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Pancreatic ductal adenocarcinoma (PDAC) is expected to be the second most deadly cancer by 2040, owing to the high incidence of metastatic disease and limited responses to treatment1,2. Less than half of all patients respond to the primary treatment for PDAC, chemotherapy3,4, and genetic alterations alone cannot explain this5. Diet is an environmental factor that can influence the response to therapies, but its role in PDAC is unclear. Here, using shotgun metagenomic sequencing and metabolomic screening, we show that the microbiota-derived tryptophan metabolite indole-3-acetic acid (3-IAA) is enriched in patients who respond to treatment. Faecal microbiota transplantation, short-term dietary manipulation of tryptophan and oral 3-IAA administration increase the efficacy of chemotherapy in humanized gnotobiotic mouse models of PDAC. Using a combination of loss- and gain-of-function experiments, we show that the efficacy of 3-IAA and chemotherapy is licensed by neutrophil-derived myeloperoxidase. Myeloperoxidase oxidizes 3-IAA, which in combination with chemotherapy induces a downregulation of the reactive oxygen species (ROS)-degrading enzymes glutathione peroxidase 3 and glutathione peroxidase 7. All of this results in the accumulation of ROS and the downregulation of autophagy in cancer cells, which compromises their metabolic fitness and, ultimately, their proliferation. In humans, we observed a significant correlation between the levels of 3-IAA and the efficacy of therapy in two independent PDAC cohorts. In summary, we identify a microbiota-derived metabolite that has clinical implications in the treatment of PDAC, and provide a motivation for considering nutritional interventions during the treatment of patients with cancer.

Purpose Pancreatic ductal adenocarcinoma (PDAC) is a molecularly heterogeneous tumor entity with no clinically established imaging biomarkers. We hypothesize that tumor morphology and physiology, including vascularity and perfusion, show variations that can be detected by differences in contrast agent (CA) accumulation measured non-invasively. This work seeks to establish imaging biomarkers for tumor stratification and therapy response monitoring in PDAC, based on this hypothesis. Methods and materials Regional CA accumulation in PDAC was correlated with tumor vascularization, stroma content, and tumor cellularity in murine and human subjects. Changes in CA distribution in response to gemcitabine (GEM) were monitored longitudinally with computed tomography (CT) Hounsfield Units ratio (HUr) of tumor to the aorta or with magnetic resonance imaging (MRI) ΔR1 area under the curve at 60 s tumor-to-muscle ratio (AUC60r). Tissue analyses were performed on co-registered samples, including endothelial cell proliferation and cisplatin tissue deposition as a surrogate of chemotherapy delivery. Results Tumor cell poor, stroma-rich regions exhibited high CA accumulation both in human (meanHUr 0.64 vs. 0.34, p < 0.001) and mouse PDAC (meanAUC60r 2.0 vs. 1.1, p < 0.001). Compared to the baseline, in vivo CA accumulation decreased specifically in response to GEM treatment in a subset of human (HUr −18%) and mouse (AUC60r −36%) tumors. Ex vivo analyses of mPDAC showed reduced cisplatin delivery (GEM: 0.92 ± 0.5 mg/g, vs. vehicle: 3.1 ± 1.5 mg/g, p = 0.004) and diminished endothelial cell proliferation (GEM: 22.3% vs. vehicle: 30.9%, p = 0.002) upon GEM administration. Conclusion In PDAC, CA accumulation, which is related to tumor vascularization and perfusion, inversely correlates with tumor cellularity. The standard of care GEM treatment results in decreased CA accumulation, which impedes drug delivery. Further investigation is warranted into potentially detrimental effects of GEM in combinatorial therapy regimens.

Suppl. Figure 3. A. Immunoblot of LAMC2 upon Lamc2 knockdown by a specific shRNA in 511950 and PM12167 PDAC mouse cell lines. B. Quantification of organoid number upon LAMC2 knockdown by a specific shRNA in 511950 and PM12167 PDAC mouse cell lines.C. Quantification of organoid area (AU) in same cell lines as in B. Error bars correspond to s.d. D. Immunoblot of LAMC2 upon LAMC2 knockdown in HPAFII cell line. E. Quantification of organoid number and organoid area (AU) in HPAFII cell line expressing a TET-inducible shRNA against LAMC2 (bottom) or a control shRNA (top) cultured in 3D. F. Representative images of the subcutaneous tumors from PATU8902 cells expressing a TET-inducible shRNA against LAMC2 or a control shRNA at sacrifice. G. Representative images of the subcutaneous tumors from HPAFII cells expressing a TET-inducible shRNA against LAMC2 or a control shRNA at sacrifice. H and I. Representative IHC of LAMC2 expression in subcutaneous tumors from PATU8902 (H) and HPAFII (I) cells expressing a TET-inducible shRNA against LAMC2 or a control shRNA at sacrifice J. Representative images of the tumors derived from intrapancreatic injection of PATU8902 cells expressing a TET-inducible shRNA against LAMC2 or a control shRNA at sacrifice. K. Representative images of the subcutaneous tumors from PM12167 mouse cells expressing a shRNA against Lamc2 or a control shRNA at sacrifice. L and M. Representative images of the subcutaneous (sc) tumors from PATU8902 and HPAFII expressing a TET-inducible shRNA against LAMC2 or a control shRNA at sacrifice. ShRNA expression induced after tumor establishment at Day 8. N and O. Representative IHC of LAMC2 expression in subcutaneous tumors (Tx) from PATU8902 (H) and HPAFII (I) cells expressing a TET-inducible shRNA against LAMC2 or a control shRNA, shRNA expression was induced at day 8 of tumor establishment. P. Quantification of Ki67 IHC staining in PATU8902 and HFAFII xenograft models: SC and Tx. Q. Quantification of cleaved caspase3 IHC staining in PATU8902 and HFAFII xenograft models: SC and Tx.

This file includes the Suppl. Methods, Table (1) and References

Purpose:The identification of pancreatic ductal adenocarcinoma (PDAC) dysregulated genes may unveil novel molecular targets entering inhibitory strategies. Laminins are emerging as potential targets in PDAC given their role as diagnostic and prognostic markers. Here, we investigated the cellular, functional, and clinical relevance of LAMC2 and its regulated network, with the ultimate goal of identifying potential therapies.Experimental Design:LAMC2 expression was analyzed in PDAC tissues, a panel of human and mouse cell lines, and a genetically engineered mouse model. Genetic perturbation in 2D, 3D, and in vivo allograft and xenograft models was done. Expression profiling of a LAMC2 network was performed by RNA-sequencing, and publicly available gene expression datasets from experimental and clinical studies examined to query its human relevance. Dual inhibition of pharmacologically targetable LAMC2-regulated effectors was investigated.Results:LAMC2 was consistently upregulated in human and mouse experimental models as well as in human PDAC specimens, and associated with tumor grade and survival. LAMC2 inhibition impaired cell cycle, induced apoptosis, and sensitized PDAC to MEK1/2 inhibitors (MEK1/2i). A LAMC2-regulated network was featured in PDAC, including both classical and quasi-mesenchymal subtypes, and contained downstream effectors transcriptionally shared by the KRAS signaling pathway. LAMC2 regulated a functional FOSL1–AXL axis via AKT phosphorylation. Furthermore, genetic LAMC2 or pharmacological AXL inhibition elicited a synergistic antiproliferative effect in combination with MEK1/2is that was consistent across 2D and 3D human and mouse PDAC models, including primary patient-derived organoids.Conclusions:LAMC2 is a molecular target in PDAC that regulates a transcriptional network that unveils a dual drug combination for cancer treatment.

Nanostring PanCancer Immune profiling analysis and validation.

Supplementary figure legends and supplementary tables

Supplementary Figure 1. Summary and survival of murine cohort used in the study. Supplementary Figure 2 Consort diagram of the patient distribution of surgical subcohort 1. Supplementary Figure 3. Consort diagram of the patient distribution of surgical subcohort 2. Supplementary Figure 4. Consort diagram of the patient distribution of surgical subcohort 3. Supplementary Figure 5. Schematic of relative tumor cell and stroma contribution in PDAChigh Supplementary Table 1. Statistics of the patients used in surgical subcohort 1. Supplementary Table 2. Statistics of the patients used in surgical subcohort 2. Supplementary Table 3. Statistics of the patients used in surgical subcohort 3. Supplementary Table 4. Results of a multivariable Cox regression model fit to the data of subcohort 2 that assess whether PDAC is associated with overall survival after adjustment for common predictors. Supplementary Table 5. The permutation test analysis revealing association between overall survival and lowest ADC stratified by each of the relevant categorical variables. Data used for analysis are derived from surgical subcohort 3.

Purpose: Tumor heterogeneity is a hallmark of pancreatic ductal adenocarcinoma (PDAC). It determines tumor biology including tumor cellularity (i.e., amount of neoplastic cells and arrangement into clusters), which is related to the proliferative capacity and differentiation and the degree of desmoplasia among others. Given the close relation of tumor differentiation with differences in progression and therapy response or, e.g., the recently reported protective role of tumor stroma, we aimed at the noninvasive detection of PDAC groups, relevant for future personalized approaches. We hypothesized that histologic differences in PDAC tissue composition are detectable by the noninvasive diffusion weighted- (DW-) MRI-derived apparent diffusion coefficient (ADC) parameter.Experimental design: PDAC cellularity was quantified histologically and correlated with the ADC parameter and survival in genetically engineered mouse models and human patients.Results: Histologic analysis showed an inverse relationship of tumor cellularity and stroma content. Low tumor cellularity correlated with a significantly prolonged mean survival time (PDAClow = 21.93 months vs. PDACmed = 12.7 months; log-rank P < 0.001; HR = 2.23; CI, 1.41–3.53). Multivariate analysis using the Cox regression method confirmed tumor cellularity as an independent prognostic marker (P = 0.034; HR = 1.73; CI, 1.04–2.89). Tumor cellularity showed a strong negative correlation with the ADC parameter in murine (r = −0.84; CI, −0.90– −0.75) and human (r = −0.79; CI, −0.90 to −0.56) PDAC and high preoperative ADC values correlated with prolonged survival (ADChigh = 41.7 months; ADClow = 14.77 months; log rank, P = 0.040) in PDAC patients.Conclusions: This study identifies high tumor cellularity as a negative prognostic factor in PDAC and supports the ADC parameter for the noninvasive identification of PDAC groups. Clin Cancer Res; 23(6); 1461–70. ©2016 AACR.

Despite advances in our understanding of the genetics of pancreatic ductal adenocarcinoma (PDAC), the efficacy of therapeutic regimens targeting aberrant signaling pathways remains highly limited. Therapeutic strategies are greatly hampered by the extensive desmoplasia that comprises heterogeneous cell populations. Notch signaling is a contentious pathway exerting opposite roles in tumorigenesis depending on cellular context. Advanced model systems are needed to gain more insights into complex signaling in the multilayered tumor microenvironment. In this study, we employed a dual recombinase-based in vivo strategy to modulate Notch signaling specifically in myeloid cells to dissect the tumorigenic role of Notch in PDAC stroma. Pancreas-specific KrasG12D activation and loss of Tp53 was induced using a Pdx1-Flp transgene, whereas Notch signaling was genetically targeted using a myeloid-targeting Lyz2-Cre strain for either activation of Notch2-IC or deletion of Rbpj. Myeloid-specific Notch activation significantly decreased tumor infiltration by protumorigenic M2 macrophages in spontaneous endogenous PDAC, which translated into significant survival benefit. Further characterization revealed upregulated antigen presentation and cytotoxic T effector phenotype upon Notch-induced M2 reduction. This approach is the first proof of concept for genetic targeting and reprogramming of myeloid cells in a complex disease model of PDAC and provides evidence for a regulatory role of Notch signaling in intratumoral immune phenotypes.Significance: This study provides insight into the role of myeloid-dependent NOTCH signaling in PDAC and accentuates the need to dissect differential roles of signaling pathways in different cellular components within the tumor microenvironment. Cancer Res; 78(17); 4997–5010. ©2018 AACR.

Supplemental Methods, Supplemental Figure legends Figure S1, Figure S2, Figure S3, Figure S4, Figure S5, Figure S6, Figure S7

Supplemental Figures S5A,B,C. Figure S5A: NIRF imaging of CT26 tumors (s.c.) and tumor to background ratios (TBR). Figure S5B: NIRF imaging of 4T1 tumors (o.t.)and TBR. Figure S5C: NIRF imaging of 4T1-derived metastases and TBR.

Purpose:The identification of pancreatic ductal adenocarcinoma (PDAC) dysregulated genes may unveil novel molecular targets entering inhibitory strategies. Laminins are emerging as potential targets in PDAC given their role as diagnostic and prognostic markers. Here, we investigated the cellular, functional, and clinical relevance of LAMC2 and its regulated network, with the ultimate goal of identifying potential therapies.Experimental Design:LAMC2 expression was analyzed in PDAC tissues, a panel of human and mouse cell lines, and a genetically engineered mouse model. Genetic perturbation in 2D, 3D, and in vivo allograft and xenograft models was done. Expression profiling of a LAMC2 network was performed by RNA-sequencing, and publicly available gene expression datasets from experimental and clinical studies examined to query its human relevance. Dual inhibition of pharmacologically targetable LAMC2-regulated effectors was investigated.Results:LAMC2 was consistently upregulated in human and mouse experimental models as well as in human PDAC specimens, and associated with tumor grade and survival. LAMC2 inhibition impaired cell cycle, induced apoptosis, and sensitized PDAC to MEK1/2 inhibitors (MEK1/2i). A LAMC2-regulated network was featured in PDAC, including both classical and quasi-mesenchymal subtypes, and contained downstream effectors transcriptionally shared by the KRAS signaling pathway. LAMC2 regulated a functional FOSL1–AXL axis via AKT phosphorylation. Furthermore, genetic LAMC2 or pharmacological AXL inhibition elicited a synergistic antiproliferative effect in combination with MEK1/2is that was consistent across 2D and 3D human and mouse PDAC models, including primary patient-derived organoids.Conclusions:LAMC2 is a molecular target in PDAC that regulates a transcriptional network that unveils a dual drug combination for cancer treatment.

Background: Pancreatic Ductal Adenocarcinoma (PDAC) lacks effective treatment options beyond chemotherapy. Although molecular subtypes such as classical and QM (quasi-mesenchymal)/basal-like with transcriptome-based distinct signatures have been identified, deduced therapeutic strategies and targets remain elusive. Gene expression data show enrichment of glycolytic genes in the more aggressive and therapy resistant QM subtype. However, whether the glycolytic transcripts are translated into functional glycolysis that could further be explored for metabolic targeting in QM subtype is still not known. Methods: We used different patient-derived PDAC model systems (conventional and primary patient derived cells, patient derived xenografts (PDX) and patient FFPE samples) and performed transcriptional and functional metabolic analysis. These included: RNAseq and Illumina HT12 bead array, in vitro Seahorse metabolic flux assays and metabolic drug targeting, and in vivo hyperpolarized [1-13C]pyruvate and [1-13C]lactate magnetic resonance spectroscopy (HP-MRS) in PDAC xenografts. Results: We found that glycolytic metabolic dependencies are not unambiguously functionally exposed in all QM PDACs. Metabolic analysis demonstrated functional metabolic heterogeneity in patient-derived primary cells and less so in conventional cell lines independent of molecular subtype. Importantly, we observed that the glycolytic product lactate is actively imported in the PDAC cells and used in mitochondrial oxidation in both classical and QM PDAC cells, although more actively in the QM cell lines. By using hyperpolarized 13C-magnetic resonance spectroscopy (HP-MRS), we were able to non-invasively identify highly glycolytic PDAC xenografts by detecting the last glycolytic enzymatic step and prominent intra-tumoral [1‑13C]pyruvate and [1-13C]lactate interconversion in vivo.Conclusion: Our study adds functional metabolic phenotyping to transcriptome-based analysis and proposes a functional approach to identify highly glycolytic PDACs as candidates for anti-metabolic therapeutic avenues.

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with poor prognosis. Drug resistance is the major cause for therapeutic failure in PDAC patients with progressive disease. The mechanisms underlying resistance formation are complex and remain poorly understood.To gain insights into molecular changes during the formation of resistance to oncogenic MAPK pathway inhibition we utilized short-term passaged primary tumor cells from ten PDACs of genetically engineered mice. We followed gain and loss of resistance upon MEKi exposure and withdrawal by longitudinal integrative analysis of whole genome sequencing, whole genome bisulfite sequencing, RNA-sequencing and mass spectrometry data.We found that resistant cell populations under increasing MEKi treatment evolved by the expansion of a single clone but were not a direct consequence of known resistance-conferring mutations. Rather, resistant cells showed adaptive DNA hypermethylation of 209 and hypomethylation of 8 genomic sites, most of which overlap with regulatory elements known to be active in murine PDAC cells. Both DNA methylation changes and MEKi resistance were transient and reversible upon drug withdrawal. The effector caspase CASP3 is one of the 114 genes for which transcriptional downregulation inversely correlated with the methylation status of the associated DNA region. CASP3 inactivation in resistant cells led to attenuation of drug-induced apoptosis which could be reversed by DNA methyltransferase inhibition with remarkable sensitivity exclusively in the resistant cells.Overall, our data provide a context for characterization and targeting of epigenetically mediated resistance mechanisms in PDAC.

Pancreatic ductal adenocarcinoma (PDAC) is resistant to virtually all chemo- and targeted therapeutic approaches. Epigenetic regulators represent a novel class of drug targets. Among them, BET and HDAC proteins are central regulators of chromatin structure and transcription, and preclinical evidence suggests effectiveness of combined BET and HDAC inhibition in PDAC. Here, we describe that TW9, a newly generated adduct of the BET inhibitor (+)-JQ1 and class I HDAC inhibitor CI994, is a potent dual inhibitor simultaneously targeting BET and HDAC proteins. TW9 has a similar affinity to BRD4 bromodomains as (+)-JQ1 and shares a conserved binding mode, but is significantly more active in inhibiting HDAC1 compared to the parental HDAC inhibitor CI994. TW9 was more potent in inhibiting tumor cell proliferation compared to (+)-JQ1, CI994 alone or combined treatment of both inhibitors. Sequential administration of gemcitabine and TW9 showed additional synergistic antitumor effects. Microarray analysis revealed that dysregulation of a FOSL1-directed transcriptional program contributed to the antitumor effects of TW9. Our results demonstrate the potential of a dual chromatin-targeting strategy in the treatment of PDAC and provide a rationale for further development of multitarget inhibitors.

The NETTER-1, VISION, and TheraP trials proved the efficacy of repeat intravenous application of small radioligands. Application by subcutaneous, intraperitoneal, or oral routes is an important alternative and may yield comparable or favorable organ and tumor radioligand uptake. Here, we assessed organ and tumor biodistribution for various radioligand application routes in healthy mice and models of cancer expressing somatostatin receptor (SSTR), prostate-specific membrane antigen (PSMA), and fibroblast activation protein (FAP). Methods: Healthy and tumor-bearing male C57BL/6 or NOD SCID γ-mice, respectively, were administered a mean of 6.0 ± 0.5 MBq of (68)Ga-DOTATOC (RM1-SSTR allograft), 5.3 ± 0.3 MBq of (68)Ga-PSMA11 (RM1-PSMA allograft), or 4.8 ± 0.2 MBq of (68)Ga-FAPI46 (HT1080-FAP xenograft) by intravenous, intraperitoneal, subcutaneous, or oral routes. In vivo PET images and ex vivo biodistribution in tumor, organs, and the injection site were assessed up to 5 h after injection. Healthy mice were monitored for up to 7 d after the last scan for signs of stress or adverse reactions. Results: After intravenous, intraperitoneal, and subcutaneous radioligand administration, average residual activity at the injection site was less than 17 percentage injected activity per gram (%IA/g) at 1 h after injection, less than 10 %IA/g at 2 h after injection, and no more than 4 %IA/g at 4 h after injection for all radioligands. After oral administration, at least 50 %IA/g remained within the intestines until 4 h after injection. Biodistribution in organs of healthy mice was nearly equivalent after intravenous, intraperitoneal, and subcutaneous application at 1 h after injection and all subsequent time points (≤1 %IA/g for liver, blood, and bone marrow; 11.2 ± 1.4 %IA/g for kidneys). In models for SSTR-, PSMA- and FAP-expressing cancer, tumor uptake was increased or equivalent for intraperitoneal/subcutaneous versus intravenous injection at 5 h after injection (ex vivo): SSTR, 7.2 ± 1.0 %IA/g (P = 0.0197)/6.5 ± 1.3 %IA/g (P = 0.0827) versus 2.9 ± 0.3 %IA/g, respectively; PSMA, 3.4 ± 0.8 %IA/g (P = 0.9954)/3.9 ± 0.8 %IA/g (P = 0.8343) versus 3.3 ± 0.7% IA/g, respectively; FAP, 1.1 ± 0.1 %IA/g (P = 0.9805)/1.1 ± 0.1 %IA/g (P = 0.7446) versus 1.0 ± 0.2 %IA/g, respectively. Conclusion: In healthy mice, biodistribution of small theranostic ligands after intraperitoneal/subcutaneous application is nearly equivalent to that after intravenous injection. Subcutaneous administration resulted in the highest absolute SSTR tumor and tumor-to-organ uptake as compared with the intravenous route, warranting further clinical assessment.

The in vivo assessment of tissue metabolism represents a novel strategy for the evaluation of oncologic disease. Hepatocellular carcinoma (HCC) is a high-prevalence, high-mortality tumor entity often discovered at a late stage. Recent evidence indicates that survival differences depend on metabolic alterations in tumor tissue, with particular focus on glucose metabolism and lactate production. Here, we present an in vivo imaging technique for metabolic tumor phenotyping in rat models of HCC. Endogenous HCC was induced in Wistar rats by oral diethyl-nitrosamine administration. Peak lactate-to-alanine signal ratios (L/A) were assessed with hyperpolarized magnetic resonance spectroscopic imaging (HPMRSI) after [1

The sodium iodide symporter (SLC5A5/NIS) as theranostic gene would allow for non-invasive imaging of functional NIS expression and therapeutic radioiodine application. Genetically engineered mesenchymal stem cells (MSC), based on their tumor-homing abilities, show great promise as tumor-selective NIS gene delivery vehicles for non-thyroidal tumors. As a next step towards clinical application, tumor specificity and efficacy of MSCs were investigated in an advanced genetically engineered mouse model of pancreatic ductal adenocarcinoma (PDAC). Syngeneic murine MSCs were stably transfected with a NIS-expressing plasmid driven by the CMV-promoter (NIS-MSC). In vivo 123I-scintigraphy and 124I-PET revealed significant perchlorate-sensitive NIS-mediated radioiodide accumulation in PDAC after systemic injection of NIS-MSCs. Active MSC recruitment into the tumor stroma was confirmed using NIS immunohistochemistry (IHC). A therapeutic strategy, consisting of three cycles of systemic MSC-mediated NIS delivery, followed by 131I application, resulted in a significant delay and reduction in tumor growth as compared to controls. Furthermore, IHC analysis of α-SMA and Ki67 revealed differences in the amount and behavior of activated fibroblasts in tumors of mice injected with NIS-MSCs as compared with saline-treated mice. Taken together, MSCs as NIS gene delivery vehicles in this advanced endogenous PDAC mouse model demonstrated high stromal targeting of NIS by selective recruitment of NIS-MSCs after systemic application resulting in an impressive 131I therapeutic effect. Implications: These data expand the prospect of MSC-mediated radioiodine imaging-guided therapy of pancreatic cancer using the sodium iodide symporter as a theranostic gene in a clinical setting.

Oncogenic KRAS mutations are encountered in more than 90% of pancreatic ductal adenocarcinomas. MEK inhibition has failed to procure any clinical benefits in mutant RAS-driven cancers including pancreatic ductal adenocarcinoma (PDAC). To identify potential resistance mechanisms underlying MEK inhibitor (MEKi) resistance in PDAC, we investigated lysosomal drug accumulation in PDAC models both in vitro and in vivo. Mouse PDAC models and human PDAC cell lines as well as human PDAC xenografts treated with the MEK inhibitor trametinib or refametinib led to an enhanced expression of lysosomal markers and enrichment of lysosomal gene sets. A time-dependent, increase in lysosomal content was observed upon MEK inhibition. Strikingly, there was a strong activation of lysosomal biogenesis in cell lines of the classical compared to the basal-like molecular subtype. Increase in lysosomal content was associated with nuclear translocation of the Transcription Factor EB (TFEB) and upregulation of TFEB target genes. siRNA-mediated depletion of TFEB led to a decreased lysosomal biogenesis upon MEK inhibition and potentiated sensitivity. Using LC-MS, we show accumulation of MEKi in the lysosomes of treated cells. Therefore, MEK inhibition triggers lysosomal biogenesis and subsequent drug sequestration. Combined targeting of MEK and lysosomal function may improve sensitivity to MEK inhibition in PDAC.

Binding of transcription factors to mutated DNA sequences is a likely regulator of cancer progression. Noncoding regulatory mutations such as those on the core promoter of the gene encoding human telomerase reverse transcriptase have been shown to affect gene expression in cancer. Using a protein microarray of 667 transcription factor DNA-binding domains and subsequent functional assays, we looked for transcription factors that preferentially bind the mutant hTERT promoter and characterized their downstream effects. One of them, friend leukemia integration 1 (FLI1), which belongs to the E26 transforming-specific family of transcription factors, exhibited particularly strong effects with respect to regulating hTERT expression, while the even better binding ELK3 did not. Depletion of FLI1 decreased expression of the genes for cyclin D1 (CCND1) and E2F transcription factor 2 (E2F2) resulting in a G1/S cell cycle arrest and in consequence a reduction of cell proliferation. FLI1 also affected CMTM7, another gene involved in G1/S transition, although by another process that suggests a balanced regulation of the tumor suppressor gene's activity via opposing regulation processes. FLI1 expression was found upregulated and correlated with an increase in CCND1 expression in pancreatic cancer and brain tumors. In non-neoplastic lung cells, however, FLI1 depletion led to rapid progression through the cell cycle. This coincides with the fact that FLI1 is downregulated in lung tumors. Taken together, our data indicate a cell cycle regulatory hub involving FLI1, hTERT, CCND1 and E2F2 in a tissue- and context-dependent manner.

// Kathrin A. Schmohl 1, * , Aayush Gupta 2, * , Geoffrey K. Grunwald 1, * , Marija Trajkovic-Arsic 3, 4 , Kathrin Klutz 1 , Rickmer Braren 5 , Markus Schwaiger 6 , Peter J. Nelson 7 , Manfred Ogris 8 , Ernst Wagner 9 , Jens T. Siveke 2, 3, 4 and Christine Spitzweg 1 1 Department of Internal Medicine II and IV, University Hospital of Munich, LMU Munich, Munich, Germany 2 Department of Internal Medicine II, Klinikum rechts der Isar der Technischen Universitat Munchen, Munich, Germany 3 Division of Solid Tumor Translational Oncology, West German Cancer Center, University Hospital Essen, Essen, Germany 4 German Cancer Consortium (DKTK), Partner Site Essen and German Cancer Research Center (DKFZ), Heidelberg, Germany 5 Department of Radiology, Klinikum rechts der Isar der Technischen Universitat Munchen, Munich, Germany 6 Department of Nuclear Medicine, Klinikum rechts der Isar der Technischen Universitat Munchen, Munich, Germany 7 Clinical Biochemistry Group, Department of Internal Medicine IV, University Hospital of Munich, LMU Munich, Munich, Germany 8 Department of Pharmaceutical Chemistry, Laboratory of MacroMolecular Cancer Therapeutics (MMCT), University of Vienna, Vienna, Austria 9 Pharmaceutical Biotechnology, Department of Pharmacy, Center for System-Based Drug Research and Center for Nanoscience, LMU Munich, Munich, Germany * These authors have contributed equally to this work Correspondence to: Christine Spitzweg, email: christine.spitzweg@med.uni-muenchen.de Keywords: gene therapy, sodium iodide symporter, EGFR-targeting, pancreatic ductal adenocarcinoma, genetically engineered mouse model Received: October 13, 2016 Accepted: February 27, 2017 Published: March 23, 2017 ABSTRACT The theranostic sodium iodide symporter (NIS) gene allows detailed molecular imaging of transgene expression and application of therapeutic radionuclides. As a crucial step towards clinical application, we investigated tumor specificity and transfection efficiency of epidermal growth factor receptor (EGFR)-targeted polyplexes as systemic NIS gene delivery vehicles in an advanced genetically engineered mouse model of pancreatic ductal adenocarcinoma (PDAC) that closely reflects human disease. PDAC was induced in mice by pancreas-specific activation of constitutively active Kras G12D and deletion of Trp53 . We used tumor-targeted polyplexes (LPEI-PEG-GE11/NIS) based on linear polyethylenimine, shielded by polyethylene glycol and coupled with the EGFR-specific peptide ligand GE11, to target a NIS -expressing plasmid to high EGFR-expressing PDAC. In vitro iodide uptake studies in cell explants from murine EGFR-positive and EGFR-ablated PDAC lesions demonstrated high transfection efficiency and EGFR-specificity of LPEI-PEG-GE11/NIS. In vivo 123 I gamma camera imaging and three-dimensional high-resolution 124 I PET showed significant tumor-specific accumulation of radioiodide after systemic LPEI-PEG-GE11/NIS injection. Administration of 131 I in LPEI-PEG-GE11/NIS-treated mice resulted in significantly reduced tumor growth compared to controls as determined by magnetic resonance imaging, though survival was not significantly prolonged. This study opens the exciting prospect of NIS-mediated radionuclide imaging and therapy of PDAC after systemic non-viral NIS gene delivery.

Pancreatic ductal adenocarcinoma (PDAC) remains a devastating disease with a very poor prognosis. At the same time, its incidence is on the rise, and PDAC is expected to become the second leading cause of cancer-related death by 2030. Despite extensive work on new therapeutic approaches, the median overall survival is only 6-12 months after diagnosis and the 5-year survival is less than 7%. While pancreatic cancer is particularly difficult to treat, patients usually succumb not to the growth of the primary tumor, but to extensive metastasis; therefore, strategies to reduce the migratory and metastatic capacity of pancreatic cancer cells merit close attention. The vast majority of pancreatic cancers harbor RAS mutations. The outstanding relevance of the RAS/MEK/ERK pathway in pancreatic cancer biology has been extensively shown previously. Due to their high dependency on Ras mutations, pancreatic cancers might be particularly sensitive to inhibitors acting downstream of Ras. Herein, we use a genetically engineered mouse model of pancreatic cancer and primary pancreatic cancer cells were derived from this model to demonstrate that small-molecule MEK inhibitors functionally abrogate cancer stem cell populations as demonstrated by reduced sphere and organoid formation capacity. Furthermore, we demonstrate that MEK inhibition suppresses TGFβ-induced epithelial-to-mesenchymal transition and migration in vitro and ultimately results in a highly significant reduction in circulating tumor cells in mice., P.C.H. is supported by a Max Eder Fellowship of the German Cancer Aid (111746) and by a Hector Foundation Cancer Research grant (M65.1). P.C.H. and J.M. are supported by a Collaborative Research Centre grant of the German Research Foundation (316249678–SFB 1279). J.T.S. is supported by the European Union Framework Programme 7 for research, technological development, and demonstration (FP7/CAM-PaC) under grant agreement no. 602783, the German Cancer Consortium (DKTK), and the Deutsche Forschungsgemeinschaft (DFG; KFO337/SI 1549/3-1). B.S., Jr., was funded by a Rámon y Cajal Merit Award from the Ministerio de Economía y Competitividad, Spain, and a coordinated grant from the Fundación Asociación Española Contra el Cáncer (AECC, GC16173694BARB).

Aberrations within the PI3K/AKT signaling axis are frequently observed in numerous cancer types, highlighting the relevance of these pathways in cancer physiology and pathology. However, therapeutic interventions employing AKT inhibitors often suffer from limitations associated with target selectivity, efficacy, or dose-limiting effects. Here we present the first crystal structure of autoinhibited AKT1 in complex with the covalent-allosteric inhibitor borussertib, providing critical insights into the structural basis of AKT1 inhibition by this unique class of compounds. Comprehensive biological and preclinical evaluation of borussertib in cancer-related model systems demonstrated a strong antiproliferative activity in cancer cell lines harboring genetic alterations within the PTEN, PI3K, and RAS signaling pathways. Furthermore, borussertib displayed antitumor activity in combination with the MEK inhibitor trametinib in patient-derived xenograft models of mutant KRAS pancreatic and colon cancer. Significance: Borussertib, a first-in-class covalent-allosteric AKT inhibitor, displays antitumor activity in combination with the MEK inhibitor trametinib in patient-derived xenograft models and provides a starting point for further pharmacokinetic/dynamic optimization.

MYCN is a transcription factor that is aberrantly expressed in many tumor types and is often correlated with poor patient prognosis. Recently, several lines of evidence pointed to the fact that oncogenic activation of MYC family proteins is concomitant with reprogramming of tumor cells to cope with an enhanced need for metabolites during cell growth. These adaptions are driven by the ability of MYC proteins to act as transcriptional amplifiers in a tissue-of-origin specific manner. Here, we describe the effects of MYCN overexpression on metabolic reprogramming in neuroblastoma cells. Ectopic expression of MYCN induced a glycolytic switch that was concomitant with enhanced sensitivity towards 2-deoxyglucose, an inhibitor of glycolysis. Moreover, global metabolic profiling revealed extensive alterations in the cellular metabolome resulting from overexpression of MYCN. Limited supply with either of the two main carbon sources, glucose or glutamine, resulted in distinct shifts in steady-state metabolite levels and significant changes in glutathione metabolism. Interestingly, interference with glutamine-glutamate conversion preferentially blocked proliferation of MYCN overexpressing cells, when glutamine levels were reduced. Thus, our study uncovered MYCN induction and nutrient levels as important metabolic master switches in neuroblastoma cells and identified critical nodes that restrict tumor cell proliferation.

Aberrations within the PI3K/AKT signaling axis are frequently observed in numerous cancer types, highlighting the relevance of these pathways in cancer physiology and pathology. However, therapeutic interventions employing AKT inhibitors often suffer from limitations associated with target selectivity, efficacy, or dose-limiting effects. Here we present the first crystal structure of autoinhibited AKT1 in complex with the covalent-allosteric inhibitor borussertib, providing critical insights into the structural basis of AKT1 inhibition by this unique class of compounds. Comprehensive biological and preclinical evaluation of borussertib in cancer-related model systems demonstrated a strong antiproliferative activity in cancer cell lines harboring genetic alterations within the PTEN, PI3K, and RAS signaling pathways. Furthermore, borussertib displayed antitumor activity in combination with the MEK inhibitor trametinib in patient-derived xenograft models of mutant

The sodium iodide symporter (

Despite advances in our understanding of the genetics of pancreatic ductal adenocarcinoma (PDAC), the efficacy of therapeutic regimens targeting aberrant signaling pathways remains highly limited. Therapeutic strategies are greatly hampered by the extensive desmoplasia that comprises heterogeneous cell populations. Notch signaling is a contentious pathway exerting opposite roles in tumorigenesis depending on cellular context. Advanced model systems are needed to gain more insights into complex signaling in the multilayered tumor microenvironment. In this study, we employed a dual recombinase-based in vivo strategy to modulate Notch signaling specifically in myeloid cells to dissect the tumorigenic role of Notch in PDAC stroma. Pancreas-specific KrasG12D activation and loss of Tp53 was induced using a Pdx1-Flp transgene, whereas Notch signaling was genetically targeted using a myeloid-targeting Lyz2-Cre strain for either activation of Notch2-IC or deletion of Rbpj. Myeloid-specific Notch activation significantly decreased tumor infiltration by protumorigenic M2 macrophages in spontaneous endogenous PDAC, which translated into significant survival benefit. Further characterization revealed upregulated antigen presentation and cytotoxic T effector phenotype upon Notch-induced M2 reduction. This approach is the first proof of concept for genetic targeting and reprogramming of myeloid cells in a complex disease model of PDAC and provides evidence for a regulatory role of Notch signaling in intratumoral immune phenotypes. Significance: This study provides insight into the role of myeloid-dependent NOTCH signaling in PDAC and accentuates the need to dissect differential roles of signaling pathways in different cellular components within the tumor microenvironment. Cancer Res; 78(17); 4997–5010. ©2018 AACR.

Although in vivo targeting of tumors using fluorescently labeled probes has greatly gained in importance over the last few years, most of the clinically applied reagents lack tumor cell specificity. Our novel tumor cell–penetrating peptide-based probe (TPP) recognizes an epitope of Hsp70 that is exclusively present on the cell surface of a broad variety of human and mouse tumors and metastases, but not on normal tissues. Because of the rapid turnover rate of membrane Hsp70, fluorescently labeled TPP is continuously internalized into syngeneic, spontaneous, chemically/genetically induced and xenograft tumors following intravenous administration, thereby enabling site-specific labeling of primary tumors and metastases. In contrast with the commercially available nonpeptide small molecule αvβ3-integrin antagonist IntegriSense, TPP exhibits a significantly higher tumor-to-background contrast and stronger tumor-specific signal intensity in all tested tumor models. Moreover, in contrast with IntegriSense, TPP reliably differentiates between tumor cells and cells of the tumor microenvironment, such as tumor-associated macrophages and fibroblasts, which were found to be membrane-Hsp70 negative. Therefore, TPP provides a useful tool for multimodal imaging of tumors and metastases that might help to improve our understanding of tumorigenesis and allow the establishment of improved diagnostic procedures and more accurate therapeutic monitoring. TPP might also be a promising platform for tumor-specific drug delivery and other Hsp70-based targeted therapies. Cancer Res; 74(23); 6903–12. ©2014 AACR.

Recent advances in molecular subtyping of Pancreatic Ductal Adenocarcinoma (PDAC) support individualization of therapeutic strategies in this most aggressive disease. With the emergence of various novel therapeutic strategies and neoadjuvant approaches in this quickly deteriorating disease, robust approaches for fast evaluation of therapy response are urgently needed. To this aim, we designed a preclinical imaging-guided therapy trial where genetically engineered mice harboring endogenous aggressive PDAC were treated with the MEK targeting drug refametinib, which induces rapid and profound tumor regression in this model system. Multi-parametric non-invasive imaging was used for therapy response monitoring. A significant increase in the Diffusion-Weighted Magnetic Resonance Imaging derived Apparent Diffusion Coefficient (ADC) was noted already 24 hours after treatment onset. Histopathological analyses showed increased apoptosis and matrix remodeling at this time point. Our findings suggest the ADC parameter as an early predictor of therapy response in PDAC.

The implementation of hybrid fluorescence molecular tomography (FMT) and X-ray computed tomography (CT) has been shown to be a necessary development, not only for combining anatomical with functional and molecular contrast, but also for generating optical images of high accuracy. FMT affords highly sensitive 3-D imaging of fluorescence bio-distribution, but in stand-alone form it offers images of low resolution. It was shown that FMT accuracy significantly improves by considering anatomical priors from CT. Conversely, CT generally suffers from low soft tissue contrast. Therefore utilization of CT data as prior information in FMT inversion is challenging when different internal organs are not clearly differentiated. Instead, we combined herein FMT with emerging X-ray phase-contrast CT (PCCT). PCCT relies on phase shift differences in tissue to achieve soft tissue contrast superior to conventional CT. We demonstrate for the first time FMT-PCCT imaging of different animal models, where FMT and PCCT scans were performed in vivo and ex vivo, respectively. The results show that FMT-PCCT expands the potential of FMT in imaging lesions with otherwise low or no CT contrast, while retaining the cost benefits of CT and simplicity of hybrid device realizations. The results point to the most accurate FMT performance to date.

Purpose Tumor cells, in contrast to normal cells, frequently overexpress heat shock protein 70 (Hsp70) in the cytosol, present it on their cell surface, and actively release it. Therefore, soluble Hsp70 (sHsp70) was investigated as a potential tumor biomarker for monitoring the outcome of radiation therapy. Methods and Materials Plasma from mice bearing membrane Hsp70 (mHsp70)-positive FaDu human squamous cell carcinoma of the head and neck and spontaneous pancreatic ductal adenocarcinoma (PDAC) was investigated. A cohort of mice with FaDu tumors (0.32 cm 3 ) was irradiated with 30 Gy, and plasma was collected 24 hours after irradiation, after the tumors had shrunk to 50% of their starting volume and after complete remission. sHsp70 levels in the plasma were quantified by enzyme-linked immunosorbent assay. Results sHsp70 levels were significantly higher in the blood of tumor-bearing mice than that of control animals. A correlation between increasing sHsp70 plasma levels and tumor volume in the range of 0.01 cm 3 to 0.66 cm 3 was observed. Radiation-induced regression of the tumors was associated with significantly decreased sHsp70 levels, which returned to the level of control animals after complete remission. Conclusion We propose sHsp70 as an innovative biomarker for detecting tumors and for monitoring the clinical outcome of radiation therapy in cancer patients.