title: Intratumoral heterogeneity impacts the response to anti-neu antibody therapy.
abstract: BACKGROUND
  Along with de novo resistance, continued exposure to trastuzumab, an anti-human epidermal growth factor receptor 2 (HER2/neu) antibody, can lead to acquired resistance. In this study, we characterize a new anti-HER2/neu antibody resistant and metastatic mouse breast carcinoma cell line, TUBO-P2J. This cell line was developed during in vivo experiments using the antibody sensitive and non-metastatic tumor line TUBO. In addition, TUBO-P2J was used to establish an intratumoral HER2 heterogenous animal tumor model to evaluate the therapeutic effects of anti-HER2/neu antibody.
  
  
  METHODS
  After establishing the cell line, TUBO-P2J was characterized regarding its susceptibility to anti-neu antibody and chemotherapeutics, as well as its metastatic potential in vitro and in vivo. In addition, expression profiles of metastasis related genes were also evaluated. A clinically relevant intratumoral HER2 heterogenous tumor model was established by inoculating mice with tumor cells consisting of TUBO and TUBO-P2J at a ratio of 1,000:1 or 10,000:1. Tumor growth and mouse survival were used to evaluate the therapeutic effects of anti-neu antibody.
  
  
  RESULTS
  The TUBO-P2J cell line is a HER2/neu negative and highly metastatic variant of TUBO. This cell line was resistant to anti-neu antibody therapy, and when inoculated subcutaneously, metastasized to the lungs within 14 days. Compared to the parental TUBO cell line, TUBO-P2J displayed an epithelial-mesenchymal transition (EMT) related gene expression profile including: the loss of E-cadherin, and increased Vimentin, Snail, and Twist1 expression. In addition, TUBO-P2J exhibited increased invasion and migration activity, and was resistant to chemotherapy drugs. Finally, mixed tumor implantations experiments revealed that an increased percentage of TUBO-P2J rendered tumors less responsive to anti-neu antibody therapy.
  
  
  CONCLUSIONS
  This study describes a novel model of intratumoral heterogenous metastatic breast cancer in immune competent mice that can be used to develop novel or combined immunotherapies to overcome antibody resistance.
authors.forename: Hyunkeun
authors.initials: H
authors.lastname: Song
authors.forename: Tae Oh
authors.initials: TO
authors.lastname: Kim
authors.forename: Sun Young
authors.initials: SY
authors.lastname: Ma
authors.forename: Jin-Hee
authors.initials: JH
authors.lastname: Park
authors.forename: Jae-Hyug
authors.initials: JH
authors.lastname: Choi
authors.forename: Jin-Ho
authors.initials: JH
authors.lastname: Kim
authors.forename: Mi Seon
authors.initials: MS
authors.lastname: Kang
authors.forename: Sang Kyun
authors.initials: SK
authors.lastname: Bae
authors.forename: Ki Hyaung
authors.initials: KH
authors.lastname: Kim
authors.forename: Tae Hyun
authors.initials: TH
authors.lastname: Kim
authors.forename: Su-Kil
authors.initials: SK
authors.lastname: Seo
authors.forename: Il Whan
authors.initials: IW
authors.lastname: Choi
authors.forename: Geun Am
authors.initials: GA
authors.lastname: Song
authors.forename: Eric D
authors.initials: ED
authors.lastname: Mortenson
authors.affiliation: Departmentof Microbiology and Immunology, INJE University College of Medicine, 633-165 GaegumDong, Busanjin Gu, Busan 614-735, Republic of Korea. yxfu@bsd.uchicago.edu.
authors.forename: Yang-Xin
authors.initials: YX
authors.lastname: Fu
authors.forename: SaeGwang
authors.initials: S
authors.lastname: Park
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology* / Q000627:therapeutic use; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000235:genetics* / Q000556:secondary*; D051379:Mice; D008807:Mice, Inbred BALB C; D009374:Neoplasms, Experimental; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000037:antagonists & inhibitors*; D016896:Treatment Outcome
chemical_list: D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D018719:Erb-b2 Receptor Tyrosine Kinases; C524056:Erbb2 protein, mouse