TGF-ß and αvß6 integrin act in a common pathway to suppress pancreatic cancer progression.

ABSTRACT

The TGF-ß pathway is under active consideration as a cancer drug target based on its capacity to promote cancer cell invasion and to create a protumorigenic microenvironment. However, the clinical application of TGF-ß inhibitors remains uncertain as genetic studies show a tumor suppressor function of TGF-ß in pancreatic cancer and other epithelial malignancies. Here, we used genetically engineered mouse models to investigate the therapeutic impact of global TGF-ß inhibition in pancreatic cancer in relation to tumor stage, genetic profile, and concurrent chemotherapy. We found that αvß6 integrin acted as a key upstream activator of TGF-ß in evolving pancreatic cancers. In addition, TGF-ß or αvß6 blockade increased tumor cell proliferation and accelerated both early and later disease stages. These effects were dependent on the presence of Smad4, a central mediator of TGF-ß signaling. Therefore, our findings indicate that αvß6 and TGF-ß act in a common tumor suppressor pathway whose pharmacologic inactivation promotes pancreatic cancer progression.