Activation of PyMT in β Cells Induces Irreversible Hyperplasia, but Oncogene-Dependent Acinar Cell Carcinomas When Activated in Pancreatic Progenitors

It is unclear whether the cellular origin of various forms of pancreatic cancer involves transformation or transdifferentiation of different target cells or whether tumors arise from common precursors, with tumor types determined by the specific genetic alterations. Previous studies suggested that pancreatic ductal carcinomas might be induced by polyoma middle T antigen (PyMT) expressed in non-ductal cells. To ask whether PyMT transforms and transdifferentiates endocrine cells toward exocrine tumor phenotypes, we generated transgenic mice that carry tetracycline-inducible PyMT and a linked luciferase reporter. Induction of PyMT in β cells causes β-cell hyperplastic lesions that do not progress to malignant neoplasms. When PyMT is de-induced, β cell proliferation and growth cease; however, regression does not occur, suggesting that continued production of PyMT is not required to maintain the viable expanded β cell population. In contrast, induction of PyMT in early pancreatic progenitor cells under the control of Pdx1 produces acinar cell carcinomas and β-cell hyperplasia. The survival of acinar tumor cells is dependent on continued expression of PyMT. Our findings indicate that PyMT can induce exocrine tumors from pancreatic progenitor cells, but cells in the β cell lineage are not transdifferentiated toward exocrine cell types by PyMT; instead, they undergo oncogene-dependent hyperplastic growth, but do not require PyMT for survival

Conditional and specific NF-κB blockade protects pancreatic beta cells from diabetogenic agents

Type 1 diabetes is characterized by the infiltration of inflammatory cells into pancreatic islets of Langerhans, followed by the selective and progressive destruction of insulin-secreting beta cells. Islet-infiltrating leukocytes secrete cytokines such as IL-1β and IFN-γ, which contribute to beta cell death. In vitro evidence suggests that cytokine-induced activation of the transcription factor NF-κB is an important component of the signal triggering beta cell apoptosis. To study the in vivo role of NF-κB in beta cell death, we generated a transgenic mouse line expressing a degradation-resistant NF-κB protein inhibitor (ΔNIκBα), acting specifically in beta cells, in an inducible and reversible manner, by using the tet-on regulation system. In vitro, islets expressing the ΔNIκBα protein were resistant to the deleterious effects of IL-1β and IFN-γ, as assessed by reduced NO production and beta-cell apoptosis. This effect was even more striking in vivo, where nearly complete protection against multiple low-dose streptozocin-induced diabetes was observed, with reduced intraislet lymphocytic infiltration. Our results show in vivo that beta cell-specific activation of NF-κB is a key event in the progressive loss of beta cells in diabetes. Inhibition of this process could be a potential effective strategy for beta-cell protection

Anti-invasive and anti-proliferative effects of shRNA-loaded poly(lactide-co-glycolide) nanoparticles following RAN silencing in MDA-MB231 breast cancer cells

Background Overexpression of the RAN GTP (RAN)gene has been shown to be linked to metastatic activity of MDAMB231 human breast cancer cells by increasing Ras/MEK/ ERK and PI3K/Akt/mTORC1 signalling. The aim of this study was to investigate the potential of polymeric nanoparticles to deliver two novel shRNA sequences, targeted against the RAN gene, to MDA-MB231 cells grown in culture and to assess their effects in a range of biological assays. Methods Biodegradable PLGA nanoparticles, loaded with shRNA-1 and shRNA-4, were fabricated using a double emulsion solvent evaporation technique and characterised for size, zeta potential and polydispersity index before testing on the MDA-MB231 cell line in a range of assays including cell viability, migration, invasion and gene knock down. Results shRNA-loaded nanoparticles were successfully fabricated and delivered to MDA-MB231 cells in culture, where they effectively released their payload, causing a decrease in both cell invasion and cell migration by knocking down RAN gene expression. Conclusion Results indicate the anti-RAN shRNA-loaded nanoparticles deliver and release biological payload to MDA-MB231 cells in culture. This works paves the way for further investigations into the possible use of anti-RAN * SusanHawthorne [email protected] 1 2 3 School of Pharmacy and Pharmaceutical Sciences, Ulster University, Cromore Road, Coleraine, Co. Londonderry BT52 1SA, UK School of Medicine, Dentistry and Biomedical Sciences, Queen’s University Belfast, Health Sciences Building, 97 Lisburn Road, Belfast BT9 7BL, UK Institute of Cancer Therapeutics, ICT building, University of Bradford, Richmond Road, Bradford, England BD7 1DP,UK shRNA-loaded NP formulations for the treatment of breast cancer in vivo