Disruption of TGFβ signaling pathways in human pancreatic cancer cells

Objective To investigate whether transforming growth factor beta (TGF beta) signaling is disrupted in human pancreatic cancer cells, and to study the role of TGF beta receptors and Smad genes. Summary Background Data TGF beta is a known inhibitor of pancreatic growth. Disruption of the TGF beta signaling pathway may play a role in pancreatic cancer development, Methods The effect of TGF beta on the BxPC-3, MiaPaCa-2, and PANC-1 pancreatic cancer cell lines was evaluated by [H-3]thymidine incorporation and a TGF beta-responsive reporter assay. Expression of TGF beta receptors and Smads 2 and 3 was assessed by cross-linking assays and reverse transcriptase-polymerase chain reaction (RT-PCR). The ability to restore TGF beta responsiveness was evaluated by transfection of TGF beta signaling components. Results TGF beta produced little inhibition of DNA synthesis and did not activate a TGF beta-responsive reporter in pancreatic cancer cell lines. (125)TGF beta cross-linking and RT-PCR confirmed the presence of TGF beta receptors and Smad2 and Smad3 transcripts. Transfection of TGF beta receptors or Smads 2 and 3 did not restore responsiveness. However, transfection of Smad4 into the BxPC-3 pancreatic cancer cell line restored TGF beta responsiveness. Conclusions Pancreatic cancer cells show loss of TGF beta responsiveness. Smads 2 and 3 and TGF beta receptors are not defective in the cell lines studied. Transfection of Smad4 into one of the cell lines restored TGF beta responsiveness, suggesting an important role for Smad4 in pancreatic cancer. It is likely that other, as yet unidentified genes are important in TGF beta resistance in pancreatic cancer cells.