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The development of pancreatic cancer requires recruitment and activation of different macrophage populations. However, little is known about how macrophages are attracted to the pancreas after injury or an oncogenic event, and how they crosstalk with lesion cells or other cells of the lesion microenvironment. Here, we delineate the importance of CXCL10/CXCR3 signaling during the early phase of murine pancreatic cancer. We show that CXCL10 is produced by pancreatic precancerous lesion cells in response to IFNγ signaling and that inflammatory macrophages are recipients for this chemokine. CXCL10/CXCR3 signaling in macrophages mediates their chemoattraction to the pancreas, enhances their proliferation, and maintains their inflammatory identity. Blocking of CXCL10/CXCR3 signaling in vivo shifts macrophage populations to a tumor-promoting (Ym1 + , Fizz + , Arg1 + ) phenotype, increases fibrosis, and mediates progression of lesions, highlighting the importance of this pathway in PDA development. This is reversed when CXCL10 is overexpressed in PanIN cells.

The ε4 allele of the apolipoprotein E ( APOE ) gene, a genetic risk factor for Alzheimer’s disease, is abundantly expressed in both the brain and periphery. Here, we present evidence that peripheral apoE isoforms, separated from those in the brain by the blood–brain barrier, differentially impact Alzheimer’s disease pathogenesis and cognition. To evaluate the function of peripheral apoE, we developed conditional mouse models expressing human APOE3 or APOE4 in the liver with no detectable apoE in the brain. Liver-expressed apoE4 compromised synaptic plasticity and cognition by impairing cerebrovascular functions. Plasma proteome profiling revealed apoE isoform-dependent functional pathways highlighting cell adhesion, lipoprotein metabolism and complement activation. ApoE3 plasma from young mice improved cognition and reduced vessel-associated gliosis when transfused into aged mice, whereas apoE4 compromised the beneficial effects of young plasma. A human induced pluripotent stem cell-derived endothelial cell model recapitulated the plasma apoE isoform-specific effect on endothelial integrity, further supporting a vascular-related mechanism. Upon breeding with amyloid model mice, liver-expressed apoE4 exacerbated brain amyloid pathology, whereas apoE3 reduced it. Our findings demonstrate pathogenic effects of peripheral apoE4, providing a strong rationale for targeting peripheral apoE to treat Alzheimer’s disease. Mouse models expressing liver apoE in the absence of brain apoE reveal detrimental effects of peripheral apoE4 associated with Alzheimer’s risk on cognition and amyloid pathology through compromising vascular integrity and function.

Background Production of mitochondrial reactive oxygen species (mROS) induces acinar-to-ductal metaplasia (ADM), an initiating step towards pancreatic ductal adenocarcinoma (PDAC). Manganese superoxide dismutase (SOD2, MnSOD) is the major mitochondrial ROS scavenger and less active SOD2 at the mitochondria increases risk of developing PDAC, indicating clinical relevance of SOD2. However, the role of SOD2 in PDAC tumorigenesis remains elusive. Methods To determine SOD2’s role in PDAC initiation and progression, we crossed Sod2 fl/fl mice into the p48 Cre ;LSL- Kras G12D (KC) mouse model. We also utilized mouse primary acinar cells and macrophages for in vitro ADM and ROS assays, and to evaluate initiating events downregulating Sod2 . Human expression data and tissue assessed clinical relevance. Results SOD2 is downregulated in low-grade lesions, but knockout alone is insufficient for lesion formation. In conjunction with oncogenic Kras , knockout of Sod2 facilitates dysplasia and cancer stem cell formation in the canonical PDAC progression pathway but also increases presence of oxidative stress-resistant atypical flat lesions (AFLs), which are an understudied direct precursor to PDAC. Conclusions Oncogenic Kras suppresses mitohormesis, a process whereby mitochondrial stress upregulates stress-reducing protective responses to enhance cell viability. Inflammatory macrophage signaling decreases Sod2 expression, increasing ROS and promoting ADM and canonical PanIN progression or alternatively, compensatory antioxidants GPX4 and NRF1 are upregulated in atypical flat lesions (AFLs), decreasing senescence and lipid peroxidation. With additional inflammation, increased dysplasia results in accelerated tumor formation and the presence of AFL leads to more poorly-differentiated tumor areas. This is of clinical significance, as poorly-differentiated human PDAC has a lower survival rate, and these tumors show less SOD2 expression.

The development of pancreatic cancer requires both, acquisition of an oncogenic mutation in KRAS as well as an inflammatory insult. However, the physiological causes for pancreatic inflammation are less defined. We show here that oncogenic KRas-expressing pre-neoplastic lesion cells upregulate coxsackievirus (CVB) and adenovirus receptor (CAR). This facilitates infections from enteroviruses such as CVB3, which can be detected in approximately 50% of pancreatic cancer patients. Moreover, using an animal model we show that a one-time pancreatic infection with CVB3 in control mice is transient, but in the presence of oncogenic KRas drives chronic inflammation and rapid development of pancreatic cancer. We further demonstrate that a knockout of CAR in pancreatic lesion cells blocks these CVB3-induced effects. Our data demonstrate that KRas-caused lesions promote the development of pancreatic cancer by enabling certain viral infections. Chronic pancreatitis is a risk factor for the development of pancreatic cancer. Here authors report that coxsackievirus and adenovirus receptor (CAR) expression promotes pancreatitis and pancreatic cancer upon enterovirus infections.

Protein kinase D1 is downregulated in its expression in invasive ductal carcinoma of the breast and in invasive breast cancer cells, but its functions in normal breast epithelial cells is largely unknown. The epithelial phenotype is maintained by cell-cell junctions formed by E-cadherin. In cancer cells loss of E-cadherin expression contributes to an invasive phenotype. This can be mediated by SNAI1, a transcriptional repressor for E-cadherin that contributes to epithelial-to-mesenchymal transition (EMT). Here we show that PKD1 in normal murine mammary gland (NMuMG) epithelial cells is constitutively-active in its basal state and prevents a transition to a mesenchymal phenotype. Investigation of the involved mechanism suggested that PKD1 regulates the expression of E-cadherin at the promoter level through direct phosphorylation of the transcriptional repressor SNAI1. PKD1-mediated phosphorylation of SNAI1 occurs in the nucleus and generates a nuclear, inactive DNA/SNAI1 complex that shows decreased interaction with its co-repressor Ajuba. Analysis of human tissue samples with a newly-generated phosphospecific antibody for PKD1-phosphorylated SNAI1 showed that regulation of SNAI1 through PKD1 occurs in vivo in normal breast ductal tissue and is decreased or lost in invasive ductal carcinoma. Our data describe a mechanism of how PKD1 maintains the breast epithelial phenotype. Moreover, they suggest, that the analysis of breast tissue for PKD-mediated phosphorylation of SNAI1 using our novel phosphoS11-SNAI1-specific antibody may allow predicting the invasive potential of breast cancer cells.

Differential expression of Kallikreins (KLKs) was described for established metastatic pancreatic ductal adenocarcinoma (PDAC), but their potential as markers for early detection is not known. We have performed comprehensive in silico and in situ analyses of KLK expression in PDAC at different stages of tumor development. We found that upregulation of KLK7 and KLK10 RNA and protein occurs early in tumor development and marks carcinoma in-situ lesions (stage 0, PanIN3) and early-stage (stage 1) PDAC, while non-cancerous low grade lesions stain negative for these proteases. Moreover, both KLKs are co-expressed with desmoglein-3 (DSG3) in PDAC cell lines as well as PDAC samples from treatment naïve patients. DSG3 serves as a substrate for both KLK7 and KLK10 resulting in a 30 kDa extracellular fragment. Overall, our data suggest that analyses for expression of KLK7 and KLK10 as well as their substrates could have potential as diagnostic biomarkers to distinguish non-cancerous low-grade lesions from earliest cancerous lesions in the pancreas.

Protein kinase D (PKD) enzymes regulate cofilin-driven actin reorganization and directed cell migration through both p21-activated kinase 4 (PAK4) and the phosphatase slingshot 1L (SSH1L). The relative contributions of different endogenous PKD isoforms to both signaling pathways have not been elucidated, sufficiently. We here analyzed two cell lines (HeLa and MDA-MB-468) that express the subtypes protein kinase D2 (PKD2) and protein kinase D3 (PKD3). We show that under normal growth conditions both isoforms can form a complex, in which PKD3 is basally-active and PKD2 is inactive. Basal activity of PKD3 mediates PAK4 activity and downstream signaling, but does not significantly inhibit SSH1L. This signaling constellation was required for facilitating directed cell migration. Activation of PKD2 and further increase of PKD3 activity leads to additional phosphorylation and inhibition of endogenous SSH1L. Net effect is a dramatic increase in phospho-cofilin and a decrease in cell migration, since now both PAK4 and SSH1L are regulated by the active PKD2/PKD3 complex. Our data suggest that PKD complexes provide an interface for both cofilin regulatory pathways. Dependent on the activity of involved PKD enzymes signaling can be balanced to guarantee a functional cofilin activity cycle and increase cell migration, or imbalanced to decrease cell migration. Our data also provide an explanation of how PKD isoforms mediate different effects on directed cell migration.

Current treatment options for patients with pancreatic cancer are suboptimal, resulting in a five year survival rate of about 9%. Difficulties with treatment are due to an immunosuppressive, fibrotic tumor microenvironment that prevents drugs from reaching tumor cells, but also to the limited efficacy of existing FDA-approved chemotherapeutic compounds. We here show that the nucleoside analog Sangivamycin and its closely-related compound Toyocamycin target PDA cell lines, and are significantly more efficient than Gemcitabine. Using KINOMEscan screening, we identified the kinase Haspin, which is overexpressed in PDA cell lines and human PDA samples, as a main target for both compounds. Inhibition of Haspin leads to a decrease in Histone H3 phosphorylation and prevents Histone H3 binding to survivin, thus providing mechanistic insight of how Sangivamycin targets cell proliferation, mitosis and induces apoptotic cell death. In orthotopically implanted tumors in mice, Sangivamycin was efficient in decreasing the growth of established tumors. In summary, we show that Sangivamycin and derivatives can be an efficient new option for treatment of PDA.

Dependent on their cellular localization, Protein Kinase D (PKD) enzymes regulate different processes including Golgi transport, cell signaling and response to oxidative stress. The localization of PKD within cells is mediated by interaction with different lipid or protein binding partners. With the example of PKD2, we here show that phosphorylation events can also contribute to localization of subcellular pools of this kinase. Specifically, in the present study, we show that tyrosine phosphorylation of PKD2 at residue Y87 defines its localization to the focal adhesions and leads to activation. This phosphorylation occurs downstream of RhoA signaling and is mediated via Src. Moreover, mutation of this residue blocks PKD2’s interaction with Focal Adhesion Kinase (FAK). The presence and regulation of PKD2 at focal adhesions identifies a novel function for this kinase as a modulator of cell adhesion and migration.

Focal adhesions (FAs) are highly dynamic structures that are assembled and disassembled on a continuous basis. The balance between the two processes mediates various aspects of cell behavior, ranging from cell adhesion and spreading to directed cell migration. The turnover of FAs is regulated at multiple levels and involves a variety of signaling molecules and adaptor proteins. In the present study, we show that in response to integrin engagement, a subcellular pool of Protein Kinase D1 (PKD1) localizes to the FAs. PKD1 affects FAs by decreasing turnover and promoting maturation, resulting in enhanced cell adhesion. The effects of PKD1 are mediated through direct phosphorylation of FA-localized phosphatidylinositol-4-phosphate 5-kinase type-l γ (PIP5Klγ) at serine residue 448. This phosphorylation occurs in response to Fibronectin-RhoA signaling and leads to a decrease in PIP5Klγs’ lipid kinase activity and binding affinity for Talin. Our data reveal a novel function for PKD1 as a regulator of FA dynamics and by identifying PIP5Klγ as a novel PKD1 substrate provide mechanistic insight into this process.