Background & Aims-Transforming growth factor (TGF)-β signaling occurs through Smads 2/3/4, which translocate to the nucleus to regulate transcription; TGF-β has tumor suppressive effects in some tumor models and pro-metastatic effects in others. In patients with colorectal cancer (CRC), mutations or reduced levels of Smad4 have been correlated with reduced survival. However, the function of Smad signaling and the effects of TGF-β receptor kinase inhibitors (TRKI) have not been analyzed during CRC metastasis. We investigated the role of TGF-β/Smad signaling in CRC progression.

Background The combination of autologous mesenchymal stem cells (MSCs) and cardiac stem cells (CSCs) synergistically reduces scar size and improves cardiac function in ischemic cardiomyopathy. Whereas allogeneic (allo-)MSCs are immunoevasive, the capacity of CSCs to similarly elude the immune system remains controversial, potentially limiting the success of allogeneic cell combination therapy (ACCT). Objective We tested the hypothesis that ACCT synergistically promotes cardiac regeneration without provoking immunologic reactions. Methods Gottingen swine with experimental ischemic cardiomyopathy were randomized to receive transendocardial injections of either allo-MSC + allo-CSC (ACCT: 200 million MSCs/1 million CSCs, n=7), 200 million allo-MSC (n=8), 1 million allo-CSC (n=4), or placebo (Plasma-Lyte A, n=6)]. Swine were assessed by cardiac magnetic resonance imaging (cMR) and pressure volume catheterization. Immune response was tested by histological analyses. Results Both ACCT and allo-MSCs reduced scar size by −11.1±4.8%, (p=0.012) and −9.5±4.8 (p=0.047), respectively. Only ACCT, but not MSC or CSC, prevented ongoing negative remodeling by offsetting increases in chamber volumes. Importantly, ACCT exerted the greatest effect on systolic function, improving the end-systolic pressure volume relation (+0.98±0.41 mmHg/mL, p=0.016) The ACCT group had more phospho-histone H3 (pHH3)+ (a marker of mitosis) cardiomyocytes (p=0.04), and non-cardiomyocytes (p=0.0002) compared to the placebo group in some regions of the heart. Inflammatory sites in ACCT and MSC swine contained immunotolerant CD3+/CD25+/FoxP3 regulatory T cells (p<0.0001). Histologic analysis showed absent to low grade inflammatory infiltrates without cardiomyocyte necrosis. Conclusion ACCT demonstrates synergistic effects to enhance cardiac regeneration and left ventricular functional recovery in a swine model of chronic ischemic cardiomyopathy without adverse immunological reaction. Clinical translation to humans is warranted.

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy and is highly resistant to standard treatment regimens. Targeted therapies against KRAS, a mutation present in an overwhelming majority of PDAC cases, have been largely ineffective. However, inhibition of downstream components in the KRAS signaling cascade provides promising therapeutic targets in the management of PDAC and warrants further exploration. Here, we investigated Urolithin A (Uro A), a novel natural compound derived from pomegranates, which targets numerous kinases downstream of KRAS, in particular the PI3K/AKT/mTOR signaling pathways. We showed that treatment of PDAC cells with Uro A blocked the phosphorylation of AKT and p70S6K in vitro, successfully inhibited the growth of tumor xenografts, and increased overall survival of Ptf1a Cre/þ ;LSL-Kras G12D/þ ;Tgfbr2 flox/flox (PKT) mice compared with vehicle or gemcitabine therapy alone. Histologic evaluation of these Uro A-treated tumor samples confirmed mechanistic actions of Uro A via decreased phosphorylation of AKT and p70S6K, reduced proliferation, and increased cellular apoptosis in both xenograft and PKT mouse models. In addition, Uro A treatment reprogrammed the tumor microenvironment, as evidenced by reduced levels of infiltrating immunosuppressive cell populations such as myeloid-derived suppressor cells, tumor-associated macrophages, and regulatory T cells. Overall, this work provides convincing preclinical evidence for the utility of Uro A as a therapeutic agent in PDAC through suppression of the PI3K/AKT/mTOR pathway.

Although smoking is a significant risk factor for pancreatic ductal adenocarcinoma (PDAC), the molecular mechanisms underlying PDAC development and progression in smokers are still unclear. Here, we show the role of cyclic AMP response element-binding protein (CREB) in the pathogenesis of smoking-induced PDAC. Smokers had significantly higher levels of activated CREB when compared with nonsmokers. Cell lines derived from normal pancreas and pancreatic intraepithelial neoplasm (PanIN) exhibited low baseline pCREB levels compared with PDAC cell lines. Furthermore, elevated CREB expression correlated with reduced survival in patients with PDAC. Depletion of CREB significantly reduced tumor burden after tobacco-specific nitrosamine 4-(methyl nitrosamino)-1-(3-pyridyl)-1-butanone (NNK) treatment, suggesting a CREB-dependent contribution to PDAC growth and progression in smokers. Conversely, NNK accelerated PanIN lesion and PDAC formation via GM-CSF-mediated activation of CREB in a PDAC mouse model. CREB inhibition (CREBi) in mice more effectively reduced primary tumor burden compared with control or GM-CSF blockade alone following NNK exposure. GM-CSF played a role in the recruitment of tumor-associated macrophages (TAM) and regulatory T cell (Treg) expansion and promotion, whereas CREBi significantly reduced TAM and Treg populations in NNK-exposed mice. Overall, these results suggest that NNK exposure leads to activation of CREB through GM-CSF, promoting inflammatory and Akt pathways. Direct inhibition of CREB, but not GM-CSF, effectively abrogates these effects and inhibits tumor progression, offering a viable therapeutic strategy for patients with PDAC. These findings identify GM-CSF-induced CREB as a driver of pancreatic cancer in smokers and demonstrate the therapeutic potential of targeting CREB to reduce PDAC tumor growth. http://cancerres.aacrjournals.org/content/canres/78/21/6146/F1.large.jpg .

While solitary adenomas are often resected, multifocal HAs are frequently embolized. Small adenomas can safely be observed. Given low recurrence rates, select HAs can be considered for embolization.

Glycogen synthase kinase 3β (GSK3β) can regulate a broad range of cellular processes in a variety of cell types and tissues through its ability to phosphorylate its substrates in a cell- and time-specific manner. Although it is known that Axin and presenilin help to recruit β-catenin/Smad3 and tau protein to GSK3β, respectively, it is not clear how many of the other GSK3β substrates are recruited to it. Here, we have established the binding of GSK3β with a novel scaffold protein, STRAP, through its WD40 domains. In a new finding, we have observed that STRAP, GSK3β and Axin form a ternary complex together. We show for the first time that intracellular fragment of Notch3 (ICN3) binds with GSK3β through the ankyrin repeat domain. This binding between STRAP and GSK3β is reduced by small-molecule inhibitors of GSK3β. Further studies revealed that STRAP also binds ICN3 through the ankyrin repeat region, and this binding is enhanced in a proteasomal inhibition-dependent manner. In vivo ubiquitination studies indicate that STRAP reduces ubiquitination of ICN3, suggesting a role of STRAP in stabilizing ICN3. This is supported by the fact that STRAP and Notch3 are co-upregulated and co-localized in 59% of non-small cell lung cancers, as observed in an immunohistochemical staining of tissue microarrays. These results provide a potential mechanism by which STRAP regulates GSK3β function and Notch3 stabilization and further support the oncogenic functions of STRAP.

Lack of durable response to cytotoxic chemotherapy is a major contributor to the dismal outcomes seen in pancreatic ductal adenocarcinoma (PDAC). Extensive tumor desmoplasia and poor vascular supply are two predominant characteristics which hinder the delivery of chemotherapeutic drugs into PDAC tumors and mediate resistance to therapy. Previously, we have shown that STAT3 is a key biomarker of therapeutic resistance to gemcitabine treatment in PDAC, which can be overcome by combined inhibition of the Src and EGFR pathways. Although it is well-established that concurrent EGFR and Src inhibition exert these antineoplastic properties through direct inhibition of mitogenic pathways in tumor cells, the influence of this combined therapy on stromal constituents in PDAC tumors remains unknown. In this study, we demonstrate in both orthotopic tumor xenograft and Ptf1a cre/þ ; LSL-Kras G12D/þ ;Tgfbr2 flox/flox (PKT) mouse models that concurrent EGFR and Src inhibition abrogates STAT3 activation, increases microvessel density, and prevents tissue fibrosis in vivo. Furthermore, the stromal changes induced by parallel EGFR and Src pathway inhibition resulted in improved overall survival in PKT mice when combined with gemcitabine. As a phase I clinical trial utilizing concurrent EGFR and Src inhibition with gemcitabine has recently concluded, these data provide timely translational insight into the novel mechanism of action of this regimen and expand our understanding into the phenomenon of stromal-mediated therapeutic resistance.Implications: These findings demonstrate that Src/EGFR inhibition targets STAT3, remodels the tumor stroma, and results in enhanced delivery of gemcitabine to improve overall survival in a mouse model of PDAC.

The stromal tissue, made of extracellular matrix and mesenchymal cells, is vital for the functional design of all complex tissues. Fibroblasts are key components of stromal tissue and play a crucial role during organ development, wound repair, angiogenesis and fibrosis. We have previously reported the identification of a novel WD-domain protein, STRAP1 that inhibits transforming growth factor-β (TGF-β) signaling and enhances tumorigenicity via TGF-β-dependent and TGF-β-independent mechanisms. Here, we report, for the first time, that deletion of STRAP from Mouse Embryonic Fibroblasts (MEFs) results in a loss of mesenchymal morphology. These cells lose their spindle shape and exhibit features of an epithelial morphology. Gene expression profiling has confirmed that deletion of STRAP affects expression of sets of genes important for diverse functions including cell-cell adhesion and cell polarization, and up-regulates E-cadherin expression leading to the formation of adherens junctions, subsequent localization of β-catenin to the cell membrane and downregulation of the mesenchymal markers like LEF1 (lymphoid enhancer-binding factor 1). Upregulation of WT1 (Wilms tumor homolog 1) in STRAP null MEFs plays a role in E-cadherin induction. Finally, stable expression of STRAP in these cells results in a loss of WT1 and E-cadherin expression, and a reversal from epithelial to the mesenchymal morphology. Thus, these results provide a novel TGF-β-independent function of STRAP and describe a mechanism for the role of STRAP in the maintenance of mesenchymal morphology.