14-3-3sigma Modulates pancreatic cancer cell survival and invasiveness.
OBJECTIVE
The purpose of the present study was to investigate the potential role of 14-3-3sigma in pancreatic ductal adenocarcinoma (PDAC).


METHODS
14-3-3 isoform expression was determined by real-time quantitative PCR in laser capture normal pancreatic ductal cells and pancreatic cancer cells and in 5 pancreatic cancer cell lines. PANC-1 cells, with low levels of 14-3-3sigma, were stably transfected with a human 14-3-3sigma cDNA. Conversely, high endogenous 14-3-3sigma levels in T3M4 cells were suppressed by specific short hairpin RNA. Apoptosis, motility, and invasiveness were studied.


RESULTS
The cancer cells in 7 PDAC samples expressed high levels of 14-3-3sigma mRNA by quantitative PCR when compared with normal pancreatic duct cells. 14-3-3sigma protein levels were high in BxPC3, COLO-357, and T3M4 cells, intermediate in ASPC-1 cells, and low in PANC-1 cells. Most cell lines released detectable amount of 14-3-3sigma into conditioned medium. Overexpression of 14-3-3sigma in PANC-1 cells led to resistance to cisplatinum-induced apoptosis, increased basal migration, and increased invasion in response to epidermal growth factor and insulin-like growth factor-I. By contrast, short hairpin RNA-mediated knockdown of endogenous 14-3-3sigma in T3M4 cells did not alter migration but led to enhanced cisplatinum sensitivity, increased invasiveness in response to epidermal growth factor, and decreased invasiveness in response to insulin-like growth factor-I.


CONCLUSIONS
14-3-3sigma contributes to the chemoresistance of pancreatic cancer cells and exerts cell type-dependent effects on cell migration and invasion. Therefore, strategies aimed at suppressing 14-3-3sigma expression and function may have a therapeutic benefit in subgroups of patients with PDAC.
Neupane
Divas
D
Department of Medicine and Pharmacology and Toxicology, Dartmouth-Hitchcock Medical Center and Dartmouth Medical School, Hanover, New Hamsphire 03756, USA.
Korc
Murray
M
D048948:14-3-3 Proteins / Q000235:genetics / Q000378:metabolism*; D017209:Apoptosis / Q000235:genetics; D021441:Carcinoma, Pancreatic Ductal / Q000473:pathology*; D002470:Cell Survival; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D005455:Fluorescent Antibody Technique; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D009361:Neoplasm Invasiveness / Q000235:genetics*; D010190:Pancreatic Neoplasms / Q000378:metabolism / Q000473:pathology*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D048948:14-3-3 Proteins