A modified random oligonucleotide-based combination therapy for adjuvant treatment of pancreatic ductal adenocarcinoma

Anti-cancer therapy in pancreatic ductal adenocarcinoma (PDAC) is mostly based on surgical removal or palliative therapy using antimetabolites, like 5'-fluorouracil or gemcitabine. Adjuvant treatment using these chemotherapeutics has recently proven a beneficial concept, though general survival rates are still poor. Most recently, combination therapy of gemcitabine with other targeted drugs was evaluated in clinical trials. We present here a study performed in a mouse orthotopic xenotransplant model of PDAC, using an oligo-nucleotide-based approach. We have shown previously that antisense oligonucleotides against p53 reduce the weight of orthotopic pancreatic tumours in immune-deficient mice. We further characterised terminal modifications of phosphorothioate oligonucleotides in vitro and found a random, unrelated control sequence carrying a D,L-alpha-tocopherol modification at the 5' and 3' ends to be most efficient in induction of cell death in PancTu-1 cells. Modified random oligonucleotide (MRON) were thus further tested in vivo. MRON showed a reduction of tumour weight in established primary orthotopic tumours in SCID/bg mice. In a surgically adapted pre-clinical model, where primary tumours were resected and animals received adjuvant treatment, MRON was very efficient in suppression of relapse and metastasis, when combined with gemcitabine. While the exact molecular mechanism of MRON activity still needs to be elucidated, the compound showed a remarkable preference for uptake into tumour cells in vivo.     

Stable expression of temperature-sensitive p53: a suitable model to study wild-type p53 function in pancreatic carcinoma cells

Pancreatic adenocarcinoma is an extremely aggressive malignancy with a dismal prognosis. Inactivation of the p53 tumor-suppressor gene occurs in approximately 50% of primary tumors and is thought to account for a failure of the tumor cells to undergo growth arrest and apoptosis in response to chemotherapy. Hence, it is of interest to study the consequences of the restoration of wild-type (wt) p53 function in pancreatic carcinoma cells. Therefore, we retrovirally transduced temperature-sensitive (ts) human p53 into the p53-null pancreatic carcinoma cell line AsPC-1. ts p53 has a mutant phenotype at 37.5 degrees C, and a wt conformation at 32.5 degrees C. Stable expression of p53 in wt conformation caused upregulation of the p53 responsive gene p21Waf1/Cip1, and G1 growth arrest, but failed to induce Bax expression or apoptosis. In addition, we examined the effect of wt p53 expression on DNA damaging treatment. Interestingly, the doxorubicin- and radiation-induced S-/G2-phase arrests were suppressed by p53 in wt conformation. These results demonstrate that the ts p53/AsPC-1 model is suitable to investigate the effect of wt p53 restoration in pancreatic carcinoma cells.     

Meta-analysis of microarray data on pancreatic cancer defines a set of commonly dysregulated genes

Pancreatic ductal adenocarcinoma is the eighth most common cancer with the lowest overall 5-year relative survival rate of any tumor type today. Expression profiling using microarrays has been widely used to identify genes associated with pancreatic cancer development. To extract maximum value from the available gene expression data, we applied a meta-analysis to search for commonly differentially expressed genes in pancreatic ductal adenocarcinoma. We obtained data sets from four different gene expression studies on pancreatic cancer. We selected a consensus set of 2984 genes measured in all four studies and applied a meta-analysis approach to evaluate the combined data. Of the genes identified as differentially expressed, several were validated using RT-PCR and immunohistochemistry. Additionally, we used a class discovery algorithm to identify a gene expression signature. Our meta-analysis revealed that the pancreatic cancer gene expression data sets shared a significant number of up- and downregulated genes, independent of the technology used. This interstudy crossvalidation approach generated a set of 568 genes that were consistently and significantly dysregulated in pancreatic cancer. Of these, 364 (64.1%) were upregulated and 204 (35.9%) were downregulated in pancreatic cancer. Only 127 (22%) were described in the published individual analyses. Functional annotation of the genes revealed that genes presumably associated with the cell adhesion-mediated drug resistance pathway are frequently overexpressed in pancreatic cancer. Meta-analysis is an important tool for the identification and validation of differentially expressed genes. These could represent good candidates for novel diagnostic and therapeutic approaches to pancreatic cancer.     

Parasitological and morphological findings in porcine isosporosis after treatment with symmetrical triazintriones

Neonatal porcine isosporosis is known to cause serious economic losses in piglet farms by causing severe enteritis with dehydration, weight loss and reduced development in the affected animals, predominantly during the first weeks of life. In the present study, piglets experimentally infected with Isospora suis were treated with Bay Vi 9143, a symmetrical triazintrione, at different days post-infection. As shown by clinical and pathological examinations, Bay Vi 9143 is effective against the asexual and sexual stages of I. suis at all selected treatment times. However, the therapeutic use at an early stage of asexual multiplication is most effective before the onset of clinical symptoms.     

A comprehensive characterization of pancreatic ductal carcinoma cell lines: towards the establishment of an in vitro research platform

There are a large number of stable pancreatic ductal carcinoma cell lines that are used by researchers worldwide. Detailed data about their differentiation status and growth features are, however, often lacking. We therefore attempted to classify commonly used pancreatic carcinoma cell lines according to defined cell biological criteria. Twelve pancreatic ductal adenocarcinoma cell lines were cultured as monolayers and spheroids and graded according to their ultrastructural features. The grading system was based on the integrity of membrane structures and on the presence of mucin granules, cell organelles, nuclear and cellular polymorphism, cell polarity, and lumen formation. On the basis of the resulting scores the cell lines were classified as well, moderately, or poorly differentiated. In addition, immunocytochemistry was performed for the markers cytokeratin 7, 8, 18, 19, carcinoembryonic antigen, MUC1 MUC2, MUC5, and MUC6. The population doubling time of monolayer cultures, determined by a tetrazolium salt based proliferation assay was correlated with the ultrastructural grade. The grading of the ultrastructural features of the monolayers, and particularly of the spheroids, revealed that Capan-1 and Capan-2 cells were well differentiated; Colo357, HPAF-2, Aspc-1, A818-4, BxPc3, and Panc89 cells were moderately differentiated and PancTu-I, Panc1, Pt45P1, and MiaPaCa-2 cells poorly differentiated. Membrane-bound MUC1 staining was a characteristic of well differentiated cell lines. The population doubling time of the monolayer cultures was related to the differentiation grade. No relationship was found between the p53, K-ras, DPC4/Smad4, or p16(INK4a) mutation status and the grade of differentiation. We conclude that the proposed ultrastructural grading system combined with the proliferative activity provides a basis for further comparative studies of pancreatic ductal adenocarcinoma cell lines.     

Pimecrolimus and tacrolimus differ in their inhibition of lymphocyte activation during the sensitization phase of contact hypersensitivity

BACKGROUND: As reported previously, oral administration of the calcineurin inhibitors (CNI) pimecrolimus and tacrolimus resulted in equipotent inhibition of the elicitation phase of contact hypersensitivity (CHS) in mice. The sensitization phase was inhibited by tacrolimus but was unaffected by pimecrolimus, even at higher doses. OBJECTIVE: The kinetics of lymph node hyperplasia and up-regulation of T and B cell activation antigens were analyzed to obtain a better understanding of the divergent CNI profile in CHS. METHODS: Lymph node (LN) cells of CNI-untreated and treated mice were examined with flow cytometry at various time points after sensitization with oxazolone. LN hyperplasia and drug levels were also determined. RESULTS: Sensitization induced a higher portion of LN cells expressing the activation antigens CD25, CD69 and CD134 and an increase in activated B cells (B220(+)/CD40(+)) compared to na?ve mice. Up-regulation of these markers was completely or profoundly blocked with tacrolimus, whereas pimecrolimus at the three-fold higher dose caused significantly less inhibition. Tacrolimus also completely blocked the sensitization-associated increase of CD11c(+) antigen presenting cells (APC) in LN, whereas pimecrolimus showed significantly less inhibition. In contrast to tacrolimus, LN weight and cellularity were not affected by pimecrolimus at any time point after sensitization. Concentration of tacrolimus in blood and in the draining LN substantially exceeded that of pimecrolimus by factors 6.7-14 and 5.6-5.8, respectively, at the same dose levels. CONCLUSION: In contrast to tacrolimus, systemic treatment of mice with pimecrolimus only weakly interferes with lymphocyte activation and does not affect hyperplasia of the draining lymph nodes during sensitization.     

Pimecrolimus inhibits up-regulation of OX40 and synthesis of inflammatory cytokines upon secondary T cell activation by allogeneic dendritic cells

Pimecrolimus is a new non-steroidal inhibitor of T cell and mast cell activation. In the present study, we compared the potency of pimecrolimus and cyclosporin A (CyA) to inhibit cytokine synthesis of alloantigen-primed T cells and the expression of CD134 (OX40), an inducible co-receptor molecule thought to be critical for the survival and expansion of inflammation-mediating T cells. To mimic the physiological situation of recurrent antigenic stimulation, we have used dendritic cells (DC) as stimulators of purified CD4+ T cells in the primary and secondary allogeneic mixed lymphocyte culture (allo-MLC). Pimecrolimus inhibited surface expression of OX40 and prevented the up-regulation of CD25 and CD54 with a 10-fold higher potency compared to CyA. Similarly, 50% inhibition of allo-DC-mediated T cell proliferation by pimecrolimus was obtained at 0.55 nm, compared to about 12 nm for CyA. Furthermore, pimecrolimus blocked the increase of OX40 on primed T cells restimulated on day 10 in secondary allo-MLC. Allo-DC-primed T cells showed a restricted cytokine profile characterized by the production of TNF-alpha, IFN-gamma and IL-2 but low to undetectable levels of IL-4 and IL-10. The synthesis of TNF-alpha and IFN-gamma and the up-regulation of OX40 on T cells after secondary allogeneic stimulation were almost entirely blocked by 10 nm pimecrolimus. Taken together, pimecrolimus inhibits T cell proliferation and Th1 cytokine synthesis and also prevents the up-regulation of the OX40 co-receptor on primed T cells indicating its potential in the therapy of chronic inflammation and autoimmunity.     

Granulocyte-macrophage colony-stimulating factor (GM-CSF) has opposing effects on the capacity of monocytes versus monocyte-derived dendritic cells to stimulate the antigen-specific proliferation of a human T cell clone

GM-CSF is widely used in combination with IL-4 to differentiate monocytes into potent T cell stimulatory cells, referred to as monocyte-derived dendritic cells (MoDC). These cytokines further increased the stimulatory function of MoDC when present during their incubation with antigen, as determined by the proliferative response of an allergen-specific T cell clone. Conversely, the incubation of freshly isolated monocytes with antigen in the presence of GM-CSF or GM-CSF and IL-4 strongly inhibited the specific stimulation of the T cells, compared with monocytes pulsed in the absence of cytokines. This suppression was partly due to the secretion of prostaglandin E2 (PGE2) and IL-10 by GM-CSF-treated monocytes, since the combined use of indomethacin and anti-IL-10 antibodies during GM-CSF incubation and antigen pulsing restored T cell growth to about 65% of control levels. As confirmed by culture supernatant transfer experiments, maximal inhibition of T cell stimulation was also dependent on the direct contact between the T cells and GM-CSF-treated monocytes during antigen presentation. Collectively, these results imply that GM-CSF can either inhibit or enhance the re-stimulation of primed T cells by antigen-presenting monocytes or MoDC, respectively.     

Shedding of endogenous MHC class I‐related chain molecules A and B from different human tumor entities: Heterogeneous involvement of the “a disintegrin and metalloproteases” 10 and 17

The interaction of the MHC class I‐related chain molecules A and B (MICA and MICB) with the corresponding natural killer group 2, member D (NKG2D) receptor triggers cytotoxic effector activity of natural killer cells and certain T‐cell subsets and provides a costimulatory signal for cytokine production. Thus, the presence of MICA/B on transformed cells contributes to tumor immunosurveillance. Consequently, the proteolytic cleavage of MICA/B is regarded as an important immune escape mechanism of various cancer cells. To investigate the molecular machinery responsible for the shedding of endogenous MICA/B, we analyzed different human tumor entities including mammary, pancreatic and prostate carcinomas. Flow cytometry and enzyme‐linked immunosorbent assay (ELISA) revealed that all tested tumor cells constitutively expressed MICA and MICB on the cell surface and also released NKG2D ligands into the supernatant. We demonstrate that the “a disintegrin and metalloproteases” (ADAMs) 10 and 17 are largely responsible for the generation of soluble MICA/B. Pharmacological inhibition of metalloproteases reduced the level of released MICA/B and increased cell surface expression. Studies using RNA interference not only revealed a prominent role of ADAM10 and ADAM17 in NKG2D ligand shedding but also a tumor cell‐specific role of ADAM10 and/or ADAM17 in shedding of MICA or MICB. Moreover, we report that in the prostate carcinoma cell line PC‐3, MICA was not shed at all but rather was secreted in exosomes. These data indicate that the release of NKG2D ligands from individual tumor entities is by far more complex than suggested in previously reported MICA/B transfection systems.