title: Receptor-interacting protein kinase 2 promotes triple-negative breast cancer cell migration and invasion via activation of nuclear factor-kappaB and c-Jun N-terminal kinase pathways.
abstract: BACKGROUND
  Metastasis is the main cause of breast cancer morbidity and mortality. Processes that allow for tumor cell migration and invasion are important therapeutic targets. Here we demonstrate that receptor-interacting protein kinase 2 (RIP2), a kinase known to be involved in inflammatory processes, also has novel roles in cancer cell migration and invasion.
  
  
  METHODS
  A total of six breast cancer expression databases, including The Cancer Genome Atlas, were assessed for RIP2 expression among various clinical subtypes and its role as a prognostic biomarker. mRNA fluorescence in situ hybridization (FISH) for RIP2 was performed on 17 stage III breast cancers to determine if there was a correlation between RIP2 expression and lymph node involvement. RNA-interference was used to knock-down RIP2 expression in MDA-MB-231, Htb126, SUM149PT, MCF7, T47D, and HCC1428 cells. Cell migration and invasion were measured in vitro by scratch/wound healing and transwell migration assays. A xenograft mouse model was used to assess tumor growth and chemosensitivity to docetaxel in vivo in MDA-MB-231 cells with and without RIP2 small hairpin RNA knockdown. Western blot and immunofluorescence imaging were used to evaluate protein expressions.
  
  
  RESULTS
  Interrogation of expression databases showed that RIP2 expression is significantly over-expressed in triple-negative breast cancers (TNBC: estrogen-receptor (ER) negative, progesterone-receptor (PR) negative, Her2/neu- (Her2) negative), compared to other clinical subtypes. High RIP2 expression correlates with worse progression-free survival using a combined breast cancer expression array dataset consisting of 946 patients. Multivariate analysis shows RIP2 as an independent prognostic biomarker. Knock-down of RIP2 significantly decreases migration in both scratch/wound healing and transwell migration assays in MDA-MB-231, Htb126, SUM149PT, MCF7, and T47D cells and is correlated with decreased Nuclear Factor-kappaB and c-Jun N-terminal kinase (JNK) activation. Finally, RIP2 knock-down leads to increased sensitivity to docetaxel and decreased tumor mass and lung metastases in a xenograft mouse model.
  
  
  CONCLUSIONS
  These results highlight RIP2 as a pro-metastasis kinase in patients with advanced breast cancer. These results also illustrate a novel role for this kinase in addition to its known role in inflammation, and suggest that targeting RIP2 may improve outcomes in advanced breast cancer patients, in which it is overexpressed.
authors.forename: Stina M
authors.initials: SM
authors.lastname: Singel
authors.forename: Kimberly
authors.initials: K
authors.lastname: Batten
authors.forename: Crystal
authors.initials: C
authors.lastname: Cornelius
authors.forename: Gaoxiang
authors.initials: G
authors.lastname: Jia
authors.forename: Gail
authors.initials: G
authors.lastname: Fasciani
authors.forename: Summer L
authors.initials: SL
authors.lastname: Barron
authors.forename: Woodring E
authors.initials: WE
authors.lastname: Wright
authors.forename: Jerry W
authors.initials: JW
authors.lastname: Shay
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics*; D000077143:Docetaxel; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D053208:Kaplan-Meier Estimate; D008175:Lung Neoplasms / Q000235:genetics / Q000517:prevention & control / Q000556:secondary; D061986:MCF-7 Cells; D008856:Microscopy, Fluorescence; D016328:NF-kappa B / Q000378:metabolism*; D009361:Neoplasm Invasiveness; D011379:Prognosis; D034622:RNA Interference; D053475:Receptor-Interacting Protein Serine-Threonine Kinase 2 / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D043823:Taxoids / Q000494:pharmacology; D064726:Triple Negative Breast Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D047368:Tumor Burden / Q000187:drug effects / Q000235:genetics; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D016328:NF-kappa B; D043823:Taxoids; D000077143:Docetaxel; C506253:RIPK2 protein, human; D053475:Receptor-Interacting Protein Serine-Threonine Kinase 2; D048031:JNK Mitogen-Activated Protein Kinases