Treatment of glioblastoma multiforme cells with temozolomide-BioShuttle ligated by the inverse Diels-Alder ligation chemistry

Cryoablation and Immunotherapy: An Enthralling Synergy for Cancer Treatment

As less invasive options for surgical tumor removal, minimally invasive ablative techniques have gained popularity. Several solid tumors are being treated with cryoablation, a non-heat-based ablation technique. Cryoablation data in comparison over time demonstrates better tumor response and faster recovery. Combining cryosurgery with other cancer therapies has been explored to improve the cancer-killing process. Cryoablation with the combination of immunotherapy, results in a robust and efficient attack on the cancer cells. This article focuses on investigating the ability of cryosurgery to create a strong antitumor response when combined with immunologic agents resulting in a synergetic effect. To achieve this objective, we combined cryosurgery with immunotherapy using Nivolumab and lpilimumab. Five clinical cases of lymph node, lung cancer, bone, and lung metastasis were followed and analyzed. In this series of patients, percutaneous cryoablation and addressing immunity agents were technically feasible. In the follow-ups, there appeared to be no radiological evidence of new tumor development.

Application of the Inverse-Electron-Demand Diels-Alder Reaction for Metabolic Glycoengineering

The inverse electron-demand Diels-Alder (IEDDA or DAinv) reaction is an emerging bioorthogonal ligation reaction that finds application in all areas of chemistry and chemical biology. In this review we highlight its application in metabolic glycoengineering (MGE). MGE is a versatile tool to introduce unnatural sugar derivatives that are modified with a chemical reporter group into cellular glycans. The IEDDA reaction can then be used to modify the chemical reporter group allowing, for instance, the visualization or isolation of glycoconjugates. During the last years, many different sugar derivatives as well as reporter groups have been published. These probes are summarized, and their chemical and biological properties are discussed. Furthermore, we discuss examples of MGE and subsequent IEDDA reaction that highlight its suitability for application within living systems.

Cyclopropene derivatives of aminosugars for metabolic glycoengineering

Cyclopropenes have been proven valuable chemical reporter groups for metabolic glycoengineering (MGE). They readily react with tetrazines in an inverse electron-demand Diels-Alder (DAinv) reaction, a prime example of a bioorthogonal ligation reaction, allowing their visualization in biological systems. Here, we present a comparative study of six cyclopropene-modified hexosamine derivatives and their suitability for MGE. Three mannosamine derivatives in which the cyclopropene moiety is attached to the sugar by either an amide or a carbamate linkage and that differ by the presence or absence of a stabilizing methyl group at the double bond have been examined. We determined their DAinv reaction kinetics and their labeling intensities after metabolic incorporation. To determine the efficiencies by which the derivatives are metabolized to sialic acids, we synthesized and investigated the corresponding cyclopropane derivatives because cyclopropenes are not stable under the analysis conditions. From these experiments, it became obvious that N-(cycloprop-2-en-1-ylcarbonyl)-modified (Cp-modified) mannosamine has the highest metabolic acceptance. However, carbamate-linked N-(2-methylcycloprop-2-en-1-ylmethyloxycarbonyl)-modified (Cyoc-modified) mannosamine despite its lower metabolic acceptance results in the same cell-surface labeling intensity due to its superior reactivity in the DAinv reaction. Based on the high incorporation efficiency of the Cp derivative we synthesized and investigated two new Cp-modified glucosamine and galactosamine derivatives. Both compounds lead to comparable, distinct cell-surface staining after MGE. We further found that the amide-linked Cp-modified glucosamine derivative but not the Cyoc-modified glucosamine is metabolically converted to the corresponding sialic acid.

Inverse electron demand Diels-Alder (IEDDA) reactions in peptide chemistry

Click chemistry is applied to selectively modify, lable and ligate peptides for their use as therapeutics, in biomaterials or analytical investigations. The inverse electron demand Diels-Alder (IEDDA) reaction is a catalyst-free click reaction with pronounced chemoselectivity and fast reaction rates. Applications and achievements of the IEDDA reaction in peptide chemistry since 2008 are described in this review.

On-resin Diels–Alder reaction with inverse electron demand: an efficient ligation method for complex peptides with a varying spacer to optimize cell adhesion

The DAR_invon resin is a new orthogonal reaction in peptide synthesis and the benefits for cell adhesion are discussed.

NIR-Cyanine Dye Linker: a Promising Candidate for Isochronic Fluorescence Imaging in Molecular Cancer Diagnostics and Therapy Monitoring

Personalized anti-cancer medicine is boosted by the recent development of molecular diagnostics and molecularly targeted drugs requiring rapid and efficient ligation routes. Here, we present a novel approach to synthetize a conjugate able to act simultaneously as an imaging and as a chemotherapeutic agent by coupling functional peptides employing solid phase peptide synthesis technologies. Development and the first synthesis of a fluorescent dye with similarity in the polymethine part of the Cy7 molecule whose indolenine-N residues were substituted with a propylene linker are described. Methylating agent temozolomide is functionalized with a tetrazine as a diene component whereas Cy7-cell penetrating peptide conjugate acts as a dienophilic reaction partner for the inverse Diels-Alder click chemistry-mediated ligation route yielding a theranostic conjugate, 3-mercapto-propionic-cyclohexenyl-Cy7-bis-temozolomide-bromide-cell penetrating peptide. Synthesis route described here may facilitate targeted delivery of the therapeutic compound to achieve sufficient local concentrations at the target site or tissue. Its versatility allows a choice of adequate imaging tags applicable in e.g. PET, SPECT, CT, near-infrared imaging, and therapeutic substances including cytotoxic agents. Imaging tags and therapeutics may be simultaneously bound to the conjugate applying click chemistry. Theranostic compound presented here offers a solid basis for a further improvement of cancer management in a precise, patient-specific manner.

A novel bispecific immunotoxin delivered by human bone marrow-derived mesenchymal stem cells to target blood vessels and vasculogenic mimicry of malignant gliomas

Background

In previous years, immunotoxins have been shown to be a greatly promising therapeutic tool for brain malignancies, such as gliomas. Human mesenchymal stem cells (hMSCs) exhibit tropism to tumor tissue. However, the effect of bispecific immunotoxins in malignant gliomas is still unknown. The aim of this study was to investigate the function of bispecific immunotoxins in human malignant gliomas.

Materials and methods

In the present study, the bispecific immunotoxin VEGF₁₆₅-ephrin A1-PE38KDEL was established using deoxyribonucleic acid shuffling and cloning techniques. The VEGF₁₆₅-ephrin A1-PE38KDEL was delivered by hMSCs to mouse malignant gliomas. The effects of the bispecific immunotoxins on glioma-derived blood vessels and vasculogenic mimicry to elucidate the molecular mechanisms underlying the antitumorigenic effects of immunotoxins were examined in vivo.

Results

In vitro, transfected hMSCs significantly inhibited the cell viability of gliomas cell lines U87 and U251 in a dose-dependent manner compared with untransfected hMSCs (P<0.01). In vivo, the intratumoral injection of engineered hMSCs was effective at inhibiting tumor growth in a malignant glioma tumor model.

Conclusion

The bispecific immunotoxin secreted from hMSCs acts as a novel strategy for improving treatment options for malignant gliomas in the clinic.

Temozolomide nanoparticles for targeted glioblastoma therapy

Glioblastoma (GBM) is a deadly and debilitating brain tumor with an abysmal prognosis. The standard therapy for GBM is surgery followed by radiation and chemotherapy with Temozolomide (TMZ). Treatment of GBMs remains a challenge, largely because of the fast degradation of TMZ, the inability to deliver an effective dose of TMZ to tumors, and a lack of target specificity that may cause systemic toxicity. Here, we present a simple method for synthesizing a nanoparticle-based carrier that can protect TMZ from rapid degradation in physiological solutions and can specifically deliver them to GBM cells through the mediation of a tumor-targeting peptide chlorotoxin (CTX). Our nanoparticle, namely NP-TMZ-CTX, had a hydrodynamic size of <100 nm, exhibited sustained stability in cell culture media for up to 2 weeks, and could accommodate stable drug loading. TMZ bound to nanoparticles showed a much higher stability at physiological pH, with a half-life 7-fold greater than that of free TMZ. NP-TMZ-CTX was able to target GBM cells and achieved 2-6-fold higher uptake and a 50-90% reduction of IC50 72 h post-treatment as compared to nontargeted NP-TMZ. NP-TMZ-CTX showed great promise in its ability to deliver a large therapeutic dose of TMZ to GBM cells and could serve as a template for targeted delivery of other therapeutics.

Cryo-ablation improves anti-tumor immunity through recovering tumor educated dendritic cells in tumor-draining lymph nodes

BACKGROUND

In addition to minimally invasive destruction of tumors, cryo-ablation of tumors to some extent modulated anti-tumor immunity. Cryo-ablated tumors in glioma mice models induced anti-tumor cellular immunologic response which increases the percentage of CD3(+) and CD4(+)T cells in blood as well as natural killer cells. As a crucial role in triggering anti-tumor immunity, dendritic cells (DCs) were educated by tumors to adopt a tolerance phenotype which helps the tumor escape from immune monitoring. This study aims to study whether cryo-ablation could influence the tolerogenic DCs, and influence anti-tumor immunity in tumor-draining lymph nodes (TDLNs).

METHODS

Using the GL261 subcutaneous glioma mouse model, we created a tumor bearing group, cryo-ablation group, and surgery group. We analyzed alteration in phenotype and function of tolerogenic DCs, and evaluated the factors of anti-tumor immunity inhibition.

RESULTS

DCs in TDLNs in GL261 subcutaneous glioma mouse model expressed tolerogenic phenotype. In contrast to surgery, cryo-ablation improved the quantity and quality of these tolerogenic DCs. Moreover, the DCs decreased the expression of intracellular interleukin-10 (IL-10) and extra-cellular IL-10. In vitro, DCs from the cryo-ablation group recovered their specific function and induced potent anti-tumor immunity through triggering T cells. In vivo, cryo-ablation showed weak anti-tumor immunity, only inhibiting the growth of rechallenged tumors. But many IL-10-low DCs, rather than IL-10-high DCs, infiltrated the tumors. More importantly, Tregs inhibited the performance of these DCs; and depletion of Tregs greatly improved anti-tumor immunity in vivo.

CONCLUSION

Cryo-ablation could recover function of tumor induced tolerogenic DCs in vitro; and depletion of Tregs could improve this anti-tumor effect in vivo. The Tregs/CD4(+)T and Tregs/CD25(+)T cells in TDLNs inhibit DCs' activity and function.

Expanding the scope of cyclopropene reporters for the detection of metabolically engineered glycoproteins by Diels-Alder reactions

Monitoring glycoconjugates has been tremendously facilitated by the development of metabolic oligosaccharide engineering. Recently, the inverse-electron-demand Diels-Alder reaction between methylcyclopropene tags and tetrazines has become a popular ligation reaction due to the small size and high reactivity of cyclopropene tags. Attaching the cyclopropene tag to mannosamine via a carbamate linkage has made the reaction even more efficient. Here, we expand the application of cyclopropene tags to N-acylgalactosamine and N-acylglucosamine derivatives enabling the visualization of mucin-type O-glycoproteins and O-GlcNAcylated proteins through Diels-Alder chemistry. Whereas the previously reported cyclopropene-labeled N-acylmannosamine derivative leads to significantly higher fluorescence staining of cell-surface glycoconjugates, the glucosamine derivative gave higher labeling efficiency with protein preparations containing also intracellular proteins.

SPPS resins impact the PNA-syntheses' improvement

The personalized medicine, also documented as "individualized medicine", is an effective and therapeutic approach. It is designed to treat the disease of the individual patient whose precise differential gene expression profile is well known. The trend in the biomedical and biophysical research shows important consequences for the pharmaceutical drug and diagnostics research. It requires a high variability in the design and safety of target-specific pharmacologically active molecules and diagnostic components for imaging of metabolic processes. A key technology which may fulfill the highest demands during synthesis of these individual drugs and diagnostics is the solid phase synthesis which is congenial to automated manufacturing. Additionally the choice of tools like resins and reagents is pivotal to synthesize drugs and diagnostics in high quality and yields. Here we demonstrate the solid phase synthesis effects dependent on the choice of resin and of the deprotection agent.

Improved synthesis strategy for peptide nucleic acids (PNA) appropriate for cell-specific fluorescence imaging

Progress in genomics and proteomics attended to the door for better understanding the recent rapid expanding complex research field of metabolomics. This trend in biomedical research increasingly focuses to the development of patient-specific therapeutic approaches with higher efficiency and sustainability. Simultaneously undesired adverse reactions are avoided. In parallel, the development of molecules for molecular imaging is required not only for the imaging of morphological structures but also for the imaging of metabolic processes like the aberrant expression of the cysteine protease cathepsin B (CtsB) gene and the activity of the resulting product associated with metastasis and invasiveness of malign tumors. Finally the objective is to merge imaging and therapy at the same level. The design of molecules which fulfil these responsibilities is pivotal and requires proper chemical methodologies. In this context our modified solid phase peptide chemistry using temperature shifts during synthesis is considered as an appropriate technology. We generated highly variable conjugates which consist of molecules useful as diagnostically and therapeutically active molecules. As an example the modular PNA products with the complementary sequence to the CtsB mRNA and additionally with a cathepsin B cleavage site had been prepared as functional modules for distinction of cell lines with different CtsB gene expression. After ligation to the modular peptide-based BioShuttle carrier, which was utilized to facilitate the delivery of the functional modules into the cells' cytoplasm, the modules were scrutinized.

Gain of a 500-fold sensitivity on an intravital MR contrast agent based on an endohedral gadolinium-cluster-fullerene-conjugate: a new chance in cancer diagnostics

Among the applications of fullerene technology in health sciences the expanding field of magnetic resonance imaging (MRI) of molecular processes is most challenging. Here we present the synthesis and application of a Gd(x)Sc(3-x)N@C(80)-BioShuttle-conjugate referred to as Gd-cluster@-BioShuttle, which features high proton relaxation and, in comparison to the commonly used contrast agents, high signal enhancement at very low Gd concentrations. This modularly designed contrast agent represents a new tool for improved monitoring and evaluation of interventions at the gene transcription level. Also, a widespread monitoring to track individual cells is possible, as well as sensing of microenvironments. Furthermore, BioShuttle can also deliver constructs for transfection or active pharmaceutical ingredients, and scaffolding for incorporation with the host's body. Using the Gd-cluster@-BioShuttle as MRI contrast agent allows an improved evaluation of radio- or chemotherapy treated tissues.

The Diels-Alder-reaction with inverse-electron-demand, a very efficient versatile click-reaction concept for proper ligation of variable molecular partners

The ligation of active pharmaceutical ingredients (API) for working with image processing systems in diagnostics (MRT) attracts increasing notice and scientific interest. The Diels-Alder ligation Reaction with inverse electron demand (DAR(inv)) turns out to be an appropriate candidate. The DAR(inv) is characterized by a specific distribution of electrons of the diene and the corresponding dienophile counterpart. Whereas the reactants in the classical Diels-Alder Reaction feature electron-rich diene and electron-poor dienophile compounds, the DAR(inv) exhibits exactly the opposite distribution of electrons. Substituents with pushing electrones increase and, with pulling electrons reduce the electron density of the dienes as used in the DAR(inv).We report here that the DAR(inv) is an efficient route for coupling of multifunctional molecules like active peptides, re-formulated drugs or small molecules like the alkyalting agent temozolomide (TMZ). This is an example of our contribution to the "Click chemistry" technology. In this case TMZ is ligated by DAR(inv) as a cargo to transporter molecules facilitating the passage across the cell membranes into cells and subsequently into subcellular components like the cell nucleus by using address molecules. With such constructs we achieved high local concentrations at the desired target site of pharmacological action. The DAR(inv) ligation was carried out using the combination of several technologies, namely: the organic chemistry and the solid phase peptide synthesis which can produce 'tailored' solutions for questions not solely restricted to the medical diagnostics or therapy, but also result in functionalizations of various surfaces qualified amongst others also for array development.We like to acquaint you with the DAR(inv) and we like to exemplify that all ligation products were generated after a rapid and complete reaction in organic solutions at room temperature, in high purity, but also, hurdles and difficulties on the way to the TMZ-BioShuttle conjugate should be mentioned.With this report we would like to stimulate scientists working with the focus on "Click chemistry" to intensify research with this expanding DAR(inv )able to open the door for new solutions inconceivable so far.

High-resolution flow cytometry: a suitable tool for monitoring aneuploid prostate cancer cells after TMZ and TMZ-BioShuttle treatment

If metastatic prostate cancer gets resistant to antiandrogen therapy, there are few treatment options, because prostate cancer is not very sensitive to cytostatic agents. Temozolomide (TMZ) as an orally applicable chemotherapeutic substance has been proven to be effective and well tolerated with occasional moderate toxicity especially for brain tumors and an application to prostate cancer cells seemed to be promising. Unfortunately, TMZ was inefficient in the treatment of symptomatic progressive hormone-refractory prostate cancer (HRPC). The reasons could be a low sensitivity against TMZ the short plasma half-life of TMZ, non-adapted application regimens and additionally, the aneuploid DNA content of prostate cancer cells suggesting different sensitivity against therapeutical interventions e.g. radiation therapy or chemotherapy. Considerations to improve this unsatisfying situation resulted in the realization of higher local TMZ concentrations, sufficient to kill cells regardless of intrinsic cellular sensitivity and cell DNA-index. Therefore, we reformulated the TMZ by ligation to a peptide-based carrier system called TMZ-BioShuttle for intervention. The modular-composed carrier consists of a transmembrane transporter (CPP), connected to a nuclear localization sequence (NLS) cleavably-bound, which in turn was coupled with TMZ. The NLS-sequence allows an active delivery of the TMZ into the cell nucleus after transmembrane passage of the TMZ-BioShuttle and intra-cytoplasm enzymatic cleavage and separation from the CPP. This TMZ-BioShuttle could contribute to improve therapeutic options exemplified by the hormone refractory prostate cancer. The next step was to syllogize a qualified method monitoring cell toxic effects in a high sensitivity under consideration of the ploidy status. The high-resolution flow cytometric analysis showed to be an appropriate system for a better detection and distinction of several cell populations dependent on their different DNA-indices as well as changes in proliferation of cell populations after chemotherapeutical treatment.