title: Characteristics of CD44 alternative splice pattern in the course of human colorectal adenocarcinoma progression.
abstract: BACKGROUND
  CD44 is considered as 'a' metastasis associated gene, despite the fact that it is an umbrella term for a group of molecules produced from a single gene by alternative splicing. However, little consideration is given to the above in the literature of colorectal carcinomas as well as other tumour types, leading to confusion and contradictory results about its possible role in tumour progression.
  
  
  METHODS
  We compared the CD44 alternative splice pattern (ASP) of three genetically different human colorectal cancer cell lines (HT25, HT29, HCT116) using a series of PCR reactions and next- generation sequencing method, as well as identified a colorectal adenocarcinoma specific CD44 ASP. This ASP was further investigated in terms of its qualitative and quantitative stability in our experimental iso- and xenograft mouse models for colorectal cancer progression. A complex preclinical experimental set-up was established to separately test the different steps of tumour progression and the role of tumour microenvironment, respectively, focusing on the role of 'CD44' in this process.
  
  
  RESULTS
  We managed to present a colorectal cancer-specific CD44 ASP, which remained unchanged from cell lines throughout primary tumour formation and metastatic progression. Furthermore, we report a unique roster of all expressed CD44 variant isoforms characteristic to colorectal cancer. Finally, on quantitative assessment of the variable exons v3 and v6, higher co-expression levels were found to be characteristic to metastatically potent tumour cells.
  
  
  CONCLUSIONS
  Particular CD44 variant isoforms seem to act as "metastasis genes" via tumour microenvironment-driven shifts in v3 and v6 expressions. However, this function may just affect a minority of tumour subclones. This fact and the huge potential number of different CD44 splice variants that can contain v3 and v6 domains can explain incoherence of clinical studies regarding functional asessment of CD44 variants, as well as diminish the chances of using CD44 variants for predictive purpose.
authors.affiliation: 2nd Institute of Pathology, Semmelweis University, Budapest, Hungary. bankybalazs@yahoo.com
authors.forename: Balázs
authors.initials: B
authors.lastname: Bánky
authors.forename: Lívia
authors.initials: L
authors.lastname: Rásó-Barnett
authors.forename: Tamás
authors.initials: T
authors.lastname: Barbai
authors.forename: József
authors.initials: J
authors.lastname: Tímár
authors.forename: Péter
authors.initials: P
authors.lastname: Becságh
authors.forename: Erzsébet
authors.initials: E
authors.lastname: Rásó
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D017398:Alternative Splicing; D000818:Animals; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D005091:Exons; D045325:HCT116 Cells; D019073:HT29 Cells; D006801:Humans; D018960:Hyaluronan Receptors / Q000235:genetics* / Q000378:metabolism; D008175:Lung Neoplasms / Q000235:genetics / Q000556:secondary; D051379:Mice; D020033:Protein Isoforms; D055550:Protein Stability; D014183:Transplantation, Heterologous
chemical_list: D018960:Hyaluronan Receptors; D020033:Protein Isoforms