title: Inflammatory mediators drive metastasis and drug resistance in head and neck squamous cell carcinoma.
abstract: OBJECTIVE
  The presence of regional metastases in head and neck squamous cell carcinoma (HNSCC) patients is a common and adverse event associated with poor prognosis. Understanding the molecular mechanisms that mediate HNSCC metastasis may enable identification of novel therapeutic targets. E-cadherin plays a key role in epithelial intercellular adhesion; its downregulation is a hallmark of the epithelial-to-mesenchymal transition (EMT) (an essential process during tumor progression); and it is associated with invasion, metastasis, and decreased survival. Inflammatory cytokines have been implicated in the progression of HNSCC. Herein, the mechanisms by which the inflammatory mediator, Interleukin-1β (IL-1β), might contribute to EMT in HNSCC is investigated. The pathways involved in E-cadherin regulation in HNSCC had not previously been defined. It is hypothesized that 1) inflammatory mediators upregulate cyclooxygenase-2/prostaglandin E2 (COX-2/PGE2), which then in turn regulate E-cadherin expression in HNSCC; and 2) PGE2 downregulates E-cadherin via transcriptional repressors of E-cadherin (such as Snail) in HNSCC. The outcome of the proposed research will allow us to define how resistance to epidermal growth factor receptor (EGFR)-selective tyrosine kinase inhibitors is mediated and whether the benefits of combination therapy are due to the capacity of COX-2 inhibitors to increase E-cadherin expression and thus create a more sensitive target for EGFR TK inhibition.
  
  
  METHODS
  Basic science, molecular biology, animal model, immunohistochemistry.
  
  
  METHODS
  We evaluated the effect of IL-1β on the molecular events of EMT in surgical specimens and HNSCC cell lines. We examined the correlation with tumor histologic features, and a severely compromised immunodeficient (SCID) xenograft model was used to assess the effects in vivo.
  
  
  RESULTS
  COX-2-dependent pathways contribute to the modulation of E-cadherin expression in HNSCC. An inverse relationship between COX-2 and E-cadherin was demonstrated in situ by double immunohistochemical staining of human HNSCC tissue sections. Treatment of HNSCC cells with IL-1β caused the downregulation of E-cadherin expression and upregulation of COX-2 expression. This effect was blocked in the presence of COX-2 small hairpin RNA (shRNA). IL-1β -treated HNSCC cell lines demonstrated a significant decrease in E-cadherin messenger RNA (mRNA) and an increase in the mRNA expression of the transcriptional repressor Snail. IL-1β exposure led to enhanced Snail binding at the chromatin level. ShRNA-mediated knockdown of Snail interrupted the capacity of IL-1β to downregulate E-cadherin. Snail overexpression in normal oral keratinocytes and HNSCC cells is sufficient to drive EMT and confers resistance to erlotinib. In a SCID xenograft model, HNSCC Snail overexpressing cells demonstrated significantly increased primary and metastatic tumor burdens.
  
  
  CONCLUSIONS
  The inflammatory mediator IL-1β modulates Snail and thereby regulates COX-2-dependent E-cadherin expression in HNSCC. This is the first report indicating the role of Snail in the inflammation-induced promotion of EMT in HNSCC. This newly defined pathway for transcriptional regulation of E-cadherin in HNSCC has important implications for targeted chemoprevention and therapy.
  
  
  METHODS
  N/A.
authors: Department of Head and Neck Surgery, UCLA Head and Neck Cancer Program, Jonsson Comprehensive Cancer Center, David Geffen School of Medicine at UCLA, Los Angeles, California, U.S.A.
authors: Maie A
authors: MA
authors: St John
mesh_terms: D000818:Animals; D015820:Cadherins / Q000502:physiology; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy* / Q000276:immunology / Q000556:secondary*; D051546:Cyclooxygenase 2 / Q000502:physiology; D019008:Drug Resistance, Neoplasm; D058750:Epithelial-Mesenchymal Transition; D006258:Head and Neck Neoplasms / Q000188:drug therapy* / Q000276:immunology / Q000556:secondary*; D006801:Humans; D018836:Inflammation Mediators / Q000502:physiology*; D053583:Interleukin-1beta / Q000502:physiology; D051379:Mice; D000071250:Snail Family Transcription Factors; D000077195:Squamous Cell Carcinoma of Head and Neck; D014157:Transcription Factors / Q000502:physiology; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
chemical_list: D015820:Cadherins; D018836:Inflammation Mediators; D053583:Interleukin-1beta; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human
keywords: COX-2; E-cadherin; EMT; HNSCC; metastasis