Disruption of TGFbeta signaling pathways in human pancreatic cancer cells.
OBJECTIVE
To investigate whether transforming growth factor beta (TGFbeta) signaling is disrupted in human pancreatic cancer cells, and to study the role of TGFbeta receptors and Smad genes.


BACKGROUND
TGFbeta is a known inhibitor of pancreatic growth. Disruption of the TGFbeta signaling pathway may play a role in pancreatic cancer development.


METHODS
The effect of TGFbeta on the BxPC-3, MiaPaCa-2, and PANC-1 pancreatic cancer cell lines was evaluated by [3H]thymidine incorporation and a TGFbeta-responsive reporter assay. Expression of TGFbeta receptors and Smads 2 and 3 was assessed by cross-linking assays and reverse transcriptase-polymerase chain reaction (RT-PCR). The ability to restore TGFbeta responsiveness was evaluated by transfection of TGFbeta signaling components.


RESULTS
TGFbeta produced little inhibition of DNA synthesis and did not activate a TGFbeta-responsive reporter in pancreatic cancer cell lines. 125TGFbeta cross-linking and RT-PCR confirmed the presence of TGFbeta receptors and Smad2 and Smad3 transcripts. Transfection of TGFbeta receptors or Smads 2 and 3 did not restore responsiveness. However, transfection of Smad4 into the BxPC-3 pancreatic cancer cell line restored TGFbeta responsiveness.


CONCLUSIONS
Pancreatic cancer cells show loss of TGFbeta responsiveness. Smads 2 and 3 and TGFbeta receptors are not defective in the cell lines studied. Transfection of Smad4 into one of the cell lines restored TGFbeta responsiveness, suggesting an important role for Smad4 in pancreatic cancer. It is likely that other, as yet unidentified genes are important in TGFbeta resistance in pancreatic cancer cells.
Simeone
D M
DM
Department of Surgery, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA. simeone@umich.edu
Pham
T
T
Logsdon
C D
CD
D000818:Animals; D004268:DNA-Binding Proteins / Q000502:physiology*; D006801:Humans; D010190:Pancreatic Neoplasms / Q000235:genetics / Q000503:physiopathology*; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D051899:Smad2 Protein; D051900:Smad3 Protein; D051901:Smad4 Protein; D015534:Trans-Activators / Q000502:physiology*; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000502:physiology*; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; C497782:SMAD2 protein, human; C497790:SMAD3 protein, human; C497796:SMAD4 protein, human; D051899:Smad2 Protein; C497784:Smad2 protein, rat; D051900:Smad3 Protein; C497787:Smad3 protein, rat; D051901:Smad4 Protein; C490811:Smad4 protein, rat; D015534:Trans-Activators; D016212:Transforming Growth Factor beta