Mechanisms of synergistic agonist stimulation and modulation of the electrochemical driving force for anion secretion are still not fully explored in human pancreatic duct epithelial cells. The first ...objective of this study was therefore to test whether combined agonist stimulation augments anion transport responses in the Capan-1 monolayer model of human pancreatic duct epithelium. The second objective was to test the influence of H
+
,K
+
-ATPase inhibition on anion transport in Capan-1 monolayers. The third objective was to analyze the expression and function of K
+
channels in Capan-1, which could support anion secretion and cooperate with H
+
,K
+
-ATPases in pH and potassium homeostasis. The human pancreatic adenocarcinoma cell line Capan-1 was cultured conventionally or as polarized monolayers that were analyzed by Ussing chamber electrophysiological recordings. Single-cell intracellular calcium was assayed with Fura-2. mRNA isolated from Capan-1 was analyzed by use of the nCounter assay or RT-PCR. Protein expression was assessed by immunofluorescence and western blot analyses. Combined stimulation with different physiological agonists enhanced anion transport responses compared to single agonist stimulation. The responsiveness of Capan-1 cells to histamine was also revealed in these experiments. The H
+
,K
+
-ATPase inhibitor omeprazole reduced carbachol- and riluzole-induced anion transport responses. Transcript analyses revealed abundant TASK-2, TWIK-1, TWIK-2, TASK-5, K
Ca3.1
, and KCNQ1 mRNA expression. KCNE1 mRNA and TREK-1, TREK-2, TASK-2, and KCNQ1 protein expression were also shown. This study shows that the Capan-1 model recapitulates key physiological aspects of a bicarbonate-secreting epithelium and constitutes a valuable model for functional studies on human pancreatic duct epithelium.
Pancreatic ductal adenocarcinoma (PDAC) represents the most common form of pancreatic cancer with rising incidence in developing countries. Unfortunately, the overall 5-year survival rate is still ...less than 5%. The most frequent oncogenic mutations in PDAC are loss-of function mutations in p53 and gain-of-function mutations in KRAS. Here we show that clofazimine (Lamprene), a drug already used in the clinic for autoimmune diseases and leprosy, is able to efficiently kill in vitro five different PDAC cell lines harboring p53 mutations. We provide evidence that clofazimine induces apoptosis in PDAC cells with an EC50 in the µM range via its specific inhibitory action on the potassium channel Kv1.3. Intraperitoneal injection of clofazimine resulted in its accumulation in the pancreas of mice 8 hours after administration. Using an orthotopic PDAC xenotransplantation model in SCID beige mouse, we show that clofazimine significantly and strongly reduced the primary tumor weight. Thus, our work identifies clofazimine as a promising therapeutic agent against PDAC and further highlights ion channels as possible oncological targets.
TNF-like weak inducer of apoptosis, TWEAK, is a typical member of the TNF ligand family. Thus, it is initially expressed as a type II transmembrane protein from which a soluble variant can be ...released by proteolytic processing. In this study, we show that membrane TWEAK is superior to soluble variant of TWEAK (sTWEAK) with respect to the activation of the classical NF-kappaB pathway, whereas both TWEAK variants are potent inducers of TNFR-associated factor-2 depletion, NF-kappaB-inducing kinase accumulation and p100 processing, hallmarks of activation of the noncanonical NF-kappaB pathway. Like other soluble TNF ligands with a poor capability to activate their corresponding receptor, sTWEAK acquires an activity resembling those of the transmembrane ligand by oligomerization or cell surface-immobilization. Blockade of the Fn14 receptor inhibited NF-kappaB signaling irrespective of the TWEAK form used for stimulation, indicating that the differential activities of the two TWEAK variants on classical and noncanonical NF-kappaB signaling is not related to the use of different receptors.
With the development of increasingly sophisticated three-dimensional volumetric imaging methods, tumor volume can serve as a robust and reproducible measurement of drug efficacy. Since the use of ...molecularly targeted agents in the clinic will almost certainly involve combinations with other therapeutic modalities, the use of volumetric determination can help to identify a dosing schedule of sequential combinations of cytostatic drugs resulting in long term control of tumor growth with minimal toxicity. The aim of this study is to assess high resolution sonography imaging for the in vivo monitoring of efficacy of Infliximab in pancreatic tumor.
In the first experiment, primary orthotopic pancreatic tumor growth was measured with Infliximab treatment. In the second experiment, orthotopic tumors were resected ten days after inoculation of tumor cells and tumor recurrence was measured following Infliximab treatment. Tumor progression was evaluated using 3D high resolution sonography.
Sonography measurement of tumor volume in vivo showed inhibitory effect of Infliximab on primary tumor growth in both non-resected and resected models. Measurement of the dynamics of tumor growth by sonography revealed that in the primary tumor Infliximab is effective against established tumors while in the resection model, Infliximab is more effective at an early stage following tumor resection. Infliximab treatment is also effective in inhibiting tumor growth growth as a result of tumor cell contamination of the surgical field.
Clinical application of Infliximab is feasible in both the neoadjuvant and adjuvant setting. Infliximab is also effective in slowing the growth of tumor growth under the peritoneum and may have application in treating peritoneal carcinomatosis. Finally the study demonstrates that high resolution sonography is a sensitive imaging modality for the measurement of pancreatic tumor growth.
Upon ligand binding, plasma membrane–located TNF-related apoptosis-inducing ligand (TRAIL)–receptors 1 and 2 induce apoptosis as well as cancer-promoting signaling in cancer cells. TRAIL-R3 and ...TRAIL-R4 are believed to negatively regulate TRAIL-mediated apoptosis. Intracellular localization of TRAIL-receptors, as observed in many tumor cells, has been associated with oncogenic features, which are distinct from membrane-associated TRAIL-R signaling. Here, analyzing a panel of 354 breast cancer specimens, we found that an unfavorable outcome correlating with cancer-promoting properties of TRAIL-R1, TRAIL-R2, and TRAIL-R4 was most significantly defined by their intracellular distribution and mutual co-expression. A nuclear or cytoplasmic heterogeneous expression pattern correlated with markedly decreased overall survival and discriminated high-risk breast cancer patients from low-risk patients with a homogeneous distribution of expression, i.e., nuclear and cytoplasmic expression. The homogeneous TRAIL-R expression was associated with favorable breast cancer surrogate markers corresponding with excellent survival prognoses at 5 years after diagnosis (hazard ratio, 0.043) and over the complete course of follow-up (hazard ratio, 0.098; both
p
< 0.001). No associations with specific intrinsic breast cancer subtypes were found. Our data suggest that the determination of intracellular co-expression patterns of TRAIL-R1, TRAIL-R2, and TRAIL-R4 provides an innovative and robust method for risk stratification in breast cancer patients beyond conventional prognostic markers.
Key messages
A total of 70% of breast cancer specimens show comparably high levels of intracellular TRAIL-Rs.
Nuclear or cytoplasmic TRAIL-R co-expression occurs in the majority of tumors.
A total of 25% of tumors show a heterogeneous expression of cytoplasmic or nuclear TRAIL-Rs.
Patients with a heterogeneous TRAIL-R expression present with poor prognoses.
Additive TRAIL-R-based risk stratification comprises different breast cancer subtypes.
Tumor necrosis factor related apoptosis-inducing ligand (TRAIL) and agonistic anti-DR4/TRAIL-R1 and anti-DR5/TRAIL-R2 antibodies are currently under clinical investigation for treatment of different ...malignancies. TRAIL activates DR4 and DR5 and thereby triggers apoptotic and non-apoptotic signaling pathways, but possible different roles of DR4 or DR5 in these responses has poorly been addressed so far. In the present work, we analyzed cell viability, DISC formation as well as IL-8 and NF–κB activation side by side in responses to TRAIL and agonistic antibodies against DR4 (mapatumumab) and against DR5 (lexatumumab) in pancreatic ductal adenocarcinoma cells. We found that all three reagents are able to activate cell death and pro-inflammatory signaling. Death-inducing signaling complex (DISC) analysis revealed that mapatumumab and lexatumumab induce formation of homocomplexes of either DR4 or DR5, whereas TRAIL additionally stimulated the formation of heterocomplexes of both receptors. Notably, blocking of receptors using DR4- and DR5-specific Fab fragments indicated that TRAIL exerted its function predominantly via DR4. Interestingly, inhibition of PKC by Goe6983 enabled DR5 to trigger apoptotic signaling in response to TRAIL and also strongly enhanced lexatumumab-mediated cell death. Our results suggest the existence of mechanisms that silence DR5 for TRAIL- but not for agonistic-antibody treatment.
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has raised attention as a novel anticancer therapeutic as it induces apoptosis preferentially in tumor cells. However, first-generation ...TRAIL-receptor agonists (TRAs), comprising recombinant TRAIL and agonistic receptor-specific antibodies, have not demonstrated anticancer activity in clinical studies. In fact, cancer cells are often resistant to conventional TRAs. Therefore, in addition to TRAIL-sensitizing strategies, next-generation TRAs with superior apoptotic activity are warranted. APG350 is a novel, highly potent TRAIL-receptor agonist with a hexavalent binding mode allowing the clustering of six TRAIL-receptors per drug molecule. Here we report on preclinical in vitro and in vivo studies testing the activity of APG350 on pancreatic ductal adenocarcinoma (PDAC) cells. We found that APG350 potently induced apoptosis of Colo357, PancTuI and Panc89 cells in vitro. In addition, APG350 treatment activated non-canonical TRAIL signaling pathways (MAPK, p38, JNK, ERK1/ERK2 and NF-κB) and induced the secretion of IL-8. Stable overexpression of Bcl-xL inhibited APG350-induced cell death and augmented activation of non-canonical pathways. Intriguingly, pre-treatment of Bcl-xL-overexpressing cells with the BH3-mimic Navitoclax restored their sensitivity to APG350. To study the effects of APG350 on PDAC cells in vivo, we applied two different orthotopic xenotransplantation mouse models, with and without primary tumor resection, representing adjuvant and palliative treatment regimes, respectively. APG350 treatment of established tumors (palliative treatment) significantly reduced tumor burden. These effects, however, were not seen in tumors with enforced overexpression of Bcl-xL. Upon primary tumor resection and subsequent APG350 treatment (adjuvant therapy), APG350 limited recurrent tumor growth and metastases. Importantly, therapeutic efficacy of APG350 treatment was more effective compared with treatment with soluble TRAIL in both models. In conclusion, APG350 represents a promising next-generation TRA for the treatment of PDAC. Moreover, our results suggest that combining APG350 with Navitoclax might be a succesfull strategy for cancers harboring mitochondrial apoptosis resistance.
Abstract
Since the first description of CD95/Fas this member of the death receptor superfamily has been regarded as paradigmatic for death receptors, capable of induction of caspase-driven apoptosis. ...More recently, CD95 has also emerged as an inducer of other signaling pathways including pro-inflammatory and migratory mechanisms (for an overview see Roeder C. et al., Eur J Cell Biol. 2011). Previously, we demonstrated a strong induction of NFkB activity after CD95 stimulation of pancreatic cancer cells resulting in increased invasiveness under in vitro conditions. Inhibition of CD95 mediated mechanisms in tumor gains importance since malignant cells may misuse this system for progression as demonstrated by others eg. for ovarian cancer and glioblastoma. From a clinical point of view, several observations also point into the same direction. Studies on colorectal cancer, head and neck, hepatocellular carcinoma for example suggest CD95 ligand expression to correlate negatively with patients prognosis.
APG101 is an inhibitor of CD95 ligand consisting of the CD95 receptor extracellular domain fused to the Fc domain of IgG. A randomized controlled phase II ‘proof-of-concept’ study in patients with recurrent glioblastoma was successfully completed recently (NCT01071837). Up to date there exist no in vivo studies concerning the influence of blocking the interaction between CD95 and its ligand using this recombinant inhibitor in pancreatic cancer. Thus we tested this novel tool in a palliative and adjuvant orthotopic xenotransplantation model of human pancreatic cancer.
In this study PancTuI Luc cells were used, which establish a highly infiltrating primary tumor with very low/no metastatic capacity in the liver. All mice (n=8/group) survived the operative procedures for the palliative treatment and were randomly assigned into five groups: control group; treatment with different concentrations of APG101: 12.5, 25, 50, and 100 µg/g bw. (i.p. injection, twice per week). Upon tumor resection (2/3rd pancreatectomy 10 days after tumor cell inoculation) local as well as distant recurrent disease (primarily in the liver) is regularly observed. All mice surviving the operative procedures for the adjuvant treatment (n=9/group) were randomly assigned into two groups: control group with 200 µl saline 0.9 % i.p. and the APG 101 group with a dose of 25 µg/g bw i.p (twice a week). Treatment was started three days after subtotal pancreatectomy and lasted for 28 days until sacrifice of the animals.
Palliative treatment: mean tumor weight was 353 ± 179 mg for animals in the control group compared to 210.4 ± 86.5 mg to the mice treated with 25 µg APG101/g bw (p = 0.09) and 221.4 ± 94 mg (p = 0.021) in the group treated with 50 µg APG101/g bw Tumor volume was significantly reduced in all treatment groups, again with 25 µg APG101/g bw achieving maximal growth inhibition. Within the 4 weeks no metastases occurred in any group as previously observed within this model.
Adjuvant treatment: All mice developed recurrent tumors. The mean weight of locally recurrent tumor was 887.5 ± 467.3 mg in the control group (treated with 0.9% saline). The other group treated with APG101 (25 µg/g bw) showed a local tumor recurrence with a significant lower tumor weight (p=0.027). The average number of metastases per mouse in the therapy group was 2.3 versus 4 metastases / mouse in the control group.
Reduced tumor growth in both therapeutic settings was reflected by a reduced Ki67 proliferation index.
Our data underline the importance of the CD95 antagonist APG101 as a new option in pancreatic cancer therapy that might be further evaluated also in combination with chemotherapies.
Note: These results were published in the International Journal of Cancer as a full-length article before the online publication of this abstract. Citation information: Inhibition of IL-6 signaling significantly reduces primary tumor growth and recurrencies in orthotopic xenograft models of pancreatic cancer. Goumas FA, Holmer R, Egberts JH, Gontarewicz A, Heneweer C, Geisen U, Hauser C, Mende MM, Legler K, Röcken C, Becker T, Waetzig GH, Rose-John S, Kalthoff H. Int J Cancer. 2015 Jan 21. doi: 10.1002/ijc.29445. Epub ahead of print PMID: 25604508.
Citation Format: Freya Goumas, Khalid Rhashid, Anna Trauzold, Harald Fricke, Michael Kluge, Thomas Becker, Jan Egberts, Holger Kalthoff. The CD95 ligand inhibitor APG 101 reduces tumor recurrence and metastasis in an adjuvant orthotopic mouse model of pancreatic cancer as well as primary tumor load in a palliative setting. abstract. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr A115.
The novel early response gene p22/PRG1 is linked to cell cycle entry and the induction of proliferation in various cell types although its exact function is still unknown. The p22/PRG1 promoter ...region contains a 20 bp sequence matching the consensus binding motif for the tumor suppressor protein p53. Gel shift assays demonstrated that p53 specifically binds to an oligonucleotide derived from the p53 binding site of the p22/PRG1 promoter. Chloramphenicol acetyltransferase (CAT) reporter gene assays confirmed that this site confers p53-dependent transcriptional activity to the p22/PRG1 promoter. In Hela cells, p22/PRG1 promoter constructs induced CAT expression only when cotransfected with an expression plasmid for wild-type, but not for mutant p53. Similarly, CAT expression was inducible at the permissive (31 degrees C) but not at the non-permissive temperature (39 degrees C) in the rat embryo fibroblast-derived cell line clone-6 that expresses a temperature-sensitive mutant p53. Conversion of this mutant p53 to a functional p53 at the permissive temperature was accompanied by a significant increase of endogenous p22/PRG1 mRNA level in this cell line. Gamma-irradiation of rat splenocytes or doxorubicin-treatment of Hela cells increased p53 levels followed by transcriptional activation of p22/PRG1 and p21/Waf1 in parallel. Our data demonstrate that p22/PRG1 transcription is induced by p53 during p53-dependent cell cycle arrest and apoptosis. Therefore, p22/PRG1 represents a novel target for transcriptional activation by p53.
Pancreatic ductal adenocarcinoma (PDAC) is characterized by both, overexpression of transforming growth factor (TGF)β and resistance of the tumor cells to many apoptosis-inducing stimuli. The latter ...negatively impacts the outcome of therapeutic efforts and represents one important mechanism which tumor cells utilize to escape the immune surveillance. Since TGFβ acts as a tumor promoter in advanced tumor stages and suppression of apoptosis is a known driver of tumor progression, it is possible that TGFβ functions as a crucial determinant of tumor cell sensitivity to apoptosis in PDAC. Here, we have studied the impact of TGFβ on TNF-related apoptosis inducing ligand (TRAIL)-induced signaling in PDAC cells. In TGFβ-responsive Panc1 and Colo357 cells, TGFβ1 reduced total and plasma membrane-associated levels of TRAIL-R1 but not those of TRAIL-R2. Consistent with the known predominant role of TRAIL-R1 in TRAIL-mediated signaling in PDAC, TGFβ1 inhibited TRAIL-induced DISC formation and apoptosis as well as phosphorylation of MAPKs and IκBα. Similarly, it also reduced signaling of TRAIL-R1 following its specific activation with an agonistic antibody. In contrast, specific TRAIL-R2 signaling remained unchanged. The TGFβ1 effect on TRAIL-R1 expression was mimicked by ectopic expression of a kinase-active version of the TGFβ type I receptor ALK5 (ALK5-T204D) but not by ALK5 double mutant lacking the ability to phosphorylate Smad proteins (RImL45-T204D). Moreover, TGFβ regulation of TRAIL-R1 was absent in two PDAC cell lines lacking the Smad4 gene DPC4 and siRNA-mediated silencing of Smad4 in Smad4-positive Panc1 cells abolished the TGFβ-mediated decrease in TRAIL-R1 expression, together showing that ALK5/Smad4 signaling is crucial for TGFβ regulation of TRAIL-R1 expression. Our results suggest a novel tumor-promoting function of TGFβ1. By downregulating TRAIL-R1, TGFβ1 may not only promote tumor escape from immune surveillance but also negatively impact on TRAIL- or TRAIL-R1-based therapy regimens for treatment of PDAC.
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