Targeting DNA repair to enhance the efficacy of sorafenib in hepatocellular carcinoma.

The multityrosine kinase inhibitor sorafenib remains an important systemic treatment option for hepatocellular carcinoma (HCC). Signaling pathways, which are targeted by sorafenib, are involved in checkpoint and DNA repair response, RAD51 being a candidate protein. Here, we aim to evaluate the effect of the human RAD51 inhibitor B02 in combination with sorafenib in human HCC cells. Impact of RAD51 expression on HCC patient survival was evaluated by an in silico approach using Human Protein Atlas dataset. Cell viability of HUH7, AKH12, AKH13, and 3P was assessed by neutral red assay. To measure the cytotoxicity, we quantified loss of membrane integrity by lactate dehydrogenase release. We also employed colony formation assay and hanging drop method to assess clonogenic and invasive ability of HCC cell lines upon sorafenib and B02 treatment. Cell cycle distribution and characterization of apoptosis was evaluated by flow cytometry. In silico approach revealed that HCC patients with higher expression of RAD51 messenger RNA had a significantly shorter overall survival. The RAD51 inhibitor B02 alone and in combination with sorafenib significantly reduced viability, colony formation ability, and invasion capacity of HCC cells. Cell cycle analysis revealed that the combination of both agents reduces the proportion of cells in the G2/M phase while leading to an accumulating in the subG1 phase. The RAD51 inhibitor B02 seems to be a promising agent for HCC treatment and enhances the antitumor effects of sorafenib in vitro.

Targeting fibroblast growth factor receptors to combat aggressive ependymoma.

Ependymomas (EPN) are central nervous system tumors comprising both aggressive and more benign molecular subtypes. However, therapy of the high-risk subtypes posterior fossa group A (PF-A) and supratentorial RELA-fusion positive (ST-RELA) is limited to gross total resection and radiotherapy, as effective systemic treatment concepts are still lacking. We have recently described fibroblast growth factor receptors 1 and 3 (FGFR1/FGFR3) as oncogenic drivers of EPN. However, the underlying molecular mechanisms and their potential as therapeutic targets have not yet been investigated in detail. Making use of transcriptomic data across 467 EPN tissues, we found that FGFR1 and FGFR3 were both widely expressed across all molecular groups. FGFR3 mRNA levels were enriched in ST-RELA showing the highest expression among EPN as well as other brain tumors. We further identified high expression levels of fibroblast growth factor 1 and 2 (FGF1, FGF2) across all EPN subtypes while FGF9 was elevated in ST-EPN. Interrogation of our EPN single-cell RNA-sequencing data revealed that FGFR3 was further enriched in cycling and progenitor-like cell populations. Corroboratively, we found FGFR3 to be predominantly expressed in radial glia cells in both mouse embryonal and human brain datasets. Moreover, we detected alternative splicing of the FGFR1/3-IIIc variant, which is known to enhance ligand affinity and FGFR signaling. Dominant-negative interruption of FGFR1/3 activation in PF-A and ST-RELA cell models demonstrated inhibition of key oncogenic pathways leading to reduced cell growth and stem cell characteristics. To explore the feasibility of therapeutically targeting FGFR, we tested a panel of FGFR inhibitors in 12 patient-derived EPN cell models revealing sensitivity in the low-micromolar to nano-molar range. Finally, we gain the first clinical evidence for the activity of the FGFR inhibitor nintedanib in the treatment of a patient with recurrent ST-RELA. Together, these preclinical and clinical data suggest FGFR inhibition as a novel and feasible approach to combat aggressive EPN.

Synthesis and Cytotoxic Activity of Chiral Sulfonamides Based on the 2-Azabicycloalkane Skeleton.

A series of chiral sulfonamides containing the 2-azabicycloalkane scaffold were prepared from aza-Diels-Alder cycloadducts through their conversion to amines based on 2-azanorbornane or the bridged azepane skeleton, followed by the reaction with sulfonyl chlorides. The cytotoxic activity of the obtained bicyclic derivatives was evaluated using human hepatocellular carcinoma (HCC), medulloblastoma (MB), and glioblastoma (GBM) cell lines. Chosen compounds were shown to notably reduce cell viability as compared to nonmalignant cells.

MALDI-MS Protein Profiling of Chemoresistance in Extracellular Vesicles of Cancer Cells.

Cancer cells communicate with the whole organism via extracellular vesicles (EVs), which propagate molecular information in support of the malignant phenotype. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was employed for protein profiling of EVs derived from CCL-228 as the primary colon tumor, the lymph node metastasis CCL-227, and subclones resistant to 5, 25, and 125 µM 5-fluorouracil (FU). EVs were harvested from cell culture supernatant by ultracentrifugation to serve as a model for circulating cancer cell-derived biomarker carriers from body fluids (i.e., liquid biopsy). Protein mass spectra were recorded using standard MALDI matrixes (e.g., CHCA, sinapinic acid) in the range m/ z 2000-20000 on different MALDI-TOF-MS systems and subjected to multivariate data analysis . By using hierarchical clustering, PCA and PLS-DA, discriminatory protein patterns of the EVs from the different cell populations were obtained. Peaks in the range  m/ z 2000-6500 and m/ z 5500-15500 were found to be unique to EVs and the cells, respectively. This clearly demonstrates the differential expression of proteins in EVs as the result of an increasing chemoresistance of their parent cells. The sensitivity of the MALDI-MS based assay was in the low µg/mL (≈1.2-5 × 1010 particles/mL) range. Consequently, our MALDI-MS protein profiling approach shows the potential to serve as novel tool for minimally invasive cancer diagnostics and chemotherapy monitoring in the future, e.g., for early detection of therapy resistance without biopsy.

Colon cancer cell-derived 12(S)-HETE induces the retraction of cancer-associated fibroblast via MLC2, RHO/ROCK and Ca2+ signalling.

Retraction of mesenchymal stromal cells supports the invasion of colorectal cancer cells (CRC) into the adjacent compartment. CRC-secreted 12(S)-HETE enhances the retraction of cancer-associated fibroblasts (CAFs) and therefore, 12(S)-HETE may enforce invasivity of CRC. Understanding the mechanisms of metastatic CRC is crucial for successful intervention. Therefore, we studied pro-invasive contributions of stromal cells in physiologically relevant three-dimensional in vitro assays consisting of CRC spheroids, CAFs, extracellular matrix and endothelial cells, as well as in reductionist models. In order to elucidate how CAFs support CRC invasion, tumour spheroid-induced CAF retraction and free intracellular Ca2+ levels were measured and pharmacological- or siRNA-based inhibition of selected signalling cascades was performed. CRC spheroids caused the retraction of CAFs, generating entry gates in the adjacent surrogate stroma. The responsible trigger factor 12(S)-HETE provoked a signal, which was transduced by PLC, IP3, free intracellular Ca2+, Ca2+-calmodulin-kinase-II, RHO/ROCK and MYLK which led to the activation of myosin light chain 2, and subsequent CAF mobility. RHO activity was observed downstream as well as upstream of Ca2+ release. Thus, Ca2+ signalling served as central signal amplifier. Treatment with the FDA-approved drugs carbamazepine, cinnarizine, nifedipine and bepridil HCl, which reportedly interfere with cellular calcium availability, inhibited CAF-retraction. The elucidation of signalling pathways and identification of approved inhibitory drugs warrant development of intervention strategies targeting tumour-stroma interaction.

Loss of miR-200 family in 5-fluorouracil resistant colon cancer drives lymphendothelial invasiveness in vitro.

Invasive colorectal cancer is associated with poor prognosis requiring treatment with systemic chemotherapies usually including 5-fluorouracil. A consequence of prolonged treatment is the acquisition of resistance eventually resulting in the recurrence of highly metastatic cancer cells. To address the relationship between drug resistance and increased lymphatic metastatic potential, we used a 3D co-culture model of colon tumour cell spheroids of parent CCL227 cells and subclones with gradually increasing resistance against 5-fluorouracil. From each investigated cell line, homogeneous tumour spheroids were generated in the presence of methylcellulose yielding emboli of ∼700 µm diameter. When invasive, tumour spheroids disrupt the continuous lymphendothelial cell (LEC) layer and generate a 'circular chemorepellent-induced defect' (CCID), reminiscent of the entry gates through which tumour emboli intravasate lymphatic vasculature. Here we provide evidence that increasingly chemoresistant colon cancer spheroids were strongly associated with enhanced intravasative properties. In naïve CCL227 spheroids, miR-200 family members were released into exosomes thereby repressing the epithelial to mesenchymal transition-regulating transcription factors ZEB1 and SLUG in LEC. As a consequence of attenuated plasticity and migration of LEC, CCID formation was impaired. Loss of exosomal transferred miR-200c in resistant colon cells rendered LEC more susceptible to pro-migratory signals that were generated and directly transmitted by colon cancer spheroids. This observation indicates a common molecular axis in colon cancer and LEC where miR-200 family members act as regulators of ZEB proteins. The data support the notion that horizontal miR-200 signalling prevents the permeation of cells into adjacent epithelia and contributes to organ integrity.

Overexpression of minichromosome maintenance protein 10 in medulloblastoma and its clinical implications.

BACKGROUND: Overexpression of minichromosome maintenance (MCM) proteins 2, 3, and 7 is associated with migration and invasion in medulloblastoma (MB). However, expression profiling of all prereplication complex (pre-RC) has not been addressed in MBs. PROCEDURE: We performed mRNA expression profiling of a large set of pre-RC elements in cell lines and tumor tissues of MB. RNAi technology was employed for functional studies in MB cell lines. RESULTS: Our data showed that most of the pre-RC components are significantly overexpressed in MB. Among all pre-RC mRNAs, MCM10 showed the highest level of expression (∼500- to 1,000-fold) in MB cell lines and tissues compared to the levels detected in cerebellum. In addition, RNAi silencing of MCM10 caused reduced cell proliferation and cell viability in MB cells. CONCLUSIONS: Taken together, our study reveals that the pre-RC is dysregulated in MB. In addition, MCM10, a member of this complex, is significantly overexpressed in MB and is required for tumor cell proliferation.

Distribution of Bevacizumab into the Cerebrospinal Fluid of Children and Adolescents with Recurrent Brain Tumors.

BACKGROUND: To date, evidence has been lacking regarding bevacizumab pharmacokinetics in the cerebrospinal fluid (CSF). OBJECTIVE: This study assessed the penetration of bevacizumab, as part of a metronomic antiangiogenic treatment regimen, into the CSF of children, adolescents, and young adults with recurrent brain tumors. PATIENTS AND METHODS: Serum and CSF concentrations, malignant cells, and vascular endothelial growth factor A (VEGF-A) were analyzed in 12 patients (5-27 years) following 10 mg/kg bevacizumab intravenous biweekly administration (EudraCT number 2009-013024-23). A population pharmacokinetic model including body weight, albumin, and tumor type as influential factors was extended to quantify the CSF penetration of bevacizumab. RESULTS: Apart from in serum (minimum concentration/maximum concentration [Cmin/Cmax] 77.0-305/267-612 mg/L, median 144/417 mg/L), bevacizumab could be quantified in the CSF (0.01-2.26 mg/L, median 0.35 mg/L). The CSF/serum ratio was 0.16 and highly variable between patients. Malignant cells could be detected in CSF before initiation of treatment in five of 12 patients; after treatment, the CSF was cleared in all patients. VEGF-A was detected in three patients before treatment (mean ± SD: 20 ± 11 pg/mL), and was still measurable in one of these patients despite treatment (16 pg/mL). CONCLUSIONS: This pharmacokinetic pilot study indicated penetration of bevacizumab into the CSF in a population of children, adolescents, and young adults with recurrent brain tumors.

Proof-of-Concept for Liquid Biopsy Disease Monitoring of MYC-Amplified Group 3 Medulloblastoma by Droplet Digital PCR.

BACKGROUND: Liquid biopsy diagnostic methods are an emerging complementary tool to imaging and pathology techniques across various cancer types. However, there is still no established method for the detection of molecular alterations and disease monitoring in MB, the most common malignant CNS tumor in the pediatric population. In the presented study, we investigated droplet digital polymerase chain reaction (ddPCR) as a highly sensitive method for the detection of MYC amplification in bodily fluids of group 3 MB patients. METHODS: We identified a cohort of five MYC-amplified MBs by methylation array and FISH. Predesigned and wet-lab validated probes for ddPCR were used to establish the detection method and were validated in two MYC-amplified MB cell lines as well as tumor tissue of the MYC-amplified cohort. Finally, a total of 49 longitudinal CSF samples were analyzed at multiple timepoints during the course of the disease. RESULTS: Detection of MYC amplification by ddPCR in CSF showed a sensitivity and specificity of 90% and 100%, respectively. We observed a steep increase in amplification rate (AR) at disease progression in 3/5 cases. ddPCR was proven to be more sensitive than cytology for the detection of residual disease. In contrast to CSF, MYC amplification was not detectable by ddPCR in blood samples. CONCLUSIONS: ddPCR proves to be a sensitive and specific method for the detection of MYC amplification in the CSF of MB patients. These results warrant implementation of liquid biopsy in future prospective clinical trials to validate the potential for improved diagnosis, disease staging and monitoring.

Cytotoxic Activity of Piperazin-2-One-Based Structures: Cyclic Imines, Lactams, Aminophosphonates, and Their Derivatives.

N-Heterocycles are considered as desirable scaffolds for the development of novel lead compounds for anticancer drug research. Among them, phosphorus-containing amino-derivatives play a crucial role. A series of imines and products of their further reactions with P-nucleophiles were obtained starting from vicinal bisamines. Reaction of ethylenediamine and α-carbonyl esters yielded in novel unexpected products, which structures were confirmed by crystallographic measurements. The cytotoxic activity evaluation was done on a variety of cell lines including HUH7, AKH12, DAOY, UW228-2, D283, D425, and U251. Human umbilical vein endothelial cells (HUVECs) were used as control. Two of the tested compounds, bearing TADDOL-derived, and trifluoromethyl substituents showed a significant effect on cell viability, though comparable to nonmalignant cells.

High impact of miRNA-4521 on FOXM1 expression in medulloblastoma.

Medulloblastoma, an embryonal tumor of the cerebellum/fourth ventricle, is one of the most frequent malignant brain tumors in children. Although genetic variants are increasingly used in treatment stratification, survival of high-risk patients, characterized by leptomeningeal dissemination, TP53 mutation or MYC amplification, is still poor. FOXM1, a proliferation-specific oncogenic transcription factor, is deregulated in various solid tumors, including medulloblastoma, and triggers cellular proliferation, migration and genomic instability. In tissue samples obtained from medulloblastoma patients, the significant upregulation of FOXM1 was associated with a loss of its putative regulating microRNA, miR-4521. To understand the underlying mechanism, we investigated the effect of miR-4521 on the expression of the transcription factor FOXM1 in medulloblastoma cell lines. Transfection of this microRNA reduced proliferation and invasion of several medulloblastoma cell lines and induced programmed cell death through activation of caspase 3/7. Further, downstream targets of FOXM1 such as PLK1 and cyclin B1 were significantly reduced thus affecting the cell cycle progression in medulloblastoma cell lines. In conclusion, a restoration of miRNA-4521 may selectively suppress the pathophysiological effect of aberrant FOXM1 expression and serve as a targeted approach for medulloblastoma therapy.

Intravasation of SW620 colon cancer cell spheroids through the blood endothelial barrier is inhibited by clinical drugs and flavonoids in vitro.

Mechanisms how colorectal cancer (CRC) cells penetrate blood micro-vessel endothelia and metastasise is poorly understood. To study blood endothelial cell (BEC) barrier breaching by CRC emboli, an in vitro assay measuring BEC-free areas underneath SW620 cell spheroids, so called "circular chemorepellent induced defects" (CCIDs, appearing in consequence of endothelial retraction), was adapted and supported by Western blotting, EIA-, EROD- and luciferase reporter assays. Inhibition of ALOX12 or NF-κB in SW620 cells or BECs, respectively, caused attenuation of CCIDs. The FDA approved drugs vinpocetine [inhibiting ALOX12-dependent 12(S)-HETE synthesis], ketotifen [inhibiting NF-κB], carbamazepine and fenofibrate [inhibiting 12(S)-HETE and NF-κB] significantly attenuated CCID formation at low µM concentrations. In the 5-FU-resistant SW620-R/BEC model guanfacine, nifedipine and proadifen inhibited CCIDs stronger than in the naïve SW620/BEC model. This indicated that in SW620-R cells formerly silent (yet unidentified) genes became expressed and targetable by these drugs in course of resistance acquisition. Fenofibrate, and the flavonoids hispidulin and apigenin, which are present in medicinal plants, spices, herbs and fruits, attenuated CCID formation in both, naïve- and resistant models. As FDA-approved drugs and food-flavonoids inhibited established and acquired intravasative pathways and attenuated BEC barrier-breaching in vitro, this warrants testing of these compounds in CRC models in vivo.

Lymphatic exosomes promote dendritic cell migration along guidance cues.

Lymphatic endothelial cells (LECs) release extracellular chemokines to guide the migration of dendritic cells. In this study, we report that LECs also release basolateral exosome-rich endothelial vesicles (EEVs) that are secreted in greater numbers in the presence of inflammatory cytokines and accumulate in the perivascular stroma of small lymphatic vessels in human chronic inflammatory diseases. Proteomic analyses of EEV fractions identified >1,700 cargo proteins and revealed a dominant motility-promoting protein signature. In vitro and ex vivo EEV fractions augmented cellular protrusion formation in a CX3CL1/fractalkine-dependent fashion and enhanced the directional migratory response of human dendritic cells along guidance cues. We conclude that perilymphatic LEC exosomes enhance exploratory behavior and thus promote directional migration of CX3CR1-expressing cells in complex tissue environments.

The microRNA-200 family: still much to discover.

In the last decade, microRNAs (miRs or miRNAs) became of great interest in cancer research due to their multifunctional and active regulation in a variety of vital cellular processes. In this review, we discuss the miR-200 family, which is composed of five members (miR-141, miR-200a/200b/200c and miR-429). Although being among the best investigated miRNAs in the field, there are still many open issues. Here, we describe the potential role of miR-200 as prognostic and/or predictive biomarker, its influence on motility and cell migration as well as its role in epithelial to mesenchymal transition (EMT) and metastasis formation in different tumour types. Recent studies also demonstrated the influence of miR-200 on drug resistance and described a correlation between miR-200 expression levels and overall survival of patients. Despite intense research in this field, the full role of the miR-200 family in cancer progression and metastasis is not completely understood and seems to differ between different tumour types and different cellular backgrounds. To elucidate these differences further, a finer characterisation of the role of the individual miRNA-200 family members is currently under investigation.

Colorectal cancer cell-derived microRNA200 modulates the resistance of adjacent blood endothelial barriers in vitro.

Since cancer cells, when grown as spheroids, display drug sensitivity and radiation resistance patterns such as seen in vivo we recently established a three­dimensional (3D) in vitro model recapitulating colorectal cancer (CRC)-triggered lymphatic endothelial cell (LEC)­barrier breaching to study mechanisms of intra­/extravasation. CRC metastasizes not only through lymphatics but also through blood vessels and here we extend the 3D model to the interaction of blood endothelial cells (BECs) with naïve and 5­fluorouracil (5­FU)­resistant CRC CCL227 cells. The 3D model enabled quantifying effects of tumour­derived microRNA200 (miR200) miR200a, miR200b, miR200c, miR141 and miR429 regarding the induction of so-called 'circular chemorepellent­induced defects' (CCIDs) within the BEC­barrier, which resemble gates for tumour transmigration. For this, miR200 precursors were individually transfected and furthermore, the modulation of ZEB family expression was analysed by western blotting. miR200c, miR141 and miR429, which are contained in exosomes from naïve CCL227 cells, downregulated the expression of ZEB2, SNAI and TWIST in BECs. The exosomes of 5­FU­resistant CCL227­RH cells, which are devoid of miR200, accelerated CCID formation in BEC monolayers as compared to exosomes from naïve CCL227 cells. This confirmed the reported role of ZEB2 and SNAI in CRC metastasis and highlighted the active contribution of the stroma in the metastatic process. CCL227 spheroids affected the integrity of BEC and LEC barriers alike, which was in agreement with the observation that CRC metastasizes via blood stream (into the liver) as well as via lymphatics (into lymph nodes and lungs). This further validated the CRC/LEC and CRC/BEC in vitro model to study mechanisms of CRC spreading through vascular systems. Treatment of CCL227­RH cells with the HDAC inhibitors mocetinostat and sulforaphane reduced CCID formation to the level triggered by naïve CCL227 spheroids, however, without significantly influencing miR200 expression in CCL227-RH cells.

NF-κB contributes to MMP1 expression in breast cancer spheroids causing paracrine PAR1 activation and disintegrations in the lymph endothelial barrier in vitro.

RELA, RELB, CREL, NFKB1 and NFKB2, and the upstream regulators NEMO and NIK were knocked-down in lymph endothelial cells (LECs) and in MDA-MB231 breast cancer spheroids to study the contribution of NF-κB in vascular barrier breaching. Suppression of RELA, NFKB1 and NEMO inhibited "circular chemo-repellent induced defects" (CCIDs), which form when cancer cells cross the lymphatic vasculature, by ~20-30%. Suppression of RELB, NFKB2 and NIK inhibited CCIDs by only ~10-15%. In MDA-MB231 cells RELA and NFKB1 constituted MMP1 expression, which caused the activation of PAR1 in adjacent LECs. The knock-down of MMP1 in MDA-MB231 spheroids and pharmacological inhibition of PAR1 in LECs inhibited CCID formation by ~30%. Intracellular Ca(2+) release in LECs, which was induced by recombinant MMP1, was suppressed by the PAR1 inhibitor SCH79797, thereby confirming a functional intercellular axis: RELA/NFKB1 - MMP1 (MDA-MB231) - PAR1 (LEC). Recombinant MMP1 induced PAR1-dependent phosphorylation of MLC2 and FAK in LECs, which is indicative for their activity and for directional cell migration such as observed during CCID formation. The combined knock-down of the NF-κB pathways in LECs and MDA-MB231 spheroids inhibited CCIDs significantly stronger than knock-down in either cell type alone. Also the knock-down of ICAM-1 in LECs (a NF-κB endpoint with relevance for CCID formation) and knock-down of MMP1 in MDA-MB231 augmented CCID inhibition. This evidences that in both cell types NF-κB significantly and independently contributes to tumour-mediated breaching of the lymphatic barrier. Hence, inflamed tumour tissue and/or vasculature pose an additional threat to cancer progression.