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.

Preparation and evaluation of cytotoxic potential of paclitaxel containing poly-3-hydroxybutyrate-co-3-hydroxyvalarate (PTX/PHBV) nanoparticles

Paclitaxel (PTX) is a potent anticancer drug. In the present study, PTX was loaded in poly-3-hydroxybutyrate-co-3-hydroxyvalarate (PHBV) to fabricate the PTX/PHBV (drug-loaded) nanoparticles via the nanoprecipitation method. Blank PHBV nanoparticles were also prepared. The drug-encapsulation efficiency of PTX/PHBV nanoparticles was 45±0.4%. The PTX/PHBV nanoparticles exhibited a pH-sensitive release profile and followed a quasi-Fickian diffusion mechanism. Cytotoxic properties of PHBV and PTX/PHBV nanoparticles were checked against the MCF-7 and Caco-2 cell lines. The PHBV nanoparticle did not inhibit the proliferation of MCF-7 and Caco-2 cell lines, thus depicting their non-toxic and biocompatible nature. On the other hand, the PTX/PHBV nanoparticles demonstrated 1.03-fold higher cytotoxicity and 1.61-fold enhanced apoptosis after treatment with the PTX/PHBV nanoparticles versus free PTX. In summary, the PHBV nanoparticles could be a potential candidate for the delivery of PTX for cancer treatment.

Khasianine Affects the Expression of Sugar-Sensitive Proteins in Pancreatic Cancer Cells, Which Are Altered in Data from the Rat Model and Patients

Pancreatic ductal adenocarcinoma (PDAC) is a deadly malignancy with no effective treatment, particularly in the advanced stage. This study explored the antiproliferative activity of khasianine against pancreatic cancer cell lines of human (Suit2-007) and rat (ASML) origin. Khasianine was purified from Solanum incanum fruits by silica gel column chromatography and analyzed by LC-MS and NMR spectroscopy. Its effect in pancreatic cancer cells was evaluated by cell proliferation assay, chip array and mass spectrometry. Proteins showing sensitivity to sugars, i.e. sugar-sensitive lactosyl-Sepharose binding proteins (LSBPs), were isolated from Suit2-007 cells by competitive affinity chromatography. The eluted fractions included galactose-, glucose-, rhamnose- and lactose-sensitive LSBPs. The resulting data were analyzed by Chipster, Ingenuity Pathway Analysis (IPA) and GraphPad Prism. Khasianine inhibited proliferation of Suit2-007 and ASML cells with IC50 values of 50 and 54 μg/mL, respectively. By comparative analysis, khasianine downregulated lactose-sensitive LSBPs the most (126%) and glucose-sensitive LSBPs the least (85%). Rhamnose-sensitive LSBPs overlapped significantly with lactose-sensitive LSBPs and were the most upregulated in data from patients (23%) and a pancreatic cancer rat model (11.5%). From IPA, the Ras homolog family member A (RhoA) emerged as one of the most activated signaling pathways involving rhamnose-sensitive LSBPs. Khasianine altered the mRNA expression of sugar-sensitive LSBPs, some of which were modulated in data from patients and the rat model. The antiproliferative effect of khasianine in pancreatic cancer cells and the downregulation of rhamnose-sensitive proteins underscore the potential of khasianine in treating pancreatic cancer.

Anticancer genes (NOXA, PAR-4, TRAIL) are de-regulated in breast cancer patients and can be targeted by using a ribosomal inactivating plant protein (riproximin)

BACKGROUND

Anticancer genes are an endogenous defense against transformed cells as they impose antineoplastic effects upon ectopic expression. Profiling the expression of these genes is fundamental for exploring their prognostic and therapeutic relevance in cancers. Natural compounds can upregulate anticancer genes in malignant cells and thus be useful for therapeutic purposes. In this study, we identified the expression levels of anticancer genes in breast cancer clinical isolates. In addition, the purified and sequenced plant protein (riproximin) was evaluated for its potential to induce anticancer genes in two breast cancer cell lines.

METHODOLOGY

Expression profiles of three anticancer genes (NOXA, PAR-4, TRAIL) were identified by immunohistochemistry in 45 breast cancer clinical isolates. Breast cancer cells were exposed to riproximin and expression of the anticancer genes was determined by microarray, real-time PCR and western blot methodologies. Lastly, a bioinformatic approach was adopted to highlight the molecular/functional significance of the anticancer genes.

RESULTS

NOXA expression was evenly de-regulated among the clinical isolates, while PAR-4 was significantly down-regulated in majority of the breast cancer tissues. In contrast, TRAIL expression was increased in most of the clinical samples. Expression levels of the anticancer genes followed a distinct trend in accordance with the disease severity. Riproximin showed a substantial potential of inducing expression of the anticancer genes in breast cancer cells at transcriptomic and protein levels. The bioinformatic approach revealed involvement of anticancer genes in multiple cellular functions and signaling cascades.

CONCLUSION

Anticancer genes were de-regulated and showed discrete expression patterns in breast cancer patient samples. Riproximin effectively induced the expression of selected anticancer genes in breast cancer cells.

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.

Re-Expression of Poly/Oligo-Sialylated Adhesion Molecules on the Surface of Tumor Cells Disrupts Their Interaction with Immune-Effector Cells and Contributes to Pathophysiological Immune Escape

Glycans linked to surface proteins are the most complex biological macromolecules that play an active role in various cellular mechanisms. This diversity is the basis of cell-cell interaction and communication, cell growth, cell migration, as well as co-stimulatory or inhibitory signaling. Our review describes the importance of neuraminic acid and its derivatives as recognition elements, which are located at the outermost positions of carbohydrate chains linked to specific glycoproteins or glycolipids. Tumor cells, especially from solid tumors, mask themselves by re-expression of hypersialylated neural cell adhesion molecule (NCAM), neuropilin-2 (NRP-2), or synaptic cell adhesion molecule 1 (SynCAM 1) in order to protect themselves against the cytotoxic attack of the also highly sialylated immune effector cells. More particularly, we focus on α-2,8-linked polysialic acid chains, which characterize carrier glycoproteins such as NCAM, NRP-2, or SynCam-1. This characteristic property correlates with an aggressive clinical phenotype and endows them with multiple roles in biological processes that underlie all steps of cancer progression, including regulation of cell-cell and/or cell-extracellular matrix interactions, as well as increased proliferation, migration, reduced apoptosis rate of tumor cells, angiogenesis, and metastasis. Specifically, re-expression of poly/oligo-sialylated adhesion molecules on the surface of tumor cells disrupts their interaction with immune-effector cells and contributes to pathophysiological immune escape. Further, sialylated glycoproteins induce immunoregulatory cytokines and growth factors through interactions with sialic acid-binding immunoglobulin-like lectins. We describe the processes, which modulate the interaction between sialylated carrier glycoproteins and their ligands, and illustrate that sialic acids could be targets of novel therapeutic strategies for treatment of cancer and immune diseases.

Dual Akt and Bcl-2 inhibition induces cell-type specific modulation of apoptotic and autophagic signaling in castration resistant prostate cancer cell lines

BACKGROUND

Cancer cell survival depends on the cross-regulation between apoptosis and autophagy which share common signaling pathways including PI3K/Akt/mTOR and Bcl-2. The aim of this study was to elucidate the modulation patterns between apoptosis and autophagy following dual inhibition by Akt inhibitor erufosine and Bcl-2 inhibitor ABT-737 in castration-resistant prostate cancer (CRPC) cell lines, PC-3 (Bax+) and DU-145 (Bax-).

METHODS AND RESULTS

Cell cycle progression, apoptotic and autophagic signaling were examined by flow cytometry, multi-caspase assay, Hoechst staining, acridine orange staining of acidic vesicular organelles (AVOs), qRT-PCR and Western Blot. Dual inhibition increased G2/M arrest in PC-3 and DU-145, but not in the healthy prostate epithelium cells, PNT-1A. Only in PC-3, dual inhibition induced synergistic apoptotic and additive autophagic effects. In DU-145 and PNT-1A cells, ABT-737 did not display any remarkable effect on multicaspase activity and erufosine and ABT-737, neither alone nor in combination induced AVOs. By dual inhibition, AKT, BCL-2 and NF-κB gene expressions were downregulated in PC-3, both ATG-5 and BECLIN-1 gene expressions were upregulated in DU-145 but Beclin-1 protein expression was substantially reduced in both CRPC cells. Dual inhibition-induced synergistic multicaspase activation in PC-3 degrades and disrupts autophagic activity of Beclin-1, enhancing caspase-dependent apoptosis. However, in DU-145, following dual inhibition, rate of multicaspase induction and apoptosis are lower but autophagy is completely abolished despite markedly increased BECLIN-1 gene expression.

CONCLUSION

In conclusion, antineoplastic drug combinations may display cell-type specific modulation of apoptotic and autophagic signaling and lack of protective autophagy may not necessarily indicate increased chemotherapeutic sensitivity in heterogenous tumor subpopulations.

Activating Natural Killer Cell Receptors, Selectins, and Inhibitory Siglecs Recognize Ebolavirus Glycoprotein

Expression of the extensively glycosylated Ebolavirus glycoprotein (EBOV-GP) induces physical alterations of surface molecules and plays a crucial role in viral pathogenicity. Here we investigate the interactions of EBOV-GP with host surface molecules using purified EBOV-GP, EBOV-GP-transfected cell lines, and EBOV-GP-pseudotyped lentiviral particles. Subsequently, we wanted to examine which receptors are involved in this recognition by binding studies to cells transfected with the EBOV-GP as well as to recombinant soluble EBOV-GP. As the viral components can also bind to inhibitory receptors of immune cells (e.g., Siglecs, TIM-1), they can even suppress the activity of immune effector cells. Our data show that natural killer (NK) cell receptors NKp44 and NKp46, selectins (CD62E/P/L), the host factors DC-SIGNR/DC-SIGN, and inhibitory Siglecs function as receptors for EBOV-GP. Our results show also moderate to strong avidity of homing receptors (P-, L-, and E-selectin) and DC-SIGNR/DC-SIGN to purified EBOV-GP, to cells transfected with EBOV-GP, as well as to the envelope of a pseudotyped lentiviral vector carrying the EBOV-GP. The concomitant activation and inhibition of the immune system exemplifies the evolutionary antagonism between the immune system and pathogens. Altogether these interactions with activating and inhibitory receptors result in a reduced NK cell-mediated lysis of EBOV-GP-expressing cells. Modulation of these interactions may provide new strategies for treating infections caused by this virus.

Sniffer dogs can identify lung cancer patients from breath and urine samples

BACKGROUND

Lung cancer is the most common oncological cause of death in the Western world. Early diagnosis is critical for successful treatment. However, no effective screening methods exist. A promising approach could be the use of volatile organic compounds as diagnostic biomarkers. To date there are several studies, in which dogs were trained to discriminate cancer samples from controls. In this study we evaluated the abilities of specifically trained dogs to distinguish samples derived from lung cancer patients of various tumor stages from matched healthy controls.

METHODS

This single center, double-blind clinical trial was approved by the local ethics committee, project no FF20/2016. The dog was conditioned with urine and breath samples of 36 cancer patients and 150 controls; afterwards, further 246 patients were included: 41 lung cancer patients comprising all stages and 205 healthy controls. From each patient two breath and urine samples were collected and shock frozen. Only samples from new subjects were presented to the dog during study phase randomized, double-blinded. This resulted in a specific conditioned reaction pointing to the cancer sample.

RESULTS

Using a combination of urine and breath samples, the dog correctly predicted 40 out of 41 cancer samples, corresponding to an overall detection rate of cancer samples of 97.6% (95% CI [87.1, 99.9%]). Using urine samples only the dog achieved a detection rate of 87.8% (95% CI [73.8, 95.9%]). With breath samples, the dog correctly identified cancer in 32 of 41 samples, resulting in a detection rate of 78% (95% CI [62.4, 89.4%]).

CONCLUSIONS

It is known from current literature that breath and urine samples carry VOCs pointing to cancer growth. We conclude that olfactory detection of lung cancer by specifically trained dogs is highly suggestive to be a simple and non-invasive tool to detect lung cancer. To translate this approach into practice further target compounds need to be identified.

The Treatment of Capsular Contracture Around Breast Implants Induced by Fractionated Irradiation: The Collagenase of the Bacterium Clostridium Histolyticum as a Novel Therapeutic Approach

BACKGROUND

Irradiation therapy limits the utilization of silicone implants for breast reconstruction due to a significant risk for capsular contracture. The injection of the collagenase of the bacterium Clostridium histolyticum (CCH) might trivialize this risk by providing a minimal-invasive treatment option by capsular contracture degradation. However, efficacy in degrading breast implant capsules induced by fractionated irradiation remains unclear.

METHODS

Twenty-four rats in three groups received miniature silicone implants in a submuscular pocket. After 3D dose calculation and treatment field definition, rats of two groups underwent fractionated radiotherapy (6 × 8 Gy) using a linear accelerator. A third group served as control. On day 120, one irradiated group received injections of 0.3 mg/ml collagenase. Administration of plain solvent solution served as control in the two other groups. Outcome parameters included CT-imaging, histology, vessel wall analysis, immunohistochemistry, chemical collagen quantification and gene expression analysis.

RESULTS

Fractioned irradiation leads to a significant increase in collagen deposition around silicone implants with higher capsule thickness and collagen density when comparing all groups. Additionally, significant alterations of collagen fiber deposition were evident. Vessel wall thickness was significantly increased after radiotherapy. The injection of collagenase led to a significant reduction of capsule thickness, collagen density and content. However, the collagenase application induced a significant overexpression of TGFβ1. No side effects were monitored.

CONCLUSIONS

The CCH proved to be a safe and effective approach to degrade capsule tissue induced by fractionated irradiation in an animal model. This may pave its way for clinical application in implant-based breast reconstruction patients.

LEVEL OF EVIDENCE

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Discovery of Novel CCR5 Ligands as Anticolorectal Cancer Agents by Sequential Virtual Screening

C-C chemokine receptor type 5 (CCR5) is a member of the G protein-coupled receptor. CCR5 and its interaction with chemokine ligands have been crucial for understanding and tackling human immunodeficiency virus (HIV)-1 entry into target cells. In recent years, the change in CCR5 expression has been related to the progression of different cancer types. Patients treated with the CCR5 ligand, maraviroc (MVC), showed a deceleration in tumor development especially for metastatic colorectal cancer. Based on the crystal structure of CCR5, we herein describe a multistage virtual screening protocol including pharmacophore screening, molecular docking, and protein-ligand interaction fingerprint (PLIF) postdocking filtration for discovery of novel CCR5 ligands. The applied virtual screening protocol led to the identification of four hits with binding modes showing access to the major and minor pockets of the MVC binding site. Compounds 2-4 showed a decrease in cellular proliferation upon testing on the metastatic colorectal cancer cell line, SW620, displaying 12, 16, and 4 times higher potency compared to MVC, respectively. Compound 3 induced apoptosis by arresting cells in the G0/G1 phase of the cell cycle similar to MVC. Further in vitro assays showed compound 3 drastically decreasing the CCR5 expression and cellular migration 48 h post treatment, indicating its ability to inhibit metastatic activity in SW620 cells. The discovered hits represent potential leads for the development of novel classes of anticolorectal cancer agents targeting CCR5.

A subgroup of lactosyl-Sepharose binding proteins requires calcium for affinity and galactose for anti-proliferation

Lactosyl-Sepharose binding proteins (LSBPs) were recently described in human pancreatic ductal adenocarcinoma (PDAC) Suit2-007 cells regarding their lectin-like properties and role in metastasis. This study further investigated how calcium and galactose influence the binding of LSBPs to the lactosyl resin as well as their anti-proliferative effect in Suit2-007 cells. Altered binding of LSBPs to the lactosyl resin was evaluated by affinity chromatography and mass spectrometry. Calcium binding EF-hand proteins were aligned and identified with a motif derived from the Uniprot protein database. The antiproliferative effects of LSBPs and monosaccharides were determined by MTT assay. In addition, LSBPs and galactose effects were investigated by chip array and tumor take in nude rats. LSBPs reduced Suit2-007 cells' proliferation with an IC₅₀ of 125 μg/mL. Coincubation of LSBPs with EGTA decreased the number of LSBPs binding to the lactosyl resin by ~50%. Ca²⁺ -sensitive LSBPs included subgroups of galactose-sensitive (10%) and EF-hand calcium binding motifs containing (2.5%) proteins. In vitro, the combination of LSBPs with monosaccharides including galactose synergistically decreased cell proliferation compared to single agents (p < 0.05). In addition, LSBPs in combination with galactose prevented the tumor growth of Suit2-007 cells in nude rats, as opposed to single treatments. At mRNA level, the combination treatment modulated 5% of Ca²⁺ -sensitive LSBPs and downregulated 216 genes, 18% of which were up-regulated during PDAC progression. This study highlights the importance of calcium and galactose in modulating the affinity and anti-proliferative activity of LSBPs and their potential application as therapeutic agents for metastatic PDAC.

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.

Antineoplastic effect of a novel nanosized curcumin on cutaneous T cell lymphoma

Cutaneous T cell lymphomas (CTCLs) are a group of heterogeneous, life-threatening, extra-nodal and lymphoproliferative T cell neoplasms. Since chronic inflammation serves a key role in CTCL progression, curcumin, a natural pigment with proven anti-inflammatory and antineoplastic properties, as well as minimal toxicity, may be used as a therapeutic agent. In the present study, two formulations of curcumin (standard ethanolic and a Pluronic^®P-123/F-127 micellar solution) were compared regarding their cytotoxic efficacy and speed of internalization in three CTCL cell lines, namely HuT-78, HH and MJ. In addition, the modulating effect of curcumin on selected proteins involved in the proliferation and progression of the disease was determined. The results indicated the superiority of the Pluronic^®P-123/F-127 micellar curcumin over the standard ethanol solution in terms of cellular internalization efficiency as determined by spectrophotometric analysis. Notably, the presence of commonly used media components, such as phenol red, may interfere when interpreting the cytotoxicity of curcumin, due to their overlapping absorbance peaks. Therefore, it was concluded that phenol red-free media are superior over media with phenol red in order to correctly measure the cytotoxic efficacy and cell penetration of curcumin. Depending on the cell line, the IC₅₀ values of micellar curcumin varied from 29.76 to 1.24 µΜ, with HH cells demonstrating the highest sensitivity. This cell line had the lowest expression levels of the Wilms' tumor-1 transcription factor. Performing western blot analyses of treated and untreated CTCL cells, selective signal transduction changes were recorded for the first time, thus making curcumin nano-formulation an attractive and prospective option with therapeutic relevance for CTCL as a rare orphan disease.

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.

Multiple Facets of Autophagy and the Emerging Role of Alkylphosphocholines as Autophagy Modulators

Autophagy is a highly conserved multistep process and functions as passage for degrading and recycling protein aggregates and defective organelles in eukaryotic cells. Based on the nature of these materials, their size and degradation rate, four types of autophagy have been described, i.e. chaperone mediated autophagy, microautophagy, macroautophagy, and selective autophagy. One of the major regulators of this process is mTOR, which inhibits the downstream pathway of autophagy following the activation of its complex 1 (mTORC1). Alkylphosphocholine (APC) derivatives represent a novel class of antineoplastic agents that inhibit the serine-threonine kinase Akt (i.e. protein kinase B), which mediates cell survival and cause cell cycle arrest. They induce autophagy through inhibition of the Akt/mTOR cascade. They interfere with phospholipid turnover and thus modify signaling chains, which start from the cell membrane and modulate PI3K/Akt/mTOR, Ras-Raf-MAPK/ERK and SAPK/JNK pathways. APCs include miltefosine, perifosine, and erufosine, which represent the first-, second- and third generation of this class, respectively. In a high fraction of human cancers, constitutively active oncoprotein Akt1 suppresses autophagy in vitro and in vivo. mTOR is a down-stream target for Akt, the activation of which suppresses autophagy. However, treatment with APC derivatives will lead to dephosphorylation (hence deactivation) of mTOR and thus induces autophagy. Autophagy is a double-edged sword and may result in chemotherapeutic resistance as well as cancer cell death when apoptotic pathways are inactive. APCs display differential autophagy induction capabilities in different cancer cell types. Therefore, autophagy-dependent cellular responses need to be well understood in order to improve the chemotherapeutic outcome.

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.

Modulation of the Endothelin System in Colorectal Cancer Liver Metastasis: Influence of Epigenetic Mechanisms?

Targeting of endothelin system genes is a promising strategy in cancer therapy. The modulation of these genes was explored in a model of colorectal cancer (CRC) liver metastasis and in a panel of CRC tumor cell lines that were exposed to the demethylating agent decitabine. The CC531 rat model mimicking CRC liver metastasis was used for tumor cell re-isolation and analysis of the endothelin system genes and DNA methyltransferases (DNMTs) by microarray. To mimic the effects caused by methylation changes, a panel of seven CRC cell lines was treated with the demethylating agent decitabine. Three genes of the endothelin system were potently modulated at messenger RNA (mRNA) level in rat CC531 cells during liver colonization. The concomitant decrease of two DNMTs suggested an influence from altered methylation. Changes in gene expression were also accomplished by exposure of CRC cells to the demethylating agent decitabine, when using daily low concentrations for 3 days, with minimal cytotoxic effects. Sensitive human SW480 cells showed an almost 100fold upregulation of endothelin-1 mRNA compared to untreated cells. This, however, was different in LS174T cells, which showed no significant increase in gene expression although the methylation levels were significantly decreased at a variety of corresponding loci. We suggest that the mechanism induced by methylation on gene expression in metastatic CRC cells can be compromised. The results question the overall success of treating metastatic CRC by methylation inhibitors.

Alkylphospholipids are Signal Transduction Modulators with Potential for Anticancer Therapy

BACKGROUND

Alkylphospholipids (APLs) are synthetically derived from cell membrane components, which they target and thus modify cellular signalling and cause diverse effects. This study reviews the mechanism of action of anticancer, antiprotozoal, antibacterial and antiviral activities of ALPs, as well as their clinical use.

METHODS

A literature search was used as the basis of this review.

RESULTS

ALPs target lipid rafts and alter phospholipase D and C signalling cascades, which in turn will modulate the PI3K/Akt/mTOR and RAS/RAF/MEK/ERK pathways. By feedback coupling, the SAPK/JNK signalling chain is also affected. These changes lead to a G2/M phase cell cycle arrest and subsequently induce programmed cell death. The available knowledge on inhibition of AKT phosphorylation, mTOR phosphorylation and Raf down-regulation renders ALPs as attractive candidates for modern medical treatment, which is based on individualized diagnosis and therapy. Corresponding to their unusual profile of activities, their side effects result from cholinomimetic activity mainly and focus on the gastrointestinal tract. These aspects together with their bone marrow sparing features render APCs well suited for modern combination therapy. Although the clinical success has been limited in cancer diseases so far, the use of miltefosine against leishmaniosis is leading the way to better understanding their optimized use.

CONCLUSION

Recent synthetic programs generate congeners with the increased therapeutic ratio, liposomal formulations, as well as diapeutic (or theranostic) derivatives with optimized properties. It is anticipated that these innovative modifications will pave the way for the further successful development of ALPs.

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.

Abstract 4307: Molecular basis of cell cycle arrest induced by erufosine in metastatic breast cancer cells

Introduction: Breast cancer, a major health care burden with limited curative options for advanced metastatic phase, demands a search for novel therapeutic compounds. Synthetic alkyl-phospholipids (ALPs) comprise a promising class of anti-cancer agents in this context, where 1st and 2nd generation compounds are already in clinical use to treat various malignancies. Erufosine is the latest (3rd) generation of ALPs and has shown promising anti-tumour activities against breast cancer with minimal toxicity towards GI tract, negligible haemolytic activity and a good pharmacological profile in laboratory settings. Previously, we highlighted the significant potential of erufosine to induce arrest in G2/M phase of cell cycle in breast cancer cells. Currently, we decipher the mechanistic basis of these observed effects at molecular levels.

Materials & Methods: Metastatic breast cancer cells (MDA-MB-231) were exposed to low (IC25, 12.3µM), medium (IC50, 19.5µM) and high (IC75, 30.2µM) concentrations of erufosine for 48h. Distribution of the cells in different phases of the cell cycle was determined by propidium iodide based labelling of the DNA and flow cytometry analysis. Expressional modulations in 84 cell cycle relevant genes in response to erufosine exposure (IC75, 48h) were studied by using a ready-made panel (Qiagen, Cat#330231) and real-time PCR methodology. Alterations in expressional profile of significantly altered genes (≥2fold) were used to design a signalling pathway with the help of Ingenuity Pathway Analysis at core facility of DKFZ, Heidelberg, Germany.

Results: Exposure with erufosine induced a significant arrest in the G2/M phase of cell cycle in MDA-MB-231 cells in a concentration dependant format. Significant alterations (≥2fold) were found in 39% (33/84) of the cell cycle relevant genes incorporated in the ready-made panel. Most of the altered genes (28/33) were down-regulated in response to erufosine exposure. Significantly altered genes belong to various groups like kinases (ATM, AURKA, B), phosphatases (CDC25A, C), tumour suppressors (BRCA1), anti-apoptotic genes ( BCL2, BIRC5), cyclins (CCNA2, CCNB1, CCNB2, CCND2, CCNF, CCNG2), their target kinases (CDKs), activators (CDC6, MK167), inhibitors (CDKN1A, 2A, CDKN3, CKS1B), regulators (CDC20, MKI67), facilitators of the cell cycle (MCM2, 3, 4) and transcription factors (CKS2, E2F1).

Conclusion: Erufosine is a significant cytostatic agent and induces a major halt in the G2/M phase of cell cycle in metastatic breast cancer cells. The compound imposes noteworthy alterations in various cell cycle relevant genes to cause these cytostatic effects. Erufosine, provided with further studies in laboratory (in vitro and in vivo) and clinical settings, could be a valuable therapeutic agent for metastatic breast cancer.

Citation Format: Asim Pervaiz, Muhammad Shoaib Akhtar, Saqib Mahmood, Osheen Sajjad, Saba Khaliq, Martin R. Berger. Molecular basis of cell cycle arrest induced by erufosine in metastatic breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4307.

Abstract 3938: The alkylphosphocholine erufosine induces ER and mitochondrial stress in OSCC cells

Endoplasmic reticulum (ER) plays an essential role in cell function and survival. Accumulation of unfolded or misfolded proteins in the lumen of the ER activates the unfolded protein response (UPR), resulting in ER-stress and subsequent apoptosis. The alkylphosphocholine erufosine is a known Akt-mTOR inhibitor in oral squamous cell carcinoma (OSCC). In the present study we decipher a new facet of erufosine's mechanism of action and evaluate its role to induce ER and mitochondrial stress leading to autophagy, apoptosis and ROS induction. The cellular toxicity of erufosine was determined by MTT assay after 24h, 48h and 72h exposure in two OSCC cell lines, HN-5 and SCC-61. Based on these results, HN-5 cells were exposed to erufosine at concentrations corresponding to IC25, IC50 and IC75 concentrations, and then their mRNA was isolated and analyzed by Illumina Chip array. Gene expression and gene set enrichment analyses were performed to identify core KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways and GO (Gene Ontology) terms. A positive enrichment of ER stress upon erufosine exposure was observed, which was verified at protein level for the ER stress sensors and their downstream mediators. Upon erufosine exposure, calcium influx into the cytoplasm of the two OSCC cell lines was also observed. A differential regulation of genes and positive enrichment of processes pertaining to autophagy and apoptosis was also observed upon erufosine exposure. Autophagy was confirmed by increased acidic vacuoles and LC3-B levels. Apoptosis was confirmed by nuclear staining, annexin-V and immuno-blotting of caspases. The induction of mitochondrial stress upon erufosine exposure was predicted by gene enrichment analysis and shown by erufosine's effect on mitochondrial membrane potential, ATP and ROS production in OSCC cells. These data show that ER and mitochondrial targeting by erufosine represents a new facet of its mechanism of action as well as a promising new framework in the treatment of head and neck cancers. They furthermore support the future evaluation of erufosine as a therapeutic approach in cancer treatment alone, or in combination.

Citation Format: Shariq S. Ansari, Ashwini Sharma, Doaa M. Ali, Rainer Köng, Martin R. Berger. The alkylphosphocholine erufosine induces ER and mitochondrial stress in OSCC cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3938.

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.

The ribosome inhibiting protein riproximin shows antineoplastic activity in experimental pancreatic cancer liver metastasis

Pancreatic ductal adenocarcinoma (PDAC) has one of the poorest prognoses of all malignancy types. To improve the survival of patients with PDAC, the development of novel anticancer agents is warranted. Riproximin (Rpx) is a newly identified plant lectin, which was isolated from Ximenia americana. The ribosome inactivating protein of type II exhibits potent anticancer activity as recently demonstrated. The rat PDAC cell line ASML was used for in vitro and in vivo studies. The antiproliferative effect of Rpx was assessed using an MTT assay. The modulation of proteins involved in apoptosis was evaluated using western blotting. Tumor-bearing nude rats were treated with Rpx, gemcitabine (GEM) or dinaline (DIN) as single agents, or a combination of Rpx with GEM, or DIN. Rpx was administered intraperitoneally at doses of 1.7–5.4 µg/kg, three times/week, GEM was administered intravenously (50 mg/kg/week) and DIN perorally (10 mg/kg, 5 times/week). Rpx inhibited ASML cell proliferation at IC₅₀-values of 0.8–172 pM, caused apoptosis and reduced tumor growth significantly by 90% (P<0.05). The survival rate of rats was significantly increased (21.8 days for Rpx treated vs. 17.6 days for control rats; P=0.05). Higher doses of Rpx caused no further reduction in tumor size when compared with the low dose of Rpx or a combination of Rpx with GEM, or DIN. The standard drug GEM alone was less effective compared with Rpx. In addition, DIN was ineffective, and in combination, reduced the activity of Rpx. These results suggest that Rpx has an evident potential for use in pancreatic cancer treatment. Further experiments are required in order to elucidate its affinity for certain cancer cells and to optimize the combination therapy with other antineoplastic agents.

Investigation of Metastasis-Related Genes: A Rat Model Mimicking Liver Metastasis of Colorectal Carcinoma

Liver is the main target of colorectal cancer (CRC) metastasis. Currently, the number of reports is small, which describe changes in gene expression supporting liver metastasis. Here, a rat model was used for analyzing mRNA modulations during liver colonization and compared with available literature. In the model, CC531 rat CRC cells were injected via a mesenteric vein into isogenic WAG/Rij rats and re-isolated at early, intermediate, advanced, and terminal stages of liver colonization. These cells were used for RNA isolation. Microarrays were used for analyzing mRNA profiles of expression. The number of deregulated genes is comparatively large and only part of it has been studied so far. As reported to date, claudins and insulin-like growth factor-binding proteins (IGFBPs) were found to be deregulated. The fact that the chosen method is efficient is confirmed by the study of claudins and IGFBPs, which show altered expression in the initial stages of liver colonization and then return to normalcy. In addition, cadherin was described to be downregulated in epithelial-mesenchymal transition models. It can, therefore, be concluded that the models used are helpful in finding genes, which are instrumental for metastatic liver colonization.

Abstract 116: Erufosine, a third-generation alkylphosphocholine with cytotoxic and cytostatic effects in breast and colorectal cancer cells

Introduction Breast and colorectal cancers are highly malignant diseases with low 5-year survival rate (&lt;21%) in advanced stages, which highlights the need of finding new therapeutic options. Considering this, we are interested in exploring the anticancer potential of erufosine, a membrane targeting synthetic lipid analogue belonging to a class of antineoplastic agents known as alkylphosphocholines (APCs). Properties such as intravenous administration and significantly reduced hemolytic activity as compared to previous APC generations, and efficient cytotoxic effects against malignant cells make it an attractive anticancer compound.

Materials and Methods In the present experiments, we studied the effects of erufosine against breast (MDA-MB-231 and MCF-7) and colorectal (SW480 and SW620) cancer cell lines. Following exposure to erufosine (0.78-100µM) for 24, 48 and 72h, cytotoxic effects were measured by MTT dye reduction assay and inhibitory concentrations (IC) were identified by GraphPad Prism software 6. Erufosine mediated cytostatic effects were highlighted by means of propidium iodide (PI) based labeling of the DNA followed by flow cytometry analysis. Furthermore, the cells were exposed to increasing concentrations of erufosine (IC25, 50, 75) and alterations in cell cycle relevant genes (CCNA1, CCND1, CCNE1, CCNE2, CDK1, CDK4) were investigated by qRT-PCR methodology.

Results Erufosine was highly active against the selected cell lines (IC50 &lt; 10µM, 24h) and induced significant arrest in the G2/M phase of the cell cycle. The cytostatic effects were more pronounced in the two metastatic cell lines of breast (MDA-MB-231) and colorectal (SW620) cancers. At molecular levels, erufosine induced expression of CCNA1 (≥ 2fold) in SW480, SW620, and MCF-7 cells, while the expression was inhibited in MDA-MB-231 cells at high concentrations (IC50, IC75). There were no significant alterations (≤ 2fold) in the expression levels of CCND1, CCNE1 and CDK4 in the four cell lines. CCNE2 was significantly downregulated in breast cancer cell lines only. Noteworthy, alterations in CDK1 were associated with cell lines from primary cancers, where the expression was upregulated in SW480 cells and downregulated in MCF-7 cells.

Conclusion Antineoplastic effects of erufosine contribute to decreased proliferation of breast and colorectal cancer cell lines. This synthetic lipid induces arrest in G2/M phase and alterations in cell cycle relevant genes in the selected panel of breast and colorectal cancer cells. Characteristics like in vivo stability, minimal hemolytic activity, no toxicity to bone marrow and antineoplastic effects (cytotoxic/cytostatic) against cancer cells make it an attractive therapeutic compound. Further understanding at molecular levels supported by in vivo experimentation will pave the way to validate its therapeutic potential against cancers.

Citation Format: Asim Pervaiz, Saqib Mahmood, Martin R. Berger. Erufosine, a third-generation alkylphosphocholine with cytotoxic and cytostatic effects in breast and colorectal cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 116. doi:10.1158/1538-7445.AM2017-116

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.

Long-Term Effects of the Collagenase of the Bacterium Clostridium histolyticum for the Treatment of Capsular Fibrosis After Silicone Implants

BACKGROUND

Capsular contracture remains the most frequent long-term complication after augmentation mammoplasty with silicone implants. Thereby, the main part of the fibrotic capsule is collagen. The collagenase of the bacterium Clostridium histolyticum is approved for the treatment of fibrotic diseases and has been demonstrated to be effective for capsular fibrosis treatment in the short term. However, long-term effectiveness is currently unknown but mandatory for clinical utilization.

MATERIALS AND METHODS

Forty-eight rats received miniature silicone implants and an injection with either collagenase (treatment group) or plain solvent solution (control group) 120 days post insertion. Ten and 60 days after the injections, the rats underwent 7-Tesla magnetic resonance imaging (MRI) and high-resolution ultrasound (HR-US). Capsule tissue was harvested, and capsule thickness and collagen density were evaluated through histology. Furthermore, the expression levels of inflammatory (CD68, IL4, IL10, IL12, IL13), pro-, and anti-fibrotic (TGFb1, TGFb3, Smad3, Col1-4) genes were analyzed using qRT-PCR.

RESULTS

On days 10 and 60 after injection of collagenase, histology showed that capsule thickness was significantly reduced in the treatment group when compared with the control (p < 0.05). Thickness measurements were verified by MRI and HR-US analysis. Skin perforation occurred in two cases after collagenase injection. The initial up-regulation of pro-fibrotic and inflammatory genes 10 days after collagenase injection did not persist in the long term. Contrarily, on day 60, a slight trend towards lower expression levels with a significant down-regulation of TGFb3 was detected in the treatment group.

CONCLUSION

The collagenase of the bacterium C. histolyticum effectively degrades capsular fibrosis around silicone implants with stable outcomes throughout 60 days post injection. Skin perforation and adequate and uniform drug distribution within the implant pocket are issues that need to be addressed. Further studies are warranted to clarify whether collagenase injections have the potential to become a viable treatment option for capsular contracture.

NO LEVEL ASSIGNED

This journal requires that authors 46 assign a level of evidence to each article. For a full 47 description of these Evidence-Based Medicine ratings, 48 please refer to the Table of Contents or the online 49 Instructions to Authors. www.springer.com/00266 .

Effects of tai chi exercise on bone health in perimenopausal and postmenopausal women: a systematic review and meta-analysis

Tai chi exercise may have positive effects on bone health in perimenopausal and postmenopausal women. This systematic review is the first to summarize evidence to clarify the efficacy of tai chi exercise in bone health. The benefits of tai chi exercise on bone health remain unclear; further studies are needed. Emerging randomized controlled trials (RCTs) exploring the efficacy of tai chi exercise on bone health among older women, but yielded inconclusive results. Our objective is to conduct a systematic review to evaluate evidence from RCTs to clarify the efficacy of tai chi exercise on bone mineral density (BMD), and bone turnover markers (BTM) in perimenopausal and postmenopausal women. Six electronic databases were searched, and reference lists of systematic reviews and identified studies from the search strategy were also screened. We included all RCTs that investigate tai chi exercise for bone health in perimenopausal and postmenopausal women. Data selection, extraction, and evaluation of risk of bias were performed independently by two reviewers. Ten trials detailed in 11 articles were included. Six of the 11 studies reported positive outcomes on bone health. Results of our meta-analysis showed a significant effect of tai chi exercise on BMD change at the spine compared with no treatment in perimenopausal and postmenopausal women. When tai chi exercise combined with a calcium supplement was compared with the calcium supplement alone, the result of BMD change at the spine showed no significant effect. Because the measurable effect observed was minimal, and due to the low quality of methodology of the studies, we conclude that the result is of limited reliability. Tai chi exercise may have benefits on bone health in perimenopausal and postmenopausal women, but the evidence is sometimes weak, poor, and inconsistent. Consequently, only limited conclusions can be drawn regarding the efficacy of tai chi exercise on bone health. Further well designed studies with low risk of bias are needed.

Abstract 1548: Re-isolated metastatic pancreatic cancer cells show distinct modulation of gene expression during liver colonization

Gastrointestinal cancers typically metastasize into the liver. By re-isolation of pancreatic ductal adenocarcinoma (PDAC) cells from the liver of rats harboring these cells in their liver we assessed gene expression during various stages and investigated whether extracellular matrix (ECM) genes play a role in metastatic pancreatic cancer cells. We used ASML rat pancreatic cancer cells, which were inoculated into the portal vein of isogenic BDX rats. These cells had been marked by eGFP, which allowed their re-isolation following liver perfusion by FACS sorting after early (1,3 days), intermediate (9 days), advanced (16 days), and terminal (21 days) stages of liver metastasis. Re-isolated ASML cells were used for total RNA isolation and subsequently their gene expression was investigated by Illumina chip array for mRNA and miRNA species, followed by Ingenuity pathway analysis (IPA).

Pending on the time span following re-isolation, 7-15% of all known genes and 10% of miRNA species were modulated significantly in expression. By IPA analysis, significant alterations in diseases, disorders and canonical pathways were found. Interestingly, cancer was ranked second within the five top diseases and disorders at early and terminal stages, and third at intermediate and advanced stages. Within the cancer category, the gene groups related to metastasis and advanced malignant tumor were most significantly altered, but found decreased at early and advanced stages, and increased at the terminal stage only. In addition, ECM genes were modulated significantly. These genes included gene families as chemokines, transforming growth factor -beta (TGF-β), laminins, A Disintegrin and Metalloproteinase (ADAM) peptidases, matrix metallopeptidases (MMPs), collagens, and others. From all 59 chemokines investigated, 18 and 11 mRNAs were significantly up- and down regulated. Similarly, from 21 MMPs, 6 and 2 mRNAs were significantly up and down modulated. Finally, from 39 collagens, 16 and 7 were significantly up and down regulated in expression. Also, the respective miRNAs species were modulated: In case of collagens, the miR-29b-3p species was significantly down modulated (2-fold) in accord with the upregulation of respective target collagens. Also, the miRNA species regulating chemokines were altered as shown e.g. for CCR5, which was more than 10 fold increased at mRNA level with the corresponding miR-125b-5p being ca. 2 fold decreased.

In conclusion, among the top five modulated diseases and disorders,

cancer ranked only at intermediate positions. In addition, the expression profiles of ECM genes were altered significantly in metastatic pancreatic cancer cells and thus hypothetically contributed to successful colonization of the liver by these cells.

Citation Format: Khamael M K Al-Taee, Martin R. Berger, Hassan Adwan. Re-isolated metastatic pancreatic cancer cells show distinct modulation of gene expression during liver colonization. [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 1548.

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.

Analysis of the expression of SDF-1 splicing variants in human colorectal cancer and normal mucosa tissues

C-X-C motif chemokine ligand 12 (CXCL12), also termed stromal cell-derived factor-1 (SDF-1) is a small protein 8-14 kDa in length that is expressed as six isoforms, consisting of SDF-1α, SDF-1β, SDF-1γ, SDF-1δ, SDF-1ε and SDF-1θ. All six isoforms are encoded by the single CXCL12 gene on chromosome 10. This gene regulates leukocyte trafficking and is variably expressed in a number of normal and cancer tissues. The potential role of the novel CXCL12 splice variants as components of the CXCR4 axis in cancer development is not fully understood. The present study aimed to analyze the expression profile of the various SDF-1 isoforms and SDF-1 polymorphisms, and the association with the clinicopathological features and overall survival of patients with colorectal cancer (CRC). SDF-1 polymorphism analysis was performed using restriction fragment length polymorphism (RFLP) analysis in 73 histologically confirmed human CRC tissue samples at various stages of disease. The expression pattern of the SDF-1 isoforms was analyzed by reverse transcription-polymerase chain reaction in 40 histologically confirmed human CRC tissue samples obtained at various stages of disease, as well as in matched adjacent normal mucosa samples. The presence of the CXCL12 gene polymorphism rs1801157 demonstrated an association with local progression of the primary tumor, as indicated by the T stage. The frequency of the GG genotype was slightly increased in patients with stage 3 and 4 tumors (78.0%) compared with the incidence of the GA/AA genotype (69.5%; P=0.067). The expression of SDF-1β was associated with the presence of metastases (P=0.0656) and the expression of SDF-1γ was significantly associated with tumor size (P=0.0423). The present study is the first to analyze the association between the expression profile of the chemokine CXCL12 splice variants in human CRC tissues and their clinical relevance. The present results reveal that the CXCL12 G801A polymorphism is a low-penetrance risk factor for the development of CRC, and was associated with the T stage. All six isoforms of SDF-1 were expressed in CRC tissues. The expression of SDF-1β was found to be associated with metastases and SDF-1γ appears to be a possible tumor marker for local tumor progression.

Abstract B22: Inhibition of c-MYC expression in oral squamous carcinoma cells contributes to the antiproliferative activity of the alkylphosphocholine erufosine

Erufosine is a third generation alkylphosphocholine, which has been shown to inhibit the proliferation of oral squamous cell carcinoma (OSCC) cells. It simultaneously induces apoptosis and autophagy by modulating the Akt–mTOR signaling pathway and is known to down regulate the expression of cell cycle related proteins, but the exact mechanism of action of this membrane seeking compound is still unknown.

For investigating the mechanism of action in a systematic way, we studied the effects of erufosine in a panel of OSCC cell lines (Cal-27, FaDu and HN-5). The concentration effecting the 50% inhibition in cell proliferation (IC50) in response to erufosine was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay using concentrations ranging from 0.6µM – 100µM at various time points (24h, 48h and 72h) after exposure. Based on these results, FaDu cells were exposed to erufosine at concentrations effecting IC25, IC50 and IC75, and then the mRNA of respectively treated cells was isolated and subjected to microarray analysis by Illumina Chip array. Selected genes with highly modulated mRNA expression were further investigated by quantitative RT-PCR and Western Blot. IC50 values in response to erufosine, following exposure for 24h, 48h and 72h exposure ranged from 20µM to 9.7µM for Cal-27 -, 27µM to 14µM for FaDu - , and 43µM to 37µM for HN-5 cells.

Analysis of microarray data by the Ingenuity Pathways Analysis (IPA; Ingenuity® Systems, www.ingenuity.com) software revealed that 725 genes were modulated at 16h, averaged for all concentrations, with 47 genes being modulated more than 3 fold. The respective 24h gene expression analysis revealed that 1215 genes were significantly modulated, with 77 genes deregulated over 3 fold, whereas a total of 1305 genes were altered at the end of 48h, with 93 genes being deregulated over 3 fold. In a first approach, we concentrated on genes related to the c-MYC signaling pathway. The cyclin-dependent kinase inhibitor 1A (p21, Cip1) was found to be upregulated 9.2, 7.9 and 9.9 fold, averaged for all concentrations, at 16h, 24h and 48h, respectively. The Max dimerization protein 1 (MDX1) was upregulated 3.7 fold and 3.3 fold over the untreated control at 24h and 48h post treatment. The combined modulation of the two mRNA species hints at the involvement of c-MYC as a target of erufosine treatment. These results were further validated by qRT-PCR, which also confirmed the modulation of these genes across the OSCC cell panel. In line with this, the Western blots also showed a clear decrease in c-MYC protein levels and a corresponding increase in p21 in a concentration- and time-dependent manner.

In summary, the known effect of erufosine on cell cycle related proteins as well as the increased mRNA (p21, MDX-1) and protein (p21) expression reported here is in accordance with the decreased expression of c-MYC at protein level. These findings support the hypothesis that c-MYC is an indirect target of erufosine in OSCC cells.

Citation Format: Shariq S. Ansari, Martin R. Berger. Inhibition of c-MYC expression in oral squamous carcinoma cells contributes to the antiproliferative activity of the alkylphosphocholine erufosine. [abstract]. In: Proceedings of the AACR Special Conference on Myc: From Biology to Therapy; Jan 7-10, 2015; La Jolla, CA. Philadelphia (PA): AACR; Mol Cancer Res 2015;13(10 Suppl):Abstract nr B22.

Antitumor Lipids--Structure, Functions, and Medical Applications

Cell proliferation and metastasis are considered hallmarks of tumor progression. Therefore, efforts have been made to develop novel anticancer drugs that inhibit both the proliferation and the motility of tumor cells. Synthetic antitumor lipids (ATLs), which are chemically divided into two main classes, comprise (i) alkylphospholipids (APLs) and (ii) alkylphosphocholines (APCs). They represent a new entity of drugs with distinct antiproliferative properties in tumor cells. These compounds do not interfere with the DNA or mitotic spindle apparatus of the cell, instead, they incorporate into cell membranes, where they accumulate and interfere with lipid metabolism and lipid-dependent signaling pathways. Recently, it has been shown that the most commonly studied APLs inhibit proliferation by inducing apoptosis in malignant cells while leaving normal cells unaffected and are potent sensitizers of conventional chemo- and radiotherapy, as well as of electrical field therapy. APLs resist catabolic degradation to a large extent, therefore accumulate in the cell and interfere with lipid-dependent survival signaling pathways, notably PI3K-Akt and Raf-Erk1/2, and de novo phospholipid biosynthesis. They are internalized in the cell membrane via raft domains and cause downstream reactions as inhibition of cell growth and migration, cell cycle arrest, actin stress fibers collapse, and apoptosis. This review summarizes the in vitro, in vivo, and clinical trials of most common ATLs and their mode of action at molecular and biochemical levels.

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

Abstract 5539: Antiproliferative and apoptotic effects of some African natural products in solid and hematopoietic malignant cell lines

Background: Natural products have played a very important role in health care from time immemorial in curation and prevention of diseases. Antiproliferative and apoptotic effects of extracts of some African natural products like Hymelocardia acida, Moringa oleifera leaves as well as Pleurotus pulmonarius mushroom metabolites were studied in a panel of solid and hematopoietic malignant derived cell lines such as SUIT2-007, MDA-MB 231, SW480, K562 and HL60 cells.

Methods: MTT assay was used to determine the growth inhibition of respective cells in vitro. Apoptosis of the cells was demonstrated by fluorescence microscopy and Hoechst 33342 staining, DNA ladder formation assay and flow cytometry with propidium iodide staining.

Results: MTT results showed that extracts of Hymelocardia acida stem, Moringa oleifera leaves as well as Pleurotus pulmonarius metabolites could inhibit the proliferation of SUIT2-007, MDA-MB 231, SW480, K562 and HL60 cells in a time and dose dependent manner. Our results show that the ethanol extract of Hymelocardia acida stem had a positive effect and induced apoptosis as shown by fluorescence microscopy and flow cytometry assay. Apoptotic effects were demonstrated by nuclear staining with Hoechst showing clear signs for nuclear fragmentation in cells treated with Hymelocardia acida stem and Moringa oleifera leaves extracts. FACS analysis with propidium iodide showed that the sub G1 fraction increased in treated cells. DNA ladder formation, however, showed no clear DNA fragmentation, which does not exclude a clearer picture with isolated compounds.

Conclusion: The present study indicates that the extracts studied can effectively inhibit proliferation and induce apoptosis in cells of panel of tumor cell lines investigated.

Citation Format: Olufemi E. Akanni, Martin R. Berger. Antiproliferative and apoptotic effects of some African natural products in solid and hematopoietic malignant cell lines. [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 5539. doi:10.1158/1538-7445.AM2015-5539

Riproximin: A type II ribosome inactivating protein with anti-neoplastic potential induces IL24/MDA-7 and GADD genes in colorectal cancer cell lines

Riproximin (Rpx) is a type II ribosome inactivating protein, which was extracted and purified from the seeds of Ximenia americana. Previous studies demonstrated cytotoxicity of Rpx against a variety of cell lines originating from solid and non-solid cancers. In this study, we investigated the mechanistic aspects of Rpx in selected human and rat colorectal cancer (CRC) cell lines. Cytotoxic levels of Rpx were determined by MTT assay, while cytostatic and apoptotic effects were investigated by flow cytometry and nuclear staining procedures. Effects of Rpx exposure on colony formation/migration of CRC cells and expressional modulations in anticancer/stress-related genes were also studied. Rpx showed significant and comparable levels of cytotoxicity in CRC cells as determined by inhibitory concentration (IC) values. Similar inhibitory effects were found for clonogenicity, while more pronounced inhibition of migration was observed in response to Rpx exposure. Profound arrest in S phases of the cell cycle was noted especially in primary CRC cells. Apoptotic effects were more prominent in rat CRC cells as indicated by Annexin V-FITC assay and Hoechst 33342 nuclear staining. Rpx exposure induced significantly increased levels of the IL24/MDA-7, a well characterized anticancer gene, in all CRC cells. In addition, following Rpx treatment, high expression levels of growth arrest and DNA damage (GADD family) genes were also observed. Increased expression of two additional GADD genes (34 and 153) only in rat CRC cells (CC531) conferred higher sensitivity towards Rpx and subsequent anti-proliferative/apoptotic effects as compared to human CRC cells (SW480 and SW620). The present investigation indicates the anticancer potential of Rpx in CRC and favor further evaluation of this natural compound as therapeutic agent.

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.

CCR5 blockage by maraviroc induces cytotoxic and apoptotic effects in colorectal cancer cells

Alterations in the expression of C-C chemokine receptor type 5 (CCR5 or CD195) have been correlated with disease progression in different cancers. Recently, a few investigations have reported the blockage of this receptor by an antagonist (maraviroc) and its antineoplastic effects on tumor cell growth. However, little is known about the mechanistic reasons behind these antineoplastic effects of CCR5 blockage by maraviroc. In this study, we blocked the CCR5 receptor by maraviroc in SW480 and SW620 colorectal cancer cells to study the resulting changes in biological properties and related pathways. This blockage induced significantly reduced proliferation and a profound arrest in G1 phase of the cell cycle. Concomitantly, maraviroc caused significant signs of apoptosis at morphological level. Significant modulation of multiple apoptosis-relevant genes was also noticed at mRNA levels. In addition, we found remarkable increases in cleaved caspases at protein level. These modulations led us to propose a signaling pathway for the observed apoptotic effects. In conclusion, blocking the CCR5 by maraviroc induces significant cytotoxic and apoptotic effects in colorectal cancer cells. Thus, maraviroc can be considered a model compound, which may foster the development of further CCR5 antagonists to be used for the treatment of colorectal cancer.