ABSTRACT
The transcription factor Zeb1 has been identified as a crucial player in Kras-dependent oncogenesis. In pancreatic ductal adenocarcinoma (PDAC), Zeb1 is highly expressed in myofibroblasts and correlates with poor prognosis. As Kras mutations are key drivers in PDAC, we aimed here to assess the necessity of Zeb1 for Kras-driven PDAC and to define the role of Zeb1-expressing myofibroblasts in PDAC development. Genetically engineered mice with conditional pancreatic KrasG12D and Trp53 mutations (KPC) were crossed with Zeb1 haploinsufficient mice (Z+/-). Extensive PDAC was prominent in all 20-week-old KPC;Z+/+ mice, whereas only low-grade precursor lesions were detected in age-matched KPC;Z+/- littermates, with PDAC developing eventually in KPC;Z+/- aged animals. Zeb1 expression in myofibroblasts occurred early in tumorigenesis and Zeb1 haploinsufficiency retarded native expansion of stromal myofibroblasts during precursor-to-cancer progression. Zeb1 downregulation in mPSC repressed their activated gene profile, impaired their migratory and proliferative activity, and attenuated their tumor-supporting features. Conditioned media from Z+/+ mouse-activated (myofibroblast-like) pancreatic stellate cells (mPSC) boosted Ras activity in pancreatic cancer cells carrying mutant Kras; this effect was not observed when using conditioned media from Z+/- mPSC, revealing a paracrinal cooperative axis between Zeb1-expressing PSC and oncogenic Kras-bearing tumor cells. We conclude that Zeb1-expressing stromal myofibroblasts enable a heterotypic collaboration with the Kras-fated epithelial compartment, thus supporting pancreatic malignancy.Significance: Zeb1 expression in stromal myofibroblasts supports PDAC development via collaboration with the epithelial compartment bearing oncogenic Kras mutations. Cancer Res; 78(10); 2624-37. ©2018 AACR.
Subject(s)
Adenocarcinoma/pathology , Carcinoma, Pancreatic Ductal/pathology , Cell Transformation, Neoplastic/pathology , Myofibroblasts/pathology , Pancreatic Neoplasms/pathology , Proto-Oncogene Proteins p21(ras)/metabolism , Zinc Finger E-box-Binding Homeobox 1/metabolism , Animals , Cell Line, Tumor , Cell Transformation, Neoplastic/genetics , Culture Media, Conditioned/pharmacology , Haploinsufficiency/genetics , Mice , Mice, Inbred C57BL , Mice, Transgenic , Proto-Oncogene Proteins p21(ras)/genetics , RNA Interference , RNA, Small Interfering/genetics , Tumor Suppressor Protein p53/genetics , Zinc Finger E-box-Binding Homeobox 1/geneticsABSTRACT
Astrocytes actively participate in neuro-inflammatory processes associated to Alzheimer's disease (AD), and other brain pathologies. We recently showed that an astrocyte-specific intracellular signaling pathway involving an interaction of the phosphatase calcineurin with the transcription factor FOXO3 is a major driver in AD-associated pathological inflammation, suggesting a potential new druggable target for this devastating disease. We have now developed decoy molecules to interfere with calcineurin/FOXO3 interactions, and tested them in astrocytes and neuronal co-cultures exposed to amyloid-ß (Aß) toxicity. We observed that interference of calcineurin/FOXO3 interactions exerts a protective action against Aß-induced neuronal death and favors the production of a set of growth factors that we hypothesize form part of a cytoprotective pathway to resolve inflammation. Furthermore, interference of the Aß-induced interaction of calcineurin with FOXO3 by decoy compounds significantly decreased amyloid-ß protein precursor (AßPP) synthesis, reduced the AßPP amyloidogenic pathway, resulting in lower Aß levels, and blocked the expression of pro-inflammatory cytokines TNFα and IL-6 in astrocytes. Collectively, these data indicate that interrupting pro-inflammatory calcineurin/FOXO3 interactions in astrocytes triggered by Aß accumulation in brain may constitute an effective new therapeutic approach in AD. Future studies with intranasal delivery, or brain barrier permeable decoy compounds, are warranted.
