The tumor microenvironment is highly heterogeneous. For gliomas, the tumor-associated inflammatory response is pivotal to support growth and invasion. Factors of glioma growth, inflammation, and ...invasion, such as the translocator protein (TSPO) and matrix metalloproteinases (MMP), may serve as specific imaging biomarkers of the glioma microenvironment. In this study, noninvasive imaging by PET with
FDPA-714 (TSPO) and
FBR-351 (MMP) was used for the assessment of localization and quantification of the expression of TSPO and MMP. Imaging was performed in addition to established clinical imaging biomarker of active tumor volume (
FFET) in conjunction with MRI. We hypothesized that each imaging biomarker revealed distinct areas of the heterogeneous glioma tissue in a mouse model of human glioma. Tracers were found to be increased 1.4- to 1.7-fold, with
FFET showing the biggest volume as depicted by a thresholding-based, volumes of interest analysis. Tumor areas, which could not be detected by a single tracer and/or MRI parameter alone, were measured. Specific compartments of
FDPA-714 (14%) and
FBR-351 (11%) volumes along the tumor rim could be identified.
FDPA-714 (TSPO) and
FBR-351 (MMP) matched with histology. Glioma-associated microglia/macrophages (GAM) were identified as TSPO and MMP sources. Multitracer and multimodal molecular imaging approaches may allow us to gain important insights into glioma-associated inflammation (GAM, MMP). Moreover, this noninvasive technique enables characterization of the glioma microenvironment with respect to the disease-driving cellular compartments at the various disease stages.
.
KRAS mutations are frequent driver mutations in multiple cancers. KRAS mutations also induce anti-EGFR antibody resistance in adenocarcinoma such as colon cancer. The aim of this study was to ...overcome anti-EGFR antibody resistance by coupling the antibody to KRAS-specific siRNA.
The anti-EGFR antibody was chemically coupled to siRNA. The resulting complex was tested for antibody binding efficiency, serum stability and ability to deliver siRNA to EGFR-expressing cells. Western blotting, viability, apoptosis, and colony formation assays were performed for efficacy evaluation in vitro. Furthermore, therapeutic activity of the antibody-KRAS-siRNA complexes was examined in in vivo xenograft mouse tumor models.
Antibody-siRNA complexes were targeted and internalized via the EGFR receptor. Upon internalization, target gene expression was strongly and specifically repressed, followed by a reduced proliferation and viability, and induced apoptosis of the cells in vitro. Clonogenic growth of mutant KRAS-bearing cells was suppressed by KRAS-siRNA-anti-EGFR antibody complexes. In xenograft mouse models, anti-EGFR antibody-KRAS-siRNA complexes significantly slowed tumor growth in anti-EGFR-resistant cells.
The coupling of siRNA against KRAS to anti-EGFR antibodies provides a novel therapy approach for KRAS-mutated EGFR-positive cancer cells in vitro and in vivo. These findings provide an innovative approach for cancer-specific siRNA application and for enhanced therapeutic potential of monoclonal antibody therapy and personalized treatment of cancer entities.
Epigenomic changes are an important feature of malignant tumors. How tumor aggressiveness is affected by DNA methylation of specific loci is largely unexplored. In genome‐wide DNA methylation ...analyses, we identified the KCa3.1 channel gene (KCNN4) promoter to be hypomethylated in an aggressive non–small‐cell lung carcinoma (NSCLC) cell line and in patient samples. Accordingly, KCa3.1 expression was increased in more aggressive NSCLC cells. Both findings were strong predictors for poor prognosis in lung adenocarcinoma. Increased KCa3.1 expression was associated with aggressive features of NSCLC cells. Proliferation and migration of pro‐metastatic NSCLC cells depended on KCa3.1 activity. Mechanistically, elevated KCa3.1 expression hyperpolarized the membrane potential, thereby augmenting the driving force for Ca2+ influx. KCa3.1 blockade strongly reduced the growth of xenografted NSCLC cells in mice as measured by positron emission tomography–computed tomography. Thus, loss of DNA methylation of the KCNN4 promoter and increased KCa3.1 channel expression and function are mechanistically linked to poor survival of NSCLC patients.
What's New?
Another possible avenue for thwarting metastasis has been found: the potassium channel KCa3.1. Aggressiveness in lung cancer (NSCLC) is linked to methylation of the potassium channel promoter gene. When the promoter is under‐methylated, more of the potassium channel protein is produced, and the cancer cells proliferate and spread more aggressively. The authors also showed that blocking KCa3.1 stops the cells from dividing and spreading, both in vitro and in mice, suggesting that KCa3.1 could make a promising therapeutic target.
Purpose
Multimodal molecular imaging allows a direct coregistration of different images, facilitating analysis of the spatial relation of various imaging parameters. Here, we further explored the ...relation of proliferation, as measured by
18
FFLT PET, and water diffusion, as an indicator of cellular density and cell death, as measured by diffusion-weighted (DW) MRI, in preclinical tumor models. We expected these parameters to be negatively related, as highly proliferative tissue should have a higher density of cells, hampering free water diffusion.
Procedures
Nude mice subcutaneously inoculated with either lung cancer cells (
n
= 11 A549 tumors,
n
= 20 H1975 tumors) or colorectal cancer cells (
n
= 13 Colo205 tumors) were imaged with
18
FFLT PET and DW-MRI using a multimodal bed, which was transferred from one instrument to the other within the same imaging session. Fiducial markers allowed coregistration of the images. An automatic post-processing was developed in MATLAB handling the spatial registration of DW-MRI (measured as apparent diffusion coefficient, ADC) and
18
FFLT image data and subsequent voxel-wise analysis of regions of interest (ROIs) in the tumor.
Results
Analyses were conducted on a total of 76 datasets, comprising a median of 2890 data points (ranging from 81 to 13,597). Scatterplots showing
18
FFLT vs. ADC values displayed various grades of relations (Pearson correlation coefficient (PCC) varied from − 0.58 to 0.49, median: -0.07). When relating PCC to tumor volume (median: 46 mm
3
, range: 3 mm
3
to 584 mm
3
), lung tumors tended to have a more pronounced negative spatial relation of
18
FFLT and ADC with increasing tumor size. However, due to the low number of large tumors (> ~ 200 mm
3
), this conclusion has to be treated with caution.
Conclusions
A spatial relation of water diffusion, as measured by DW-MRI, and cellular proliferation, as measured by
18
FFLT PET, cannot be detected in the experimental datasets investigated in this study.
Cadherins mediate cohesive contacts between isotypic cells by homophilic interaction and prevent contact between heterotypic cells. Breast cancer cells neighboring endothelial cells (ECs) atypically ...express vascular endothelial (VE)-cadherin. To understand this EC-induced VE-cadherin expression in breast cancer cells, MCF7 and MDA-MB-231 cells expressing different endogenous cadherins were co-cultured with ECs and analyzed for VE-cadherin at the transcriptional level and by confocal microscopy, flow cytometry, and immunoblotting. After losing their endogenous cadherins and neo-expression of VE-cadherin, these cells integrated into an EC monolayer without compromising the barrier function instantly. However, they induced the death of nearby ECs. EC-derived extracellular vesicles (EVs) contained soluble and membrane-anchored forms of VE-cadherin. Only the latter was re-utilized by the cancer cells. In a reporter gene assay, EC-adjacent cancer cells also showed a juxtacrine but no paracrine activation of the endogenous VE-cadherin gene. This cadherin switch enabled intimate contact between cancer and endothelial cells in a chicken chorioallantoic membrane tumor model showing vasculogenic mimicry (VM). This EV-mediated, EC-induced cadherin switch in breast cancer cells and the neo-expression of VE-cadherin mechanistically explain the mutual communication in the tumor microenvironment. Hence, it may be a target to tackle VM, which is often found in breast cancers of poor prognosis.
Addition of temozolomide (TMZ) to radiation therapy is the standard treatment for patients with glioblastoma (GBM). However, there is uncertainty regarding the effectiveness of TMZ. Considering the ...rapid evolution of the disease, methods to assess TMZ efficacy early during treatment would be of great benefit. Our aim was to monitor early effects of TMZ in a mouse model of GBM using positron emission tomography (PET) with 3'-deoxy-3'-(18)Ffluorothymidine ((18)FFLT).
Human glioma cells sensitive to TMZ (Gli36dEGFR-1) were treated with sub-lethal doses of TMZ to obtain cells with lower sensitivity to TMZ (Gli36dEGFR-2), as measured by growth and clonogenic assays. Gli36dEGFR-1 and Gli36dEGFR-2 cells were subcutaneously (s.c.) or intracranially (i.c.) xenografted into nude mice. Mice were treated for 7 days with daily injection of 25 or 50 mg/kg TMZ. Treatment efficacy was measured using (18)FFLT-PET before treatment and after 2 days. Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) were used to determine tumor volumes before treatment and after 7 days.
A significant difference was observed between TMZ and DMSO treated tumors in terms of variations of (18)FFLT T/B ratio as soon as day 2 in the i.c. as well as in the s.c. mouse model. Variations of (18)FFLT T/B uptake ratio between days 0 and 2 correlated with variations of tumor size between days 0 and 7 (s.c. model: n(tumor) = 17 in n(mice) = 11, P<0.01; i.c. model: n(tumor/mice) = 9, P<0.01).
Our results indicate that (18)FFLT-PET may be useful for an early evaluation of the response of GBM to TMZ chemotherapy in patients with glioma.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this work, we investigate the potential of highly sulfated synthetic glycomimetics to act as inhibitors of viral binding/infection. Our results indicate that both long-chain glycopolymers and ...short-chain glycooligomers are capable of preventing viral infection. Notably, glycopolymers efficiently inhibit Human Papillomavirus (HPV16) infection in vitro and maintain their antiviral activity in vivo, while the glycooligomers exert their inhibitory function post attachment of viruses to cells. Moreover, when we tested the potential for broader activity against several other human pathogenic viruses, we observed broad-spectrum antiviral activity of these compounds beyond our initial assumptions. While the compounds tested displayed a range of antiviral efficacies, viruses with rather diverse glycan specificities such as Herpes Simplex Virus (HSV), Influenza A Virus (IAV), and Merkel Cell Polyomavirus (MCPyV) could be targeted. This opens new opportunities to develop broadly active glycomimetic inhibitors of viral entry and infection.
For specific imaging of bacterial infections we aimed at targeting the exclusive bacterial iron transport system
via
siderophore-based radiotracers.
De novo
synthesis and radiolabeling yielded the ...salmochelin-based PET radiotracer
68
GaGa-
RMA693
, which showed a favourable biodistribution and a bacteria-specific uptake in an animal model of
Escherichia coli
infection.
A
68
Ga-labelled salmochelin-related PET-radiotracer was developed based on a Trojan horse strategy by targeting the siderophore mediated iron-transport for specific imaging of bacterial infection.
Correction
Unfortunately, the original version of Figs. 4, 5 and 6b in the article 1 contained errors in the
n
numbers as indicated on the columns. Please note that column heights and error bars in ...the original figures and data in the ESM tables are correct and statistical tests are valid. These corrections do not affect any results or conclusions in this article.
Chimeric antigen receptor (CAR) engineering of T cells allows one to specifically target tumor cells via cell surface antigens. A candidate target in Ewing sarcoma is the ganglioside G
, but ...heterogeneic expression limits its value. Here we report that pharmacological inhibition of Enhancer of Zeste Homolog 2 (EZH2) at doses reducing H3K27 trimethylation, but not cell viability, selectively and reversibly induces G
surface expression in Ewing sarcoma cells. EZH2 in Ewing sarcoma cells directly binds to the promoter regions of genes encoding for two key enzymes of G
biosynthesis, and EZH2 inhibition enhances expression of these genes. G
surface expression in Ewing sarcoma cells is not associated with distinct in vitro proliferation, colony formation, chemosensitivity, or in vivo tumorigenicity. Moreover, disruption of G
synthesis by gene editing does not affect its in vitro behavior. EZH2 inhibitor treatment sensitizes Ewing sarcoma cells to effective cytolysis by G
-specific CAR gene-modified T cells. In conclusion, we report a clinically applicable pharmacological approach for enhancing efficacy of adoptively transferred G
-redirected T cells against Ewing sarcoma, by enabling recognition of tumor cells with low or negative target expression.
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