title: Unexpected alteration of β-catenin and c-KIT expression by 5-FU and docetaxel in p16-positive squamous cell carcinoma compared to HPV-negative HNSCC cells in vitro.
abstract: BACKGROUND
  Head and neck squamous cell carcinoma (HNSCC) is the sixth most common type of cancer worldwide. In several tumour entities, the tyrosine kinase receptor c-KIT is associated with tumour transformation in the epithelial tissue in cases of aberrant expression. Furthermore, tumour development and dissemination are a result of dysregulated cellular pathways such as the WNT/β-catenin pathway. β-Catenin is a multifunctional protein within the canonical WNT signalling pathway and a pivotal factor for the stabilization of cell-cell interactions. In malignant tissues, β-catenin triggers tumour proliferation and progression. The aim of this study is to investigate the expression patterns of c-KIT and β-catenin in human papillomavirus-negative and p16-positive SCC and to evaluate the chemosensitivity of the tumour cells to the chemotherapeutical agents docetaxel and 5-fluorouracil (5-FU).
  
  
  METHODS
  We incubated the tumour cell lines with docetaxel (5 μmol/ml) and 5-FU (1 μmol/ml) and detected β-catenin and c-KIT by immunohistochemistry and enzyme-linked immunosorbent assay (ELISA) after 48, 72, 120, 192 and 240 h.
  
  
  RESULTS
  We found a reliable trend towards decreased β-catenin expression levels in p16-positive and p16-negative tumour cell lines when incubated with docetaxel, in addition to induced apoptotic effect. At best, 5-FU had a slight influence on the alteration of the expression of β-catenin. Dose escalation of docetaxel and 5-FU had no statistically significant effect on the expression of β-catenin or c-KIT. In HPV-negative HNSCC, a reduced expression level of β-catenin and c-KIT was detected in an incubation period-dependent manner. p16-transformed SCC (CERV196) cells were characterized by a reduced susceptibility to docetaxel induced alteration of β-catenin expression.
  
  
  CONCLUSIONS
  We were unable to confirm the clinically-substantiated increased chemosensitivity of p16-positive tumour cells in vitro. Extended studies and clinical trials are needed to investigate these findings further in HPV-associated HNSCC.
authors.affiliation: Department of Otorhinolaryngology, Head and Neck Surgery, Medical Faculty of Mannheim, University of Heidelberg, Mannheim, Germany. claudia.umbreit@umm.de
authors.forename: Claudia
authors.initials: C
authors.lastname: Umbreit
authors.forename: Christoph
authors.initials: C
authors.lastname: Aderhold
authors.forename: Anne
authors.initials: A
authors.lastname: Faber
authors.forename: Jörg Ulrich
authors.initials: JU
authors.lastname: Sommer
authors.forename: Alexander
authors.initials: A
authors.lastname: Sauter
authors.forename: Ralf-Dieter
authors.initials: RD
authors.lastname: Hofheinz
authors.forename: Jens
authors.initials: J
authors.lastname: Stern-Sträter
authors.forename: Karl
authors.initials: K
authors.lastname: Hoermann
authors.forename: Johannes David
authors.initials: JD
authors.lastname: Schultz
mesh_terms: D000963:Antimetabolites / Q000627:therapeutic use; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy / Q000378:metabolism / Q000821:virology; D045744:Cell Line, Tumor; D000077143:Docetaxel; D004797:Enzyme-Linked Immunosorbent Assay; D005472:Fluorouracil / Q000494:pharmacology / Q000627:therapeutic use; D006258:Head and Neck Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000821:virology; D052162:Human papillomavirus 16; D006801:Humans; D007150:Immunohistochemistry; D030361:Papillomavirus Infections / Q000150:complications*; D019009:Proto-Oncogene Proteins c-kit / Q000096:biosynthesis*; D015398:Signal Transduction / Q000187:drug effects; D043823:Taxoids / Q000494:pharmacology / Q000627:therapeutic use; D060449:Wnt Signaling Pathway / Q000187:drug effects; D051176:beta Catenin / Q000096:biosynthesis*
chemical_list: D000963:Antimetabolites; D000970:Antineoplastic Agents; D043823:Taxoids; D051176:beta Catenin; D000077143:Docetaxel; D019009:Proto-Oncogene Proteins c-kit; D005472:Fluorouracil
keywords: 5-FU; c-KIT; docetaxel; epithelial mesenchymal transition (EMT); extracellular matrix; head and neck squamous cell carcinoma; human papillomavirus (HPV); protein tyrosine kinase; β-catenin