title: MYB is a novel regulator of pancreatic tumour growth and metastasis.
abstract: BACKGROUND
  MYB encodes for a transcription factor regulating the expression of a wide array of genes involved in cellular functions. It is reported to be amplified in a sub-set of pancreatic cancer (PC) cases; however, its pathobiological association has remained unclear thus far.
  
  
  METHODS
  Expression of MYB and other cellular proteins was analysed by immunoblot or qRT-PCR analyses. MYB was stably overexpressed in non-expressing (BxPC3) and silenced in highly expressing (MiaPaCa and Panc1) PC cells. Effect on growth was analysed by automated cell counting at 24-h interval. Cell-cycle progression and apoptotic indices of PC cells with altered MYB expression were measured through flow cytometry upon staining with respective biomarkers. Cell motility/invasion was examined in a Boyden's chamber assay using non-coated or Matrigel-coated membranes. Effect on tumorigenicity and metastatic potential was examined by non-invasive imaging and through end-point measurements of luciferase-tagged MYB-altered PC implanted in the pancreas of nude mice.
  
  
  RESULTS
  MYB was aberrantly expressed in all malignant cases of pancreas, whereas remained undetectable in normal pancreas. All the tested established PC cell lines except BxPC3 also exhibited MYB expression. Forced expression of MYB in BxPC3 cells promoted their growth, cell-cycle progression, survival and malignant behaviour, whereas its silencing in MiaPaCa and Panc1 cells produced converse effects. More importantly, ectopic MYB expression was sufficient to confer tumorigenic and metastatic capabilities to non-tumorigenic BxPC3 cells, while its silencing resulted in significant loss of the same in MYB-overexpressing cells as demonstrated in orthotopic mouse model. We also identified several MYB-regulated genes in PC cells that might potentially mediate its effect on tumour growth and metastasis.
  
  
  CONCLUSIONS
  MYB is aberrantly overexpressed in PC cells and acts as a key determinant of pancreatic tumour growth and metastasis.
authors.affiliation: Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, USA.
authors.forename: Sanjeev K
authors.initials: SK
authors.lastname: Srivastava
authors.affiliation: Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, USA.
authors.forename: Arun
authors.initials: A
authors.lastname: Bhardwaj
authors.affiliation: Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, USA.
authors.forename: Sumit
authors.initials: S
authors.lastname: Arora
authors.affiliation: Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, USA.
authors.forename: Seema
authors.initials: S
authors.lastname: Singh
authors.affiliation: Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, USA.
authors.forename: Shafquat
authors.initials: S
authors.lastname: Azim
authors.affiliation: Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, USA.
authors.forename: Nikhil
authors.initials: N
authors.lastname: Tyagi
authors.affiliation: Department of Pathology, College of Medicine, University of South Alabama, Mobile, Alabama, USA.
authors.forename: James E
authors.initials: JE
authors.lastname: Carter
authors.affiliation: Department of Mathematics and Statistics, University of South Alabama, Mobile, Alabama, USA.
authors.forename: Bin
authors.initials: B
authors.lastname: Wang
authors.affiliation: Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, USA.|Department of Biochemistry and Molecular Biology, College of Medicine, University of South Alabama, Mobile, Alabama, USA.
authors.forename: Ajay P
authors.initials: AP
authors.lastname: Singh
mesh_terms: D000818:Animals; D002453:Cell Cycle; D002455:Cell Division / Q000235:genetics*; D020570:Genes, myb; D064593:Heterografts; D006801:Humans; D051379:Mice; D009362:Neoplasm Metastasis / Q000235:genetics*; D010190:Pancreatic Neoplasms / Q000235:genetics / Q000473:pathology*