EPI-X4, a CXCR4 antagonist inhibits tumor growth in pancreatic cancer and lymphoma models

Endogenous peptide inhibitor for CXCR4 (EPI-X4) is a CXCR4 antagonist with potential for cancer therapy. It is a processed fragment of serum albumin from the hemofiltrate of dialysis patients. This study reports the efficacy of fifteen EPI-X4 derivatives in pancreatic cancer and lymphoma models. In vitro, the peptides were investigated for antiproliferation (cytotoxicity) by MTT assay. The mRNA expression for CXCR4 and CXCL12 was determined by RT-PCR, chip array and RNA sequencing. Chip array analysis yielded 634 genes associated with CXCR4/CXCL12 signaling. About 21% of these genes correlated with metastasis in the context of cell motility, proliferation, and survival. Expression levels of these genes were altered in pancreatic cancer (36%), lymphoma models (53%) and in patients' data (58%). EPI-X4 derivatives failed to inhibit cell proliferation due to low expression of CXCR4 in vitro, but inhibited tumor growth in the bioassays with significant efficacy. In the pancreatic cancer model, EPI-X4a, f and k inhibited mean tumor growth by > 50% and even caused complete remissions. In the lymphoma model, EPI-X4b, n and p inhibited mean tumor growth by > 70% and caused stable disease. Given the non-toxic and non-immunogenic properties of EPI-X4, these findings underscore its status as a promising therapy of pancreatic cancer and lymphoma and warrant further studies. SIMPLE SUMMARY: This study examined the value of chemokine receptor CXCR4 as an antineoplastic target for the endogenous peptide inhibitor of CXCR4 (EPI-X4), a 12-meric peptide derived from serum albumin. EPI-X4 inhibits CXCR4 interaction with its natural ligand, CXCL12 (SDF1). Therefore, malignancies (including pancreatic cancer and lymphoma) that depend on the CXCR4/CXCL12 pathway for progression can be targeted with EPI-X4. Of 634 genes that were linked to the CXCR4/CXCL12 pathway, 21% were associated with metastasis. In cultured human Suit2-007 pancreatic cancer cells, CXCR4 showed low to undetectable expression, which was why EPI-X4 did not inhibit pancreatic cancer cell proliferation. These findings were different in vivo, where CXCR4 was highly expressed and EPI-X4 inhibited tumor growth in rodents harboring pancreatic cancer or lymphoma. In the pancreatic cancer model, EPI-X4 derivatives a, f and k caused complete remissions, while in lymphomas EPI-X4 derivatives b, n and p caused stable disease.

Hosing of a Long Relativistic Particle Bunch in Plasma

Experimental results show that hosing of a long particle bunch in plasma can be induced by wakefields driven by a short, misaligned preceding bunch. Hosing develops in the plane of misalignment, self-modulation in the perpendicular plane, at frequencies close to the plasma electron frequency, and are reproducible. Development of hosing depends on misalignment direction, its growth on misalignment extent and on proton bunch charge. Results have the main characteristics of a theoretical model, are relevant to other plasma-based accelerators and represent the first characterization of hosing.

Expression profiling of anticancer genes in colorectal cancer patients and their in vitro induction by riproximin, a ribosomal inactivating plant protein

BACKGROUND

Ectopic expression of anticancer genes (ACGs) imposes antineoplastic effects on transformed cells. Clinically, reduced expression of these genes has been linked with poor prognosis, metastasis and chemo/radiotherapy resistance in cancers. Identifying expression pattern of ACGs is crucial to establish their prognostic and therapeutic relevance in colorectal cancer (CRC). In addition to the clinical perspective, naturally occurring compounds can be explored in parallel for inducing ACGs to achieve cancer cell-specific death.

METHODOLOGY

Expression profiles of three ACGs (NOXA, PAR-4, TRAIL) were identified via real-time PCR in CRC clinical isolates. Time lapse-based expression modifications in ACGs were studied in a CRC liver metastasis animal model using microarray methodology. Effects of a purified plant protein (riproximin) on selected ACGs were identified in three primary and metastatic CRC cell lines by real-time PCR. Lastly, importance of the ACGs in a cellular environment was highlighted via bioinformatic analysis.

RESULTS

ACGs (except NOXA) were persistently downregulated in clinical isolates when comparing the overall mean expression values with normal mucosa levels. In vivo studies showed a prominent inhibition of NOXA and PAR-4 genes in implanted CRC cells during rat liver colonization. TRAIL showed deviation from this theme while showing marked induction during the early period of liver colonization (days 3 and 6 after CRC cell implantation). Riproximin exhibited substantial potential of inducing ACGs at transcriptome levels in selected CRC cell lines. Bioinformatic analysis showed that vital molecular/functional aspects of a cell are associated with the presence of ACGs.

CONCLUSION

ACGs are downregulated in primary and metastatic phase of CRC. Riproximin effectively induces ACGs in CRC cells and can be exploited for clinical investigations over time.

Controlled Growth of the Self-Modulation of a Relativistic Proton Bunch in Plasma

A long, narrow, relativistic charged particle bunch propagating in plasma is subject to the self-modulation (SM) instability. We show that SM of a proton bunch can be seeded by the wakefields driven by a preceding electron bunch. SM timing reproducibility and control are at the level of a small fraction of the modulation period. With this seeding method, we independently control the amplitude of the seed wakefields with the charge of the electron bunch and the growth rate of SM with the charge of the proton bunch. Seeding leads to larger growth of the wakefields than in the instability case.

The collagenase of the bacterium Clostridium histolyticum does not favor metastasis of breast cancer

BACKGROUND

Breast cancer is the most common malignancy among women worldwide. As survival rates increase, breast reconstruction and quality of life gain importance. Of all women undergoing breast reconstruction, approximately, 70% opt for silicone implants and 50% of those develop capsular contracture, the most prevalent long-term complication. The collagenase of the bacterium Clostridium histolyticum (CCH) showed promising results in the therapy of capsule contracture; however, its influence on residual cancer cells is unknown. The aim of this study was to investigate whether CCH-treatment negatively impacts breast cancer cells in vitro and in vivo.

METHODS

MDA-MB-231 and MCF-7 cells were used in this study. In vitro, we tested the influence of CCH on proliferation, wound healing, migration and cell cycle by MTT-assay, scratch-assay, transwell-migration-assay, and flow cytometry. In vivo, solid tumors were induced in immune-deficient mice. CCH was injected into the tumors and tumor growth and metastasis formation was monitored by caliper measurement, in vivo bioluminescence imaging and histology. Gene expression analysis was performed by microarray including 27,190 genes.

RESULTS

CCH-incubation led to a dose-dependent reduction in proliferation for both cell lines, while wound healing was reduced only in MDA-MB-231 cells. No morphological alterations were monitored in cell cycle or apoptosis. In vivo, bioluminescence imaging and histology did not show any evidence of metastasis. Although CCH led to changes in gene expression of breast cancer cells, no relevant alterations in metastasis-related genes were monitored.

CONCLUSION

CCH has no impact on tumor growth or metastasis formation in vitro and in vivo. This paves the way for first clinical trials.

Transition between Instability and Seeded Self-Modulation of a Relativistic Particle Bunch in Plasma

We use a relativistic ionization front to provide various initial transverse wakefield amplitudes for the self-modulation of a long proton bunch in plasma. We show experimentally that, with sufficient initial amplitude [≥(4.1±0.4)  MV/m], the phase of the modulation along the bunch is reproducible from event to event, with 3%-7% (of 2π) rms variations all along the bunch. The phase is not reproducible for lower initial amplitudes. We observe the transition between these two regimes. Phase reproducibility is essential for deterministic external injection of particles to be accelerated.

Proton Bunch Self-Modulation in Plasma with Density Gradient

We study experimentally the effect of linear plasma density gradients on the self-modulation of a 400 GeV proton bunch. Results show that a positive or negative gradient increases or decreases the number of microbunches and the relative charge per microbunch observed after 10 m of plasma. The measured modulation frequency also increases or decreases. With the largest positive gradient we observe two frequencies in the modulation power spectrum. Results are consistent with changes in wakefields' phase velocity due to plasma density gradients adding to the slow wakefields' phase velocity during self-modulation growth predicted by linear theory.

Riproximin Exhibits Diversity in Sugar Binding, and Modulates some Metastasis-Related Proteins with Lectin like Properties in Pancreatic Ductal Adenocarcinoma

Riproximin (Rpx) is a type II ribosome-inactivating protein with specific anti-proliferative activity. It was purified from Ximenia americana by affinity chromatography using a resin coupled with lactosyl residues. The same technique facilitated isolation of proteins with lectin-like properties from human Suit2-007 and rat ASML pancreatic cancer cells, which were termed lactosyl-sepharose binding proteins (LSBPs). The role of these proteins in cancer progression was investigated at mRNA level using chip array data of Suit2-007 and ASML cells re-isolated from nude rats. These data compared significant mRNA expression changes when relating primary (pancreas) and metastatic (liver) sites following orthotopic and intraportal implantation of Pancreatic Ductal Adenocarcinoma (PDAC) cells, respectively. The affinity of Rpx to 13 simple sugar structures was modeled by docking experiments, the ranking of which was principally confirmed by NMR-spectroscopy. In addition, Rpx and LSBPs were evaluated for anti-proliferative activity and their cellular uptake was assessed by fluorescence microscopy. From 13 monosaccharides evaluated, open-chain rhamnose, β-d-galactose, and α-l-galactopyranose showed the highest affinities for site 1 of Rpx’s B-chain. NMR evaluation yielded a similar ranking, as galactose was among the best binders. Both, Rpx and LSBPs reduced cell proliferation in vitro, but their anti-proliferative effects were decreased by 15–20% in the presence of galactose. The program “Ingenuity Pathway Analysis” identified 2,415 genes showing significantly modulated mRNA expression following exposure of Suit2-007 cells to Rpx in vitro. These genes were then matched to those 1,639 genes, which were significantly modulated in the rat model when comparing primary and metastatic growth of Suit2-007 cells. In this overlap analysis, LSBP genes were considered separately. The potential suitability of Rpx for treating metastatic Suit2-007 PDAC cells was reflected by those genes, which were modulated by Rpx in a way opposite to that observed in cancer progression. Remarkably, these were 14% of all genes modulated during cancer progression, but 71% of the respective LSBP gene subgroup. Based on these findings, we predict that Rpx has the potential to treat PDAC metastasis by modulating genes involved in metastatic progression, especially by targeting LSBPs.

Abstract 4717: Ly6-neurotoxin1 knockout in PDAC cells inhibits their growth in vitro and in vivo

Ly6/neurotoxin1 (Lynx1) functions as a brake for nicotinic receptors and was defined as a tumor suppressor in lung cancer. As pancreatic cancer development may be slowed down by cholinergic signaling, we investigated the role of Lynx1 in pancreatic ductal adenocarcinoma (PDAC) cell lines, both in vitro and in vivo. Lynx1 knockout cell clones were generated by transfecting the CRISPRCas9 plasmid - (pSpCas9 (BB)-2A-Puro) into Miapacaluci and BXPC3luci PDAC cells using jet Pei and jet Prime as transfecting agents, respectively. The annealed gRNA was directed towards exon 3 of the Lynx1 gene. Control clones were transfected with the plasmid alone. Clones from both cell lines were tested by qRT-PCR and Western blot for knockout efficiency as well as by proliferation assay. In addition, the expression levels of p-MEK, p-MAPK, p-mTOR and p-Rictor were verified in two BXPC3 cell clones in relation to Lynx1 expression. Furthermore, 4x106 cells of four BXPC3 cell clones (one control, 3 knockout clones) were injected, respectively, into the portal vein of nude rats to control for a possibly reduced tumor growth in the liver. The knockdown of Lynx1 was incomplete at mRNA level and ranged from 20 to 60% in BXPC3 clones and from 0 to 30% in Miapaca clones. At protein level, the respective values ranged from 0 to 90% in BXPC3 and from 22 to 50% in Miapaca clones. However, Lynx1 protein levels increased at later time points. All BXPC3 clones proliferated less quickly than the respective control when tested by MTT assay. Miapaca clones, however, didn't show a significant difference from the respective control, although their growth was clearly disturbed shortly after transfection. Concomitantly with reduced Lynx1 protein levels, there was reduction of p-mTOR (90%), p-Rictor (30%) and p-MEK (40%) in BXPC3 cells. In vivo, the BXPC3 clones showed a lag period of 1 to 2 weeks till the appearance of a first bioluminescence signal indicating tumor growth. Rats injected with cells from the control clone showed a steady increase in the bioluminescence signal (n=7 of 10) as compared to the most sensitive knockdown clone, which didn't show any signal in any of 4 injected rats (p=0.05). Cells of 2 other BXPC3 clones showed a reduced growth rate at best in 2 of 2 rats used for each clone, respectively. In conclusion, knockout of Lynx1 was incomplete at both mRNA and protein levels. Nevertheless, the respective BXPC3 clones exhibited reduced proliferation in vitro, which was associated with diminished p-mTOR, p-Rictor and p-MEK levels. In addition, they failed to establish a tumor in vivo or showed a reduced tumor growth rate. These findings suggest that Lynx1 is a vital gene and may play an important role in the growth and establishment of PDAC cells.

Citation Format: Doaa Ali, Michael Zepp, Matthias Bozza, Maria Nikolova, Richard Harbottle, Martin R. Berger. Ly6-neurotoxin1 knockout in PDAC cells inhibits their growth in vitro and in vivo [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4717.

Abstract 6086: Integrin beta3 is a target for treating breast cancer skeletal metastasis

Integrin β3 (ITGB3) is expressed by breast cancer cells and its heterodimer αvβ3 is related to skeletal metastasis. Here we aimed to investigate this mechanism for defining its role as target in anti-metastatic therapy. Therefore, we generated two MDA-MB-231 breast cancer cell clones (I3, I5) with conditional doxycycline-dependent miRNA-mediated ITGB3 knockdown. In the absence of doxycycline the bi-directional Ptet promoter drives the simultaneous expression of firefly luciferase, red fluorescent protein mCherry and a specific miRNA targeting ITGB3 mRNA. In the presence of doxycycline, their expression is switched off. This model allowed monitoring the effects of ITGB3 inhibition at defined time points on cellular and molecular properties by flow cytometry analysis, proliferation and migration assays, as well as expression profiling analysis. Furthermore, the I5 clone was examined in a nude rat model for breast cancer skeletal metastasis for up to 5 weeks of miRNA treatment. Finally, ITGB3 was analyzed in exosomes secreted from breast cancer (MDA-MB-231, MCF7) and from breast epithelial cells (MCF10), as well as from plasma of healthy and MDA-MB-231 implanted rats with skeletal metastasis. MDA-MB-231 cells were incubated with these ex vivo exosomes for 72h and ITGB3 production was analyzed. Also, the levels of ITGB3 were investigated in exosomes isolated from cell clone I5. ITGB3 was well regulated in cell clones I3 and I5, as shown by knockdown at mRNA (78% and 73%) and protein (22% and 40%) levels after 6 days in medium without doxycycline. After this period the proliferation was decreased only in I5 cells (22%), whereas the migration was inhibited in both cell clones, again more pronounced in I5 (87%) than in I3 cells (20%). Furthermore, decreased tumor sizes and even complete remissions were detected in rats bearing the I5 clone after 4 to 5 weeks of miRNA treatment by bioluminescence and magnetic resonance imaging, as well as volume computed tomography. MDA-MB-231 cells secreted higher levels of ITGB3 in exosomes than MCF7 or MCF10 cells. Also, exosomes from rats bearing MDA-MB-231 induced skeletal metastases contained higher levels of ITGB3 than exosomes from healthy controls. MDA-MB-231 cells incubated with these ex vivo exosomes showed increased ITGB3 levels, too. In line, decreased ITGB3 levels were detected in exosomes from cells with conditional knockdown of this protein. The microarray data of cells with ITGB3 knockdown for 3 or 6 days showed a downregulation of genes, which have specific roles in angiogenesis (NPTN, RRM2), tumor growth (NPTN), energy metabolism (ISCA1), cytokinesis (SEPT11), migration (RRM2, STX6), cell proliferation, invasiveness, senescence, tumorigenesis (RRM2) and vesicle trafficking (SEPT11, STX6). In conclusion, ITGB3 has a function related to skeletal metastasis of breast cancer cells and mediates its distant effects via exosomes, which points to this protein as target for treating the disease.

Citation Format: Marineta Kovacheva, Michael Zepp, Martin R. Berger. Integrin beta3 is a target for treating breast cancer skeletal metastasis [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6086.

Lactosyl-sepharose binding proteins from pancreatic cancer cells show differential expression in primary and metastatic organs

In normal cells, glycan binding proteins mediate various cellular processes upon recognition and binding to respective ligands. In tumor cells, these proteins have been associated with metastasis. Lactosyl-sepharose binding proteins (LSBPs) were isolated and identified in a workflow involving lactosyl affinity chromatography and label-free quantification mass spectrometry (LFQ MS). A binding study with monosaccharides was performed by microscale thermophoresis and nuclear magnetic resonance spectroscopy. Influence of galactose on LSBPs’ binding to the lactosyl resin was investigated by competitive affinity chromatography followed by LFQ MS. An analysis of amino acids with sugar binding motifs was searched using bioinformatics tools. The expression profiles of these proteins at the mRNA level, as determined by a chip array from a pancreatic ductal adenocarcinoma (PDAC) liver metastasis model, were used for evaluating their potential role in cancer progression. Proteomics data and their respective genes were analyzed by MaxQuant and Ingenuity Pathway Analysis. In total, 1295 LSBPs were isolated and identified from Suit2-007 human pancreatic adenocarcinoma cells. Interaction studies revealed that these proteins exhibit low to moderate affinity for monosaccharide sugars. Some of these LSBPs even showed reduced affinity after calcium depletion. Among the isolated proteins were annexins and galectins in addition to other families, with no history of binding lactosyl residues. A subset of LSBPs exhibited differential profiles in the pancreas, liver, and lung environments. These modulations may be related to tumor progression. In conclusion, we show that PDAC cells contain LSBPs, a subset of which binds galactose with calcium dependency. The differential expression of these proteins in a rat model highlights their value for diagnosis and as potential drug targets for PDAC therapy. Future work will be required to validate these findings in patient samples.

Impact statement

Interaction of glycan binding proteins with aberrantly expressed glycans in tumor environment is crucial for metastasis. Here, we established a work flow for investigating the presence of a subset of these proteins in PDAC cells, which bind to a lactosyl-sepharose resin. The resin had been designed to isolate proteins with lectin-like properties. The corresponding lactosyl-sepharose binding proteins (LSBPs) show affinity for galactose and other monosaccharides. A subset of the LSBPs shows also calcium dependency. The importance of these proteins is highlighted by their differential expression profiles in PDAC cells growing in primary (pancreas) and metastatic (liver and lung) organ sites. Based on their affinity for the lactosyl-resin and monosaccharides, LSBPs hold potential for PDAC diagnosis and as drug targets. This work has set the stage for further investigation of the occurrence and the role of LSBPs in patient samples using the newly established workflow.

Conditional Knockdown of Osteopontin Inhibits Breast Cancer Skeletal Metastasis

High osteopontin (OPN) expression is linked to breast cancer bone metastasis. In this study we modulated osteopontin levels conditionally and investigated any related antineoplastic effects. Therefore, we established cell clones from human breast cancer MDA-MB-231 cells, in which the expression of OPN is regulated by the Tet-Off tet-off system. These cells, which conditionally express a specific miRNA targeting OPN, were used for in vitro studies as well as for a bone metastasis model in nude rats. Changes in whole-genome expression elicited by conditional OPN knockdown and vesicle formation were also analyzed. The alkylphosphocholine erufosine was used for combination therapy. Conditional OPN knockdown caused mild anti-proliferative, but more intensive anti-migratory and anti clonogenic effects, as well as partial and complete remissions of soft tissue and osteolytic lesions. These effects were associated with specific gene and protein expression modulations following miRNA-mediated OPN knockdown. Furthermore, high levels of OPN were detected in vesicles derived from rats harboring breast cancer skeletal metastases. Finally, the combination of OPN inhibition and erufosine treatment caused an additive reduction of OPN levels in the investigated breast cancer cells. Thus, knockdown of OPN alone or in combination with erufosine is a promising strategy in breast cancer skeletal metastasis treatment.

Abstract 551: Human recombinant anti BSP antibody fused to cell penetrating peptides has improved cytotoxic properties

Elevated serum levels of bone sialoprotein (BSP) indicate subsequent bone metastasis and are related to poor survival of respective breast cancer patients. Here we describe the preclinical activity of a human recombinant anti-BSP antibody (AF165) in MDA-MB-231 human breast cancer cells in vitro and in vivo. In addition, this antibody was fused to cell penetrating peptides (CPPs) and the resulting fusion proteins were examined for their cellular uptake and antiproliferative activities.

AF165 was produced in HEK cells and tested for its affinity against BSP by microscale thermophoresis. Its antiproliferative activity was evaluated by MTT assay, the antimetastatic efficacy was determined in soft tissue and skeletal lesions, which had been induced in nude rats by intra-arterial injection of human MDA-MB-231 breast cancer cells. Fusion of AF165 to CPPs (Pep1, TAT) was accomplished by adding the respective DNA sequences with or without a linker (glycine-serine (GS)) to the AF165 gene. The affinity of these fusion proteins to BSP was measured by microscale thermophoresis, as well. In addition, their intracellular uptake and antiproliferative activities were determined by confocal fluorescent microscopy and MTT assay. Finally, changes in protein expression in response to these fusion proteins were detected by western blot.

AF165 showed no uptake into MDA-MB-231 cells and inhibited their growth in cell culture only marginally. However, this antibody induced dose dependent remissions in nude rats harboring MDA-MB-231 induced soft tissue and skeletal lesions. Subcutaneous administration of AF165 caused complete remission in 2 of 9 animals (10mg/kg/week), as well as in 3 of 6 animals (20 mg/kg/week). Interestingly, the affinity of AF165 (Kd = 7.7×10-7 M) was lower than that of fusion proteins, Kd values of which ranged from 3.6×10-8M (AF165-multiGS-Pep1) to 2.2×10-9M (AF165-multiGS-TAT). In contrast to AF165, all fusion proteins were taken up into MDA-MB-231 cells and after 24-48h caused morphologic changes, indicative of apoptosis. MDA-MB-231 cell proliferation was inhibited by 50 % after 48 hours of exposure to the conjugates AF-GS-TAT and AF-multiGS-Pep1 (600nM). The other conjugates caused similar cytotoxicity at higher concentration only (1200nM). The exposure to the fusion proteins led to downregulation of BSP protein levels and upregulation of proteins EGR1, ATF3 and ID2.

In conclusion, the human recombinant anti-BSP antibody AF165 is inactive in vitro, but highly active in a rat model mimicking skeletal metastasis. Fusion proteins of AF165 with CPPs show 10 to 100 fold higher affinity to BSP, as well as uptake into MDA-MB-231 cells, thus causing cytotoxicity in vitro. Therefore, the fusion proteins may have potential for antimetastatic therapy in vivo.

Citation Format: Marineta Kovacheva, Michael Zepp, Franz-Paul Armbruster, Martin R. Berger. Human recombinant anti BSP antibody fused to cell penetrating peptides has improved cytotoxic properties [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 551.

Abstract 4836: Ly6-neurotoxin1 is a potential target in pancreatic ductal adenocarcinoma cells

Ly6/neurotoxin1 (Lynx1) is a cholinergic transmission modulator, which was described as a tumor suppressor in lung cancer. In addition, the expression of Lynx1 was downregulated in rat PDAC cells colonizing rat liver. As cholinergic signaling via the vagus nerve may slow pancreatic tumor progression, we investigated the role of Lynx1 in human PDAC cell lines.

Transient gene knockdown (KD) by siRNA was used to modulate the expression of Lynx1 in BXPC3 and Miapaca cells and KD was confirmed by qRT-PCR and western blot (WB). Resulting effects were determined by respective assays for proliferation, migration and colony formation. Induction of apoptosis was assessed by Hoechst and Annexin V-FITC staining. Induction of autophagy was determined by acridine orange and immunofluorescence (IF) staining for LC3b. Finally, we performed microarrays for gene expression in cells with Lynx1 KD and analyzed by WB cancer pathways of related signaling molecules.

Following successful KD of Lynx1, the response of Miapaca and BXPC3 cells was altered regarding proliferation (-60% and -10%), migration (+200% and -10%) at 72 h after transfection and colony formation (-50% and -40%) at 9 d after transfection. Hoechst staining revealed increased rates of apoptosis in both cell lines. This was confirmed by Annexin V assay in Miapaca cells and these changes were associated with significantly reduced BCL2 levels. Autophagy was increased in both cell lines as were LC3b levels detected by IF. Alterations in mRNA expression, as assessed by microarray, were analyzed by IPA software using a 1.5 fold cutoff. Miapaca cells showed significant activation of 43 pathways including phospholipase C signaling, cholecystokinin/gastrin mediated signaling, and cell cycle regulation. In addition, five pathways showed uniform downregulation, i.e estrogen mediated S phase entry, sirtuin signaling, small cell lung cancer signaling, cyclins and cell cycle regulation, and ataxia-telangiectasia-mutated (ATM) signaling. In contrast to the more sensitive Miapaca cells, BXPC3 cells showed modulation of few pathways only: activation of G protein beta gamma signaling and osteoarthritis pathways, as well as downregulation of the sirtuin signaling pathway. At protein level, the mTOR pathway was downregulated in both cell lines (including phosphorylated forms of mTOR, Rictor, Raptor, PRAS40), as were the upstream regulators PI3K and p-AKT.

In conclusion, KD of Lynx1 caused changes in gene product levels, which are related to cholinergic signal transmission as well as to DNA damage and repair systems. The observed decreased colony formation in Lynx1 KD cells is also indicative of defective cholinergic signaling. Reduced mTOR pathway signaling caused induction of autophagy. These findings suggest that Lynx1 is beneficial for regular cellular functions and its lack will contribute to increased apoptosis, DNA damage and autophagy.

Citation Format: Doaa M. Ali, Nevena Nedyalkova, Michael Zepp, Martin R. Berger. Ly6-neurotoxin1 is a potential target in pancreatic ductal adenocarcinoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4836.

Pancreatic carcinoma cells colonizing the liver modulate the expression of their extracellular matrix genes

Liver is the main target of pancreatic ductal adenocarcinoma (PDAC) metastasis. Here, a rat model was used for analysing gene expression modulations during liver colonization. ASML PDAC cells were injected to isogenic rats and re-isolated at various stages of liver colonization for RNA isolation or re-cultivation. Microarrays were used for analysing mRNA and miRNA profiles of expres­sion. The results were partially confirmed by (q) RT-PCR and western blot. Selected genes were knocked down by siRNA transfection and the resulting cell behaviour was analysed. The ratio of up- and down regulated genes decreased from 20:1 (early stage) to 1.2:1 (terminal stage). Activation of cancer relevant gene categories varied between stages of liver colonization, with a nadir in the intermediate stage. The cells' environment triggered up to hundredfold changed expression for collagens, matrix metalloproteinases and chemokines. These modulations in mRNA expression were related to respective changes at miRNA levels. Gene expression knockdown of Mmp2 and Ccl20, which were highly modulated in vivo, was correlated with reduced prolif­eration and migration in vitro. Thus, target genes and temporal alterations in expression were identified, which can serve as basis for future therapeutic or diagnostic purposes.

Development of a prognostic tool for the occurrence of feather pecking and cannibalism in laying hens

In July 2015, a German voluntary decree stipulated that the keeping of beak-trimmed laying hens after the 1st of January 2017 will no longer be permitted. Simultaneously, the present project was initiated to validate a newly developed prognostic tool for laying hen farmers to forecast, at the beginning of a laying period, the probability of future problems with feather pecking and cannibalism in their flock. For this purpose, we used a computer-based prognostic tool in form of a questionnaire that was easy and quick to complete and facilitated comparisons of different flocks. It contained various possible risk factors that were classified into 3 score categories (1 = "no need for action," 2 = "intermediate need for action," 3 = "instant need for action"). For the validation of this tool, 43 flocks of 41 farms were examined twice, at the beginning of the laying period (around the 20th wk of life) and around the 67th wk of life. At both visits, the designated investigators filled out the questionnaire and assessed the plumage condition and the skin lesions (as indicators of occurrence of feather pecking and cannibalism) of 50 laying hens of each flock. The average prognostic score of the first visit was compared with the existence of feather pecking and cannibalism in each flock at the end of the laying period. The results showed that the prognostic score was negatively correlated with the plumage score (r = -0.32; 95% confidence interval [CI]: [-0.56; -0.02]) and positively correlated with the skin lesion score (r = 0.38; 95% CI: [0.09; 0.61]). These relationships demonstrate that a better prognostic score was associated with a better plumage and skin lesion score. After performing a principal component analysis on the single scores, we found that only 6 components are sufficient to obtain highly sensitive and specific prognostic results. Thus, the data of this analysis should be used for creating applicable software for use on laying hen farms.

The expression of genes contributing to pancreatic adenocarcinoma progression is influenced by the respective environment

Pancreatic adenocarcinoma is a highly aggressive malignancy with dismal prognosis and limited curative options. We investigated the influence of organ environments on gene expression in RNU rats by orthotopic and intraportal infusion of Suit2-007luc cells into the pancreas, liver and lung respectively. Tumor tissues from these sites were analyzed by chip array and histopathology. Generated data was analyzed by Chipster and Ingenuity Pathway Analysis (±1.5 expression fold change and p<0.05). Further analysis of functional annotations derived from IPA, was based on selected genes with significant modulation of expression. Comparison of groups was performed by creating ratios from the mean expression values derived from pancreas and respective in vitro values, whereas those from liver and lung were related to pancreas, respectively. Genes of interest from three functional annotations for respective organs were identified by exclusion-overlap analyses. From the resulting six genes, transglutaminase2 (TGM2) was further investigated by various assays. Its knockdown with siRNA induced dose dependent inhibitory and stimulatory effects on cell proliferation and cell migration, respectively. DNA fragmentation indicated apoptotic cell death in response to TGM2 knockdown. Cell cycle analysis by FACS showed that TGM2 knockdown induced G1/S blockade. Therefore, TGM2 and its associated genes may be promising therapeutic targets.

Upregulation of cell cycle genes in head and neck cancer patients may be antagonized by erufosine's down regulation of cell cycle processes in OSCC cells

The TCGA database was analyzed to identify deregulation of cell cycle genes across 24 cancer types and ensuing effects on patient survival. Pan-cancer analysis showed that head and neck squamous cell carcinoma (HNSCC) ranks amongst the top four cancers showing deregulated cell cycle genes. Also, the median gene expression of all CDKs and cyclins in HNSCC patient samples was higher than that of the global gene expression. This was verified by IHC staining of CCND1 from HNSCC patients. When evaluating the quartiles with highest and lowest expression, increased CCND1/CDK6 levels had negative implication on patient survival. In search for a drug, which may antagonize this tumor profile, the potential of the alkylphosphocholine erufosine was evaluated against cell lines of the HNSCC subtype, oral squamous cell carcinoma (OSCC) using in-vitro and in-vivo assays. Erufosine inhibited growth of OSCC cell lines concentration dependently. Initial microarray findings revealed that cyclins and CDKs were down-regulated concentration dependently upon exposure to erufosine and participated in negative enrichment of cell cycle processes. These findings, indicating a pan-cdk/cyclin inhibition by erufosine, were verified at both, mRNA and protein levels. Erufosine caused a G2/M block and inhibition of colony formation. Significant tumor growth retardation was seen upon treatment with erufosine in a xenograft model. For the decreased cyclin D1 and CDK 4/6 levels found in tumor tissue, these proteins can serve as biomarker for erufosine intervention. The findings demonstrate the potential of erufosine as cell cycle inhibitor in HNSCC treatment, alone or in combination with current therapeutic agents.

IDK1 is a rat monoclonal antibody against hypoglycosylated bone sialoprotein with application as biomarker and therapeutic agent in breast cancer skeletal metastasis

Changes in glycosylation are salient features of cancer cells. Here, we report on the diagnostic and therapeutic properties of IDK1, an antibody against tumour associated, hypoglycosylated bone sialoprotein (hypo‐BSP). The affinity of the rat monoclonal antibody IDK1 for hypo‐BSP, as determined by microscale thermophoresis, was three orders of magnitude higher than for mature BSP, whereas the mouse monoclonal antibody used had similar affinity for both BSP forms. IDK1 showed no activity against the proliferation or migration of normal or cancer cells growing in vitro. In vivo, however, IDK1 caused dose‐dependent regression of soft tissue and skeletal lesions in nude rats harbouring human MDA‐MB‐231 cells. At optimal dose, 80% of the treated rats showed complete remission of all tumour lesions. Analysis of BSP expression in vitro by fluorescence‐activated cell sorting (FACS) and immunocytochemistry showed basal levels of this protein, which were visible only in a fraction of these cells. Cells of the metastatic cell lines MDA‐MB‐231 and PC‐3 were more often positive for hypo‐BSP. In addition, there was co‐expression of both forms in some cells, but almost no co‐localization; rather, hypo‐BSP was present in the nucleus, and mature BSP was detected extra‐cellularly. Normal osteoblasts and osteoclasts were negative for hypo‐BSP. Breast cancer tissue, however, showed strong expression of mature BSP, which was present intra‐cellularly as well as in vesicles outside cells. Hypo‐BSP was present mainly in lesions from skeletal sites, thus explaining the antineoplastic activity of IDK1, which was high in lesions growing in the vicinity of the skeleton but low in lesions growing subcutaneously. Finally, hypo‐BSP was detected in specimens from breast cancer patients, with a significantly greater intensity in skeletal metastases as compared to the respective primary cancers. In conclusion, IDK‐1 is an antibody with diagnostic and therapeutic applications in skeletal metastases of breast cancer.

Abstract P2-04-23: A monoclonal antibody against hypo-glycosylated bone sialoprotein II has application for diagnostic purposes in samples of breast cancer patients and for treatment of skeletal metastasis caused by MDA-MB-231 breast cancer cells in rats

The SIBLING protein bone sialoprotein II (BSP) has been implicated in lytic skeletal metastasis as it is expressed in a subset of primary breast cancers and can be detected at elevated levels in the serum of patients with increased risk to develop skeletal metastasis. The aim of this study was to investigate the potential application of a rat monoclonal antibody against hypo-glycosylated BSP (IDK1) for diagnostic and therapeutic purposes.

The diagnostic part of this study was based on breast cancer specimens from the biobank / repository of the Institute of Pathology of the Municipal Hospital Kassel, Germany. Immune-histochemical analyses were performed with IDK1 for comparing BSP expression between ten human primary breast tumor sections and their corresponding bone metastatic tissue samples. The therapeutic part of this study was based on a model in nude rats, in which the rats were implanted with human MDA-MB-231 breast cancer cells for selective and orthotopic appearance of osteolytic skeletal lesions. Tumor bearing rats were treated with IDK1 starting at two or four weeks after tumor cell inoculation into the femoral artery of one hind leg. Tumor growth was monitored by light emission, caused by luciferase mediated metabolism of luciferin. Photon emission was recorded at regular intervals by a Xenogen IVIS 100 imaging system. After sacrifice, samples of lesions and apparently healthy tissues were investigated by H&E staining as well as by immune-histological staining for BSP.

BSP staining was found within the cytoplasm of tumor cells. Increased expression of BSP was also detected in healthy bone cells, e.g. osteoblasts, as soon as breast tumor cells invaded bone tissue. An elevation of BSP expression near necrotic centers was also found. Expression of BSP in primary breast tumors was positively correlated with BSP expression in bone metastases. Furthermore, bone metastases showed higher and more intensive expression of BSP than their respective primary breast tumors (p&lt;0.0039).

In the experimental treatment part, all but one untreated tumor bearing rats showed rapid tumor growth accompanied with lytic destruction of femur and tibia of the respective hind leg (18/19; tumor take rate 95%). In contrast, rats treated with the anti-BSP antibody did not show a significant increase in light emission nor a clinical deterioration. In fact, 8 of 10 rats receiving the antibody at a dose of 10 mg/kg/week starting at two weeks after tumor implantation did not show any light emission after 4 to 6 weeks (p = 0.01 versus control) as well as 6 of 10 rats receiving the antibody at the same dose starting at four weeks after tumor implantation (p &lt; 0.05). Radiological and histological examination confirmed that animals without light emission were free of tumor growth, corresponding to a complete remission.

In conclusion, the rat monoclonal antibody directed against BSP is a powerful tool with potential for diagnostic and therapeutic applications in breast cancer skeletal metastasis and warrants further development.

Citation Format: Berger MR, Zepp M, Westphal G, Berger I, Armbruster FP. A monoclonal antibody against hypo-glycosylated bone sialoprotein II has application for diagnostic purposes in samples of breast cancer patients and for treatment of skeletal metastasis caused by MDA-MB-231 breast cancer cells in rats [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-04-23.

Abstract 3818: Therapeutic potential of blocking CCR5 by maraviroc in breast cancer bone metastasis

Introduction:

Bone metastasis is a highly unfavorable condition observed in up to 70% of the patients with breast cancer. Treatment options for this condition are not curative, but palliative, only, which highlights the need for exploring new therapeutic options. In this study, we propose that targeting a chemokine receptor (CCR5), often upregulated in primary and secondary breast cancers, can contribute to a more successful treatment of breast cancer bone metastasis.

Methodology:

Following the blockage of CCR5 by maraviroc, cytotoxic effects were measured by MTT assay, while the migratory effects were determined by migration and scratch healing assays. Apoptosis related activities were investigated by nuclear staining and western blot analysis. Maraviroc mediated cytostatic changes were analyzed by a ready-made Human Cell Cycle Regulation Panel (Roche, Germany). In vivo experiments were performed by implanting MDA-MB-231 cells via the saphenous artery to the left hind limb of male nude rats (RNU strain) for inducing bone metastasis. Treatment with maraviroc was started from 2nd and 7th day of transplantation in two groups of rats (n = 6/group) designated as A and B, respectively, and was compared with an untreated control group (n = 8 rats).

Results:

CCR5 blockage by maraviroc (concentration &gt; 100μM) induced concentration dependent cytotoxicity in MDA-MB-231 and MCF-7 cells. Maraviroc exposure also showed significant inhibition of migration of the cells, while nuclear staining indicated the condensation/fragmentation of nuclear content. Maraviroc exposure induced significant expression of cleaved caspase 7 and PARP, while real time RT-PCR showed pronounced inhibition of multiple genes (≥2fold) including cyclins, CDKs and their down-stream targets. Treatment of tumor bearing animals, with intra-peritoneal injections of maraviroc (25mg/kg, 3-4 weeks daily), reduced the tumor burden significantly (p &lt; 0.05) in group A (50-75%), while the effects were minimal in group B (&lt;25%). Concomitantly, no signs of toxicity were observed in rats of the two groups.

Conclusion:

CCR5 blockage by maraviroc induces significant anti-neoplastic effects in breast cancer cells. At mechanistic level, these effects included induction of apoptosis and alterations in cell cycle. Considerable inhibition in group A, but minimal inhibition of tumor burden in group B indicates that targeting CCR5 by maraviroc during early stages of breast cancer bone metastasis is a promising treatment option which should be further explored.

Citation Format: Asim Pervaiz, Michael Zepp, Doaa M. Ali, Martin R. Berger, Hassan Adwan. Therapeutic potential of blocking CCR5 by maraviroc in breast cancer bone metastasis. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3818.

Abstract 2474: A rat monoclonal antibody against bone sialoprotein II shows differential activity in MDA-MB-231 cells growing in vitro or in vivo

Elevated serum levels of the small integrin binding ligand N-linked glycoprotein (SIBLING) family member bone sialoprotein II (BSP) have been related to breast cancer skeletal metastasis. Also, knockdown of BSP was associated with significant anti-proliferative, anti-migratory and anti-clonogenic effects in MDA-MB-231 human breast cancer cells, and rats presenting with osteolytic metastases following femoral artery injection of these cells underwent complete remission following BSP knockdown, thus validating BSP as target. In order to follow a translational perspective, we used the IDK-1 rat monoclonal antibody against BSP (Immundiagnostik, Bensheim, Germany) for treating MDA-MB-231 cells in vitro and in vivo.

MDA-MB-231 cells were exposed to IDK-1 for assessing its effect on proliferation and migration. The presence of BSP in the cytosol and on cell membranes was checked by FACS analysis. In addition, the location of BSP was investigated by immunocytochemistry. For in vivo experiments, 1×105 MDA-MB-231luc breast cancer cells were injected into the femoral artery of male nude rats with skeletal lesions developing subsequently in the respective hind leg. A preventive arm based on pretreated rats and / or MDA-MB-231 cells was compared with a treatment arm, in which antibody administration (10 mg/kg/week) started when tumor bearing rats had shown stable tumor growth. The appearance and growth of soft tissue tumors was monitored by luciferin induced light emission and recorded by a Xenogen IVIS 100 imaging system. Concomitant skeletal lesions were detected by CT scans. Tumors as well as skeletal lesions were subjected to pathohistological evaluation by hematoxylin and eosin staining as well as immunohistochemical staining for BSP.

There was no effect of the anti-BSP antibody IDK-1 on the proliferation or migration of MDA-MB-231 cells. In line with this, FACS analysis revealed only low concentrations of BSP in MDA-MB-231 cells growing in vitro. Immunocytochemical staining for BSP showed that this SIBLING protein could be detected only in a minority of the MDA-MB-231 cells. However, when treating nude rats bearing fully established MDA-MB-231 tumors, administration of the IDK-1 antibody caused complete remissions in 80% of treated rats (10mg/kg/week for 6 weeks). When pre-treating the nude rats, however, and / or pre-exposing the MDA-MB-231 cells to IDK-1 in addition to treating the established tumors, the above mentioned effect could not be increased. Interestingly, histological evaluation of serial sections of MDA-MB-231 tumors growing in nude rats showed a very robust expression and vesicular secretion of BSP.

It is concluded, that the in vivo growth of MDA-MB-231 cells is associated with dramatically increased expression and secretion of BSP, which then is a valid target for the anti-BSP antibody, leading to complete remissions of MDA-MB-231 tumors in nude rats.

Citation Format: Michael Zepp, Irina Berger, Heidegard Hilbig, Franz-Paul Armbruster, Martin R. Berger. A rat monoclonal antibody against bone sialoprotein II shows differential activity in MDA-MB-231 cells growing in vitro or in vivo. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2474. doi:10.1158/1538-7445.AM2015-2474

Sustained conditional knockdown reveals intracellular bone sialoprotein as essential for breast cancer skeletal metastasis

Increased bone sialoprotein (BSP) serum levels are related to breast cancer skeletal metastasis, but their relevance is unknown. We elucidated novel intracellular BSP functions by a conditional knockdown of BSP. Conditional MDA-MB-231 subclones were equipped with a novel gene expression cassette containing a tet-regulated miRNA providing knockdown of BSP production. These clones were used to assess the effect of BSP on morphology, proliferation, migration, colony formation and gene expression in vitro, and on soft tissue and osteolytic lesions in a xenograft model by three imaging methods. BSP knockdown caused significant anti-proliferative, anti-migratory and anti-clonogenic effects in vitro (p<0.001). In vivo, significant decreases of soft tissue and osteolytic lesions (p<0.03) were recorded after 3 weeks of miRNA treatment, leading to complete remission within 6 weeks. Microarray data revealed that 0.3% of genes were modulated in response to BSP knockdown. Upregulated genes included the endoplasmic reticulum stress genes ATF3 and DDIT3, the tumor suppressor gene EGR1, ID2 (related to breast epithelial differentiation), c-FOS and SERPINB2, whereas the metastasis associated genes CD44 and IL11 were downregulated. Also, activation of apoptotic pathways was demonstrated. These results implicate that intracellular BSP is essential for breast cancer skeletal metastasis and a target for treating these lesions.

Abstract 2614: Bone sialoprotein is an essential target in breast cancer skeletal metastasis

Breast cancer is a leading cause of cancer related death in women due to onset of metastasis. Bone metastasis is the most frequent complication occurring in patients with advanced breast cancer and bone sialoprotein (BSP) is related to this process. However, the underlying mechanisms are not clear yet. Therefore, the aim of the study was to analyze BSP functions in greater detail and to decipher its signaling pathways contributing to bone metastasis.

To that purpose a combination of the tetracycline-controlled transcription activation system (“Tet-Off system”) and RNA interference was used to initiate and maintain the conditional knockdown of BSP for any intended period. This new technique was established in MDA-MB-231 subclones by recombinase-mediated cassette exchange. Additionally, the cell clones were equipped with the reporter genes mCherry and firefly luciferase for testing their regulative properties and following their fate. In absence of doxycycline, the expression of a miRNA targeting BSP was activated and after six days of BSP knockdown the ensuing cellular, metastatic or molecular properties were monitored by fluorescent microscopy, flow cytometry analysis, assays for proliferation, migration and colony formation, as well as expression profiling analysis. Furthermore, the cell clones were examined in a nude rat model for soft tissue and osteolytic lesions after 2 to 6 weeks of miRNA treatment. The clones revealed good regulative properties to doxycycline. Phenotypic changes indicating apoptosis were observed after 6 days of conditional knockdown which was characterized by up to 86% decreased BSP levels and resulted in significant anti-proliferative, anti-migratory and anti-clonogenic effects in vitro. Additionally, the effect of miRNA-mediated BSP knockdown was assessed in vivo. Significant decreases (p &lt; 0.03) and even complete remissions of soft tissue and osteolytic lesions were found following 3 and 6 weeks of miRNA treatment by bioluminescence and magneting resonance imaging, as well as volume computed tomography. The microarray data showed modulated expression in 1.3% of all genes, thus hinting to specific effects in response to BSP knockdown. These genes included increased expression of endoplasmic reticulum stress and apoptosis related genes (ATF3, CHOP), of transcription factor c-FOS, of the gene related to breast epithelial differentiation (ID2) and the tumor suppressor gene EGR1.

Conversely, there was suppression of metastasis associated genes (CD44, IL11). These findings were confirmed by western blot for induction of intrinsic and extrinsic apoptotic pathways as shown by cleavage of caspases 8, 9, 3 and 7, and of PARP, as well as the upregulation of ATF3, DDIT3 (CHOP), c-FOS, ID2 and CD44.

In conclusion, the role of BSP in the development of skeletal metastasis has been defined more precisely and renders this protein an attractive target in the treatment of this disease.

Citation Format: Marineta Kovacheva, Michael Zepp, Stefan Berger, Martin R. Berger. Bone sialoprotein is an essential target in breast cancer skeletal metastasis. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2614. doi:10.1158/1538-7445.AM2014-2614

Few genes are associated with the capability of pancreatic ductal adenocarcinoma cells to grow in the liver of nude rats

Owing to aggressiveness and chemoresistance, pancreatic ductal adenocarcinoma (PDAC) is characterised by a poor prognosis. To address this disease-spe-cific dilemma we aimed to establish animal models, which can be used for identifying new specific tumor markers, as well as serving as tools for potential therapeutic approaches. From a panel of sixteen pancreatic cancer cell lines, two human (Suit2-007 and Suit2-013) and a rat (ASML) cell line were selected for their properties to grow in the liver of male RNU rats and mimic liver metastasis of PDAC. For better monitoring of metastatic tumor growth in vivo, all three pancreatic cancer cell lines were stably transfected with eGFP and luciferase marker genes. In addition, the mRNA expression profile of 13 human PDAC cell lines was analyzed by BeadChip array analysis. Only 33 genes and 5 signaling pathways were identified as significantly associated with the ability of the cell lines to grow initially and/or consistently in rat liver. Only a minority of these genes (osteopontin, matrix metalloproteinase-1 and insulin-like growth factor 1) has been intensively studied and shown to be closely related to cancer progression. The function of the remaining 30 genes ranges from moderate to poorly investigated, and their function in cancer progression is still unclear. The ensuing three pancreatic cancer liver metastasis models vary in their aggressiveness and macroscopic growth. They will be used for preclinical evaluation of new therapeutic approaches aiming at the genes identified.

Sequential biphasic changes in claudin1 and claudin4 expression are correlated to colorectal cancer progression and liver metastasis

Terminal progression of colorectal cancer (CRC) culminates in liver metastasis. To identify genes that are involved in the metastatic phenotype, cDNA microarrays were used to analyse mRNA expression profiles of colorectal carcinoma (CC)531 rat colon adenocarcinoma cells for changes related to their homing into the liver. Briefly, CC531 cells were intraportally implanted into the liver of Wag-Rij rats and re-isolated after 3, 6, 9, 14 and 21 days. Compared to control CC531 cells, claudin1 and claudin4 were among the ≥8-fold initially down-regulated genes. The co-culture of tumour cells with isolated rat hepatocytes and Kupffer cells did not induce down-regulation of either claudin1 or 4. When the environment effective on circulating tumour cells was simulated by cell culture conditions favouring their adhesion, only claudin4 showed augmented expression. Knockdown of claudin1 and claudin4 mediated by small interfering RNA caused significantly increased migration and decreased clonogenic growth of tumour cells (P < 0.05), but had no effect on their proliferation. These experimental results were paralleled by increased claudin1 and claudin4 expression in human CRC samples in Union for International Cancer Control (UICC) stages I–III, as evaluated by real-time PCR. Increased claudin4 levels were correlated with significantly reduced overall survival (log-rank test, P= 0.018). Further, significantly (P < 0.05) reduced expression of claudin1 and claudin4 was observed in stage IV and liver metastasis by immunohistochemistry. In conclusion, sequential biphasic changes in claudin1 and claudin4 expression occur during the homing of rat CC531 CRC cells to the liver. This modulation is reflected by significant changes in claudin expression in human primary and metastatic CRC.

Silencing of skeletal metastasis-associated genes impairs migration of breast cancer cells and reduces osteolytic bone lesions

Bone sialoprotein (BSP) and osteopontin (OPN) are important factors in the metastasis of breast cancer, which were examined as targets for antineoplastic therapy by siRNA. In addition, the effect of gene silencing on their transcription factor Runx2 and their interaction partners integrin β(3) and matrix metalloproteinase 2 was studied. The effect of siRNAs directed against these genes was assessed by monitoring expression levels followed by functional assays in cell culture as well as skeletal metastases caused by human MDA-MB-231(luc) breast cancer cells in nude rats. Upon silencing of the targets, cell migration was profoundly impaired (p < 0.001 for BSP-siRNA), but the impact on proliferation was low. Systemic administration by osmotic mini-pumps of BSP-siRNA but not OPN-siRNA decreased osteolytic lesions (p = 0.067). Extraosseous tumour growth was not affected. As an alternative approach, non-viral, polymeric based formulations of siRNAs in nanoparticles (NP) were developed. Locoregional administration of the two siRNAs targeting OPN and BSP encapsulated in these biodegradable NP reduced skeletal lesions even more efficiently (p = 0.03). Compared to systemic administration, this treatment caused not only a more pronounced anti-osteolytic effect at a 25-fold lower total siRNA dose, but also had a slight reducing effect on tumour incidence (p = 0.095). In conclusion, the siRNA treatment had a small effect on cellular proliferation but a significant efficacy against migration of and osteolysis induced by MDA-MB-231 cells. Our data underline that siRNA mediated knockdown is a powerful tool for identifying targets for pharmacological intervention. In addition, encapsulation of siRNA into biodegradable NP is a strategy, which promises well for using siRNA.

P1-01-01: A Rat Monoclonal Antibody Against Bone Sialoprotein II Is Active in Preventing and Treating Tumor Growth and Osteolytic Lesions in Nude Rats Induced by MDA-MB-231 Breast Cancer Cells

The SIBLING protein bone sialoprotein II (BSPII) has been found implicated in lytic skeletal metastasis. Previous experiments had shown that targeting BSPII by a polyclonal IgY antibody or knock down of the gene's transcript are instrumental in inhibiting experimental lytic skeletal metastasis. The aim of this study was to investigate the preventive and therapeutic effects of a new rat monoclonal anti BSPII antibody against tumor growth and osteolytic activity of MDA-MB-231 breast cancer cells growing in nude rats. In the preventive arm of this study, rats were pre-treated with the antibody (0 and 10 mg/kg) starting one week before tumor inoculation. In parallel, MDA-MB-231luc cells were incubated with the antibody for one week (0 and 0.5 mg/ml). Following inoculation of 1×105 MDA-MB-231luc breast cancer cells into the femoral artery of 6 male nude rats, respectively, lesions were expected to develop only in the tibia, femur or fibula of the respective hind leg. Their appearance and development were monitored for six weeks by light emission, caused by luciferase mediated metabolism of luciferin. Photon emission was recorded at regular intervals by a Xenogen IVIS 100 imaging system. In the treatment arm of this study, the antibody administration (10 mg/kg/week) started when tumor bearing rats had shown stable tumor growth. Experimental groups of rats received the first treatment either at four (late onset; n = 8) or at two (early onset; n = 6) weeks after tumor cell implantation. Tumor bearing animals were (sham-) treated and followed for up to 8 weeks.

All 6 control rats of the preventive arm showed steady tumor growth. In variance, the rats receiving MDA-MB-231luc cells that had been pre-exposed to the antibody and those rats, which had been pre-treated with the antibody showed clearly reduced light emission as indicator of reduced tumor growth. At 6 weeks after tumor cell inoculation, only 1 of 6 rats was positive for light emission in the group receiving pre-exposed tumor cells (p&lt;0.01), 3 of 6 rats were positive in the group receiving pre-treatment with the antibody (p&lt;0.05), and 1 of 6 rats was positive in the group receiving both, pre-exposed tumor cells as well as pre-treatment with the antibody (p&lt;0.01).

In the treatment arm, all but one untreated tumor bearing rats showed rapid tumor growth accompanied with lytic destruction of femur and tibia of the respective hind leg (18/19; tumor take rate 95%). In contrast, rats treated with the anti-BSP antibody did not show a significant increase in light emission nor a clinical deterioration. In fact, 6 of 8 rats receiving the late onset therapy didn't show any light emission after 4 to 6 weeks (p = 0.01 versus control) as well as 4 of 6 rats receiving the early onset therapy with the antibody (p &lt; 0.05). Radiological and histological examination confirmed that animals without light emission were free of tumor growth, corresponding to a complete remission.

In conclusion, the rat monoclonal antibody directed against BSP II is a powerful tool in treating experimental skeletal metastasis and warrants further development.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-01-01.

Biodistribution of antisense nanoparticles in mammary carcinoma rat model

Efficient and specific delivery of antisenses (ASs) and protection of the sequences from degradation are critical factors for effective therapy. Sustained release nanoparticles (NP) offer increased resistance to nuclease degradation, increased amounts of AS uptake, and the possibility of control in dosing and sustained duration of AS administration. The biodegradable and biocompatible poly(D,L-lactic-co-glycolic acid) copolymer (PLGA) was utilized to encapsulate AS directed against osteopontin (OPN), which is a promising therapeutic target in mammary carcinoma. Whole body biodistribution of OPN AS NP was evaluated in comparison to naked AS, in intact and mammary carcinoma metastasis model bearing rats. Naked and NP encapsulated AS exhibited different biodistribution profiles. AS NP, in contrast to naked AS, tended to accumulate mostly in the spleen, liver, and at the tumor inoculation site. Drug levels in intact organs were negligible. The elimination of naked AS was faster, due to rapid degradation of the unprotected sequence. It is concluded that AS NP protect the AS from degradation, provide efficient AS delivery to the tumor tissue, and minimize AS accumulation in intact organs due to the AS sustained release profile as well as the favorable NP physicochemical properties.