The Dual Role of Senescence in Pancreatic Ductal Adenocarcinoma.

The role of senescence as a tumor suppressor is well established; however, recent evidence has revealed novel paracrine functions for senescent cells in relation to their microenvironment, most notably protumorigenic roles in certain contexts. Senescent cells are capable of altering the inflammatory microenvironment through the senescence-associated secretory phenotype, which could have important consequences for tumorigenesis. The role of senescent cells in a highly inflammatory cancer like pancreatic cancer is still largely undefined, apart from the fact that senescence abrogation increases tumorigenesis in vivo. This review will summarize our current knowledge of the phenomenon of cellular senescence in pancreatic ductal adenocarcinoma, its overlapping link with inflammation, and some urgent unanswered questions in the field.

Cardiotrophin 1 protects beta cells from apoptosis and prevents streptozotocin-induced diabetes in a mouse model.

AIMS/HYPOTHESIS: Cardiotrophin 1 (CT-1) is a recently described cytokine originally isolated from the heart where it has been shown to play an important role in apoptotic protection of cardiomyocytes and heart hypertrophy. Its beneficial properties have also been described in other organs such as liver and neuromuscular tissue. In the present study, we investigated whether CT-1 can confer protection against pro-apoptotic stimuli in pancreatic beta cells, and its role in insulin secretion and diabetes development. METHODS: The effects of CT-1 on apoptosis and function were studied using MIN6B1 cells and freshly isolated murine pancreatic islets. The impact on the development of diabetes was evaluated in Ct1-null (Ct1 (-/-)) mice (the gene Ct1 is also known as Ctf1) using two streptozotocin (STZ)-induced models of diabetes. RESULTS: CT-1 has a protective effect in MIN6B1 cells and murine islets under the pro-apoptotic stimulus of serum deprivation, which correlates with the expression of B cell lymphoma-extra large, or following exposure to a mixture of cytokines. In addition, CT-1 enhances glucose-stimulated insulin secretion in MIN6B1 cells and this was repressed by inhibitors of phospholipase C. Furthermore, Ct1 (-/-) mice were more prone to develop diabetes, and their glucose tolerance test showed impaired plasma glucose clearance which correlated with decreased pancreatic insulin secretion. CONCLUSIONS/INTERPRETATION: The results obtained from both in vitro and in vivo experiments show that CT-1 improves beta cell function and survival, and protects mice against STZ-induced diabetes.