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Ziel dieser Arbeit war die Untersuchung der psychischen Befindlichkeit und anderer gesundheitsbezogenen Konditionen der Frauen und Männer mit familiären Mamma- und Ovarialkarzinomrisiko sowie die Klärung hinsichtlich der Bewältigung und Auswirkung genetischer Risikoinformation. Es wurden Risikowahrnehmung, Informationsstand, Inanspruchnahme der Beratungsangebote sowie der Früherkennungsmaßnahmen, Einstellung gegenüber genetischer Brustkrebsdiagnostik und familiärer/sozialer Kommunikation untersucht. Die vollständig ausgefüllten Fragebögen von Ratsuchenden und Betroffenen, die an der Beratung und Befragung im Zentrum für „Familiären Brust-/Eierstockkrebs“ teilgenommen haben, wurden von uns ausgewertet. Für die beratenden Institutionen ist das Wissen der vielfältigen psychischen und sozialen Folgen bei den Testsuchenden und deren Familien sehr wichtig. Nur so kann das Betreuungskonzept und das Beratungsangebot verbessert werden.
A promising new approach for the treatment of human cancer is the use of oncolytic viruses, which exhibit tumor tropism. One of the top candidates in this area is the oncolytic vaccinia virus (VACV), which has already shown promising results in animal studies and in clinical trials. However, due to discrepancies in both innate and adaptive immunity between mice and men the evaluation of the vaccinia virus’ interactions with the host immune system in mice are not fully conclusive of what is actually happening in human cancer patients after systemic administration of vaccinia virus. Also, ethical and legal concerns as well as risk of potential toxicity limit research involving human patients. Therefore, a good in vivo model for testing interactions between vaccinia virus and human immune cells, avoiding the numerous limitations and risks associated with human studies, could be a humanized mouse model.
LIVP-1.1.1, GLV-2b372, GLV-1h68, GLV-1h375, GLV-1h376 and GLV-1h377 VACVs were provided by Genelux Corporation. GLV-2b372 was constructed by inserting TurboFP635 expression cassette into the J2R locus of the parental LIVP-1.1.1. GLV-1h375, -1h376 and -1h377 VACVs encode the human CTLA4-blocking single-chain antibody (CTLA4 scAb). Performed replication and cytotoxicity assays demonstrated that all six viruses were able to infect, replicate in and kill human tumor cells in virus-dose- and time-dependent fashion. CTLA4 scAb and β-glucuronidase (GusA) expression as well as viral titers in GLV-1h376-infected cells were analyzed by ELISA, β-glucuronidase assay and standard plaque assay, respectively, and compared. An excellent correlation with correlation coefficients R2>0.9806 were observed. GLV-1h376-encoded CTLA4 scAb was successfully purified from supernatants of infected CV-1 cells and demonstrated in vitro affinity to its human CTLA4 target and lack of cross-reactivity to mouse CTLA4. CTLA4 scAb functionality was confirmed in Jurkat cells. LIVP-1.1.1, GLV-2b372, GLV-1h68 and GLV-1h376 were next studied in non-tumorous and/or tumor-bearing humanized mice.
It was demonstrated that injection of human CD34+ stem cells into the liver of preconditioned newborn NSG mice let to a successful systemic reconstitution with human immune cells. CD19+ B cells, CD4 and CD8 single positive CD3+ T cell, NKp46+CD56- and NKp46+CD56+ NK cells as well as CD33+ myeloid cells developed. At early time points after engraftment, majority of the human hematopoietic cells detected in the mouse blood were CD19+ B cells and only a small portion were CD3+ T cells. With time a significant change in CD19+/CD3+ ratio was reported with a decrease of B cells and an increase of T cells. Implantation of A549 cells under the skin of those humanized NSG mice resulted in a progressive tumor growth, described for the first time in this thesis. Successful colonization of subcutaneous A549 tumors with VACVs was visualized and demonstrated by detection of virus-mediated TurboFP635 and GFP expression as well as by standard plaque assay and immunohistochemistry. The human CD45+ cell population in tumors was represented mainly by NKp46+CD56bright NK cells and a large portion of activated CD4+ and cytotoxic CD8+ T cells. However, no significant differences were observed between control and LIVP-1.1.1-infected tumors, suggesting that the recruitment of NK and activated T cells were more tumor tissue specific than virus-dependent. Unfortunately, virus-mediated CTLA4 scAb expression in the GLV-1h376-infected tumors was also not able to significantly increase activation of T cells compared to control and GLV-1h68-treated mice. Importantly, ELISA, β-glucuronidase and standard plaque assays showed an excellent correlation with correlation coefficients R2>0.9454 between CTLA4 scAb, GusA concentrations and viral titers in tumor samples from those GLV-1h376 treated mice.
T cells isolated from the spleens of such control or GLV-1h68- or -1h376-treated A549 tumor-bearing mice were functional and could successfully be activated with human T cells activation beads. However, although no significant difference was observed between the three mouse groups, a slightly higher percentage of the GLV-1h376-treated mice-derived T cells were expressing CD25 and producing IFN-ɣ after ex vivo activation, probably due to the CTLA4 blockade by the virus-encoded CTLA4 scAb in the GLV-1h376-treated mice. Also, slightly higher levels of IL-2 were detected in the culture supernatant of those splenocytes compared to control samples. In contrast, T cells from all three mouse groups were not able be activated by A549 tumor cells ex vivo.
Our model has the specific advantage that tumors develop under the skin of the humanized mice, which allows accurate monitoring of the tumor growth and evaluation of the oncolytic virotherapy. Therefore it is important to choose the right approaches for its further improvement.
Background: Combination of oncolytic vaccinia virus therapy with conventional chemotherapy has shown promise for tumor therapy. However, side effects of chemotherapy including thrombocytopenia, still remain problematic. Methods: Here, we describe a novel approach to optimize combination therapy of oncolytic virus and chemotherapy utilizing virus-encoding hyper-IL-6, GLV-1h90, to reduce chemotherapy-associated side effects. Results: We showed that the hyper-IL-6 cytokine was successfully produced by GLV-1h90 and was functional both in cell culture as well as in tumor-bearing animals, in which the cytokine-producing vaccinia virus strain was well tolerated. When combined with the chemotherapeutic mitomycin C, the anti-tumor effect of the oncolytic virotherapy was significantly enhanced. Moreover, hyper-IL-6 expression greatly reduced the time interval during which the mice suffered from chemotherapy-induced thrombocytopenia. Conclusion: Therefore, future clinical application would benefit from careful investigation of additional cytokine treatment to reduce chemotherapy-induced side effects.
The intracellular pathogen Chlamydia is the causative agent of millions of new infections per year transmitting diseases like trachoma, pelvic inflammatory disease or lymphogranuloma venereum. Undetected or recurrent infections caused by chlamydial persistence are especially likely to provoke severe pathologies. To ensure host cell survival and to facilitate long term infections Chlamydia induces anti-apoptotic pathways, mainly at the level of mitochondria, and restrains activity of pro-apoptotic proteins. Additionally, the pathogen seizes host energy, carbohydrates, amino acids, lipids and nucleotides to facilitate propagation of bacterial progeny and growth of the chlamydial inclusion.
At the beginning of this study, Chlamydia-mediated apoptosis resistance to DNA damage induced by the topoisomerase inhibitor etoposide was investigated. In the course of this, a central cellular protein crucial for etoposide-mediated apoptosis, the tumour suppressor p53, was found to be downregulated during Chlamydia infections. Subsequently, different chlamydial strains and serovars were examined and p53 downregulation was ascertained to be a general feature during Chlamydia infections of human cells. Reduction of p53 protein level was established to be mediated by the PI3K-Akt signalling pathway, activation of the E3-ubiquitin ligase HDM2 and final degradation by the proteasome. Additionally, an intriguing discrepancy between infections of human and mouse cells was detected. Both activation of the PI3K-Akt pathway as well as degradation of p53 could not be observed in Chlamydia-infected mouse cells. Recently, production of reactive oxygen species (ROS) and damage to host cell DNA was reported to occur during Chlamydia infection. Thus, degradation of p53 strongly contributes to the anti-apoptotic environment crucial for chlamydial infection.
To verify the importance of p53 degradation for chlamydial growth and development, p53 was stabilised and activated by the HDM2-inhibiting drug nutlin-3 and the DNA damage-inducing compound etoposide. Unexpectedly, chlamydial development was severely impaired and inclusion formation was defective. Completion of the chlamydial developmental cycle was prevented resulting in loss of infectivity. Intriguingly, removal of the p53 activating stimulus allowed formation of the bacterial inclusion and recovery of infectivity. A similar observation of growth recovery was made in infected cell lines deficient for p53.
As bacterial growth and inclusion formation was strongly delayed in the presence of activated p53, p53-mediated inhibitory regulation of cellular metabolism was suspected to contribute to chlamydial growth defects. To verify this, glycolytic and pentose phosphate pathways were analysed revealing the importance of a functioning PPP for chlamydial growth. In addition, increased expression of glucose-6-phosphate dehydrogenase rescued chlamydial growth inhibition induced by activated p53. The rescuing effect was even more pronounced in p53-deficient cells treated with etoposide or nutlin-3 revealing additional p53-independent aspects of Chlamydia inhibition. Removal of ROS by anti-oxidant compounds was not sufficient to rescue chlamydial infectivity. Apparently, not only the anti-oxidant capacities of the PPP but also provision of precursors for nucleotide synthesis as well as contribution to DNA repair are important for successful chlamydial growth.
Modulation of host cell signalling was previously reported for a number of pathogens. As formation of ROS and DNA damage are likely to occur during infections of intracellular bacteria, several strategies to manipulate the host and to inhibit induction of apoptosis were invented. Downregulation of the tumour suppressor p53 is a crucial point during development of Chlamydia, ensuring both host cell survival and metabolic support conducive to chlamydial growth.
The incidence of malignant melanoma continues to increase each year with poor prognosis for survival in many relapse cases. To reverse this trend, whole body response measures are needed to discover collaborative paths to primary and secondary malignancy. Several species of fish provide excellent melanoma models because fish and human melanocytes both appear in the epidermis, and fish and human pigment cell tumors share conserved gene expression signatures. For the first time, we have examined the whole body transcriptome response to invasive melanoma as a prelude to using transcriptome profiling to screen for drugs in a medaka (Oryzias latipes) model. We generated RNA-seq data from whole body RNA isolates for controls and melanoma fish. After testing for differential expression, 396 genes had significantly different expression (adjusted p-value <0.02) in the whole body transcriptome between melanoma and control fish; 379 of these genes were matched to human orthologs with 233 having annotated human gene symbols and 14 matched genes that contain putative deleterious variants in human melanoma at varying levels of recurrence. A detailed canonical pathway evaluation for significant enrichment showed the top scoring pathway to be antigen presentation but also included the expected melanocyte development and pigmentation signaling pathway. Results revealed a profound down-regulation of genes involved in the immune response, especially the innate immune system. We hypothesize that the developing melanoma actively suppresses the immune system responses of the body in reacting to the invasive malignancy, and that this mal-adaptive response contributes to disease progression, a result that suggests our whole-body transcriptomic approach merits further use. In these findings, we also observed novel genes not yet identified in human melanoma expression studies and uncovered known and new candidate drug targets for further testing in this malignant melanoma medaka model.
In recent years, zebrafish, and to a lesser extent medaka, have become widely used small animal models for human diseases. These organisms have convincingly demonstrated the usefulness of fish for improving our understanding of the molecular and cellular mechanisms leading to pathological conditions, and for the development of new diagnostic and therapeutic tools. Despite the usefulness of zebrafish and medaka in the investigation of a wide spectrum of traits, there is evidence to suggest that other fish species could be better suited for more targeted questions. With the emergence of new, improved sequencing technologies that enable genomic resources to be generated with increasing efficiency and speed, the potential of non-mainstream fish species as disease models can now be explored. A key feature of these fish species is that the pathological condition that they model is often related to specific evolutionary adaptations. By exploring these adaptations, new disease-causing and disease-modifier genes might be identified; thus, diverse fish species could be exploited to better understand the complexity of disease processes. In addition, non-mainstream fish models could allow us to study the impact of environmental factors, as well as genetic variation, on complex disease phenotypes. This Review will discuss the opportunities that such fish models offer for current and future biomedical research.
The Ras/RAF/MEK/ERK cascade is a central cellular signal transduction pathway involved in cell proliferation, differentiation, and survival where RAF kinases are pivotal kinases implicated in cancer. The development of specific irreversible kinase inhibitors is a rewarding but difficult aim. CI-1033 was developed to irreversibly inhibit erbB receptor tyrosine kinases by reacting to the Cys113 residue (p38alpha MAP kinase numbering) of the kinase domain. In this study we tried a similar approach to target the RAF oncoproteins which posses a similar cysteine at position 108 in the hinge region between the small n-lobe and the large c-lobe of the kinase domain. A novel synthetic approach including a lyophilization step allowed us the synthesis of a diphenyl urea compound with an epoxide moiety (compound 1). Compound 1 possessed inhibitory activity in vitro. However our time kinetics experiments and mass spectroscopic studies clearly indicate that compound 1 does not react covalently with the cysteine residue in the hinge region. Moreover, in cell culture experiments, a strong activation of the RAF signaling pathway was observed, an effect which is known from several other RAF kinase inhibitors and is here reported for the first time for a diphenyl urea compound, to which the clinically used unspecific kinase inhibitor BAY 43-9006 (Sorafinib, Nexavar) belongs. Although activation was apparently independent on B- and C-RAF hetero-oligomerization in vitro, in vivo experiments support such a mechanism as the activation did not occur in starved knockout cells lacking either B-RAF or C-RAF. Furthermore, we developed a mathematical model of the Ras/RAF/MEK/ERK cascade demonstrating how stimuli induce different signal patterns and thereby different cellular responses, depending on cell type and the ratio between B-RAF and C-RAF. Based on biochemical data for activation and dephosphorylation, we set up differential equations for a dynamical model of the Ras/RAF/MEK/ERK cascade. We find a different signaling pattern and response result for B-RAF (strong activation, sustained signal) and C-RAF (steep activation, transient signal). We further support the significance of such differential modulatory signaling by showing different RAF isoform expression in various cell lines and experimental testing of the predicted kinase activities in B-RAF, C-RAF as well as mutated versions. Additionally the effect of the tumor suppressor DiRas3 (also known as Noey2 or ARHI) on RAF signaling was studied. I could show that DiRas3 down-regulates the mitogenic pathway by inhibition of MEK, a basis for a refined model of the Ras/RAF/MEK/ERK cascade.
Squamous cell carcinomas are therapeutically challenging tumor entities. Low response rates to radiotherapy and chemotherapy are commonly observed in squamous patients and, accordingly, the mortality rate is relatively high compared to other tumor entities. Recently, targeting USP28 has been emerged as a potential alternative to improve the therapeutic response and clinical outcomes of squamous patients. USP28 is a catalytically active deubiquitinase that governs a plethora of biological processes, including cellular proliferation, DNA damage repair, apoptosis and oncogenesis. In squamous cell carcinoma, USP28 is strongly expressed and stabilizes the essential squamous transcription factor ΔNp63, together with important oncogenic factors, such as NOTCH1, c-MYC and c-JUN. It is presumed that USP28 is an oncoprotein; however, recent data suggest that the deubiquitinase also has an antineoplastic effect regulating important tumor suppressor proteins, such as p53 and CHK2. In this review, we discuss: (1) The emerging role of USP28 in cancer. (2) The complexity and mutational landscape of squamous tumors. (3) The genetic alterations and cellular pathways that determine the function of USP28 in squamous cancer. (4) The development and current state of novel USP28 inhibitors.
Several oncolytic viruses (OVs) including various human and canine adenoviruses, canine distemper virus, herpes-simplex virus, reovirus, and members of the poxvirus family, such as vaccinia virus and myxoma virus, have been successfully tested for canine cancer therapy in preclinical and clinical settings. The success of the cancer virotherapy is dependent on the ability of oncolytic viruses to overcome the attacks of the host immune system, to preferentially infect and lyse cancer cells, and to initiate tumor-specific immunity. To date, several different strategies have been developed to overcome the antiviral host defense barriers. In our study, we used canine adipose-derived mesenchymal stem cells (cAdMSCs) as a “Trojan horse” for the delivery of oncolytic vaccinia virus Copenhagen strain to achieve maximum oncolysis against canine soft tissue sarcoma (CSTS) tumors. A single systemic administration of vaccinia virus-loaded cAdMSCs was found to be safe and led to the significant reduction and substantial inhibition of tumor growth in a CSTS xenograft mouse model. This is the first example that vaccinia virus-loaded cAdMSCs could serve as a therapeutic agent against CSTS tumors.
Deregulated expression of MYC is a driver of colorectal carcinogenesis, necessitating novel strategies to inhibit MYC function. The ubiquitin ligase HUWE1 (HECTH9, ARF-BP1, MULE) associates with both MYC and the MYC-associated protein MIZ1. We show here that HUWE1 is required for growth of colorectal cancer cells in culture and in orthotopic xenograft models. Using high-throughput screening, we identify small molecule inhibitors of HUWE1, which inhibit MYC-dependent transactivation in colorectal cancer cells, but not in stem and normal colon epithelial cells. Inhibition of HUWE1 stabilizes MIZ1. MIZ1 globally accumulates on MYC target genes and contributes to repression of MYC-activated target genes upon HUWE1 inhibition. Our data show that transcriptional activation by MYC in colon cancer cells requires the continuous degradation of MIZ1 and identify a novel principle that allows for inhibition of MYC function in tumor cells.
Oncolytic viruses refer to those that are able to eliminate malignancies by direct targeting and lysis of cancer cells, leaving non-cancerous tissues unharmed. Several oncolytic viruses including adenovirus strains, canine distemper virus and vaccinia virus strains have been used for canine cancer therapy in preclinical studies. However, in contrast to human studies, clinical trials with oncolytic viruses for canine cancer patients have not been reported. An ‘ideal’ virus has yet to be identified. This review is focused on the prospective use of oncolytic viruses in the treatment of canine tumors - a knowledge that will undoubtedly contribute to the development of oncolytic viral agents for canine cancer therapy in the future.
The nuclear paraspeckle assembly transcript 1 (NEAT1) locus encodes two long non-coding (lnc)RNA isoforms that are upregulated in many tumours and dynamically expressed in response to stress. NEAT1 transcripts form ribonucleoprotein complexes with numerous RNA-binding proteins (RBPs) to assemble paraspeckles and modulate the localisation and activity of gene regulatory enzymes as well as a subset of messenger (m)RNA transcripts. The investigation of the dynamic composition of NEAT1-associated proteins and mRNAs is critical to understand the function of NEAT1. Interestingly, a growing number of biochemical and genetic tools to assess NEAT1 interactomes has been reported. Here, we discuss the Hybridisation Proximity (HyPro) labeling technique in the context of NEAT1. HyPro labeling is a recently developed method to detect spatially ordered interactions of RNA-containing nuclear compartments in cultured human cells. After introducing NEAT1 and paraspeckles, we describe the advantages of the HyPro technology in the context of other methods to study RNA interactomes, and review the key findings in mapping NEAT1-associated RNA transcripts and protein binding partners. We further discuss the limitations and potential improvements of HyPro labeling, and conclude by delineating its applicability in paraspeckles-related cancer research.
In vitro evidence for senescent multinucleated melanocytes as a source for tumor-initiating cells
(2015)
Oncogenic signaling in melanocytes results in oncogene-induced senescence (OIS), a stable cell-cycle arrest frequently characterized by a bi-or multinuclear phenotype that is considered as a barrier to cancer progression. However, the long-sustained conviction that senescence is a truly irreversible process has recently been challenged. Still, it is not known whether cells driven into OIS can progress to cancer and thereby pose a potential threat. Here, we show that prolonged expression of the melanoma oncogene N-RAS\(^{61K}\) in pigment cells overcomes OIS by triggering the emergence of tumor-initiating mononucleated stem-like cells from senescent cells. This progeny is dedifferentiated, highly proliferative, anoikis-resistant and induces fast growing, metastatic tumors. Our data describe that differentiated cells, which are driven into senescence by an oncogene, use this senescence state as trigger for tumor transformation, giving rise to highly aggressive tumor-initiating cells. These observations provide the first experimental in vitro evidence for the evasion of OIS on the cellular level and ensuing transformation.
Fish of the genus Xiphophorus belong to the oldest animal models in cancer research. The oncogene responsible for the generation of spontaneous aggressive melanoma encodes for a mutated epidermal growth factor receptor (Egfr) and is called xmrk for Xiphophorus melanoma receptor kinase. Xmrk constitutive activation mechanisms and subsequent signaling pathways have already been investigated and charaterized but it is still unknown if Egfr ligands may also play a role in Xmrk-driven melanoma formation. To investigate the potential role of Egfr ligands in Xmrk-driven melanoma, I firstly analyzed the evolution of teleost and tetrapod Egfr/Egfr ligand systems. I especially focused on the analysis on the medaka fish, a closely related species to Xiphophorus, for which the whole genome has been sequenced. I could identify all seven Egfr ligands in medaka and could show that the two teleost-specific Egfr copies of medaka display dissimilar expression patterns in adult tissues together with differential expression of Egfr ligand subsets, arguing for subfunctionalization of receptor functions in this fish. Our phylogenetic and synteny analyses supported the hypothesis that only one gene in the chordate ancestor gave rise to the diversity of Egfr ligands found in vertebrate genomes today. I also could show that the Egfr extracellular subdomains implicated in ligand binding are not evolutionary conserved between tetrapods and teleosts, making the use of heterologous ligands in experiments with fish cells debatable. Despite its well understood and straight-forward process, Xmrk-driven melanomagenesis in Xiphophorus is problematic to further investigate in vivo. Our laboratory recently established a new melanoma animal model by generating transgenic mitf::xmrk medaka fishes, a Xiphophorus closely related species offering many more advantages. These fishes express xmrk under the control of the pigment-cell specific Mitf promoter. During my PhD thesis, I participated in the molecular analysis of the stably transgenic medaka and could show that the Xmrk-induced signaling pathways are similar when comparing Xiphophorus with transgenic mitf::xmrk medaka. These data together with additional RNA expression, protein, and histology analyses showed that Xmrk expression under the control of a pigment cell-specific promoter is sufficient to induce melanoma in the transgenic medaka, which develop very stereotyped tumors, including uveal and extracutaneous melanoma, with early onset during larval stages. To further investigate the potential role of Egfr ligands in Xmrk-driven melanoma, I made use of two model systems. One of them was the above mentioned mitf::xmrk medaka, the other was an in-vitro cell culture system, where the EGF-inducible Xmrk chimera HERmrk is stably expressed in murine melanocytes. Here I could show that HERmrk activation strongly induced expression of amphiregulin (Areg) and heparin-binding EGF-like growth factor (Hbegf) in melanocytes. This regulation was dependent on the MAPK and SRC signaling pathways. Moreover, upregulation of Adam10 and Adam17, the two major sheddases of Egfr ligands, was observed. I also could demonstrate the functionality of the growth factors by invitro analyses. Using the mitf::xmrk medaka model I could also show the upregulation of a subset of ligand genes, namely egf, areg, betacellulin (btc) and epigen (epgn) as well as upregulation of medaka egfrb in tumors from fish with metastatic melanoma. All these results converge to support an Xmrk-induced autocrine Egfr ligand loop. Interestingly, my in-vitro experiments with conditioned supernatant from medaka Egf- and Hbegf-producing cells revealed that not only Xiphophorus Egfrb, but also the pre-activated Xmrk could be further stimulated by the ligands. Altogether, I could show with in-vitro and in-vivo experiments that Xmrk is capable of inducing a functional autocrine Egfr ligand loop. These data confirm the importance of autocrine loops in receptor tyrosine kinase (RTK)-dependent cancer development and show the possibility for a constitutively active RTK to strengthen its oncogenic signaling by ligand binding.
Inefficient vascularisation of solid tumours leads to the formation of oxygen and nutrient gradients. In order to mimic this specific feature of the tumour microenvironment, a multicellular tumour spheroid (SPH) culture system was used. These experiments were implemented in p53 isogenic colon cancer cell lines (HCT116 p53 +/+ and HCT116 p53-/-) since Tp53 has important regulatory functions in tumour metabolism. First, the characteristics of the cells cultured as monolayers and as spheroids were investigated by using RNA sequencing and metabolomics to compare gene expression and metabolic features of cells grown in different conditions. This analysis showed that certain features of gene expression found in tumours are also present in spheroids but not in monolayer cultures, including reduced proliferation and induction of hypoxia related genes. Moreover, comparison between the different genotypes revealed that the expression of genes involved in cholesterol homeostasis is induced in p53 deficient cells compared to p53 wild type cells and this difference was only detected in spheroids and tumour samples but not in monolayer cultures. In addition, it was established that loss of p53 leads to the induction of enzymes of the mevalonate pathway via activation of the transcription factor SREBP2, resulting in a metabolic rewiring that supports the generation of ubiquinone (coenzyme Q10). An adequate supply of ubiquinone was essential to support mitochondrial electron transport and pyrimidine biosynthesis in p53 deficient cancer cells under conditions of metabolic stress. Moreover, inhibition of the mevalonate pathway using statins selectively induced oxidative stress and apoptosis in p53 deficient colon cancer cells exposed to oxygen and nutrient deprivation. This was caused by ubiquinone being required for electron transfer by dihydroorotate dehydrogenase, an essential enzyme of the pyrimidine nucleotide biosynthesis pathway. Supplementation with exogenous nucleosides relieved the demand for electron transfer and restored viability of p53 deficient cancer cells under metabolic stress. Moreover, the mevalonate pathway was also essential for the synthesis of ubiquinone for nucleotide biosynthesis to support growth of intestinal tumour organoids. Together, these findings highlight the importance of the mevalonate pathway in cancer cells and provide molecular evidence for an enhanced sensitivity towards the inhibition of mitochondrial electron transfer in tumour-like metabolic environments.
Simple Summary
Despite significant strides in multimodal therapy, cancers still rank within the first three causes of death especially in industrial nations. A lack of individualized approaches and accurate preclinical models are amongst the major barriers that limit the development of novel therapeutic options and drugs. Recently, the 3D culture system of organoids was developed which stably retains the genetic and phenotypic characteristics of the original tissue, healthy as well as diseased. In this review, we summarize current data and evidence on the relevance and reliability of such organoid culture systems in cancer research, focusing on their role in drug investigations (in a personalized manner).
Abstract
Organoids are a new 3D ex vivo culture system that have been applied in various fields of biomedical research. First isolated from the murine small intestine, they have since been established from a wide range of organs and tissues, both in healthy and diseased states. Organoids genetically, functionally and phenotypically retain the characteristics of their tissue of origin even after multiple passages, making them a valuable tool in studying various physiologic and pathophysiologic processes. The finding that organoids can also be established from tumor tissue or can be engineered to recapitulate tumor tissue has dramatically increased their use in cancer research. In this review, we discuss the potential of organoids to close the gap between preclinical in vitro and in vivo models as well as clinical trials in cancer research focusing on drug investigation and development.
Oncolytic virotherapy represents a promising approach to revolutionize cancer therapy. Several preclinical and clinical trials display the safety of oncolytic viruses as wells as their efficiency against solid tumors. The development of complementary diagnosis and monitoring concepts as well as the optimization of anti-tumor activity are key points of current virotherapy research. Within the framework of this thesis, the diagnostic and therapeutic prospects of beta-glucuronidase expressed by the oncolytic vaccinia virus strain GLV-1h68 were evaluated. In this regard, a beta-glucuronidase-based, therapy-accompanying biomarker test was established which is currently under clinical validation. By using fluorescent substrates, the activity of virally expressed beta-glucuronidase could be detected and quantified. Thereby conclusions about the replication kinetics of oncolytic viruses in animal models and virus-induced cancer cell lysis could be drawn. These findings finally led to the elaboration and establishment of a versatile biomarker assay which allows statements regarding the replication of oncolytic viruses in mice based on serum samples. Besides the analysis of retrospective conditions, this test is able to serve as therapy-accompanying monitoring tool for virotherapy approaches with beta-glucuronidase-expressing viruses. The newly developed assay also served as complement to routinely used plaque assays as well as reference for virally expressed anti-angiogenic antibodies in additional preclinical studies. Further validation of this biomarker test is currently taking place in the context of clinical trials with GL-ONC1 (clinical grade GLV-1h68) and has already shown promising preliminary results. It was furthermore demonstrated that fluorogenic substrates in combination with beta-glucuronidase expressed by oncolytic viruses facilitated the optical detection of solid tumors in preclinical models. In addition to diagnostic purposes, virus-encoded enzymes could also be combined with prodrugs resulting in an improved therapeutic outcome of oncolytic virotherapy. In further studies, the visualization of virus-induced immune reactions as well as the establishment of innovative concepts to improve the therapeutic outcome of oncolytic virotherapy could be accomplished. In conclusion, the results of this thesis provide crucial findings about the influence of virally expressed beta-glucuronidase on various diagnostic concepts in the context of oncolytic virotherapy. In addition, innovative monitoring and therapeutic strategies could be established. Our preclinical findings have important clinical influence, particularly by the development of a therapy-associated biomarker assay which is currently used in different clinical trials.
Overexpressed c-Myc sensitizes cells to TH1579, a mitotic arrest and oxidative DNA damage inducer
(2022)
Previously, we reported that MTH1 inhibitors TH588 and TH1579 selectively induce oxidative damage and kill Ras-expressing or -transforming cancer cells, as compared to non-transforming immortalized or primary cells. While this explains the impressive anti-cancer properties of the compounds, the molecular mechanism remains elusive. Several oncogenes induce replication stress, resulting in under replicated DNA and replication continuing into mitosis, where TH588 and TH1579 treatment causes toxicity and incorporation of oxidative damage. Hence, we hypothesized that oncogene-induced replication stress explains the cancer selectivity. To test this, we overexpressed c-Myc in human epithelial kidney cells (HA1EB), resulting in increased proliferation, polyploidy and replication stress. TH588 and TH1579 selectively kill c-Myc overexpressing clones, enforcing the cancer cell selective killing of these compounds. Moreover, the toxicity of TH588 and TH1579 in c-Myc overexpressing cells is rescued by transcription, proteasome or CDK1 inhibitors, but not by nucleoside supplementation. We conclude that the molecular toxicological mechanisms of how TH588 and TH1579 kill c-Myc overexpressing cells have several components and involve MTH1-independent proteasomal degradation of c-Myc itself, c-Myc-driven transcription and CDK activation.
In a variety of established tumour cell lines, but also in primary mammary epithelial cells metalloprotease-dependent transactivation of the EGFR, and EGFR characteristic downstream signalling events were observed in response to stimulation with physiological concentrations of GPCR agonists such as the mitogens LPA and S1P as well as therapeutically relevant concentrations of cannabinoids. Moreover, this study reveals ADAM17 and HB-EGF as the main effectors of this mechanism in most of the cancer cell lines investigated. However, depending on the cellular context and GPCR agonist, various different members of the ADAM family are selectively recruited for specific ectodomain shedding of proAR and/or proHB-EGF and subsequent EGFR activation. Furthermore, biological responses induced by LPA or S1P such as migration in breast cancer and HNSCC cells, depend on ADAM17 and proHB-EGF/proAR function, respectively, suggesting that highly abundant GPCR ligands may play a role in tumour development and progression. Moreover, EGFR signal transactivation could be identified as the mechanistic link between cannabinoid receptors and the activation of mitogen activated protein kinases (MAPK) ERK1/2 as well as pro-survival Akt/PKB signalling. Depending on the cellular context, cannabinoid-induced signal cross-communication was mediated by shedding of proAmphiregulin and/or proHB-EGF by ADAM17. Most importantly, our data show that concentrations of THC comparable to those detected in the serum of patients after THC administration accelerate proliferation of cancer cells instead of apoptosis and thereby may contribute to cancer progression in patients.
Recent progress in nanotechnology has attracted interest to a biomedical application of the carbon nanoparticle C60 fullerene (C60) due to its unique structure and versatile biological activity. In the current study the dual functionality of C60 as a photosensitizer and a drug nanocarrier was exploited to improve the efficiency of chemotherapeutic drugs towards human leukemic cells.
Pristine C60 demonstrated time-dependent accumulation with predominant mitochondrial localization in leukemic cells. C60’s effects on leukemic cells irradiated with high power single chip LEDs of different wavelengths were assessed to find out the most effective photoexcitation conditions. A C60-based noncovalent nanosized system as a carrier for an optimized drug delivery to the cells was evaluated in accordance to its physicochemical properties and toxic effects. Finally, nanomolar amounts of C60-drug nanocomplexes in 1:1 and 2:1 molar ratios were explored to improve the efficiency of cell treatment, complementing it with photodynamic approach.
A proposed treatment strategy was developed for C60 nanocomplexes with the common chemotherapeutic drug Doxorubicin, whose intracellular accumulation and localization, cytotoxicity and mechanism of action were investigated. The developed strategy was revealed to be transferable to an alternative potent anticancer drug – the herbal alkaloid Berberine.
Hereafter, a strong synergy of treatments arising from the combination of C60-mediated drug delivery and C60 photoexcitation was revealed. Presented data indicate that a combination of chemo- and photodynamic treatments with C60-drug nanoformulations could provide a promising synergetic approach for cancer treatment.