Galit Rotman

Widespread occurrence of antisense transcription in the human genome

An increasing number of eukaryotic genes are being found to have naturally occurring antisense transcripts. Here we study the extent of antisense transcription in the human genome by analyzing the public databases of expressed sequences using a set of computational tools designed to identify sense-antisense transcriptional units on opposite DNA strands of the same genomic locus. The resulting data set of 2,667 sense-antisense pairs was evaluated by microarrays containing strand-specific oligonucleotide probes derived from the region of overlap. Verification of specific cases by northern blot analysis with strand-specific riboprobes proved transcription from both DNA strands. We conclude that ≥60% of this data set, or ∼1,600 predicted sense-antisense transcriptional units, are transcribed from both DNA strands. This indicates that the occurrence of antisense transcription, usually regarded as infrequent, is a very common phenomenon in the human genome. Therefore, antisense modulation of gene expression in human cells may be a common regulatory mechanism.

The novel Mas agonist, CGEN-856S, attenuates isoproterenol-induced cardiac remodeling and myocardial infarction injury in rats.

CGEN-856S is a novel Mas agonist. Herein, we examined the effects of this peptide on isoproterenol (ISO)-induced cardiac remodeling and myocardial infarction (MI) injury. We also sought to determine whether CGEN-856S activates the underlying mechanisms related to Mas receptor activation. Heart hypertrophy and fibrosis were induced by ISO (2 mg·kg−1·day−1) in Wistar rats. After a 7-day treatment period with CGEN-856S (90 µg·kg−1·day−1) or vehicle, the cardiomyocyte diameter was evaluated in left ventricular sections stained with hematoxylin and eosin, and immunofluorescence labeling and quantitative confocal microscopy were used to quantify the deposition of type I and III collagen and fibronectin in the left ventricles. MI was induced by coronary artery ligation, and CGEN-856S (90 µg·kg−1·day−1) or saline was administered for 14 days. The Langendorff technique was used to evaluate cardiac function, and left ventricular sections were stained with Masson’s trichrome dye to quantify the infarct area. Using Chinese hamster ovary cells stably transfected with Mas cDNA, we evaluated whether CGEN-856S alters AKT and endothelial nitric oxide synthase (eNOS) phosphorylation. CGEN-856S reduced the degree of ISO-induced hypertrophy (13.91±0.17 µm vs. 12.41±0.16 µm in the ISO+CGEN-856S group). In addition, the Mas agonist attenuated the ISO-induced increase in collagen I, collagen III, and fibronectin deposition. CGEN-856S markedly attenuated the MI-induced decrease in systolic tension, as well as in +dT/dt and -dT/dt. Furthermore, CGEN-856S administration significantly decreased the infarct area (23.68±2.78% vs. 13.95±4.37% in the MI+CGEN-856S group). These effects likely involved the participation of AKT and NO, as CGEN-856S administration increased the levels of p-AKT and p-eNOS. Thus, our results indicate that CGEN-856S exerts cardioprotective effects on ISO-induced cardiac remodeling and MI-mediated heart failure in rats through a mechanism likely involving the eNOS/AKT pathway.

Evolution of multicellularity in Metazoa: comparative analysis of the subcellular localization of proteins in Saccharomyces, Drosophila and Caenorhabditis

A comparison of the subcellular assignments of proteins between the unicellular Saccharomyces cerevisiae and the multicellular Drosophila melanogaster and Caenorhabditis elegans was performed using a computational tool for the prediction of subcellular localization. Nine subcellular compartments were studied: (1) extracellular domain, (2) cell membrane, (3) cytoplasm, (4) endoplasmic reticulum, (5) Golgi apparatus, (6) lysosome, (7) peroxisome, (8) mitochondria, and (9) nucleus. The transition to multicellularity was found to be characterized by an increase in the total number of proteins encoded by the genome. Interestingly, this increase is distributed unevenly among the subcellular compartments. That is, a disproportionate increase in the number of proteins in the extracellular domain, the cell membrane, and the cytoplasm is observed in multicellular organisms, while no such increase is seen in other subcellular compartments.

Identification of novel immune checkpoints as targets for cancer immunotherapy

Members of the B7/CD28 family of immune checkpoints, such as CTLA-4, PD1 and PDL-1, play critical roles in T cell regulation and have emerged as promising drug targets for cancer immunotherapy. Utilizing Compugen’s predictive discovery platform, we identified novel members of this family that may serve as immune checkpoints. The therapeutic relevance of these proteins was confirmed following the validation of their immunomodulatory properties and their expression in various cancers. Here we present results obtained for two of our novel B7/CD28 family members: CGEN-15001T and CGEN-15022. Fusion proteins, consisting of the extracellular domain of the predicted proteins fused to an IgG Fc domain, display robust inhibition of T cell activation and therapeutic effects in T-cell driven animal models, EAE and CIA. The Fc fused protein of CGEN-15001T also showed enhancement of iTregs induction. Immunohistochemistry studies on a variety of healthy and malignant tissues indicate expression of both molecules in various types of epithelial and hematopoietic cancers, with each protein showing a unique expression pattern. Expression was also detected on tumor infiltrating immune cells. Based on their immunomodulatory activity and expression in malignant and immune cells, CGEN-15001T and CGEN-15022 show potential as targets for cancer immunotherapy.

ILDR2 Is a Novel B7-like Protein That Negatively Regulates T Cell Responses

The B7-like protein family members play critical immunomodulatory roles and constitute attractive targets for the development of novel therapies for human diseases. We identified Ig-like domain–containing receptor (ILDR)2 as a novel B7-like protein with robust T cell inhibitory activity, expressed in immune cells and in immune-privileged and inflamed tissues. A fusion protein, consisting of ILDR2 extracellular domain with an Fc fragment, that binds to a putative counterpart on activated T cells showed a beneficial effect in the collagen-induced arthritis model and abrogated the production of proinflammatory cytokines and chemokines in autologous synovial-like cocultures of macrophages and cytokine-stimulated T cells. Collectively, these findings point to ILDR2 as a novel negative regulator for T cells, with potential roles in the development of immune-related diseases, including autoimmunity and cancer.

S9. Proffered paper: Identification of novel immune checkpoints as targets for cancer immunotherapy

Members of the B7/CD28 family of immune checkpoints, such as CTLA4, PD1 and PDL-1, play critical roles in T cell regulation and have emerged as promising drug targets for cancer immunotherapy. We hypothesize that additional novel members of the B7/CD28 family play a role as negative immune regulators and thus may serve as targets for therapeutic mAbs. Utilising Compugen’ sp redictive discovery platform, we identified nine novel members of this family that may serve as immune checkpoints. The therapeutic relevance of three of these proteins, CGEN-15001T, CGEN-15022, and CGEN-15049, was confirmed following the validation of their immunomodulatory properties and their expression in various cancers. Two of these proteins, CGEN-15001T and CGEN-15022, are the basis of a license and collaboration agreement recently signed with Bayer as targets for cancer immunotherapy. Here we present results obtained for an additional novel immune checkpoint, CGEN-15049. Following its ectopic expression on cancer cell lines, CGEN-15049 inhibits the activity of NK cells and cytotoxic T cells (CTLs). The fusion protein, consisting of the extracellular domain of CGEN-15049 fused to an IgG Fc domain, displays robust inhibition of T cell activation and enhances iTregs differentiation. IHC studies indicate that CGEN15049 is expressed in tumour cells of numerous types of cancers, as well as in tumour infiltrating immune cells. Based on its immunomodulatory activities on several types of immune cells which play key roles in cancer immune evasion, together with its expression pattern,CGEN-15049 may serve as mAb target for cancer immunotherapy.

ILDR2-Fc Is a Novel Regulator of Immune Homeostasis and Inducer of Antigen-Specific Immune Tolerance

ILDR2 is a member of the Ig superfamily, which is implicated in tricellular tight junctions, and has a putative role in pancreatic islet health and survival. We recently found a novel role for ILDR2 in delivering inhibitory signals to T cells. In this article, we show that short-term treatment with ILDR2-Fc results in long-term durable beneficial effects in the relapsing-remitting experimental autoimmune encephalomyelitis and NOD type 1 diabetes models. ILDR2-Fc also promotes transplant engraftment in a minor mismatch bone marrow transplantation model. ILDR2-Fc displays a unique mode of action, combining immunomodulation, regulation of immune homeostasis, and re-establishment of Ag-specific immune tolerance via regulatory T cell induction. These findings support the potential of ILDR-Fc to provide a promising therapeutic approach for the treatment of autoimmune diseases.

Abstract 5027: Identification of novel immune checkpoints as potential targets for cancer immunotherapy

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Members of the B7/CD28 family of immune checkpoints, such as CTLA4, PD1 and PDL-1, play critical roles in immune cell regulation and have emerged as promising drug targets for cancer immunotherapy. We hypothesize that additional immune checkpoints play a role as negative immune regulators and thus may serve as targets for therapeutic mAbs. Utilizing Compugens predictive discovery platform, we identified novel members of this family that may serve as immune checkpoints. The therapeutic relevance of three of these proteins, CGEN-15001T, CGEN-15022, and CGEN-15049, was confirmed following the validation of their immunomodulatory properties and their expression in various cancers. Two of these proteins, CGEN-15001T and CGEN-15022, are the basis of a license and collaboration agreement recently signed with Bayer as targets for cancer immunotherapy. Here we present results obtained for an additional novel immune checkpoint, CGEN-15049. Following its ectopic expression on cancer cell lines, CGEN-15049 inhibits the activity of NK cells and cytotoxic T cells (CTLs). The fusion protein, consisting of the extracellular domain of CGEN-15049 fused to an IgG Fc domain, displays robust inhibition of T cell activation and enhances iTregs differentiation. IHC studies indicate that CGEN-15049 is expressed in tumor cells of numerous types of cancers, as well as in tumor infiltrating immune cells. Based on its immunomodulatory activities on immune cell types with key roles in cancer immune evasion, together with its expression pattern in cancer tissues, CGEN-15049 may serve as mAb target for cancer immunotherapy. Citation Format: Galit Rotman, Ofer Levy, Amir Toporik, Gady Cojocaru, Liat Dassa, Ilan Vaknin, Shirley Sameah-Greenwald, Inbal Barbiro, Jinhong Fan, Susan Watson, John Hunter, Eyal Neria, Zurit Levine. Identification of novel immune checkpoints as potential targets for cancer immunotherapy. [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 5027. doi:10.1158/1538-7445.AM2014-5027

Abstract B291: Identification of novel immune checkpoints and their implementation as mAb targets for cancer immunotherapy.

Immune checkpoints, such as CTLA4 and PD-1, have emerged as promising drug targets for cancer immunotherapy. We hypothesize that additional novel members of the B7/CD28 family play a role in T cell regulation and thus may serve as targets for therapeutic mAbs. However, the discovery of novel family members is challenging since proteins of the immune system, including proteins of the B7 protein In order to identify novel members of the B7/CD28 protein family, Compugen has developed a discovery approach integrating gene and protein information with extensive expression data, and has identified nine novel membrane proteins that possess characteristics of the B7/CD28 protein family members and are therefore predicted to play a role in T cell co-stimulation. In order to validate our predictive discovery findings, we evaluated the effect of our proteins on immune cells, particularly T cells. For that goal, we expressed the proteins on the cell surface upon ectopic expression, and also produced fusion proteins consisting of the extracellular domain of the predicted proteins, fused to an IgG Fc domain. Here we present results obtained for two of our novel proteins, CGEN-15001T and CGEN-15022. Both display robust inhibition of T cell activation. Interestingly, CGEN-15001, one of the Fc-fused proteins, leads to increased levels of anti-inflammatory cytokines such as IL-4 and IL5, while reducing pro-inflammatory cytokines such as IFN-γ and IL-17. In addition, CGEN-15001 was found to enhance iTregs differentiation. Furthermore, these molecules showed therapeutic efficacy in mouse models of multiple sclerosis and rheumatoid arthritis. To investigate the potential of these membrane proteins as drug targets for treatment of cancer we have performed extensive IHC studies, on a variety of healthy and malignant tissues. Both CGEN-15001T and CGEN-15022 were found to be expressed in numerous types of cancers, each showing a unique pattern of expression. CGEN-15001T, in addition to its expression on tumor cells, was found to be expressed on tumor infiltrating immune cells, especially on Macrophages and Mast cells. Based on the immunomodulatory activities and the expression pattern on malignant and immune cells, CGEN15001T and CGEN15022 may serve as mAb targets for cancer immunotherapy. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B291. Citation Format: Gady Cojocaru, Ofer Levy, Amir Toporik, Liat Dassa, Iris Hecht, Ilan Vaknin, Sergey Nemzer, Tania Pergan, Amit Novik, Shirley Sameah-Greenwald, Anat Oren, Zohar Tiran, Peter Steinberger, Joseph Podojil, Nora Tarcic, Eyal Neria, Galit Rotman, Zurit Levine. Identification of novel immune checkpoints and their implementation as mAb targets for cancer immunotherapy. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B291.