title: High TWIST1 mRNA expression is associated with poor prognosis in lymph node-negative and estrogen receptor-positive human breast cancer and is co-expressed with stromal as well as ECM related genes.
abstract: BACKGROUND
  The TWIST homolog 1 (TWIST1) is a transcription factor that induces epithelial to mesenchymal transition (EMT), a key process in metastasis. The purpose of this study was to investigate whether TWIST1 expression predicts disease progression in a large breast cancer cohort with long-term clinical follow-up, and to reveal the biology related to TWIST1 mediated disease progression.
  
  
  METHODS
  TWIST1 mRNA expression level was analyzed by quantitative real-time reverse polymerase chain reaction (RT-PCR) in 1,427 primary breast cancers. In uni- and multivariate analysis using Cox regression, TWIST1 mRNA expression level was associated with metastasis-free survival (MFS), disease-free survival (DFS) and overall survival (OS). Separate analyses in lymph node-negative patients (LNN, n = 778) who did not receive adjuvant systemic therapy, before and after stratification into estrogen receptor (ER)-positive (n = 552) and ER-negative (n = 226) disease, were also performed. The association of TWIST1 mRNA with survival endpoints was assessed using Kaplan-Meier analysis. Using gene expression arrays, genes showing a significant Spearman rank correlation with TWIST1 were used to identify overrepresented Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG)-annotated biological pathways.
  
  
  RESULTS
  Increased mRNA expression level of TWIST1 analyzed as a continuous variable in both uni- and multivariate analysis was associated with shorter MFS in all patients (hazard ratio (HR): 1.17, 95% confidence interval, (95% CI):1.09 to 1.26; and HR: 1.17, 95% CI: 1.08 to 1.26; respectively), in LNN patients (HR: 1.22, 95% CI: 1.09 to 1.36; and HR: 1.21, 95% CI: 1.07 to 1.36; respectively) and in the ER-positive subgroup of LNN patients (HR: 1.34, 95% CI: 1.17 to 1.53; and HR: 1.32, 95% CI: 1.14 to 1.53; respectively). Similarly, high TWIST1 expression was associated with shorter DFS and OS in all patients and in the LNN/ER-positive subgroup. In contrast, no association of TWIST1 mRNA expression with MFS, DFS or OS was observed in ER-negative patients. Genes highly correlated with TWIST1 were significantly enriched for cell adhesion and ECM-related signaling pathways. Furthermore, TWIST1 mRNA was highly expressed in tumor stroma and positively related to tumor stromal content (P <0.001).
  
  
  CONCLUSIONS
  TWIST1 mRNA expression is an independent prognostic factor for poor prognosis in LNN/ER-positive breast cancer. The biological associations suggest an involvement of the tumor microenvironment in TWIST1's adverse role in breast cancer.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Riaz
authors.forename: Anieta M
authors.initials: AM
authors.lastname: Sieuwerts
authors.forename: Maxime P
authors.initials: MP
authors.lastname: Look
authors.forename: Mieke A
authors.initials: MA
authors.lastname: Timmermans
authors.forename: Marcel
authors.initials: M
authors.lastname: Smid
authors.forename: John A
authors.initials: JA
authors.lastname: Foekens
authors.forename: John W M
authors.initials: JW
authors.lastname: Martens
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000235:genetics* / Q000401:mortality / Q000473:pathology*; D005109:Extracellular Matrix / Q000235:genetics*; D005260:Female; D015870:Gene Expression; D020869:Gene Expression Profiling; D006801:Humans; D008875:Middle Aged; D060787:Neoplasm Grading; D009362:Neoplasm Metastasis; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D011379:Prognosis; D012333:RNA, Messenger / Q000235:genetics*; D011960:Receptors, Estrogen / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D017154:Stromal Cells / Q000378:metabolism* / Q000473:pathology; D016019:Survival Analysis; D047368:Tumor Burden; D051879:Twist-Related Protein 1 / Q000235:genetics* / Q000378:metabolism; D055815:Young Adult
chemical_list: D009687:Nuclear Proteins; D012333:RNA, Messenger; D011960:Receptors, Estrogen; C103173:TWIST1 protein, human; D051879:Twist-Related Protein 1