Abstract
The basement membrane (BM) is among the predominant microenvironmental factors of normal epithelia and of precancerous epithelial lesions. Evidence suggests that the BM functions not only as a barrier to tumour invasion but also as an active tumour-suppressing signalling substrate during premalignancy. However, the molecular foundations of such mechanisms have not been elucidated. Here we explore potential tumour-suppressing functions of the BM during precancer evolution, focusing on the expression and function of the extracellular matrix receptor dystroglycan in the pancreas and pancreatic disease. We show that the dystroglycan protein is highly expressed in the acinar compartment of the normal pancreas but lower in the ductal compartment. Moreover, there is a strong suppression of dystroglycan protein expression with acinar-to-ductal metaplasia in chronic pancreatitis and in all stages of pancreatic precancer and cancer evolution, from acinar-to-ductal metaplasia to dysplasia to adenocarcinoma. The conditional knockout of dystroglycan in the murine pancreas produced little evidence of developmental or functional deficiency. However, conditional deletion of dystroglycan expression in the context of oncogenic Kras expression led to a clear acceleration of pancreatic disease evolution, including accelerated dysplasia development and decreased survival. These data establish dystroglycan as a suppressor of pancreatic dysplasia development and one that is muted in chronic pancreatitis and at the earliest stages of oncogene-induced transformation. We conclude that dystroglycan is an important mediator of the tumour-suppressing functions of the BM during precancer evolution and that reduced dystroglycan function increases cancer risk, highlighting the dynamics of cell-BM interactions as important determinants of early cancer progression. © 2024 The Pathological Society of Great Britain and Ireland.