In Vitro Examinations of Cell Death Induction and the Immune Phenotype of Cancer Cells Following Radiative-Based Hyperthermia with 915 MHz in Combination with Radiotherapy

Multimodal tumor treatment settings consisting of radiotherapy and immunomodulating agents such as immune checkpoint inhibitors are more and more commonly applied in clinics. In this context, the immune phenotype of tumor cells has a major influence on the anti-tumor immune response as well as the composition of the tumor microenvironment. A promising approach to further boost anti-tumor immune responses is to add hyperthermia (HT), i.e., heating the tumor tissue between 39 °C to 45 °C for 60 min. One key technique is the use of radiative hyperthermia systems. However, knowledge is limited as to how the frequency of the used radiative systems affects the immune phenotype of the treated tumor cells. By using our self-designed in vitro hyperthermia system, we compared cell death induction and expression of immune checkpoint molecules (ICM) on the tumor cell surface of murine B16 melanoma and human MDA-MB-231 and MCF-7 breast cancer cells following HT treatment with clinically relevant microwaves at 915 MHz or 2.45 GHz alone, radiotherapy (RT; 2 × 5 Gy or 5 × 2 Gy) alone or in combination (RHT). At 44 °C, HT alone was the dominant cell death inductor with inactivation rates of around 70% for B16, 45% for MDA-MB-231 and 35% for MCF-7 at 915 MHz and 80%, 60% and 50% at 2.45 GHz, respectively. Additional RT resulted in 5-15% higher levels of dead cells. The expression of ICM on tumor cells showed time-, treatment-, cell line- and frequency-dependent effects and was highest for RHT. Computer simulations of an exemplary spherical cell revealed frequency-dependent local energy absorption. The frequency of hyperthermia systems is a newly identified parameter that could also affect the immune phenotype of tumor cells and consequently the immunogenicity of tumors

Differences of the immune phenotype of breast cancer cells after ex vivo hyperthermia by warm-water or microwave radiation in a closed-loop system alone or in combination with radiotherapy

The treatment of breast cancer by radiotherapy can be complemented by hyperthermia. Little is known about how the immune phenotype of tumor cells is changed thereby, also in terms of a dependence on the heating method. We developed a sterile closed-loop system, using either a warm-water bath or a microwave at 2.45 GHz to examine the impact of ex vivo hyperthermia on cell death, the release of HSP70, and the expression of immune checkpoint molecules (ICMs) on MCF-7 and MDA-MB-231 breast cancer cells by multicolor flow cytometry and ELISA. Heating was performed between 39 and 44◦C. Numerical process simulations identified temperature distributions. Additionally, irradiation with 2 × 5 Gy or 5 × 2 Gy was applied. We observed a release of HSP70 after hyperthermia at all examined temperatures and independently of the heating method, but microwave heating was more effective in cell killing, and microwave heating with and without radiotherapy increased subsequent HSP70 concentrations. Adding hyperthermia to radiotherapy, dynamically or individually, affected the expression of the ICM PD-L1, PD-L2, HVEM, ICOS-L, CD137-L, OX40-L, CD27-L, and EGFR on breast cancer cells. Well-characterized pre-clinical heating systems are mandatory to screen the immune phenotype of tumor cells in clinically relevant settings to define immune matrices for therapy adaption. © 2020 by the authors. Licensee MDPI, Basel, Switzerland

Stable five- and six-coordinate cobalt (III) complexes with a pentadentate bispidine ligand

I am ligand: A pentadentate bispidine ligand with two tertiary amine and three pyridine donors stabilizes the uncommon intermediate-spin electronic configuration of Co¹¹¹(S=1; see picture: C gray, N blue, O red, Co violet). Dissociation of the monodentate coligand yields a catalytically active pentacoordinate complex

Paramagnetic NMR Analysis of Substituted Biscyclooctatetraene Lanthanide Complexes

Cyclooctatetraene derivatives (COT^R) with two carbocycles attached to the central ring have been used as dianionic ligands for the synthesis of double-decker complexes of the type [(COT^R)₂M]⁻. Two ligand derivatives were combined with diamagnetic Y³⁺ and with the five paramagnetic lanthanide ions from Tb³⁺ to Tm³⁺. The more complex substitution pattern in comparison to the parent ligand COT or the popular bis-trimethylsilyl derivative allows a sufficient number of signals to be obtained for a comprehensive paramagnetic NMR analysis. The anionic double-decker complexes gave well-resolved NMR spectra where almost all ¹H and ¹³C NMR signals could be detected and assigned. With these data, it was possible to separate the two main contributions to the paramagnetic shift (pseudocontact and Fermi contact shifts, respectively) and to determine the magnetic anisotropy of the lanthanide ions in their ligand fields. We can easily obtain the sign and the magnitude of the anisotropy of the magnetic susceptibility, which is itself strongly related to the energy barrier for spin reversal in single-molecule magnets. Our results confirm that Bleaney factors are inadequate descriptors for magnetic anisotropy in these lanthanide complexes

First-Generation Bispidine Chelators for 213BiIII Radiopharmaceutical Applications

Hepta- and octadentate bispidines (3,7-diazabicyclo[3.3.1]nonane, diazaadamantane) with acetate, methyl-pyridine and methyl-picolinate pendant groups at the amine donors of the bispidine platform have been prepared and used to investigate their BiIII coordination chemistry. Crystal structural and solution spectroscopic data (NMR spectroscopy and mass spectrometry) confirm that the rigid and relatively large bispidine cavity with an axially distorted geometry is well suited for BiIII and in all cases forms 9-coordinate complexes, and this is supported by an established hole size and shape analysis. It follows that nonadentate bispidines probably will be more suited as bifunctional chelators for 213BiIII based radiopharmaceuticals. However, the two isomeric picolinate-/acetate-based heptadentate ligands already show very efficient complexation kinetics with 213BiIII at ambient temperature and kinetic stability that is comparable with the standard ligands used in this field. The experimentally determined hydrophilicities (log D7.4 values) show that the BiIII complexes reported are relatively hydrophilic and well suited for medicinal applications, and we also present a very efficient and relatively accurate method to compute charge distributions and hydrophilicities, and this will help to further optimize the systems reported here.JRC.G.I.5-Advanced Nuclear Knowledg

Paramagnetic NMR Analysis of Substituted Biscyclooctatetraene Lanthanide Complexes

Cyclooctatetraene derivatives (COT^R) with two carbocycles attached to the central ring have been used as dianionic ligands for the synthesis of double-decker complexes of the type [(COT^R)₂M]⁻. Two ligand derivatives were combined with diamagnetic Y³⁺ and with the five paramagnetic lanthanide ions from Tb³⁺ to Tm³⁺. The more complex substitution pattern in comparison to the parent ligand COT or the popular bis-trimethylsilyl derivative allows a sufficient number of signals to be obtained for a comprehensive paramagnetic NMR analysis. The anionic double-decker complexes gave well-resolved NMR spectra where almost all ¹H and ¹³C NMR signals could be detected and assigned. With these data, it was possible to separate the two main contributions to the paramagnetic shift (pseudocontact and Fermi contact shifts, respectively) and to determine the magnetic anisotropy of the lanthanide ions in their ligand fields. We can easily obtain the sign and the magnitude of the anisotropy of the magnetic susceptibility, which is itself strongly related to the energy barrier for spin reversal in single-molecule magnets. Our results confirm that Bleaney factors are inadequate descriptors for magnetic anisotropy in these lanthanide complexes

Trinuclear {M1}CN{M2}2 complexes (M1= CrIII, FeIII, CoIII; M2= CuII, NiII, MnII). Are single molecule magnets predictable?

The structures and magnetic properties of a series of hexacyanometalate-based trinuclear complexes with linear or bent geometries is analyzed with an orbital-dependent extended Heisenberg Hamiltonian. The absence of SMM behavior is shown to be due to the large angular distortions of the hexacyanoferrate centers

Data publication: One chelator for imaging and therapy with lutetium-177 and actinium-225

Bei diesem Datensatz handelt es sich um analytische Charakterisierungen (ESI-MS, HR-MS, MALDI-TOF-MS) und Radiomarkierungsuntersuchungen zum nonadentaten Bispidin-Chelator bzw. Bispidin-TATE Konjugat mit Lutetium-177, Indium-111 und/oder Actinium-225. 1H, 13 C NMR and crystallographic data stored by collaboration partner (Heidelberg University