title: Improving gastric cancer preclinical studies using diverse in vitro and in vivo model systems.
abstract: BACKGROUND
  "Biomarker-driven targeted therapy," the practice of tailoring patients' treatment to the expression/activity levels of disease-specific genes/proteins, remains challenging. For example, while the anti-ERBB2 monoclonal antibody, trastuzumab, was first developed using well-characterized, diverse in vitro breast cancer models (and is now a standard adjuvant therapy for ERBB2-positive breast cancer patients), trastuzumab approval for ERBB2-positive gastric cancer was largely based on preclinical studies of a single cell line, NCI-N87. Ensuing clinical trials revealed only modest patient efficacy, and many ERBB2-positive gastric cancer (GC) patients failed to respond at all (i.e., were inherently recalcitrant), or succumbed to acquired resistance.
  
  
  METHODS
  To assess mechanisms underlying GC insensitivity to ERBB2 therapies, we established a diverse panel of GC cells, differing in ERBB2 expression levels, for comprehensive in vitro and in vivo characterization. For higher throughput assays of ERBB2 DNA and protein levels, we compared the concordance of various laboratory quantification methods, including those of in vitro and in vivo genetic anomalies (FISH and SISH) and xenograft protein expression (Western blot vs. IHC), of both cell and xenograft (tissue-sectioned) microarrays.
  
  
  RESULTS
  The biomarker assessment methods strongly agreed, as did correlation between RNA and protein expression. However, although ERBB2 genomic anomalies showed good in vitro vs. in vivo correlation, we observed striking differences in protein expression between cultured cells and mouse xenografts (even within the same GC cell type). Via our unique pathway analysis, we delineated a signaling network, in addition to specific pathways/biological processes, emanating from the ERBB2 signaling cascade, as a potential useful target of clinical treatment. Integrated analysis of public data from gastric tumors revealed frequent (10 - 20 %) amplification of the genes NFKBIE, PTK2, and PIK3CA, each of which resides in an ERBB2-derived subpathway network.
  
  
  CONCLUSIONS
  Our comprehensive bioinformatics analyses of highly heterogeneous cancer cells, combined with tumor "omics" profiles, can optimally characterize the expression patterns and activity of specific tumor biomarkers. Subsequent in vitro and in vivo validation, of specific disease biomarkers (using multiple methodologies), can improve prediction of patient stratification according to drug response or nonresponse.
authors.affiliation: New Experimental Therapeutics Branch, National Cancer Center of Korea, Ilsan, Goyang-si, Gyeonggi-do, Republic of Korea. haeryung.chang@ip-korea.org.|Cancer Biology Research Laboratory, Institut Pasteur Korea, Bundang, Seongnam-si, Gyeonggi-do, Republic of Korea. haeryung.chang@ip-korea.org.
authors.forename: Hae Ryung
authors.initials: HR
authors.lastname: Chang
authors.affiliation: Animal Sciences Branch, National Cancer Center of Korea, Ilsan, Goyang-si, Gyeonggi-do, Republic of Korea. heeseo@ncc.re.kr.
authors.forename: Hee Seo
authors.initials: HS
authors.lastname: Park
authors.affiliation: New Experimental Therapeutics Branch, National Cancer Center of Korea, Ilsan, Goyang-si, Gyeonggi-do, Republic of Korea. yzahn@ncc.re.kr.
authors.forename: Young Zoo
authors.initials: YZ
authors.lastname: Ahn
authors.affiliation: New Experimental Therapeutics Branch, National Cancer Center of Korea, Ilsan, Goyang-si, Gyeonggi-do, Republic of Korea. nams@gachon.ac.kr.|Department of Life Sciences, College of BioNano Technology, Gachon University, Sungnam, South Korea. nams@gachon.ac.kr.|College of Medicine, Gachon University, Incheon, South Korea. nams@gachon.ac.kr.
authors.forename: Seungyoon
authors.initials: S
authors.lastname: Nam
authors.affiliation: New Experimental Therapeutics Branch, National Cancer Center of Korea, Ilsan, Goyang-si, Gyeonggi-do, Republic of Korea. hrjung3@ncc.re.kr.
authors.forename: Hae Rim
authors.initials: HR
authors.lastname: Jung
authors.affiliation: New Experimental Therapeutics Branch, National Cancer Center of Korea, Ilsan, Goyang-si, Gyeonggi-do, Republic of Korea. oscar.park@gmail.com.|Department of Life Sciences, College of BioNano Technology, Gachon University, Sungnam, South Korea. oscar.park@gmail.com.|College of Medicine, Gachon University, Incheon, South Korea. oscar.park@gmail.com.
authors.forename: Sungjin
authors.initials: S
authors.lastname: Park
authors.affiliation: Animal Sciences Branch, National Cancer Center of Korea, Ilsan, Goyang-si, Gyeonggi-do, Republic of Korea. leej@ncc.re.kr.
authors.forename: Sang Jin
authors.initials: SJ
authors.lastname: Lee
authors.affiliation: Department of Pharmacology and Experimental Therapeutics, University of Toledo College of Pharmacy, Toledo, OH, USA. curt.balch@gmail.com.
authors.forename: Curt
authors.initials: C
authors.lastname: Balch
authors.affiliation: Cancer Center, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, USA. gpowis@sbpdiscovery.org.
authors.forename: Garth
authors.initials: G
authors.lastname: Powis
authors.affiliation: SNU Korean Cell Line Bank, Cancer Research Institute, Seoul National University, Seoul, Republic of Korea. kujalok@snu.ac.kr.
authors.forename: Ja-Lok
authors.initials: JL
authors.lastname: Ku
authors.affiliation: New Experimental Therapeutics Branch, National Cancer Center of Korea, Ilsan, Goyang-si, Gyeonggi-do, Republic of Korea. yhkim@ncc.re.kr.|Cancer Biology Research Laboratory, Institut Pasteur Korea, Bundang, Seongnam-si, Gyeonggi-do, Republic of Korea. yhkim@ncc.re.kr.
authors.forename: Yon Hui
authors.initials: YH
authors.lastname: Kim
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D015415:Biomarkers; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D004353:Drug Evaluation, Preclinical; D005260:Female; D005784:Gene Amplification; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D053263:Gene Regulatory Networks; D006801:Humans; D051379:Mice; D058990:Molecular Targeted Therapy; D009367:Neoplasm Staging; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013274:Stomach Neoplasms / Q000188:drug therapy / Q000209:etiology* / Q000378:metabolism* / Q000473:pathology; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D015415:Biomarkers; D018719:Erb-b2 Receptor Tyrosine Kinases