Targeted sequencing of cancer-related genes reveals a recurrent TOP2A variant which affects DNA binding and coincides with global transcriptional changes in glioblastoma

High-grade gliomas are aggressive, deadly primary brain tumors. Median survival of patients with glioblastoma (GBM, WHO grade 4) is 14 months and <10% of patients survive 2 years. Despite improved surgical strategies and forceful radiotherapy and chemotherapy, the prognosis of GBM patients is poor and did not improve over decades. We performed targeted next-generation sequencing with a custom panel of 664 cancer- and epigenetics-related genes, and searched for somatic and germline variants in 180 gliomas of different WHO grades. Herein, we focus on 135 GBM IDH-wild type samples. In parallel, mRNA sequencing was accomplished to detect transcriptomic abnormalities. We present the genomic alterations in high-grade gliomas and the associated transcriptomic patterns. Computational analyses and biochemical assays showed the influence of TOP2A variants on enzyme activities. In 4/135 IDH-wild type GBMs we found a novel, recurrent mutation in the TOP2A gene encoding topoisomerase 2A (allele frequency [AF] = 0.03, 4/135 samples). Biochemical assays with recombinant, wild type (WT) and variant proteins demonstrated stronger DNA binding and relaxation activity of the variant protein. GBM patients carrying the altered TOP2A had shorter overall survival (median OS 150 vs 500 days, P = .0018). In the GBMs with the TOP2A variant we found transcriptomic alterations consistent with splicing dysregulation. luA novel, recurrent TOP2A mutation, which was found exclusively in four GBMs, results in the TOP2A E948Q variant with altered DNA binding and relaxation activities. The deleterious TOP2A mutation resulting in transcription deregulation in GBMs may contribute to disease pathology.

Exploring Novel Therapeutic Opportunities for Glioblastoma Using Patient-Derived Cell Cultures

Glioblastomas (GBM) are the most common, primary brain tumors in adults. Despite advances in neurosurgery and radio- and chemotherapy, the median survival of GBM patients is 15 months. Recent large-scale genomic, transcriptomic and epigenetic analyses have shown the cellular and molecular heterogeneity of GBMs, which hampers the outcomes of standard therapies. We have established 13 GBM-derived cell cultures from fresh tumor specimens and characterized them molecularly using RNA-seq, immunoblotting and immunocytochemistry. Evaluation of proneural (OLIG2, IDH1^R132H, TP53 and PDGFRα), classical (EGFR) and mesenchymal markers (CHI3L1/YKL40, CD44 and phospho-STAT3), and the expression of pluripotency (SOX2, OLIG2, NESTIN) and differentiation (GFAP, MAP2, β-Tubulin III) markers revealed the striking intertumor heterogeneity of primary GBM cell cultures. Upregulated expression of VIMENTIN, N-CADHERIN and CD44 at the mRNA/protein levels suggested increased epithelial-to-mesenchymal transition (EMT) in most studied cell cultures. The effects of temozolomide (TMZ) or doxorubicin (DOX) were tested in three GBM-derived cell cultures with different methylation status of the MGMT promoter. Amongst TMZ- or DOX-treated cultures, the strongest accumulation of the apoptotic markers caspase 7 and PARP were found in WG4 cells with methylated MGMT, suggesting that its methylation status predicts vulnerability to both drugs. As many GBM-derived cells showed high EGFR levels, we tested the effects of AG1478, an EGFR inhibitor, on downstream signaling pathways. AG1478 caused decreased levels of phospho-STAT3, and thus inhibition of active STAT3 augmented antitumor effects of DOX and TMZ in cells with methylated and intermediate status of MGMT. Altogether, our findings show that GBM-derived cell cultures mimic the considerable tumor heterogeneity, and that identifying patient-specific signaling vulnerabilities can assist in overcoming therapy resistance, by providing personalized combinatorial treatment recommendations.

Regulatory networks driving expression of genes critical for glioblastoma are controlled by the transcription factor c-Jun and the pre-existing epigenetic modifications

BACKGROUND

Glioblastoma (GBM, WHO grade IV) is an aggressive, primary brain tumor. Despite extensive tumor resection followed by radio- and chemotherapy, life expectancy of GBM patients did not improve over decades. Several studies reported transcription deregulation in GBMs, but regulatory mechanisms driving overexpression of GBM-specific genes remain largely unknown. Transcription in open chromatin regions is directed by transcription factors (TFs) that bind to specific motifs, recruit co-activators/repressors and the transcriptional machinery. Identification of GBM-related TFs-gene regulatory networks may reveal new and targetable mechanisms of gliomagenesis.

RESULTS

We predicted TFs-regulated networks in GBMs in silico and intersected them with putative TF binding sites identified in the accessible chromatin in human glioma cells and GBM patient samples. The Cancer Genome Atlas and Glioma Atlas datasets (DNA methylation, H3K27 acetylation, transcriptomic profiles) were explored to elucidate TFs-gene regulatory networks and effects of the epigenetic background. In contrast to the majority of tumors, c-Jun expression was higher in GBMs than in normal brain and c-Jun binding sites were found in multiple genes overexpressed in GBMs, including VIM, FOSL2 or UPP1. Binding of c-Jun to the VIM gene promoter was stronger in GBM-derived cells than in cells derived from benign glioma as evidenced by gel shift and supershift assays. Regulatory regions of the majority of c-Jun targets have distinct DNA methylation patterns in GBMs as compared to benign gliomas, suggesting the contribution of DNA methylation to the c-Jun-dependent gene expression.

CONCLUSIONS

GBM-specific TFs-gene networks identified in GBMs differ from regulatory pathways attributed to benign brain tumors and imply a decisive role of c-Jun in controlling genes that drive glioma growth and invasion as well as a modulatory role of DNA methylation.

615 Reactivating antitumor immunity in gliomas with osteopontin/integrin blocking peptide

Background

Glioblastoma (GBM) is the most common and aggressive primary brain tumor in adults. Despite improvements in imaging, surgical techniques, radiotherapy and chemotherapy, the prognosis of patients with GBM remains poor with a median overall survival of 15 months [1,2]. GBM is immunologically a ”cold” tumor with low infiltration of functional T and NK cells, which imposes poor responsiveness of GBM patients to immunotherapies. The immunosuppressive microenvironment in GBM is created by the malignant cells and tumor-associated macrophages (TAMs), such as resident brain microglia and recruited peripheral myeloid cells [3]. Osteopontin/Spp1 is one of glioma-derived factors that is responsible for the protumorigenic reprogramming of TAMs [4]. SPP1 expression is highly elevated in tumor tissues and sera from GBM patients, and inversely correlates with patient survival [5]. Cross-talk between malignant cells and TAMs relays on osteopontin binding to integrin receptors (mainly αvβ3 and αvβ5) via its RGD motif [6]. Thus, with the use of a RGD peptide (our in-house designed competitor of binding to integrins) we interfered with glioma-microglia interaction in vitro and evaluated the in vivo antitumor efficacy of integrin blockade as a monotherapy and in combination with an immune check-point inhibitor.

Methods

The efficacy of the RGD peptide to block microglia-dependent glioma invasion was determined in a Matrigel invasion assay. Antitumor activity of the peptide was assessed in a murine syngeneic orthotopic GL261 glioma model. RGD peptide was administrated intratumorally via osmotic pomps. For combination therapy, the animals received anti-PD-1 or isotype IgG antibody (4 inj. x 10 mg/kg i.p.). Tumor volume was measured using MRI. Heterogeneity of the immune cells compartment of glioma microenvironment was analysed by flow cytometry. The transcriptomes of CD11b+ cells immunosorted from tumor-bearing mouse brains were evaluated using RNAseq. Cytokine levels in the blood and the brain homogenates were measured using Luminex bead-based assays.

Results

The microglia-stimulated invasion of GL261 glioma cells was reduced significantly in the presence of the RGD peptide in the in vitro co-culture system. The RGD peptide administrated to tumor-bearing mice induced proinflammatory reprogramming of TAMs. Combination of the RGD peptide with anti-PD-1 therapy increased the production of proinflammatory cytokines and the percentage of effector CD8+(CD44+CD62L-) cells in the tumors.

Conclusions

These results demonstrate that blockade of osteopontin/integrin signaling using the RGD peptide can mitigate the immunosuppressive microenvironment, reactivate the antitumor immunity and lay ground for improved response to immunotherapy in GBM.

References

Jemal A, Murray T, Ward E, Samuels A, Tiwari RC, Ghafoor A, Feuer EJ, Thun MJ: Cancer statistics, 2005. CA Cancer J Clin 2005, 55(1):10–30.

Stupp R, Hegi ME, Mason WP, van den Bent MJ, Taphoorn MJ, Janzer RC, Ludwin SK, Allgeier A, Fisher B, Belanger K et al: Effects of radiotherapy with concomitant and adjuvant temozolomide versus radiotherapy alone on survival in glioblastoma in a randomised phase III study: 5-year analysis of the EORTC- NCIC trial. Lancet Oncol 2009, 10(5):459–466.

Woroniecka KI, Rhodin KE, Chongsathidkiet P, Keith KA, Fecci PE: T-cell Dysfunction in Glioblastoma: Applying a New Framework. Clin Cancer Res 2018, 24(16):3792–3802

Denhardt, D.T., M. Noda, A.W. O’Regan, D. Pavlin, and J.S. Berman. 2001. Osteopontin as a means to cope with environmental insults: regulation of inflammation, tissue remodeling, and cell survival. J Clin Invest 107:1055–1061.

Grassinger, J., D.N. Haylock, M.J. Storan, G.O. Haines, B. Williams, G.A. Whitty, et al. 2009. Thrombin-cleaved osteopontin regulates hemopoietic stem and progenitor cell functions through interactions with alpha9beta1 and alpha4beta1 integrins. Blood 114:49–59.

Anborgh, P.H., J.C. Mutrie, A.B. Tuck, and A.F. Chambers. 2010. Role of the metastasis-promoting protein osteopontin in the tumour microenvironment. Journal of cellular and molecular medicine 14:2037–2044

Ethics Approval

All research protocols conformed to the Guidelines for the Care and Use of Laboratory Animals (European and national regulations 2010/63/UE September 22, 2010 and Dz. Urz. UE L276/20.10.2010, respectively). Animals were decapitated by a qualified researcher. The First Warsaw Local Ethics Committee for Animal Experimentation approved the study (approval no. 812/2019).

BSCI-15. Osteopontin plays a crucial role in invasiveness of triple negative breast cancer cells in the context of human microglia

The triple-negative breast cancer (TNBC) is the most malignant among breast cancers and has the high risk of developing metastasis into the brain. Metastases of breast cancers are increasing and pose a clinical challenge as the current treatments are not effective due to the unique brain microenvironment for metastatic breast cancer cells. While the contribution of brain macrophages to the formation of the metastatic niche is established, factors responsible for the crosstalk between cells remain elusive. SPP1 encoding a secreted phosphoprotein 1 (ostepontin) is highly overexpressed in malignant breast cancers. We evaluated the role of SPP1 in invasion and metastasis of human breast cancer cells. We found the increased invasion of triple-negative MDA-MB-231 (MDA-231) cells in the presence of human microglial HMSV40 cells. Using Western blot analysis demonstrated the elevated levels of focal adhesion kinase (FAK) and signal transducer and activator of transcription 3 (STAT3) in MDA-231 cells in co-cultures. Moreover, blocking SPP1 and integrin interactions with the synthetic RGD peptide, efficiently diminished both basic and microglia-induced invasion of MDA-231. To assess the role of SPP1 in cell invasion, we established the MDA-231 cells with knocked-down SPP1 expression using shRNA (shSPP1). Interestingly, the shSPP1 cells were unresponsive towards HMSV40 microglia. We have previously found that an antibiotic minocycline reduces SPP1 expression in glioma cells. We performed cell toxicity studies on 4 breast cancer cell lines and various non-malignant cells. All tested malignant cancer cells were more sensitize to minocycline than non-cancerous cells and breast cancer cells derived from TNBC were the most susceptible. Altogether, we demonstrate that microglia support invasion of breast cancer cells via SPP1/osteopontin triggering the integrin signalling, and minocycline by downregulating SPP1 expression may reduce both basic and microglia-induced cancer invasion. Therefore, we purpose that minocycline could be a new therapeutics targeting metastatic brain cancers.

Delivery of the VIVIT Peptide to Human Glioma Cells to Interfere with Calcineurin-NFAT Signaling

The activation of NFAT (nuclear factor of activated T cells) transcription factors by calcium-dependent phosphatase calcineurin is a key step in controlling T cell activation and plays a vital role during carcinogenesis. NFATs are overexpressed in many cancers, including the most common primary brain tumor, gliomas. In the present study, we demonstrate the expression of NFATs and NFAT-driven transcription in several human glioma cells. We used a VIVIT peptide for interference in calcineurin binding to NFAT via a conserved PxIxIT motif. VIVIT was expressed as a fusion protein with a green fluorescent protein (VIVIT-GFP) or conjugated to cell-penetrating peptides (CPP), Sim-2 or 11R. We analyzed the NFAT expression, phosphorylation, subcellular localization and their transcriptional activity in cells treated with peptides. Overexpression of VIVIT-GFP decreased the NFAT-driven activity and inhibited the transcription of endogenous NFAT-target genes. These effects were not reproduced with synthetic peptides: Sim2-VIVIT did not show any activity, and 11R-VIVIT did not inhibit NFAT signaling in glioma cells. The presence of two calcineurin docking sites in NFATc3 might require dual-specificity blocking peptides. The cell-penetrating peptides Sim-2 or 11R linked to VIVIT did not improve its action making it unsuitable for evaluating NFAT dependent events in glioma cells with high expression of NFATc3.

Mapping chromatin accessibility and active regulatory elements reveals pathological mechanisms in human gliomas

Chromatin structure and accessibility, and combinatorial binding of transcription factors to regulatory elements in genomic DNA control transcription. Genetic variations in genes encoding histones, epigenetics-related enzymes or modifiers affect chromatin structure/dynamics and result in alterations in gene expression contributing to cancer development or progression. Gliomas are brain tumors frequently associated with epigenetics-related gene deregulation. We perform whole-genome mapping of chromatin accessibility, histone modifications, DNA methylation patterns and transcriptome analysis simultaneously in multiple tumor samples to unravel epigenetic dysfunctions driving gliomagenesis. Based on the results of the integrative analysis of the acquired profiles, we create an atlas of active enhancers and promoters in benign and malignant gliomas. We explore these elements and intersect with Hi-C data to uncover molecular mechanisms instructing gene expression in gliomas.

Tumour-derived CSF2/granulocyte macrophage colony stimulating factor controls myeloid cell accumulation and progression of gliomas

BACKGROUND

Malignant tumours release factors, which attract myeloid cells and induce their polarisation to pro-invasive, immunosuppressive phenotypes. Brain-resident microglia and peripheral macrophages accumulate in the tumour microenvironment of glioblastoma (GBM) and induce immunosuppression fostering tumour progression. Macrophage colony stimulating factors (CSFs) control the recruitment of myeloid cells during peripheral cancer progression, but it is disputable, which CSFs drive their accumulation in gliomas.

METHODS

The expression of CSF2 (encoding granulocyte-macrophage colony stimulating factor) was determined in TCGA datasets and five human glioma cell lines. Effects of stable CSF2 knockdown in glioma cells or neutralising CSF2 or receptor CSF2Rα antibodies on glioma invasion were tested in vitro and in vivo.

RESULTS

CSF2 knockdown or blockade of its signalling reduced microglia-dependent glioma invasion in microglia-glioma co-cultures. CSF2-deficient human glioma cells encapsulated in cell-impermeable hollow fibres and transplanted to mouse brains, failed to attract microglia, but stimulated astrocyte recruitment. CSF2-depleted gliomas were smaller, attracted less microglia and macrophages, and provided survival benefit in tumour-bearing mice. Apoptotic microglia/macrophages were detected in CSF2-depleted tumours.

CONCLUSIONS

CSF2 is overexpressed in a subset of mesenchymal GBMs in association with high immune gene expression. Tumour-derived CSF2 attracts, supports survival and induces pro-tumorigenic polarisation of microglia and macrophages.

Novel engineered TRAIL-based chimeric protein strongly inhibits tumor growth and bypasses TRAIL resistance

Targeting of the TRAIL-DR4/5 pathway was proposed as a promising approach for specific induction of apoptosis in cancer cells. Clinical trials, however, showed inadequate efficiency of TRAIL as a monotherapy. It is a widely held view that the application of multifunctional molecules or combination therapy may lead to substantial improvement. Here, we demonstrate the effectiveness and safety of a novel chimeric protein, AD-O51.4, which is a TRAIL equipped with positively charged VEGFA-derived effector peptides. The study was performed in multiple cancer cell line- and patient-derived xenografts. A pharmacokinetic profile was established in monkeys. AD-O51.4 strongly inhibits tumor growth, even leading to complete long-term tumor remission. Neither mice nor monkeys treated with AD-O51.4 demonstrate symptoms of drug toxicity. AD-O51.4 exhibits a satisfactory half-life in plasma and accumulates preferentially in tumors. The cellular mechanism of AD-O51.4 activity involves both cytotoxic effects in tumor cells and antiangiogenic effects on the endothelium. The presence of DRs in cancer cells is crucial for AD-O51.4-driven apoptosis execution. The TRAIL component of the fusion molecule serves as an apoptosis inducer and a cellular anchor for the effector peptides in TRAIL-sensitive and TRAIL-resistant cancer cells, respectively. The FADD-dependent pathway, however, seems to be not indispensable in death signal transduction; thus, AD-O51.4 is capable of bypassing the refractoriness of TRAIL. AD-O51.4-driven cell death, which exceeds TRAIL activity, is achieved due to the N-terminally fused polypeptide, containing VEGFA-derived effector peptides. The high anticancer efficiency of AD-O51.4 combined with its safety has led to the entry of AD-O51.4 into toxicological studies.

SCIDOT-26. THE ROLE OF TUMOR-DERIVED GRANULOCYTE MACROPHAGE COLONY STIMULATING FACTOR (GM-CSF/CSF2) IN REGULATION OF MICROGLIA-DEPENDENT INVASION IN GLIOMAS

Brain resident immune cells (microglia) and peripheral macrophages accumulate in malignant gliomas and constitute for 30–50% of the tumor mass. These immune cells are polarized by factors released by glioma and become the pro-invasive, immunosuppressive cells that support tumor progression. We have previously found that tumor-derived granulocyte macrophage colony stimulating factor (GM-CSF/Csf-2) is a crucial factor controlling accumulation of microglia and macrophages in murine gliomas. The analysis of TCGA dataset revealed overexpression of the CSF2 gene (encoding GM-CSF) in a set of mesenchymal glioblastomas (most aggressive WHO grade IV gliomas) and its association with high immune gene expression. To study the role of GM-CSF in microglia-stimulated glioma invasion, we used a co-culture system, which mimics microglia interactions with tumor cells. We silenced the expression of CSF2 in glioma cells and found reduced microglia-dependent invasion of glioma cells. To translate those results into clinically relevant setting, we designed and tested humanized short peptides interfering with binding of GM-CSF to its receptor. Selected peptide effectively inhibited binding of GM-CSF to its receptor as demonstrated with different methods. We selected the non-cytotoxic peptides that potently blocked microglia-dependent glioma invasion in cell co-cultures. Blocking GM-CSF-receptor signaling pathway with a neutralizing antibody against a GM-CSF receptor also inhibited microglia-dependent invasion of glioma cells. Altogether, our results demonstrate that glioma-derived GM-CSF supports pro-tumorigenic polarization of microglia turning them into cells that facilitate glioma growth and shape the immune microenvironment. The study was supported by grant 2014/15/B/NZ3/04704 from The National Science Centre, Poland.

TMIC-64. THE ROLE OF TUMOR-DERIVED GRANULOCYTE MACROPHAGE COLONY STIMULATING FACTOR (GM-CSF/CSF2) IN REGULATION OF MICROGLIA-DEPENDENT INVASION IN GLIOMAS

Brain resident immune cells (microglia) and peripheral macrophages accumulate in malignant gliomas and constitute for 30–50% of the tumor mass. These immune cells are polarized by factors released by glioma and become the pro-invasive, immunosuppressive cells that support tumor progression. We have previously found that tumor-derived granulocyte macrophage colony stimulating factor (GM-CSF/CSF2) is a crucial factor controlling accumulation of microglia and macrophages in murine gliomas. The analysis of TCGA dataset revealed overexpression of the CSF2 gene (encoding GM-CSF) in a set of mesenchymal glioblastomas and its association with high immune gene expression. To study the role of GM-CSF in microglia-stimulated glioma invasion, we used a co-culture system, which mimics microglia interactions with tumor cells. We silenced the expression of CSF2 in glioma cells and found reduced microglia-dependent invasion of glioma cells. To translate those results into clinically relevant setting, we designed and tested humanized short peptides interfering with binding of GM-CSF to its receptor. Selected peptide effectively inhibited binding of GM-CSF to its receptor as demonstrated with different methods. We selected the non-cytotoxic peptides that potently blocked microglia-dependent glioma invasion in cell co-cultures. Blocking GM-CSF-receptor signaling pathway with a neutralizing antibody against a GM-CSF receptor also inhibited microglia-dependent invasion of glioma cells. Altogether, our results demonstrate that glioma-derived GM-CSF supports pro-tumorigenic polarization of microglia turning them into cells that facilitate glioma growth and shape the immune microenvironment. This work was supported by statutory budget of Nencki Institute of Experimental Biology and grant PBS3/B7/19/2015 from The National Centre for Research and Development, Poland.

Molecular interactions between tumor and its microenvironment in malignant gliomas

Growing evidence supports a critical role of the tumor-reprogrammed stromal cells in tumor growth and progression. Several extracellular communication networks are hijacked by the tumors to influence the surrounding tumor microenvironment. In malignant gliomas, tumor derived factors attract brain resident microglia and peripheral macrophages. These cells, instead of initiating antitumor responses, are re-educated by tumor cells and participate in matrix remodeling, support invasion and angiogenesis, and induce immunosuppression. Molecular underlining of these mutual and complex interactions in malignant gliomas is the main scope of this review.

Abstract 3796: Biochemical and biophysical characterization of AD-O51.4 a novel anticancer biological therapeutic agent with dual mechanism of action

Background

Cancer growth and development is tightly related to both new vessels formation for tissue remodeling and inhibition of anti-apoptotic signals. Vascular endothelial growth factor (VEGF) is important for vascular development in physiological and pathological processes. Blockade of VEGF pathway has been shown to inhibit both pathological angiogenesis and tumor growth. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL/Apo2L) has been under intense scientific evaluation because of its ability to induce apoptosis in cancer cells while omitting normal cells. However, in most cases it wasn't potent enough to become the effective single therapy agent. The AD-O51.4 is a novel anticancer fusion protein. It consists of a recombinant variant of TRAIL/Apo2L fragment, which is linked to the repeated antiangiogenic effector peptide sequence derived from the 6th exon of VEGF ligand. The peptide sequences are separated by a motif recognized by tumor-specific proteases (MMP's, uPa). The structure and biophysical properties of AD-O51.4 should be mostly derived from TRAIL/Apo2L - the carrier component of the fusion molecule. The AD-O51.4 should be targeted to both types: VEGF and TRAIL receptors and lead to sequestration of the VEGF receptors on malignant and endothelial cells making them susceptible to apoptosis induced through TRAIL/Apo2L dead receptors.

Methods

The AD-O51.4 has been produced in E. coli cells and purified using IEX chromatography. Its structure and biophysical properties were verified using circular dichroism (CD), size-exclusion chromatography (SEC), proteolytic digestion of activation sequence and finally direct N-terminus sequencing. The VEGF and TRAIL/Apo2L receptors specificity was confirmed using surface plasmon resonance (SPR). Antitumor activity was analyzed on a panel of established cancer cell lines and xenograft model of human cancer.

Results

The analysis of AD-O51.4 revealed secondary structure rich with beta-sheets and a trimeric form of the fusion molecule what is typical for TRAIL/Apo2L ligand. The molecule also displays strong specific binding for both classes of receptors: VEGF and TRAIL/Apo2L what confirms potential antiangiogenic and proapoptotic properties. Sequencing and specific digestion endorsed molecule identity. Finally specific cytotoxic and antitumor activities were confirmed for AD-O51.4.

Conclusion

We demonstrated that AD-O51.4 fusion protein has well established structure corresponding to its main component TRAIL/Apo2L. The structure of VEGF-derived peptides determines its specific interaction with therapeutic targets and as a consequence its antitumor properties. The obtained results confirm that a combination of two effectors in one protein molecule may be an effective way of anticancer compounds development.

Citation Format: Sebastian D. Pawlak, Jerzy S. Pieczykolan, Bartlomiej Zerek, Katarzyna Poleszak, Malgorzata Teska-Kaminska, Marlena Galaska, Michal Szymanik, Albert Jaworski, Anna Pieczykolan, Katarzyna Bukato, Wojciech Strozek, Piotr K. Rozga. Biochemical and biophysical characterization of AD-O51.4 a novel anticancer biological therapeutic agent with dual mechanism of action. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3796. doi:10.1158/1538-7445.AM2014-3796

Abstract 2773: AD-O56.9: A fusion of TRAIL/Apo2L with a membrane disrupting peptide as a novel anticancer therapeutic

Background

The tumor necrosis factor related apoptosis-inducing ligand (TRAIL/Apo2L) is a member of the TNF superfamily that initiates apoptosis of tumor cells through the activation of their death receptors. The ability of TRAIL to selectively induce apoptosis of tumor cells but not normal cells makes it an attractive agent for cancer therapy. However, many cancer types have developed resistance mechanisms, such as dysfunctions of proapoptotic proteins.

Hereby, we report a novel molecule - AD-O56.9, which is composed of the soluble fragment of TRAIL (acting as both carrier and also effector) fused with a cationic, alpha-helical (KLAKLAK)2 antimicrobial peptide (acting as effector). The (KLAKLAK)2 peptide fused to protein transduction domain can induce cancer cell death by triggering mitochondrial membrane permeabilization and swelling, resulting in the release of cytochrome c and induction of apoptosis. It creates also the capacity to cause aggregation of mitochondria that is also a mechanism of cytotoxic action. (KLAKLAK)2 peptide is equipped with protein transduction domain domain, to increase its internalization. To allow separation of TRAIL fragment from the effector peptide domain specifically in the tumor environment, we linked these two domains with a sequence motif recognized by MMP and uPa proteases, present in tumor cells membranes or their proximity.

Methods

AD-O56.9 protein was produced in E. coli and purified by IEC. The molecule was characterized biochemically and biophysically. MTT assay was used to estimate killing of carcinoma cells. Flow cytometric analysis was used to evaluate influence of the AD-O56.9 on plasma and mitochondrial membrane integrity, caspase 3 activation, PARP cleavage, as well as on the cell cycle of cancer cells. The tumoricidal activity of AD-O56.9 was evaluated in NOD/SCID mice bearing different types of tumor xenografts.

Results

AD-O56.9 exhibited cytotoxic effect on various cancer cell lines, both TRAIL-sensitive and TRAIL-resistant, but showed no toxic effect on normal cells. This protein was also highly cytotoxic against primary cancer cells. The component that overcomes resistance to TRAIL is RRRRRRRR(KLAKLAK)2 peptide, but only as a component of AD-O56.9 fusion protein. Analyzing cell cycle and plasma membrane integrity in relatively sensitive cell line (NCI-H460) and TRAIL-resistant cell line (A549) we showed that AD-O56.9 induced apoptosis in those cells. This protein led to activation of caspase 3, cleavage of PARP as well as caused strong depolarization of mitochondrial membrane. AD-O56.9 administration caused significant regression of TRAIL-sensitive MIA PaCa-2, OE19, Colo205 and TRAIL-resistant HepG2.

Conclusions

AD-O56.9 is able to induce cell death in many cancer cell lines, even TRAIL resistant and causes tumor regression in mice bearing human tumors. Obtained results make this molecule worth of further preclinical development.

Citation Format: Bartlomiej Maciej Zerek, Michal Szymanik, Piotr Kamil Rozga, Anna Pieczykolan, Marlena Galazka, Katarzyna Bukato, Albert Jaworski, Katarzyna Poleszak, Sebastian Dominik Pawlak, Malgorzata Teska-Kaminska, Wojciech Strozek, Jerzy Szczepan Pieczykolan. AD-O56.9: A fusion of TRAIL/Apo2L with a membrane disrupting peptide as a novel anticancer therapeutic. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2773. doi:10.1158/1538-7445.AM2014-2773

Abstract 4471: AD-O64.4 - a novel bioconjugate for tumor-targeted drug delivery

Although standard chemotherapy is still one of the most effective treatment for many types of cancer - often causes side effects. Chemotherapeutic agents primarily damage cancer cells with a rapidly dividing and growing profile, thereby also destroy healthy cells with such characteristics, which leads to side effects. Scientists are continually working to identify new, safer drugs, methods of administering chemotherapy, and combinations of existing treatments that have fewer side effects.

In recent years, drug delivery systems (DDS) based on a concept of conjugation anticancer agents to carrier protein have been developed, achieving a better clinical response and tolerability. Protein-drug conjugates represent a whole new concept for cancer treatment which, although highly effective, cause much fewer sides effects than traditional chemotherapy.

The present work is aimed to create a new conjugate molecule which essentially demonstrates greater effect than the summarized effects of its components due to specific targeting to cancer cells. We generated AD-O64.4 complex molecule, consisting of fusion protein INF- γ - TRAIL/Apo2L conjugated with the anti-mitotic agent SN-38 via the thioether linker.

Carrier protein is a fusion molecule which is composed of soluble fragment of TRAIL (acting as a targeting carrier and effector) fused with artificial dimer of IFN-γ (acting as effector).

SN-38, a topoisomerase I inhibitor with low nanomolar potency, the active metabolite of irinotecan, cannot be given directly to patients because of its toxicity and poor solubility. Linking SN-38 to the carrier fusion protein results in selective drug delivery to tumors which consequently leads to increased amount of the drug reaching the tumors and minimized damage of healthy cells.

Analysis of the conjugate was performed by LC-MS and resulted in determination of drug-protein ratio. Agregation studies of the molecule complex were conducted by DLS and fluorescent protein aggregation assay. Cytotoxicity was evaluated with MTT assay and efficacy was performed on female SCID mice xenograft model bearing Human Uterine Sarcoma (MES-SA/Dx5).

Our results show an effective process of conjugation of anticancer compound SN-38 to the carrier protein which leads to formation of an active complex with enhanced efficacy.

AD-O64.4 exhibited cytotoxic effect on various cancer cell lines, (IC50 about 10 ng/ml), but showed no toxic effect on normal cells. This conjugate was also highly cytotoxic against primary cancer cells. AD-O64.4 was highly active (up to 75% tumor remission) against subcutaneous multiple drug resistant, MES-SA/Dx5, tumor xenografts in severe combined immunodeficient mice with better activity compared to the carrier protein alone, as well as to combination of the carrier protein with free-drug. Overall, these results represent a novel and a valuable system for drug delivery to the tumor and its microenvironment.

Citation Format: Wojciech Strozek, Anna Pieczykolan, Bartlomiej Zerek, Michal Szymanik, Albert Jaworski, Marlena Galazka, Katarzyna Bukato, Piotr Rozga, Sebastian Pawlak, Katarzyna Poleszak, Malgorzata Teska-Kaminska, Jerzy Pieczykolan. AD-O64.4 - a novel bioconjugate for tumor-targeted drug delivery. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4471. doi:10.1158/1538-7445.AM2014-4471

AD-O53.2--a novel recombinant fusion protein combining the activities of TRAIL/Apo2L and Smac/Diablo, overcomes resistance of human cancer cells to TRAIL/Apo2L

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and its receptors became promising molecules for selective targeting of tumor cells without affecting normal tissue. Unfortunately, cancer cells have developed a number of mechanisms that confer resistance to TRAIL\Apo2L-induced apoptosis, which substantiates the need for development of alternative therapeutic strategies. Here we present a recombinant variant of TRAIL\Apo2L peptide, named AD-O53.2, fused to the peptide-derived from Smac/Diablo protein-the natural inhibitor of the apoptotic X-linked IAP (XIAP) protein considered as a pro-apoptotic agent. The proposed mechanism of action for this construct involves specific targeting of the tumor by TRAIL\Apo2L followed by activation and internalization of pro-apoptotic peptide into the cancer cells. While in the cytoplasm , the Smac\Diablo peptide inhibits activity of X-linked IAP (XIAP) proteins and promotes caspase-mediated apoptosis. AD-O53.2 construct was expressed in E.coli and purified by Ion Exchange Chromatography (IEC). Derived protein was initially characterized by circular dichroism spectroscopy (CD), HPLC-SEC chromatography, surface plasmon resonance, protease activation and cell proliferation assays. Our Smac/Diablo-TRAIL fusion variant was tested against a panel of cancer cells (including lung, colorectal, pancreatic, liver, kidney and uterine) and showed a potent cytotoxic effect with the IC50 values in femtomolar range for the most sensitive cell lines, while it remained ineffective against non-transformed HUVEC cells as well as isolated normal human and rat hepatocytes. Importantly, the construct was well tolerated by animals and significantly reduced the rate of the tumor growth in colon and lung adenocarcinoma animal models.

Delineation of structural domains and identification of functionally important residues in DNA repair enzyme exonuclease VII

Exonuclease VII (ExoVII) is a bacterial nuclease involved in DNA repair and recombination that hydrolyses single-stranded DNA. ExoVII is composed of two subunits: large XseA and small XseB. Thus far, little was known about the molecular structure of ExoVII, the interactions between XseA and XseB, the architecture of the nuclease active site or its mechanism of action. We used bioinformatics methods to predict the structure of XseA, which revealed four domains: an N-terminal OB-fold domain, a middle putatively catalytic domain, a coiled-coil domain and a short C-terminal segment. By series of deletion and site-directed mutagenesis experiments on XseA from Escherichia coli, we determined that the OB-fold domain is responsible for DNA binding, the coiled-coil domain is involved in binding multiple copies of the XseB subunit and residues D155, R205, H238 and D241 of the middle domain are important for the catalytic activity but not for DNA binding. Altogether, we propose a model of sequence–structure–function relationships in ExoVII.

REPAIRtoire--a database of DNA repair pathways

REPAIRtoire is the first comprehensive database resource for systems biology of DNA damage and repair. The database collects and organizes the following types of information: (i) DNA damage linked to environmental mutagenic and cytotoxic agents, (ii) pathways comprising individual processes and enzymatic reactions involved in the removal of damage, (iii) proteins participating in DNA repair and (iv) diseases correlated with mutations in genes encoding DNA repair proteins. REPAIRtoire provides also links to publications and external databases. REPAIRtoire contains information about eight main DNA damage checkpoint, repair and tolerance pathways: DNA damage signaling, direct reversal repair, base excision repair, nucleotide excision repair, mismatch repair, homologous recombination repair, nonhomologous end-joining and translesion synthesis. The pathway/protein dataset is currently limited to three model organisms: Escherichia coli, Saccharomyces cerevisiae and Homo sapiens. The DNA repair and tolerance pathways are represented as graphs and in tabular form with descriptions of each repair step and corresponding proteins, and individual entries are cross-referenced to supporting literature and primary databases. REPAIRtoire can be queried by the name of pathway, protein, enzymatic complex, damage and disease. In addition, a tool for drawing custom DNA-protein complexes is available online. REPAIRtoire is freely available and can be accessed at http://repairtoire.genesilico.pl/.

Does the change of the polarity of electrodes influence the results of transoesophageal bidirectional DC cardioversion?

The aim of the study was to compare the bidirectional transoesophageal DC cardioversion (BOC) with unidirectional transoesophageal DC cardioversion (UOC) and to evaluate, if the reversion of the polarity of electrodes alters the effectiveness and the amount of energy during BOC. UOC was attempted in 300 patients (pts) with atrial fibrillation (AF) and BOC in 241 pts with AF. In UOC mode shocks were delivered between the 4-ring oesophageal electrode (cathode) and the chest pad (anode) positioned in the precordial region. In BOC shocks were delivered between the same oesophageal electrode and two chest pads joined with each other, positioned on both sides of the sternum. First 147 pts were cardioverted with the oesophageal electrode as a cathode, next 94 with an anode in oesophageal position. The effectiveness of both modes (UOC and BOC) was very high, however in pts with chronic AF success rate was better in BOC approach (82% vs 100%). BOC, compared with UOC, allowed to decrease the threshold defibrillation significantly: in pts with recent onset of AF from 61.5 J to 33.3 J and in pts with chronic AF from 99.8 J to 75.2 J. In pts with long standing AF the reduction of the defibrillation threshold was statistically not significant (from 68.6 J to 50.6 J). The effectiveness of BOC was also very high independently of the polarity of electrodes. The change of the polarity did not affect the minimal and total successful energy of shocks, too. In pts with oesophageal electrode as a cathode defibrillation threshold was 48.4 J and in pts with the anodal electrode 43.7 J. In conclusions we found BOC as a very effective method in pts with AF. Defibrillation threshold in BOC is lower than in UOC and the polarity of electrodes does not influence the success rate and successful energy.

[Plasma electrolytes in patients with paroxysmal supraventricular arrhythmia]

In 50 patients treated for paroxysmal supraventricular tachycardia or paroxysmal atrial fibrillation, plasma concentrations of potassium, magnesium and calcium were determined during arrhythmia and after 20, 60, and 180 minutes from the return of sinus rhythm. For achieving normal rhythm digitalis, quinidine and isoptin were used or electrical cardioversion was performed. No patient received potassium of magnesium preparations during observation. It was found that: 1. In patients with paroxysmal supraventricular arrhythmia a significant increase of plasma potassium concentration was observed after regression of arrhythmia. The highest potassium concentration was found after 60 minutes from the return of sinus rhythm. 2. The increase of potassium concentration was higher in patients after episode of supraventricular tachycardia than atrial fibrillation. 3. In patients with short-lasting arrhythmia (up to 3 hours) the increase of potassium concentration after achieving normal rhythm was higher than in patients with longer-lasting arrhythmia. 4. In patients with supraventricular tachycardia and atrial fibrillation a significant decrease of plasma magnesium and calcium concentrations was found after restoration of sinus rhythm.

[Return of sinus rhythm in patients with paroxysmal heart rhythm disturbances]

The purpose of the work was an assessment of the time and mechanism of the return of sinus rhythm in patients with paroxysmal supraventricular heart rhythm disturbances, treated pharmacologically. The Holter method enabled a precise determination of the mechanism of sinus rhythm return. A group of patients could be isolated with bradycardia-tachycardia syndrome, in whom attacks of MAS syndrome occurred only after regression of arrhythmia. At the time of the return of sinus rhythm and immediately after it transient conduction disturbances and hyperexcitability may occur.

Arterial blood pressure values in children and adolescents in the Lublin population. Epidemiological studies

The frequency of arterial hypertension occurrence in the adult population is estimated at 10-20%. In the last decade attention has been called to hypertension in children and adolescents. The purpose of the present study was to determine the arterial blood pressure in the studied age groups of children and adolescents in the elementary and secondary schools in Lublin, and to establish the prevalence of hypertension in this population group.

[Arrhythmias during automobile driving in patients after acute myocardial infarction]

In 90 patients after acute whole-thickness myocardial infarction suffered 3-48 months earlier 24-hour ECG recording was done for assessment of arrhythmias occurring while they were driving cars and for their comparison with the remaining recording hours. In most patients driving cars episodes of sinus tachycardia even up to 130/min were noted, in about half the patients some increase occurred in the frequency of ventricular ectopic beats, in two patients double and in one patient triple ectopic beats (salvoes) appeared, although they had not been recorded when the patients were not driving cars. The study was carried out (and is still continued) in autumn-winter, when the conditions of car driving were worse. None of the patients was in a collision-threatening situation which could increase dangerous arrhythmias.