Chimeric Fusion Protein Research Articles

Novel insight into mechanisms of ROS1 catalytic activation via loss of the extracellular domain.

The ROS1 receptor tyrosine kinase (RTK) possesses the largest extracellular amino-terminal domain (ECD) among the human RTK family, yet the mechanisms regulating its activation are not fully understood. While chimeric ROS1 fusion proteins, resulting from chromosomal rearrangements, are well-known oncogenic drivers, their activation mechanisms also remain underexplored. To elucidate the role of the ROS1 ECD in catalytic regulation, we engineered a series of amino-terminal deletion mutants. Our functional studies compared the full-length ROS1 receptor, the CD74-ROS1 oncogenic fusion, and ECD-deleted ROS1 constructs, identifying the ECD regions that inhibit ROS1 tyrosine kinase activity. Notably, we found that deletion of the ROS1 ECD alone significantly increases constitutive catalytic activation and neoplastic transformation in the absence of an amino-terminal fusion partner, challenging the presumed necessity for a dimerization domain in the activation mechanism of kinase fusions in cancer. Our data suggest that inter-genic deletions resulting in the loss of the ECD may be underappreciated oncogenic drivers in cancer. Furthermore, our studies demonstrate that RNASE7 is not a ligand for the ROS1 receptor as previously reported, confirming that ROS1 remains an orphan receptor. Thus, the discovery of a ROS1 ligand remains an important future priority. These findings highlight the potential for disease-associated somatic aberrations or splice variants that modify the ROS1 ECD to promote constitutive receptor activation, warranting further investigation.

A recombinant chimeric spider pyriform-aciniform silk with highly tunable mechanical performance

Spider silks are natural protein-based biomaterials which are renowned for their mechanical properties and hold great promise for applications ranging from high-performance textiles to regenerative medicine. While some spiders can produce several different types of silks, most spider silk types – including pyriform and aciniform silks – are relatively unstudied. Pyriform and aciniform silks have distinct mechanical behavior and physicochemical properties, with materials produced using combinations of these silks currently unexplored. Here, we introduce an engineered chimeric fusion protein consisting of two repeat units of pyriform (Py) silk followed by two repeat units of aciniform (W) silk named Py2W2. This recombinant ∼86.5 kDa protein is amenable to expression and purification from Escherichia coli and exhibits high α-helicity in a fluorinated acid- and alcohol-based solution used to form a dope for wet-spinning. Wet-spinning enables continuous fiber production and post-spin stretching of the wet-spun fibers in air or following submersion in water or ethanol leads to increases in optical anisotropy, consistent with increased molecular alignment along the fiber axis. Mechanical properties of the fibers vary as a function of post-spin stretching condition, with the highest extensibility and strength observed in air-stretched and ethanol-treated fibers, respectively, with mechanics being superior to fibers spun from either constituent protein alone. Notably, the maximum extensibility obtained (∼157 ± 38 %) is of the same magnitude reported for natural flagelliform silks, the class of spider silk most associated with being stretchable. Interestingly, Py2W2 is also water-compatible, unlike its constituent Py2. Fiber-state secondary structure correlates well with the observed mechanical properties, with depleted α-helicity and increased β-sheet content in cases of increased strength. Py2W2 fibers thus provide enhanced materials behavior in terms of their mechanics, tunability, and fiber properties, providing new directions for design and development of biomaterials suitable and tunable for disparate applications.

Vaccine Based on Recombinant Fusion Protein Combining Hepatitis B Virus PreS with SARS-CoV-2 Wild-Type- and Omicron-Derived Receptor Binding Domain Strongly Induces Omicron-Neutralizing Antibodies in a Murine Model.

COVID-19, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become a recurrent endemic disease affecting the whole world. Since November 2021, Omicron and its subvariants have dominated in the spread of the disease. In order to prevent severe courses of disease, vaccines are needed to boost and maintain antibody levels capable of neutralizing Omicron. Recently, we produced and characterized a SARS-CoV-2 vaccine based on a recombinant fusion protein consisting of hepatitis B virus (HBV)-derived PreS and two SARS-CoV-2 wild-type RBDs. To develop a PreS-RBD vaccine which induces high levels of Omicron-specific neutralizing antibodies. We designed, produced, characterized and compared strain-specific (wild-type: W-PreS-W; Omicron: O-PreS-O), bivalent (mix of W-PreS-W and O-PreS-O) and chimeric (i.e., W-PreS-O) SARS-CoV-2 protein subunit vaccines. Immunogens were characterized in vitro using protein chemical methods, mass spectrometry, and circular dichroism in combination with thermal denaturation and immunological methods. In addition, BALB/c mice were immunized with aluminum-hydroxide-adsorbed proteins and aluminum hydroxide alone (i.e., placebo) to study the specific antibody and cytokine responses, safety and Omicron neutralization. Defined and pure immunogens could be produced in significant quantities as secreted and folded proteins in mammalian cells. The antibodies induced after vaccination with different doses of strain-specific, bivalent and chimeric PreS-RBD fusion proteins reacted with wild-type and Omicron RBD in a dose-dependent manner and resulted in a mixed Th1/Th2 immune response. Interestingly, the RBD-specific IgG levels induced with the different vaccines were comparable, but the W-PreS-O-induced virus neutralization titers against Omicron (median VNT50: 5000) were seven- and twofold higher than the W-PreS-W- and O-PreS-O-specific ones, respectively, and they were six-fold higher than those of the bivalent vaccine. Among the tested immunogens, the chimeric PreS-RBD subunit vaccine, W-PreS-O, induced the highest neutralizing antibody titers against Omicron. Thus, W-PreS-O seems to be a highly promising COVID-19 vaccine candidate for further preclinical and clinical evaluation.

Immunoprotection of FliBc chimeric fiber2 fusion proteins targeting dendritic cells against Fowl adenovirus serotype 4 infection

Hepatitis-hydropericardium syndrome (HHS) is a highly fatal disease in chickens caused by the highly pathogenic fowl adenovirus serotype 4 (FAdV-4), which has severe economic consequences. The fiber2 protein exhibits excellent potential as a candidate for a subunit vaccination against FAdV-4. Despite having a high safety profile, subunit vaccines have low immunogenicity due to their lack of infectivity, which leads to low levels of immune response. As a vaccine adjuvant, Salmonella flagellin possesses the potential to augment the immunological response to vaccinations. Additionally, a crucial strategy for enhancing vaccine efficacy is efficient presentation of immune antigens to dendritic cells (DC) for targeted vaccination. In this study, we designed FAdV-4-fiber2 protein, and a recombinant protein called FliBc-fiber2-SP which based on FAdV-4-fiber2 protein, was generated using the gene sequence FliBc, which retains only the conserved sequence at the amino and carboxyl termini of the flagellin B subunit, and a short peptide SPHLHTSSPWER (SP), which targets chicken bone marrow-derived DC. They were separately administered via intramuscular injection to 14-day-old specific pathogen-free (SPF) chickens, and their immunogenicity was compared. At 21 d postvaccination (dpv), it was found that the FliBc-fiber2-SP recombinant protein elicited significantly higher levels of IgG antibodies and conferred a vaccine protection rate of up to 100% compared to its counterpart fiber2 protein. These results suggest that the DC-targeted peptide fusion strategy for flagellin chimeric antigen construction can effectively enhance the immune protective efficacy of antigen proteins.

Anti‐inflammatory clearance of amyloid beta by a chimeric Gas6 fusion protein

AbstractBackgroundAβ immunotherapy is the most promising approach in treating Alzheimer’s disease (AD). Although Aβ‐antibodies can substantially reduce Aβ burden in the brain, solutions for antibody‐induced inflammation and subsequent ARIA (Amyloid‐related imaging abnormalities) are still in demand. Here we developed a novel chimeric protein platform, GAIA (Gas6‐mediated anti‐inflammatory adaptor). GAIA platform utilizes TAM receptors, which are expressed on glial cells and mediate phagocytosis without associated inflammatory response.MethodWe developed a GAIA‐based novel chimeric protein (αAβ‐Gas6) which is composed of two distinct functional domains; a single‐chain variable fragment of Aducanumab, which selectively binds to Aβ, fused with Gas6, a TAM receptor‐binding domain. Aβ clearance and phagocytosis‐associated inflammatory responses of αAβ‐Gas6 were measured in comparison with Aducanumab.ResultαAβ‐Gas6 showed selective uptake of Aβ through phagocytosis in vitro. While Aducanumab induced phagocytosis only in primary microglia, αAβ‐Gas6 significantly induced phagocytosis in both cultured microglia and astrocyte. In comparison with Aducanumab, αAβ‐Gas6 secreted significantly lower amount of pro‐inflammatory cytokines, such as TNF, IL‐6, and IL‐1β. In vivo application of αAβ‐Gas6 reduced Aβ burden in an extent significantly lower in mice treated with Aducanumab. Finally, αAβ‐Gas6 groups showed significantly reduced excessive synapse elimination levels comparable to non‐AD wild type groups.ConclusionWe developed a novel chimeric fusion protein αAβ‐Gas6 by engineering TAM receptor‐binding domain Gas6. In comparison with antibody drug, αAβ‐Gas6 showed advanced amyloid clearance, significantly reduced neuroinflammation, and neurotoxicity. Thus, our results suggest a novel immunotherapeutic agent which can bifunctionally target Aβ and modulate gilal cells to reduce neuroinflammation.

Streamlining the Detection of Human Thyroid Receptor Ligand Interactions with XL1-Blue Cell-Free Protein Synthesis and Beta-Galactosidase Fusion Protein Biosensors.

Thyroid receptor signaling controls major physiological processes and disrupted signaling can cause severe disorders that negatively impact human life. Consequently, methods to detect thyroid receptor ligands are of great toxicologic and pharmacologic importance. Previously, we reported thyroid receptor ligand detection with cell-free protein synthesis of a chimeric fusion protein composed of the human thyroid receptor beta (hTRβ) receptor activator and a β-lactamase reporter. Here, we report a 60% reduction in sensing cost by reengineering the chimeric fusion protein biosensor to include a reporter system composed of either the full-length beta galactosidase (β-gal), the alpha fragment of β-gal (β-gal-α), or a split alpha fragment of the β-gal (split β-gal-α). These biosensor constructs are deployed using E. coli XL1-Blue cell extract to (1) avoid the β-gal background activity abundant in BL21 cell extract and (2) facilitate β-gal complementation reporter activity to detect human thyroid receptor ligands. These results constitute a promising platform for high throughput screening and potentially the portable detection of human thyroid receptor ligands.

IL-1 blockade in cardiovascular disease: an appraisal of the evidence across different inflammatory paradigms.

Pre-clinical and clinical studies suggest a role for inflammation in the pathophysiology of cardiovascular (CV) diseases. The NLRP3 (NACHT, leucine-rich repeat, and pyrin domain-containing protein 3) inflammasome is activated during tissue injury and releases interleukin-1β (IL-1β). We describe three paradigms in which the NLRP3 inflammasome and IL-1β contribute to CV diseases. During acute myocardial infarction (AMI), necrotic cell debris, including IL-1α, induce NLRP3 inflammasome activation and further damage the myocardium contributing to heart failure (HF) (acute injury paradigm). In chronic HF, IL-1β is induced by persistent myocardial overload and injury, neurohumoral activation and systemic comorbidities favoring infiltration and activation of immune cells into the myocardium, microvascular inflammation, and a pro-fibrotic response (chronic inflammation paradigm). In recurrent pericarditis, an autoinflammatory response triggered by cell injury and maintained by the NLRP3 inflammasome/IL-1β axis is present (autoinflammatory disease paradigm). Anakinra, recombinant IL-1 receptor antagonist, inhibits the acute inflammatory response in patients with ST elevation myocardial infarction (STEMI) and acute HF. Canakinumab, IL-1β antibody, blunts systemic inflammation and prevents complications of atherosclerosis in stable patients with prior AMI. In chronic HF, anakinra reduces systemic inflammation and improves cardiorespiratory fitness. In recurrent pericarditis, anakinra and rilonacept, a soluble IL-1 receptor chimeric fusion protein blocking IL-1α and IL-1β, treat and prevent acute flares. In conclusion, the NLRP3 inflammasome and IL-1 contribute to the pathophysiology of CV diseases, and IL-1 blockade is beneficial with different roles in the acute injury, chronic inflammation and autoinflammatory disease paradigms. Further research is needed to guide the optimal use of IL-1 blockers in clinical practice.

Phase-separated nuclear bodies of nucleoporin fusions promote condensation of MLL1/CRM1 and rearrangement of 3D genome structure

NUP98 and NUP214 form chimeric fusion proteins that assemble into phase-separated nuclear bodies containing CRM1, a nuclear export receptor. However, these nuclear bodies' function in controlling gene expression remains elusive. Here, we demonstrate that the nuclear bodies of NUP98::HOXA9 and SET::NUP214 promote the condensation of mixed lineage leukemia 1 (MLL1), a histone methyltransferase essential for the maintenance of HOX gene expression. These nuclear bodies are robustly associated with MLL1/CRM1 and co-localized on chromatin. Furthermore, whole-genome chromatin-conformation capture analysis reveals that NUP98::HOXA9 induces a drastic alteration in high-order genome structure at target regions concomitant with the generation of chromatin loops and/or rearrangement of topologically associating domains in a phase-separation-dependent manner. Collectively, these results show that the phase-separated nuclear bodies of nucleoporin fusion proteins can enhance the activation of target genes by promoting the condensation of MLL1/CRM1 and rearrangement of the 3D genome structure.

Perilipin 3 promotes the formation of membrane domains enriched in diacylglycerol and lipid droplet biogenesis proteins.

Lipid droplets (LDs) serve as intracellular stores of energy-rich neutral lipids. LDs form at discrete sites in the endoplasmic reticulum (ER) and they remain closely associated with the ER during lipogenic growth and lipolytic consumption. Their hydrophobic neutral lipid core is covered by a monolayer of phospholipids, which harbors a specific set of proteins. This LD surface is coated and stabilized by perilipins, a family of soluble proteins that specifically target LDs from the cytosol. We have previously used chimeric fusion proteins between perilipins and integral ER membrane proteins to test whether proteins that are anchored to the ER bilayer could be dragged onto the LD monolayer. Expression of these chimeric proteins induces repositioning of the ER membrane around LDs. Here, we test the properties of membrane-anchored perilipins in cells that lack LDs. Unexpectedly, membrane-anchored perilipins induce expansion and vesiculation of the perinuclear membrane resulting in the formation of crescent-shaped membrane domains that harbor LD-like properties. These domains are stained by LD-specific lipophilic dyes, harbor LD marker proteins, and they transform into nascent LDs upon induction of neutral lipid synthesis. These ER domains are enriched in diacylglycerol (DAG) and in ER proteins that are important for early steps of LD biogenesis, including seipin and Pex30. Formation of the domains in vivo depends on DAG levels, and we show that perilipin 3 (PLIN3) binds to liposomes containing DAG in vitro. Taken together, these observations indicate that perilipin not only serve to stabilize the surface of mature LDs but that they are likely to exert a more active role in early steps of LD biogenesis at ER subdomains enriched in DAG, seipin, and neutral lipid biosynthetic enzymes.

Abstract LB027: In vivo delivery of novel CD89 fusion receptor to myeloid cells by mRNA activates anti-tumor immunity

Abstract Despite the revolution provided by immunotherapy, sustained clinical benefit has yet to be achieved for most of patients with advanced solid tumors. Myeloid cells readily accumulate in tumors, in some cases contributing up to 75% of the tumor mass. While supporting tumor growth and being associated with unfavorable prognosis, myeloid cells can mediate phagocytosis of cancer cells and cytotoxic tumor killing and promote adaptive immune responses through antigen presentation and co-stimulation, therefore representing promising targets in cancer therapy. The ability to engineer circulating and tumor associated myeloid cells to activate their ability to elicit anti-tumor adaptive immunity is an attractive approach to harness systemic anti-tumor immunity. However, it remains challenging to specifically target and activate myeloid cells in vivo. To overcome this hurdle, we have developed a novel in vivo myeloid cell engineering platform in which a chimeric antigen receptor (CAR) is generated by fusing a tumor recognition scFv with the alpha chain of human Fc receptors (CD89). The stable expression and function of these receptors requires the endogenously expressed common Fc receptor gamma chain (FcRγ), which expression is mostly restricted to myeloid cells. For in vivo engineering, the construct is encapsulated and delivered in lipid nanoparticles (LNP). Trophoblast cell surface antigen 2 (TROP2) is overexpressed in most human solid epithelial cancers, as compared to low expression in corresponding normal tissue. Increased TROP2 expression has been linked to increased tumor growth and has been implicated as a prognostic marker in these cancers, supporting the development of therapies targeting TROP2. Intravenous infusion of LNP encapsulating mRNA encoding the anti-TROP2-CD89 fusion protein results in the uptake of the LNPs and expression of the chimeric receptor fusion protein in myeloid cells. In immunodeficient xenograft models of hepatocellular carcinoma and triple negative breast cancer, delivery of LNP mRNA encoding GPC3-CD89 or TROP2-CD89 fusion proteins resulted in anti-tumor efficacy, confirming the ability of this approach to program myeloid cells. Repeat dosing studies showed significant anti-tumor efficacy following bi-weekly administration of TROP2-CD89. Furthermore, in the B16/10 syngeneic melanoma model, treatment with the melanoma antigen gp75-CD89 fusion protein was also associated with the initiation of broad systemic immune responses, characterized by tumor infiltration by activated CD8+ T cells, reduced tumor-associated Tregs and activation of antigen presenting cells in spleen. When infused in cynomolgus monkeys, TROP2-CD89 LNP led to cell surface expression of anti-TROP2 CAR in myeloid cells. Together these studies highlight the potential of in vivo delivery of CD89 fusion proteins to program myeloid cells to recognize and kill cancer. Citation Format: Thomas E. Prod'homme, Shannon Argueta, Hongyun Zhao, Michael Gorgievski, Neha Diwangi, Edward Cochran, Bruce McCreedy, Yuxiao Wang, Daniel Getts. In vivo delivery of novel CD89 fusion receptor to myeloid cells by mRNA activates anti-tumor immunity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB027.

Abstract LB122: Arima-HiC sequencing accurately detects clinically-relevant structural variants in pediatric leukemia samples

Abstract Genetic structural variants (SVs), especially those leading to gene fusions, are well-known oncogenic drivers. These SVs can produce overexpression or loss-of-function of certain genes, or generate chimeric fusion proteins. Thus, they serve as important disease biomarkers across several cancers and can also represent therapeutically targetable alterations. Detecting these SVs at a gene-level resolution can be challenging with lower resolution karyotyping approaches, or even RNA sequencing approaches, due to difficulties with culture, sample stability, low transcript abundance, or low-quality RNA. In addition, the ability of fluorescence in situ hybridization (FISH) techniques to detect gene fusions is limited by the targeted nature of these assays as they depend heavily on the design and selection of each probe. Here we use a novel method, Arima-HiC sequencing, that utilizes DNA to evaluate 12 pediatric leukemia samples and determine this assay’s effectiveness in detecting clinically-relevant SVs. We first selected 5 archived (cryopreserved) pediatric acute myeloid leukemia (AML) samples (archival period range: 1-4 years) known to be either fusion-positive (n=3) or fusion-negative (n=2) via prior clinical genetic testing (i.e., chromosomes, FISH, and/or microarray). All samples underwent Arima-HiC sequencing. Briefly, chromatin digestion, end-labeling, and proximity ligation were performed prior to DNA purification per the Arima-HiC protocol. Purified DNA was next prepared as a short-read sequencing library and sequenced on a HiSeq X. The raw reads were aligned and deduplicated, and SVs were called using HiC-Breakfinder software. For a discovery set, we then additionally selected 7 pediatric leukemia samples—6 precursor B-cell acute lymphoblastic leukemias (ALL) and 1 AML—for Arima-HiC sequencing (as above). These cases had undergone standard-of-care cytogenetic (karyotyping, FISH, microarray) and/or molecular (targeted cancer NGS sequencing panel) testing clinically, and a genetic driver/known gene fusion had not been identified. Using Arima-HiC sequencing, we identified the clinically-relevant SV in each of our 3 fusion-positive AML cases, consistent with the original diagnostic cytogenetic finding (n= 1 RUNX1-RUNX1T1 fusion, 1 CBFB-MYH11 fusion, and 1 CBFA2T3-GLIS2 fusion). The 2 fusion-negative AML cases were also negative for structural gene fusions by HiC data. In our discovery sample set, Arima-HiC sequencing was able to find clinically-relevant SVs that were not previously detected in 3 of 6 samples: a KMT2A-MLLT10 fusion was found in an AML case, and a ZNF384-EP300 fusion was found in each of 2 ALL cases. A ABHD17B-PTK2B fusion was found in another ALL case, although ABHD17B may be a novel partner PTK2B and is undergoing validation. Rearrangements involving KRAS and EGFR were detected in the final two ALL cases, and are also undergoing validation. Overall, this study demonstrates how Arima-HiC sequencing can provide diagnostic value in pediatric leukemia specimens via the identification of clinically relevant SVs. Citation Format: Anthony Schmitt, Shadi Melnyk, Kristin Sikkink, Lisa Lansdon, Tomi Pastinen, Erin Guest, Midhat Farooqi. Arima-HiC sequencing accurately detects clinically-relevant structural variants in pediatric leukemia samples [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB122.

Interdependence of SS18-SSX-driven YAP1 and β-Catenin Activation in Synovial Sarcoma.

This study provides deeper insights into synovial sarcoma tumor biology demonstrating a mutual dependence between YAP1/TAZ and β-catenin transcriptional activity and a complex interplay with the SS18-SSX fusion protein within the BAF complex.

Antibody induction in mice by liposome-displayed recombinant enterotoxigenic Escherichia coli (ETEC) colonization antigens

BackgroundEnterotoxigenic Escherichia coli (ETEC) strains cause infectious diarrhea and colonize host intestine epithelia via surface-expressed colonization factors. Colonization factor antigen I (CFA/I), a prevalent ETEC colonization factor, is a vaccine target since antibodies directed to this fimbria can block ETEC adherence and prevent diarrhea. MethodsTwo recombinant antigens derived from CFA/I were investigated with a vaccine adjuvant system that displays soluble antigens on the surface of immunogenic liposomes. The first antigen, CfaEB, is a chimeric fusion protein comprising the minor (CfaE) and major (CfaB) subunits of CFA/I. The second, CfaEad, is the adhesin domain of CfaE. ResultsOwing to their His-tag, recombinant CfaEB and CfaEad, spontaneously bound upon admixture with nanoliposomes containing cobalt-porphyrin phospholipid (CoPoP), as well as a synthetic monophosphoryl lipid A (PHAD) adjuvant. Intramuscular immunization of mice with sub-microgram doses CfaEB or CfaEad admixed with CoPoP/PHAD liposomes elicited serum IgG and intestinal IgA antibodies. The smaller CfaEad antigen benefitted more from liposome display. Serum and intestine antibodies from mice immunized with liposome-displayed CfaEB or CfaEad recognized native CFA/I fimbria as evidenced by immunofluorescence and hemagglutination inhibition assays using the CFA/I-expressing H10407 ETEC strain. ConclusionThese data show that colonization factor-derived recombinant ETEC antigens exhibit immunogenicity when delivered in immunogenic particle-based formulations.

Immunogenicity of the Non-toxic Form of Staphylococcus Aureus α-Hemolysin Using a Chimeric Fusion in Mice.

Staphylococcus aureus is an opportunistic pathogen responsible for various infections with diverse clinical presentation and severity. The α-hemolysin is a major virulence factor in the pathogenesis of S. aureus infections. To produce a chimeric fusion protein for hemolytic detection of the S. aureus isolates and as a component of a multi-antigen vaccine. The fused strategy employed a flexible linker to incorporate the possible B cell and T cell determinants into one chimera (HlaD). The humoral and cellular response to the HlaD in mice was assessed to reveal a non-significant difference compared with the full-length α-hemolysin mutant (Hla H35L). The results of the protective effect, the mimetic lung cell injury, and bacterial clearness demonstrated that the mice vaccinated with the HlaD alleviated the severity of the infection of the S. aureus, and the HlaD could similarly function with Hla H35L. The chimeric fusion (HlaD) provided a diagnostic antigen for hemolysis of the S. aureus strains and a potential vaccine component.

In Silico Investigation of a Chimeric IL24-LK6 Fusion Protein as a Potent Candidate Against Breast Cancer.

Targeted delivery of therapeutic anticancer chimeric molecules enhances the efficacy of drug by improving cellular uptake and circulation time. Engineering the molecules to facilitate the specific interaction between chimeric protein and its receptor is critical to elucidate biological mechanism as well as accuracy in modeling of complexes. A theoretically designed novel protein-protein interfaces can serve as a bottom-up method for comprehensive understanding of interacting protein residues. This study was aimed for in silico analyses of a chimeric fusion protein against breast cancer. The amino acid sequences of the interleukin 24 (IL-24) and LK-6 peptide were used to design the chimeric fusion protein via a rigid linker. The secondary and tertiary structures along with physicochemical properties by ProtParam and solubility were predicted using online software. The validation and quality of the fusion protein was confirmed by Rampage and ERRAT2. The newly designed fusion construct has a total length of 179 amino acids. The top-ranked structure from alpha fold2 showed 18.1 KD molecular weight by ProtParam, quality factor of 94.152 by ERRAT, and a valid structure by a Ramachandran plot with 88.5% residues in the favored region. Finally, the docking and simulation studies were performed using HADDOCK and Desmond module of Schrodinger. The quality, validity, interaction analysis, and stability of the fusion protein depict a functional molecule. The fusion gene IL24-LK6 after cloning and expression in a suitable prokaryotic cell might be a useful candidate for developing a novel anticancer therapy.

Structural Insights into (Tere)phthalate-Ester Hydrolysis by a Carboxylesterase and Its Role in Promoting PET Depolymerization.

TfCa, a promiscuous carboxylesterase from Thermobifida fusca, was found to hydrolyze polyethylene terephthalate (PET) degradation intermediates such as bis(2-hydroxyethyl) terephthalate (BHET) and mono-(2-hydroxyethyl)-terephthalate (MHET). In this study, we elucidated the structures of TfCa in its apo form, as well as in complex with a PET monomer analogue and with BHET. The structure-function relationship of TfCa was investigated by comparing its hydrolytic activity on various ortho- and para-phthalate esters of different lengths. Structure-guided rational engineering of amino acid residues in the substrate-binding pocket resulted in the TfCa variant I69W/V376A (WA), which showed 2.6-fold and 3.3-fold higher hydrolytic activity on MHET and BHET, respectively, than the wild-type enzyme. TfCa or its WA variant was mixed with a mesophilic PET depolymerizing enzyme variant [Ideonella sakaiensis PETase (IsPETase) PM] to degrade PET substrates of various crystallinity. The dual enzyme system with the wild-type TfCa or its WA variant produced up to 11-fold and 14-fold more terephthalate (TPA) than the single IsPETase PM, respectively. In comparison to the recently published chimeric fusion protein of IsPETase and MHETase, our system requires 10% IsPETase and one-fourth of the reaction time to yield the same amount of TPA under similar PET degradation conditions. Our simple dual enzyme system reveals further advantages in terms of cost-effectiveness and catalytic efficiency since it does not require time-consuming and expensive cross-linking and immobilization approaches.

A genomic DNA-based NGS method for the simultaneous detection of multiple fusion genes in pediatric leukemia.

Fusion genes are products of chromosomal translocations that generate either a dysregulated partner gene or a chimeric fusion protein with new properties, and contribute significantly to leukemia development and clinical risk stratification. However, simultaneous detection of several hundreds of fusion genes has always been a challenge in a clinical laboratory setting. In the present study, a total of 182 pediatric patients with leukemia were screened for fusion genes by employing a novel genomic DNA-, instead of RNA-, based next-generation sequencing (NGS) method. This involved the comparison of the multiply targeted capture sequencing method with a detection panel of 270 fusion genes (MTCS-270) with an RNA-based multiplex reverse transcription-PCR technique with a detection panel of 57 fusion genes (MRTP-57). MRTP-57 has been well established in the clinical lab at Beijing Hightrust Diagnostics, Co. (Beijing, China) for an up-front leukemia diagnosis and served as the control technique in the present study. In the series, MTCS-270 and MRTP-57 yielded a positive fusion gene detection rate of 50.0% (91/182) and 41.8% (76/182), respectively, indicating an advantage of MTCS-270 over MRTP-57 in overall detection sensitivity. Specifically, all the fusion genes detected by MRTP-57 were also identified by MTCS-270, clearly signifying the respectable detection accuracy of MTCS-270. Notably, across the patients screened, MTCS-270 identified more samples with fusion genes than MRTP-57, illustrating a broader fusion gene detection coverage by MTCS-270. The present study provides solid evidence that this DNA-based NGS approach can be used as a potential detection tool together with other well-established molecular cytogenetic methods for leukemia management, and to the best of our knowledge, represents the largest leukemia fusion gene identification analysis by genomic NGS.

Rilonacept and Anakinra in Recurrent Pericarditis: A Systematic Review and Meta-Analysis.

Interleukin 1 (IL-1) has been indicated as a mediator of recurrent pericarditis. Rilonacept, a soluble IL-1 receptor chimeric fusion protein neutralizing interleukin 1 alpha (IL-1α) and interleukin 1 beta (IL-1β), has demonstrated promising results in a phase II study in recurrent or refractory pericarditis. Anakinra is a recombinant inhibitor of the IL-1 receptor with a demonstrated reduction in the incidence of recurrent pericarditis. Definite pharmacological management of pericarditis is key to preventing recurrences, mostly treatment options for recurrent pericarditis refractory to conventional drugs. Here we critically discuss the existing therapy options for recurrent pericarditis, with a focus on new pharmacological approaches: rilonacept and anakinra. A systematic search was conducted across online databases such as PubMed, Cochrane, Google Scholar, ScienceDirect, CINAHL, Scopus, and Embase to obtain clinical trials that assess the effectiveness of anti-interleukin 1 therapy such as anakinra and rilonacept in the management of recurrent pericarditis. Our study concluded that anti-interleukin 1 therapy significantly improved both the quality of life and the clinical outcomes of the study population. These outcomes were most prominent with the use of rilonacept and anakinra in the trial treatment. Rilonacept and anakinra are valuable options in case of recurrent pericarditis refractory to conventional drugs.

Combination of a Novel Fusion Protein CD3εζ28 and Bispecific T Cell Engager Enhances the Persistance and Anti-Cancer Effects of T Cells.

Simple SummaryBi-specific T cell engager (BiTE) has shown promising therapeutic potential in preclinical and clinical studies. However, T cells cannot be sufficiently activated by BiTE, most likely due to lacking co-stimulatory signal. We, therefore, designed a chimeric fusion protein, named as CD3εζ28, which consists of the CD3ε extracellular region, the CD28 costimulatory signal and the intracellular region of CD3ζ in tandem. Our results demonstrated that T cells genetically modified to express CD3εζ28 could be sufficiently activated and effectively kill tumor cells in presence of BiTE molecules in vitro, and, thus, show superior anti-tumor effects on xenograft tumor models. Taken together, incorporating co-stimulatory signal may be an effective approach to improve the effector function of T cells mediated by BiTE.Bi-specific T cell engager (BiTE), an artificial bi-functional fusion protein, has shown promising therapeutic potential in preclinical and clinical studies. However, T cells cannot be sufficiently activated by BiTE, most likely due to lacking co-stimulatory signal. We reasoned that incorporating co-stimulatory signal might have the potential to enhance the T cell activation mediated by BiTE. We, therefore, designed a chimeric fusion protein, named as CD3εζ28, which consists of the CD3ε extracellular region, the CD28 costimulatory signal and the intracellular region of CD3ζ in tandem. T cells genetically modified to express both CD3εζ28 and GFP (T-CD3εζ28-GFP) were generated by retroviral transduction. The results from in vitro experiments showed that T-CD3εζCD28-GFP cells had superior cytotoxic effects on tumor cells in presence of BiTE compared with control T cells, as evidenced by IL-2 and IFN-γ production, T cell proliferation and sequential killing assay. In vivo, T-CD3εζCD28-GFP cells showed superior anti-tumor effects in Hela-BiTE. EGFRvIII xenograft tumor model, as evaluated by tumor growth rate and T cell persistence in comparison with control T cells. In order to further confirm these findings, we generated T cells modified to express both CD3εζCD28 on cell surface and BiTE.CD19 by autocrine manner (T-CD3εζCD28-BiTE.19). The superior anti-tumor effects of T-CD3εζCD28-BiTE.19 cells could also be evidenced by the similar in vitro and in vivo experiments; thus, incorporating co-stimulatory signal may be an effective approach to improve the effector function of T cells mediated by BiTE.

Abstract A031: Interplay of YAP1, β-catenin and the SS18-SSX fusion protein in synovial sarcoma

Abstract Introduction: Synovial sarcoma (SySa) is a rare soft-tissue malignancy characterized by a specific chromosomal translocation t(X;18). The resulting chimeric SS18-SSX fusion protein drives SySa pathogenesis by dysregulating gene transcription. As therapeutic targeting of SS18-SSX is notoriously difficult, the identification of SS18-SSX-dependent pathomechanisms may uncover novel molecular vulnerabilities. Since previous functional analyses revealed a connection between SS18-SSX and the activity of the transcriptional co-regulators YAP1/TAZ and β-catenin, this study examined a potential crosstalk between these effectors in SySa. Experimental Procedures: Nuclear abundance of YAP1/TAZ and β-catenin was analyzed by immunohistochemistry in a large cohort of SySa tissue specimens. Two SySa cell lines were employed to modulate YAP1/TAZ/β-catenin transcriptional activity by RNAi-mediated knockdown, small molecule inhibitors, and overexpression vectors in vitro. Changes in transcriptional activity were determined via luciferase reporter assays. As YAP1 and β-catenin showed highest interdependence, co-immunoprecipitation experiments were performed to investigate their interplay with the SS18-SSX fusion protein in SySa cells. Results: Immunohistochemically, a substantial subset of SySa tissue specimens showed concurrent nuclear accumulation of YAP1/TAZ and β-catenin. In vitro, SS18-SSX was found to promote YAP1/TAZ and β-catenin transcriptional activity. RNAi-mediated knockdown of YAP1, TAZ or β-catenin and small molecule inhibitor treatment mutually downregulated TEAD and TCF luciferase reporter activity, while expression of hyperactive variants led to a reciprocal luciferase reporter induction. Finally, co-immunoprecipitation assays demonstrated nuclear co-localization of SS18-SSX with YAP1 and β-catenin in SySa cell lines. Conclusions: This study reveals an interdependency between YAP1 and β-catenin activation and a complex interplay with the SySa-specific SS18-SSX fusion protein. Citation Format: Ilka Isfort, Ruth Berthold, Lorena Heinst, Eva Wardelmann, Marcel Trautmann, Wolfgang Hartmann. Interplay of YAP1, β-catenin and the SS18-SSX fusion protein in synovial sarcoma [abstract]. In: Proceedings of the AACR Special Conference: Sarcomas; 2022 May 9-12; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(18_Suppl):Abstract nr A031.