171411
references.citation: BMC Cancer. 2010;10:296
references.pmid: 20553615
references.citation: Proc Natl Acad Sci U S A. 1992 May 15;89(10):4495-9
references.pmid: 1584781
references.citation: Lancet. 2005 Feb 19-25;365(9460):671-9
references.pmid: 15721472
references.citation: Nature. 2012 Oct 4;490(7418):61-70
references.pmid: 23000897
references.citation: FEBS Lett. 2001 May 25;497(2-3):67-72
references.pmid: 11377414
references.citation: J Clin Invest. 2012 Apr;122(4):1541-52
references.pmid: 22446188
references.citation: Nature. 2012 Jun 21;486(7403):395-9
references.pmid: 22495314
references.citation: J Clin Invest. 2005 Jan;115(1):44-55
references.pmid: 15630443
references.citation: Proc Natl Acad Sci U S A. 2003 Apr 1;100(7):3983-8
references.pmid: 12629218
references.citation: Cell. 2004 Dec 17;119(6):847-60
references.pmid: 15607980
references.citation: N Engl J Med. 2002 Dec 19;347(25):1999-2009
references.pmid: 12490681
references.citation: Science. 1990 Aug 24;249(4971):912-5
references.pmid: 2144057
references.citation: Nat Genet. 1996 Dec;14(4):482-6
references.pmid: 8944033
references.citation: Int J Oncol. 2015 Feb;46(2):459-64
references.pmid: 25405282
references.citation: Cell. 2004 Dec 17;119(6):861-72
references.pmid: 15607981
references.citation: Br J Cancer. 1999 Aug;80(12):1968-73
references.pmid: 10471047
references.citation: Breast Cancer Res. 2007;9(3):R30
references.pmid: 17504517
references.citation: Proc Natl Acad Sci U S A. 2001 Sep 11;98(19):10869-74
references.pmid: 11553815