Pancreatic ductal adenocarcinoma (PDAC) is almost universally fatal. The annual number of deaths equals the number of newly diagnosed cases, despite maximal treatment. The overall 5-year survival ...rate of <5% has remained stubbornly unchanged over the last 30 years, despite tremendous efforts in preclinical and clinical science. There is unquestionably an urgent need to further improve our understanding of pancreatic cancer biology, treatment response and relapse, and to identify novel therapeutic targets. Rigorous research in the field has uncovered genetic aberrations that occur during PDAC development and progression. In most cases, PDAC is initiated by oncogenic mutant KRAS, which has been shown to drive pancreatic neoplasia. However, all attempts to target KRAS directly have failed in the clinic and KRAS is widely assumed to be undruggable. This has led to intense efforts to identify druggable critical downstream targets and nodes orchestrated by mutationally activated KRAS. This includes context-specific KRAS effector pathways, synthetic lethal interaction partners and KRAS-driven metabolic changes. Here, we review recent advances in oncogenic KRAS signalling and discuss how these might benefit PDAC treatment in the future.
Previous functional imaging studies of chronic stroke patients with aphasia suggest that recovery of language occurs in a pre-existing, bilateral network with an upregulation of undamaged areas and a ...recruitment of perilesional tissue and homologue right language areas. The present study aimed at identifying the dynamics of reorganization in the language system by repeated functional MRI (fMRI) examinations with parallel language testing from the acute to the chronic stage. We examined 14 patients with aphasia due to an infarction of the left middle cerebral artery territory and an age-matched control group with an auditory comprehension task in an event-related design. Control subjects were scanned once, whereas patients were scanned repeatedly at three consecutive dates. All patients recovered clinically as shown by a set of aphasia tests. In the acute phase mean: 1.8 days post-stroke (dps), patients' group analysis showed little early activation of non-infarcted left-hemispheric language structures, while in the subacute phase (mean: 12.1 dps) a large increase of activation in the bilateral language network with peak activation in the right Broca-homologue (BHo) was observed. A direct comparison of both examinations revealed the strongest increase of activation in the right BHo and supplementary motor area (SMA). These upregulated areas also showed the strongest correlation between improved language function and increased activation (rBHo = 0.88, rSMA = 0.92). In the chronic phase (mean: 321 dps), a normalization of activation with a re-shift of peak activation to left-hemispheric language areas was observed, associated with further language improvement. The data suggest that brain reorganization during language recovery proceeds in three phases: a strongly reduced activation of remaining left language areas in the acute phase is followed by an upregulation with recruitment of homologue language zones, which correlates with language improvement. Thereafter, a normalization of activation is observed, possibly reflecting consolidation in the language system.
The development dynamics and self-organization of glandular branched epithelia is of utmost importance for our understanding of diverse processes ranging from normal tissue growth to the growth of ...cancerous tissues. Using single primary murine pancreatic ductal adenocarcinoma (PDAC) cells embedded in a collagen matrix and adapted media supplementation, we generate organoids that self-organize into highly branched structures displaying a seamless lumen connecting terminal end buds, replicating in vivo PDAC architecture. We identify distinct morphogenesis phases, each characterized by a unique pattern of cell invasion, matrix deformation, protein expression, and respective molecular dependencies. We propose a minimal theoretical model of a branching and proliferating tissue, capturing the dynamics of the first phases. Observing the interaction of morphogenesis, mechanical environment and gene expression in vitro sets a benchmark for the understanding of self-organization processes governing complex organoid structure formation processes and branching morphogenesis.
Background
Delayed gastric emptying in diabetic mice and humans is associated with changes in macrophage phenotype and loss of interstitial cells of Cajal (ICC) in the gastric muscle layers. In ...diabetic mice, classically activated M1 macrophages are associated with delayed gastric emptying, whereas alternatively activated M2 macrophages are associated with normal gastric emptying. This study aimed to determine if secreted factors from M1 macrophages could injure mouse ICC in primary culture.
Methods
Cultures of gastric ICC were treated with conditioned medium (CM) from activated bone marrow‐derived macrophages (BMDMs) and the effect of CM was quantified by counting ICC per high‐powered field.
Key Results
Bone marrow‐derived macrophages were activated to a M1 or M2 phenotype confirmed by qRT‐PCR. Conditioned medium from M1 macrophages reduced ICC numbers by 41.1%, whereas M2‐CM had no effect as compared to unconditioned, control media. Immunoblot analysis of 40 chemokines/cytokines found 12 that were significantly increased in M1‐CM, including tumor necrosis factor alpha (TNF‐α). ELISA detected 0.697±0.03 ng mL−1 TNF‐α in M1‐CM. Recombinant mouse TNF‐α reduced Kit expression and ICC numbers in a concentration‐dependent manner (EC50 = 0.817 ng mL−1). Blocking M1‐CM TNF‐α with a neutralizing antibody preserved ICC numbers. The caspase inhibitor Z‐VAD.fmk partly preserved ICC numbers (cells/field; 6.63±1.04, 9.82±1.80 w/Z‐VAD.fmk, n=6, P<.05).
Conclusions & Inferences
This work demonstrates that TNF‐α secreted from M1 macrophages can result in Kit loss and directly injure ICC in vitro partly through caspase‐dependent apoptosis and may play an important role in ICC depletion in diabetic gastroparesis.
In diabetic mice, M1 macrophages are associated with delayed gastric emptying, whereas M2 macrophages are associated with normal gastric emptying. TNF‐α, a factor present in M1‐conditioned medium, reduced Kit‐positive ICC numbers and TNF‐α neutralizing antibodies blocked the effect of M1 medium. TNF‐α derived from M1 macrophages injures ICC in vitro and TNF‐α may be important in diseases like diabetic gastroparesis.
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Although histone deacetylase inhibitors (HDACi) are promising cancer therapeutics regulating proliferation, differentiation and apoptosis, molecular pathways engaged by specific HDAC isoenzymes in ...cancer are ill defined.
In this study we demonstrate that HDAC2 is highly expressed in pancreatic ductal adenocarcinoma (PDAC), especially in undifferentiated tumours. We show that HDAC2, but not HDAC1, confers resistance towards the topoisomerase II inhibitor etoposide in PDAC cells. Correspondingly, the class I selective HDACi valproic acid (VPA) synergises with etoposide to induce apoptosis of PDAC cells. Transcriptome profiling of HDAC2-depleted PDAC cells revealed upregulation of the BH3-only protein NOXA. We show that the epigenetically silenced NOXA gene locus is opened after HDAC2 depletion and that NOXA upregulation is sufficient to sensitise PDAC cells towards etoposide-induced apoptosis.
In summary, our data characterise a novel molecular mechanism that links the epigenetic regulator HDAC2 to the regulation of the pro-apoptotic BH3-only protein NOXA in PDAC. Targeting HDAC2 will therefore be a promising strategy to overcome therapeutic resistance of PDAC against chemotherapeutics that induce DNA damage.
Ertugliflozin is a highly selective and potent inhibitor of the sodium‐glucose cotransporter 2 in development for the treatment of type 2 diabetes mellitus. The glycemic efficacy of sodium‐glucose ...cotransporter 2 inhibitors such as ertugliflozin depends on glucose filtration through the kidney. This phase 1, open‐label study evaluated the effect of renal impairment on the pharmacokinetics, pharmacodynamics, and tolerability of ertugliflozin (15 mg) in type 2 diabetes mellitus and healthy subjects with normal renal function (estimated glomerular filtration rate not normalized for body surface area ≥90 mL/min) and type 2 diabetes mellitus subjects with mild (60‐89 mL/min), moderate (30‐59 mL/min), or severe (<30 mL/min) renal impairment (n = 36). Blood and urine samples were collected predose and over 96 hours postdose for pharmacokinetic evaluation and measurement of urinary glucose excretion over 24 hours. Log‐linear regression analyses indicated predicted mean area under the concentration‐time curve values for mild, moderate, and severe renal function groups that were ≤70% higher relative to subjects with normal renal function. Generally consistent results were obtained with categorical analysis based on analysis of variance. The increase in ertugliflozin exposure in subjects with renal impairment is not expected to be clinically meaningful. Regression analysis of change from baseline in urinary glucose excretion over 24 hours vs estimated glomerular filtration rate showed a decrease in urinary glucose excretion with declining renal function. A single 15‐mg dose of ertugliflozin was well tolerated in all groups.
Mutation of p53 is a frequent genetic lesion in pancreatic cancer being an unmet clinical challenge. Mutants of p53 have lost the tumour-suppressive functions of wild type p53. In addition, p53 ...mutants exert tumour-promoting functions, qualifying them as important therapeutic targets. Here, we show that the class I histone deacetylases HDAC1 and HDAC2 contribute to maintain the expression of p53 mutants in human and genetically defined murine pancreatic cancer cells. Our data reveal that the inhibition of these HDACs with small molecule HDAC inhibitors (HDACi), as well as the specific genetic elimination of HDAC1 and HDAC2, reduce the expression of mutant p53 mRNA and protein levels. We further show that HDAC1, HDAC2 and MYC directly bind to the TP53 gene and that MYC recruitment drops upon HDAC inhibitor treatment. Therefore, our results illustrate a previously unrecognized class I HDAC-dependent control of the TP53 gene and provide evidence for a contribution of MYC. A combined approach targeting HDAC1/HDAC2 and MYC may present a novel and molecularly defined strategy to target mutant p53 in pancreatic cancer.
Obesity is associated with increased risk for developing pancreatic cancer, and it is suggested that insulin resistance provides the missing link. Here we demonstrate that under the context of ...genetic susceptibility, a high fat diet (HFD) predisposes mice with oncogenic K-ras activation to accelerated pancreatic intraepithelial neoplasm (PanIN) development. Tumor promotion is closely associated with increased inflammation and abrogation of TNFR1 signaling significantly blocks this process underlining a central role for TNFα in obesity-mediated enhancement of PanIN lesions. Interestingly, however, despite increased TNFα levels, mice remain insulin sensitive. We show that, while aggravating tumor promotion, a HFD exerts dramatic changes in energy metabolism through enhancement of pancreatic exocrine insufficiency, metabolic rates, and expression of genes involved in mitochondrial fatty acid (FA) β-oxidation that collectively contribute to improved glucose tolerance in these mice. While on one hand these findings provide significant evidence that obesity is linked to tumor promotion in the pancreas, on the other it suggests alterations in inflammatory responses and bioenergetic pathways as the potential underlying cause.
Language processing requires the coordinated interaction of local and distant neural populations within distributed networks of the temporal, frontal and parietal brain regions. Poststroke aphasia is ...the consequence of both local as well as remote dysfunction within language-specific and domain-general networks. Language recovery, in turn, rests on reorganization processes within these networks. These comprise the resolution of an acute network failure (i. e. diaschisis), the subacute activation of right hemisphere homologous regions and the gradual reintegration of left hemisphere remote and perilesional areas. The application of unifocal noninvasive brain stimulation over these regions provides a means of modulating neural plasticity in order to enhance the reorganization processes underlying language recovery. The lack of knowledge as to the optimal stimulation site, the appropriate stimulation protocol and the proper timing of interventions might explain the only marginal effects of brain stimulation adjunct to speech and language therapy. In addition, individually different contributions of left and right hemisphere regions to recovery due to heterogeneous lesion sites among patients limit the possibility to identify general principles for brain stimulation. The assumption that aphasia is not only the consequence of the focal effect of a brain lesion but arises from remote dysfunctions within associated functional networks ignites the concept for individualized, potentially multifocal therapeutic network modulation.
As digital video becomes more pervasive, efficient ways of searching and annotating video according to content will be increasingly important. Such tasks arise, for example, in the management of ...digital video libraries for content-based retrieval and browsing. We develop tools based on camera motion for analyzing and annotating a class of structured video using the low-level information available directly from MPEG-compressed video. In particular, we show that in certain structured settings, it is possible to obtain reliable estimates of camera motion by directly processing data easily obtained from the MPEG format. Working directly with the compressed video greatly reduces the processing time and enhances storage efficiency. As an illustration of this idea, we have developed a simple basketball annotation system which combines the low-level information extracted from an MPEG stream with the prior knowledge of basketball structure to provide high-level content analysis, annotation, and browsing for events such as wide-angle and close-up views, fast breaks, probable shots at the basket, etc. The methods used in this example should also be useful in the analysis of high-level content of structured video in other domains.
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