title: TMEM16A alternative splicing coordination in breast cancer.
abstract: BACKGROUND
  TMEM16A, also known as Anoctamin-1, is a calcium-activated chloride channel gene overexpressed in many tumors. The role of TMEM16A in cancer is not completely understood and no data are available regarding the potential tumorigenic properties of the multiple isoforms generated by alternative splicing (AS).
  
  
  METHODS
  We evaluated TMEM16A AS pattern, isoforms distribution and Splicing Coordination (SC), in normal tissues and breast cancers, through a semi-quantitative PCR-assay that amplifies transcripts across three AS exons, 6b, 13 and 15.
  
  
  RESULTS
  In breast cancer, we did not observe an association either to AS of individual exons or to specific TMEM16A isoforms, and induced expression of the most common isoforms present in tumors in the HEK293 Flp-In Tet-ON system had no effect on cellular proliferation and migration. The analysis of splicing coordination, a mechanism that regulates AS of distant exons, showed a preferential association of exon 6b and 15 in several normal tissues and tumors: isoforms that predominantly include exon 6b tend to exclude exon 15 and vice versa. Interestingly, we found an increase in SC in breast tumors compared to matched normal tissues.
  
  
  CONCLUSIONS
  As the different TMEM16A isoforms do not affect proliferation or migration and do not associate with tumors, our results suggest that the resulting channel activities are not directly involved in cell growth and motility. Conversely, the observed increase in SC in breast tumors suggests that the maintenance of the regulatory mechanism that coordinates distant alternative spliced exons in multiple genes other than TMEM16A is necessary for cancer cell viability.
authors.affiliation: Human Molecular Genetics, International Centre for Genetic Engineering and Biotechnology, Trieste, Italy.
authors.forename: Ifeoma
authors.initials: I
authors.lastname: Ubby
authors.forename: Erica
authors.initials: E
authors.lastname: Bussani
authors.forename: Antonio
authors.initials: A
authors.lastname: Colonna
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Stacul
authors.forename: Martina
authors.initials: M
authors.lastname: Locatelli
authors.forename: Paolo
authors.initials: P
authors.lastname: Scudieri
authors.forename: Luis
authors.initials: L
authors.lastname: Galietta
authors.forename: Franco
authors.initials: F
authors.lastname: Pagani
mesh_terms: D017398:Alternative Splicing; D000075369:Anoctamin-1; D001940:Breast / Q000378:metabolism; D001943:Breast Neoplasms / Q000235:genetics*; D002465:Cell Movement / Q000235:genetics; D049109:Cell Proliferation; D018118:Chloride Channels / Q000235:genetics*; D005260:Female; D015870:Gene Expression; D057809:HEK293 Cells; D006801:Humans; D009363:Neoplasm Proteins / Q000235:genetics*; D059368:RNA Isoforms
chemical_list: C476213:ANO1 protein, human; D000075369:Anoctamin-1; D018118:Chloride Channels; D009363:Neoplasm Proteins; D059368:RNA Isoforms