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Prof. Dr. Melanie Kappelmann-Fenzl

Lehrgebiet: Angewandte Biowissenschaften

Humangenetik
Molekularbiologie
Hochdurchsatzsequenzierung (Omics)
Biomedizinische Datenanalyse

Professorin

Studiengangsleitung Life Science Informatics, Studienfachberatung Life Science Informatics, Studiengangskoordination Life Science Informatics

K 008

0991/3615-473

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Publikationen

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Zeitschriftenartikel

Ö. Ertekin
M. Monavari
R. Krüger
M. Fuentes-Chandía
B. Parma
G. Letort
P. Tripal
A. Boccaccini
A.-K. Bosserhoff
P. Ceppi
Melanie Kappelmann-Fenzl
A. Leal-Egaña

3D hydrogel-based microcapsules as an in vitro model to study tumorigenicity, cell migration and drug resistance

In: Acta Biomaterialia

13.02.2022 (2022)

DOI: 10.1016/j.actbio.2022.02.010

Abstract anzeigen

In this work, we analyzed the reliability of alginate-gelatin microcapsules as artificial tumor model. These tumor-like scaffolds are characterized by their composition and stiffness (∼25 kPa), and their capability to restrict -but not hinder- cell migration, proliferation and release from confinement. Hydrogel-based microcapsules were initially utilized to detect differences in mechano-sensitivity between MCF7 and MDA-MB-231 breast cancer cells, and the endothelial cell line EA.hy926. Additionally, we used RNA-seq and transcriptomic methods to determine how the culture strategy (i.e. 2D v/s 3D) may pre-set the expression of genes involved in multidrug resistance, being then validated by performing cytotoxicological tests and assays of cell morphology. Our results show that both breast cancer cells can generate elongated multicellular spheroids inside the microcapsules, prior being released (mimicking intravasation stages), a behavior which was not observed in endothelial cells. Further, we demonstrate that cells isolated from 3D scaffolds show resistance to cisplatin, a process which seems to be strongly influenced by mechanical stress, instead of hypoxia. We finally discuss the role played by aneuploidy in malignancy and resistance to anticancer drugs, based on the increased number of polynucleated cells found within these microcapsules. Overall, our outcomes demonstrate that alginate-gelatin microcapsules represent a simple, yet very accurate tumor-like model, enabling us to mimic the most relevant malignant hints described in vivo, suggesting that confinement and mechanical stress need to be considered when studying pathogenicity and drug resistance of cancer cells in vitro. STATEMENT OF SIGNIFICANCE: In this work, we analyzed the reliability of alginate-gelatin microcapsules as an artificial tumor model. These scaffolds are characterized by their composition, elastic properties, and their ability to restrict cell migration, proliferation, and release from confinement. Our results demonstrate four novel outcomes: (i) studying cell migration and proliferation in 3D enabled discrimination between malignant and non-pathogenic cells, (ii) studying the cell morphology of cancer aggregates entrapped in alginate-gelatin microcapsules enabled determination of malignancy degree in vitro, (iii) determination that confinement and mechanical stress, instead of hypoxia, are required to generate clones resistant to anticancer drugs (i.e. cisplatin), and (iv) evidence that resistance to anticancer drugs could be due to the presence of polynucleated cells localized inside polymer-based artificial tumors.

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Zeitschriftenartikel

L. Lämmerhirt
Melanie Kappelmann-Fenzl
Stefan Fischer
M. Pommer
T. Zimmermann
V. Kluge
A. Matthies
S. Kuphal
A.-K. Bosserhoff

Knockdown of Lamin B1 and the Corresponding Lamin B Receptor Leads to Changes in Heterochromatin State and Senescence Induction in Malignant Melanoma

In: Cells vol. 11 pg. 2154.

(2022)

DOI: 10.3390/cells11142154

Abstract anzeigen

Modifications in nuclear structures of cells are implicated in several diseases including cancer. They result in changes in nuclear activity, structural dynamics and cell signalling. However, the role of the nuclear lamina and related proteins in malignant melanoma is still unknown. Its molecular characterisation might lead to a deeper understanding and the development of new therapy approaches. In this study, we analysed the functional effects of dysregulated nuclear lamin B1 (LMNB1) and its nuclear receptor (LBR). According to their cellular localisation and function, we revealed that these genes are crucially involved in nuclear processes like chromatin organisation. RNA sequencing and differential gene expression analysis after knockdown of LMNB1 and LBR revealed their implication in important cellular processes driving ER stress leading to senescence and changes in chromatin state, which were also experimentally validated. We determined that melanoma cells need both molecules independently to prevent senescence. Hence, downregulation of both molecules in a BRAFV600E melanocytic senescence model as well as in etoposide-treated melanoma cells indicates both as potential senescence markers in melanoma. Our findings suggest that LMNB1 and LBR influence senescence and affect nuclear processes like chromatin condensation and thus are functionally relevant for melanoma progression.

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Zeitschriftenartikel

M. Heppt
A. Wessely
E. Hornig
C. Kammerbauer
S. Graf
R. Besch
L. French
A. Matthies
S. Kuphal
Melanie Kappelmann-Fenzl
A.-K. Bosserhoff
C. Berking

HDAC2 Is Involved in the Regulation of BRN3A in Melanocytes and Melanoma

In: International Journal of Molecular Sciences vol. 23 pg. 849.

(2022)

DOI: 10.3390/ijms23020849

Abstract anzeigen

The neural crest transcription factor BRN3A is essential for the proliferation and survival of melanoma cells. It is frequently expressed in melanoma but not in normal melanocytes or benign nevi. The mechanisms underlying the aberrant expression of BRN3A are unknown. Here, we investigated the epigenetic regulation of BRN3A in melanocytes and melanoma cell lines treated with DNA methyltransferase (DNMT), histone acetyltransferase (HAT), and histone deacetylase (HDAC) inhibitors. DNMT and HAT inhibition did not significantly alter BRN3A expression levels, whereas panHDAC inhibition by trichostatin A led to increased expression. Treatment with the isoform-specific HDAC inhibitor mocetinostat, but not with PCI-34051, also increased BRN3A expression levels, suggesting that class I HDACs HDAC1, HDAC2, and HDAC3, and class IV HDAC11, were involved in the regulation of BRN3A expression. Transient silencing of HDACs 1, 2, 3, and 11 by siRNAs revealed that, specifically, HDAC2 inhibition was able to increase BRN3A expression. ChIP-Seq analysis uncovered that HDAC2 inhibition specifically increased H3K27ac levels at a distal enhancer region of the BRN3A gene. Altogether, our data suggest that HDAC2 is a key epigenetic regulator of BRN3A in melanocytes and melanoma cells. These results highlight the importance of epigenetic mechanisms in regulating melanoma oncogenes.

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Zeitschriftenartikel

M. Schott
Melanie Kappelmann-Fenzl
S. Fischer
M. Fernandez-Barrena
A. Pineda-Lucena
M. Ávila
S. Kuphal
A.-K. Bosserhoff

Impact of CYLD on chromatin structure and histone methylation in malignant melanoma

In: International Journal of Molecular Medicine vol. 49

16.03.2022 (2022)

DOI: 10.3892/ijmm.2022.5122

Abstract anzeigen

The tumor suppressive role of CYLD lysine 63 deubiquitinase (CYLD) is known in melanoma. To the best of our knowledge, however, the precise mechanism underlying the tumor suppressive function of CYLD has yet to be clarified. In the present study, a novel melanoma mouse model was generated, which revealed accelerated tumor growth in Cyld‑knockout (Cyld‑/‑) compared with Cyld‑wild‑type (Cyld+/+) mice. To determine the underlying molecular mechanism, mutation analysis of primary tumor‑derived cell lines from Cyld+/+ and Cyld‑/‑ mice was performed using RNA sequencing data. Variant calling revealed no common mutations in Cyld‑/‑ compared with Cyld+/+ cells. Thus, the epigenetic processes influencing development and progression of melanoma were investigated. Initial analysis of expression pattern of known hypermethylated genes in melanoma (suppressor of cytokine signalling, methylthioadenosine phosphorylase, cadherin 1) in the presence or absence of 5'‑Aza‑deoxyctidine treatment revealed that CYLD does not play a key role in DNA methylation. Chromatin accessibility and histone H3 modification assay uncovered a role of CYLD in the formation of chromatin structure. Subsequent inhibitor experiments confirmed the effect of CYLD on H3K9me2 level associated with heterochromatin. Furthermore, enhanced H3K9 dimethylation in Cyld‑/‑ melanoma cells was associated with upregulation of euchromatic histone lysine methyltransferase 2 (EHMT2). Moreover, the specific inhibitor of EHMT2, CM272, resulted in decreased proliferation and relaxation of compact chromatin in Cyld‑deficient melanoma cells. These results reveal a novel role of CYLD in histone methylation and chromatin packaging.

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Vortrag

Melanie Kappelmann-Fenzl

Bioinformatische Analyse molekularer Mechanismen der AP-1 Transkriptionsaktivität und deren funktioneller Bedeutung im malignen Melanom

In: Deggendorfer Wissenschaftliches Kolloquium

Technische Hochschule Deggendorf Technische Hochschule Deggendorf

23.06.2022 (2022)

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Beitrag (Sammelband oder Tagungsband)

A.-K. Bosserhoff
Melanie Kappelmann-Fenzl

Next Generation Sequencing (NGS): What Can Be Sequenced?

In: Next Generation Sequencing and Data Analysis. null (Learning Materials in Biosciences) pg. 1-15.

Cham, Switzerland

(2021)

DOI: 10.1007/978-3-030-62490-3_1

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Beitrag (Sammelband oder Tagungsband)

Melanie Kappelmann-Fenzl

Alignment

In: Next Generation Sequencing and Data Analysis. null (Learning Materials in Biosciences) pg. 111-122.

Cham, Switzerland

(2021)

DOI: 10.1007/978-3-030-62490-3_9

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Zeitschriftenartikel

Melanie Kappelmann-Fenzl
S. Schmidt
Stefan Fischer
R. Schmid
L. Lämmerhirt
L. Fischer
S. Schrüfer
I. Thievessen
D. Schubert
A. Matthies
Rainer Detsch
Aldo B.
A. Arkudas
A. Kengelbach-Weigand
A.-K. Bosserhoff

Molecular Changes Induced in Melanoma by Cell Culturing in 3D Alginate Hydrogels

In: Cancers vol. 13 pg. 4111.

(2021)

DOI: 10.3390/cancers13164111

Abstract anzeigen

Alginate hydrogels have been used as a biomaterial for 3D culturing for several years. Here, gene expression patterns in melanoma cells cultivated in 3D alginate are compared to 2D cultures. It is well-known that 2D cell culture is not resembling the complex in vivo situation well. However, the use of very intricate 3D models does not allow performing high-throughput screening and analysis is highly complex. 3D cell culture strategies in hydrogels will better mimic the in vivo situation while they maintain feasibility for large-scale analysis. As alginate is an easy-to-use material and due to its favorable properties, it is commonly applied as a bioink component in the growing field of cell encapsulation and biofabrication. Yet, only a little information about the transcriptome in 3D cultures in hydrogels like alginate is available. In this study, changes in the transcriptome based on RNA-Seq data by cultivating melanoma cells in 3D alginate are analyzed and reveal marked changes compared to cells cultured on usual 2D tissue culture plastic. Deregulated genes represent valuable cues to signaling pathways and molecules affected by the culture method. Using this as a model system for tumor cell plasticity and heterogeneity, EGR1 is determined to play an important role in melanoma progression.

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Beitrag (Sammelband oder Tagungsband)

M. Eisele
Melanie Kappelmann-Fenzl

NGS Technologies

In: Next Generation Sequencing and Data Analysis. null (Learning Materials in Biosciences) pg. 47-58.

Cham, Switzerland

(2021)

DOI: 10.1007/978-3-030-62490-3_4

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Beitrag (Sammelband oder Tagungsband)

Melanie Kappelmann-Fenzl

Computer Setup

In: Next Generation Sequencing and Data Analysis. null (Learning Materials in Biosciences) pg. 59-69.

Cham, Switzerland

(2021)

DOI: 10.1007/978-3-030-62490-3_5

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Beitrag (Sammelband oder Tagungsband)

Melanie Kappelmann-Fenzl

Library Construction for NGS

In: Next Generation Sequencing and Data Analysis. null (Learning Materials in Biosciences) pg. 39-45.

Cham, Switzerland

(2021)

DOI: 10.1007/978-3-030-62490-3_3

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Beitrag (Sammelband oder Tagungsband)

Melanie Kappelmann-Fenzl

Reference Genome

In: Next Generation Sequencing and Data Analysis. null (Learning Materials in Biosciences) pg. 105-109.

Cham, Switzerland

(2021)

DOI: 10.1007/978-3-030-62490-3_8

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Zeitschriftenartikel

N. Rachinger
Stefan Fischer
I. Böhme
L. Linck-Paulus
S. Kuphal
Melanie Kappelmann-Fenzl
A.-K. Bosserhoff

Loss of Gene Information: Discrepancies between RNA Sequencing, cDNA Microarray, and qRT-PCR

In: International Journal of Molecular Sciences vol. 22 pg. 9349.

(2021)

DOI: 10.3390/ijms22179349

Abstract anzeigen

Molecular analyses of normal and diseased cells give insight into changes in gene expression and help in understanding the background of pathophysiological processes. Years after cDNA microarrays were established in research, RNA sequencing (RNA-seq) became a key method of quantitatively measuring the transcriptome. In this study, we compared the detection of genes by each of the transcriptome analysis methods: cDNA array, quantitative RT-PCR, and RNA-seq. As expected, we found differences in the gene expression profiles of the aforementioned techniques. Here, we present selected genes that exemplarily demonstrate the observed differences and calculations to reveal that a strong RNA secondary structure, as well as sample preparation, can affect RNA-seq. In summary, this study addresses an important issue with a strong impact on gene expression analysis in general. Therefore, we suggest that these findings need to be considered when dealing with data from transcriptome analyses.

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Beitrag (Sammelband oder Tagungsband)

M. Heppt
A. Wessely
E. Hornig
C. Kammerbauer
S. Graf
R. Besch
L. French
S. Kuphal
Melanie Kappelmann-Fenzl
A.-K. Bosserhoff
C. Bosserhoff
C. Berking

Brn3a expression is epigenetically controlled by HDAC2 in melanocytes and melanoma

pg. P.196.

(2021)

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Beitrag (Sammelband oder Tagungsband)

Melanie Kappelmann-Fenzl

NGS Data

In: Next Generation Sequencing and Data Analysis. null (Learning Materials in Biosciences) pg. 79-104.

Cham, Switzerland

(2021)

DOI: 10.1007/978-3-030-62490-3_7

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Beitrag (Sammelband oder Tagungsband)

Melanie Kappelmann-Fenzl

Design and Analysis of Epigenetics and ChIP-Sequencing Data

In: Next Generation Sequencing and Data Analysis. null (Learning Materials in Biosciences) pg. 177-192.

Cham, Switzerland

(2021)

DOI: 10.1007/978-3-030-62490-3_12

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Beitrag (Sammelband oder Tagungsband)

Melanie Kappelmann-Fenzl

Introduction to Command Line (Linux/Unix)

In: Next Generation Sequencing and Data Analysis. null (Learning Materials in Biosciences) pg. 71-78.

Cham, Switzerland

(2021)

DOI: 10.1007/978-3-030-62490-3_6

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Zeitschriftenartikel

M. Fuentes-Chandía
A. Vierling
Melanie Kappelmann-Fenzl
M. Monavari
G. Letort
L. Höne
B. Parma
S. Antara
Ö. Ertekin
R. Palmisano
M. Dong
K. Böpple
A. Boccaccini
P. Ceppi
A.-K. Bosserhoff
A. Leal-Egaña

3D Spheroids Versus 3D Tumor-Like Microcapsules: Confinement and Mechanical Stress May Lead to the Expression of Malignant Responses in Cancer Cells

In: Advanced Biology pg. e2000349.

07.05.2021 (2021)

DOI: 10.1002/adbi.202000349

Abstract anzeigen

As 2D surfaces fail to resemble the tumoral milieu, current discussions are focused on which 3D cell culture strategy may better lead the cells to express in vitro most of the malignant hints described in vivo. In this study, this question is assessed by analyzing the full genetic profile of MCF7 cells cultured either as 3D spheroids-considered as "gold standard" for in vitro cancer research- or immobilized in 3D tumor-like microcapsules, by RNA-Seq and transcriptomic methods, allowing to discriminate at big-data scale, which in vitro strategy can better resemble most of the malignant features described in neoplastic diseases. The results clearly show that mechanical stress, rather than 3D morphology only, stimulates most of the biological processes involved in cancer pathogenicity, such as cytoskeletal organization, migration, and stemness. Furthermore, cells entrapped in hydrogel-based scaffolds are likely expressing other physiological hints described in malignancy, such as the upregulated expression of metalloproteinases or the resistance to anticancer drugs, among others. According to the knowledge, this study represents the first attempt to answer which 3D experimental system can better mimic the neoplastic architecture in vitro, emphasizing the relevance of confinement in cancer pathogenicity, which can be easily achieved by using hydrogel-based matrices.

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Zeitschriftenartikel

L. Feuerer
S. Lamm
I. Henz
Melanie Kappelmann-Fenzl
S. Haferkamp
S. Meierjohann
C. Hellerbrand
S. Kuphal
A.-K. Bosserhoff

Role of MIA (melanoma inhibitory activity) in melanocyte senescence

In: Pigment Cell & Melanoma Research pg. 777-791.

(2019)

DOI: 10.1111/pcmr.12801

Abstract anzeigen

The protein MIA is known to be expressed in melanoma and to support melanoma progression. Interestingly, previous studies also observed the expression of MIA in nevi. Concentrating on these findings, we revealed that MIA expression is correlated with a senescent state in melanocytes. Induction of replicative or oncogene‐induced senescence resulted in increased MIA expression in vitro. Notably, MIA‐knockdown in senescent melanocytes reduced the percentage of senescence‐associated beta‐Gal‐positive cells and enhanced proliferation. Using the melanoma mouse model Tg(Grm1), MIA‐deficient mice supported the impact of MIA on senescence by showing a significantly earlier tumor onset compared to controls. In melanocytes, MIA‐knockdown led to a downregulation of the cell cycle inhibitor p21 in vitro and in vivo. In contrast, after induction of hTERT in human melanoma cells, p21 regulation by MIA was lost. In summary, our data show for the first time that MIA is a regulator of cellular senescence in human and murine melanocytes.

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Zeitschriftenartikel

Melanie Kappelmann-Fenzl
C. Gebhardt
A. Matthies
S. Kuphal
M. Rehli
A.-K. Bosserhoff

C-Jun drives melanoma progression in PTEN wild type melanoma cells

In: Cell Death & Disease vol. 10

(2019)

DOI: 10.1038/s41419-019-1821-9

Abstract anzeigen

Due to the critical impact of active AP-1 transcription factors in melanoma, it is important to define their target genes and to identify and ultimately inhibit oncogenic signals. Here we mapped the genome-wide occupancy of the AP-1 family member c-Jun in different melanoma cells and correlated AP-1 binding with transcriptome data to detect genes in melanoma regulated by c-Jun. Our analysis shows that c-Jun supports the malignant phenotype by deregulating genes in cancer-relevant signaling pathways, such as mitogen-activated protein kinase (MAPK) and phosphatidylinositol-3-kinase (PI3K) pathways. Moreover, we demonstrate that the importance of c-Jun depends on melanoma stage and mutation status of the tumor suppressor PTEN. Our study reveals that activation of c-Jun overrules the tumor suppressive effect of PTEN in early melanoma development. These findings help to understand the relevance of c-Jun within cancer pathways in different melanoma cell types, especially in relation to MAPK and PI3K pathways, which are commonly deregulated in melanomas. Consequently, targeting c-Jun in PTEN+ melanoma cells may represent a promising therapeutic strategy to inhibit survival of melanoma cells to prevent the development of a metastatic phenotype.

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Zeitschriftenartikel

Melanie Kappelmann-Fenzl
S. Kuphal
R. Krupar
D. Schadendorf
V. Umansky
L. Vardimon
C. Hellerbrand
A.-K. Bosserhoff

Complex Formation with Monomeric α-Tubulin and Importin 13 Fosters c-Jun Protein Stability and Is Required for c-Jun's Nuclear Translocation and Activity

In: Cancers vol. 11 pg. 1-12.

(2019)

DOI: 10.3390/cancers11111806

Abstract anzeigen

Microtubules are highly dynamic structures, which consist of α- and β-tubulin heterodimers. They are essential for a number of cellular processes, including intracellular trafficking and mitosis. Tubulin-binding chemotherapeutics are used to treat different types of tumors, including malignant melanoma. The transcription factor c-Jun is a central driver of melanoma development and progression. Here, we identify the microtubule network as a main regulator of c-Jun activity. Monomeric α-tubulin fosters c-Jun protein stability by protein-protein interaction. In addition, this complex formation is necessary for c-Jun's nuclear localization sequence binding to importin 13, and consequent nuclear import and activity of c-Jun. A reduction in monomeric α-tubulin levels by treatment with the chemotherapeutic paclitaxel resulted in a decline in the nuclear accumulation of c-Jun in melanoma cells in an experimental murine model and in patients' tissues. These findings add important knowledge to the mechanism of the action of microtubule-targeting drugs and indicate the newly discovered regulation of c-Jun by the microtubule cytoskeleton as a novel therapeutic target for melanoma and potentially also other types of cancer.

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Vortrag

Melanie Kappelmann-Fenzl
C. Gebhardt
A. Matthies
S. Kuphal
M. Rehli
A.-K. Bosserhoff

C-Jun drives melanoma progression in PTEN wild type melanoma cells

In: German Conference on Bioinformatics 2019

Deutsches Krebsforschungszentrum Heidelberg

16.-19.09.2019 (2019)

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Zeitschriftenartikel

P. Schummer
S. Kuphal
L. Vardimon
A.-K. Bosserhoff
Melanie Kappelmann-Fenzl

Specific c-Jun target genes in malignant melanoma

In: Cancer Biology & Therapy vol. 17 pg. 486-497.

(2016)

DOI: 10.1080/15384047.2016.1156264

Abstract anzeigen

A fundamental event in the development and progression of malignant melanoma is the de-regulation of cancer-relevant transcription factors. We recently showed that c-Jun is a main regulator of melanoma progression and, thus, is the most important member of the AP-1 transcription factor family in this disease. Surprisingly, no cancer-related specific c-Jun target genes in melanoma were described in the literature, so far. Therefore, we focused on pre-existing ChIP-Seq data (Encyclopedia of DNA Elements) of 3 different non-melanoma cell lines to screen direct c-Jun target genes. Here, a specific c-Jun antibody to immunoprecipitate the associated promoter DNA was used. Consequently, we identified 44 direct c-Jun targets and a detailed analysis of 6 selected genes confirmed their deregulation in malignant melanoma. The identified genes were differentially regulated comparing 4 melanoma cell lines and normal human melanocytes and we confirmed their c-Jun dependency. Direct interaction between c-Jun and the promoter/enhancer regions of the identified genes was confirmed by us via ChIP experiments. Interestingly, we revealed that the direct regulation of target gene expression via c-Jun can be independent of the existence of the classical AP-1 (5´-TGA(C/G)TCA-3´) consensus sequence allowing for the subsequent down- or up-regulation of the expression of these cancer-relevant genes. In summary, the results of this study indicate that c-Jun plays a crucial role in the development and progression of malignant melanoma via direct regulation of cancer-relevant target genes and that inhibition of direct c-Jun targets through inhibition of c-Jun is a potential novel therapeutic option for treatment of malignant melanoma.

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Hochschulschrift

Melanie Kappelmann-Fenzl

Regulation und Funktion des Trankriptionsfaktors c-Jun im malignen Melanom

Universität Regensburg Regensburg Naturwissenschaftliche Fakultät für Biologie und vorklinische Medizin

2014 (2014)

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Zeitschriftenartikel

Melanie Kappelmann-Fenzl
A.-K. Bosserhoff
S. Kuphal

AP-1/c-Jun transcription factors: regulation and function in malignant melanoma

In: European Journal of Cell Biology vol. 93 pg. 76-81.

(2014)

DOI: 10.1016/j.ejcb.2013.10.003

Abstract anzeigen

Malignant melanoma is an aggressive form of skin cancer with an increasing incidence worldwide. One way to address the pathology of the disease is through molecular research. In addition to the analysis of melanoma-relevant signaling pathways, the investigation of important transcription factors is a fundamental objective. The AP-1 transcription factor family is known to play an important role in melanoma progression and development. The AP-1 family member c-Jun is highly expressed and active in melanoma cells, and the mechanisms and signaling pathways regulating c-Jun protein are diverse. In addition to the common regulation and activation of c-Jun by mitogen-activated protein kinases (MAPKs), there are several other signaling pathways and interactions leading to c-Jun protein expression and thus AP-1 activation. In malignant melanoma, and many other cancer types, c-Jun has mainly oncogenic functions; however, other AP-1 proteins also have anti-oncogenic roles. Interestingly, several studies have revealed that a strong AP-1 activity in melanoma mainly depends on c-Jun. Recently, it has also been shown that the c-Jun protein is regulated and activated by several other mechanisms, including miRNAs and the cytoskeleton. In summary, there are a variety of mechanisms underlying the induction of c-Jun protein expression and activity leading to tumor progression and development, and this diverse regulatory machinery is due to the heterogeneity of different tumor types, particularly in malignant melanoma.

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Zeitschriftenartikel

S. Hagemann
L. Stöger
Melanie Kappelmann-Fenzl
I. Hassl
A. Ellinger
B. Velimirov

DNA-bearing membrane vesicles produced by Ahrensia kielensis and Pseudoalteromonas marina

In: Journal of Basic Microbiology vol. 54 pg. 1062-1072.

(2014)

DOI: 10.1002/jobm.201300376

Abstract anzeigen

Outer membrane vesicles (OMVs) derived from the alphaproteobacterium Ahrensia kielensis and from Pseudoalteromonas marina, a gammaproteobacterium, were sampled from liquid cultures in order to extract the MV-associated DNA, establish a shotgun library, and sequence randomly chosen clones to determine the origins of their DNA. We show that OMVs from A. kielensis and from P. marina both harbour DNA larger than 20 or 30 kbp. Transmission electron microscopical inspection of OMVs of A. kielensis and P. marina showed two types of vesicles: bilayered OMVs with a diameter between 30 and 250 nm and double bilayered OMVs ranging between 80 and 200 nm. Bilayered OMVs are either characterized by the presence of a large electron-dense substance or are elctron translucent. Double bilayered OMVs contained an electron dense substance in the core region surrounded by the second bilayer. 30,094 bp of the genome from OMV of A. kielensis and 45,981 bp of that from P. marina were sequenced. The results indicated that all sequences were single copy and that all sequences, with one exception, were similar to prokaryotic sequences, inserted viral sequences were not detected.

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Zeitschriftenartikel

Melanie Kappelmann-Fenzl
S. Kuphal
G. Meister
L. Vardimon
A.-K. Bosserhoff

MicroRNA miR-125b controls melanoma progression by direct regulation of c-Jun protein expression

In: Oncogene vol. 32 pg. 2984-2991.

(2013)

DOI: 10.1038/onc.2012.307

Abstract anzeigen

A fundamental event in the development and progression of malignant melanoma is the deregulation of cancer-relevant transcription factors. We recently showed that c-Jun is a main regulator of tumor progression in melanoma and thus the most important member of the AP-1 transcription factor family for this disease. Interestingly, we revealed that c-Jun expression was regulated on the post-transcriptional level and therefore speculated that miRNAs could be involved in c-Jun regulation. We determined seed sequences for miR-125b and miR-527 in the coding region of c-Jun mRNA that hints at the direct involvement of miRNA-dependent regulation on the protein level. We found that the expression of miR-125b was significantly reduced in malignant melanoma cell lines and tissue samples compared with melanocytes, whereas miR-527 remained unchanged. In further functional experiments, treatment of melanoma cells with pre-miR-125b resulted in strong suppression of cellular proliferation and migration, supporting the role of miR-125b in melanoma. In addition, transfection of pre-miR-125b led to strong downregulation of c-Jun protein but not mRNA expression in melanoma cells. Luciferase assays using reporter plasmids containing the miR-125b seed sequence in the luciferase coding region confirmed the direct interaction with miR-125b. Furthermore, immunoprecipitation of Ago-2 revealed that c-Jun mRNA accumulated in the RNA-induced silencing complex after pre-miR-125b transfection in melanoma cells. In summary, we identified an important role for miR-125b in malignant melanoma. Moreover, we demonstrated post-transcriptional regulation of c-Jun by this miRNA and showed that c-Jun is a main mediator of the effects of miR-125b on melanoma cells.

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Zeitschriftenartikel

B. Spangler
Melanie Kappelmann-Fenzl
B. Schittek
S. Meierjohann
L. Vardimon
A.-K. Bosserhoff
S. Kuphal

ETS‐1/RhoC signaling regulates the transcription factor c‐Jun in melanoma

In: International Journal of Cancer vol. 130 pg. 2801-2811.

(2012)

DOI: 10.1002/ijc.26277

Abstract anzeigen

Recently, we discovered that the loss of E‐cadherin induces c‐Jun protein expression, which is a member of the AP‐1 transcription factor family and a key player in the processes of cell proliferation and tumor development and also found in elevated levels in melanomas. Notably, the mRNA level of c‐Jun was not affected, suggesting that c‐Jun is regulated at post‐transcriptional level. Here, we present data that suggest that the dynamic cytoskeletal network, linked to E‐cadherin, is involved in the regulation of the c‐Jun protein and transcriptional activity. In a signaling cascade, the loss of E‐cadherin activates the transcriptional regulator ETS‐1 and consequently leads to the induction of RhoC expression that stabilizes c‐Jun in melanoma. The link between RhoC and c‐Jun seems to be indirect via the cytoskeleton. We conclude that the loss of E‐cadherin mediated cell‐adhesion induces c‐Jun protein expression in a multistep process, offering several possibilities for therapeutic intervention.

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GESUND

Vortrag

S. Ranganathan
D. Riewe
A. Feiner
S. Steiner
Melanie Kappelmann-Fenzl
S. Fischer

De novo assembly of Humulus lupulus transcriptome comparing different bioinformatic tools . Posterpräsentation

In: German Conference on Bioinformatics (GCB) 2021

Online

06.-08.09.2021

Angewandte Informatik
DIGITAL
GESUND

Projekte

Next Generation Genomic Data Analysis for Clinics and Research

Sonstiges

Kooperationen

Abteilung Molekularpathologie des Institutes für Pathologie und Zytologie am DONAUISAR KLINIKUM Deggendorf, Perlasberger Straße 41, 94469 Deggendorf https://www.pathologie-deggendorf.de/
Dr. Hamberger
Dr. Mohren

Mitgliedschaften:

Gesellschaft Biochemie und Molekularbiologie e.V. (GBM)
Fachgruppe Bioinformatik (FaBi)
The Society for Melanoma Research (SMR)
Hochschullehrerbund - Bundesvereinigung e.V. (hlb)
BayWISS-Kolleg Gesundheit