Molecular Tumor Cell Biology

The 3R-US network develops a versatile tissue culture platform for drug testing to replace, reduce and refine (3R) animal experiments. Currently, most studies evaluating anti-cancer therapeutics proceed from human cell culture to preclinical cell line or patient derived mouse tumor models (CDX, PDX). These CDX/PDX models poorly recapitulate the complexity, heterogeneity, and physiology of human tumors. With interdisciplinary partners in cell biology, biomedical engineering and oncology, 3R-US will therefore advance methods that enable the long-term ex vivo cultivation of mouse and human tumor tissue slices. New (targeted) therapeutics and combination therapies will be evaluated in these slice cultures and the mechanisms of drug action investigated. Furthermore, 3R-US will develop de novo human tumor models using 3D printing to study heterogeneous cell interactions and drug responses. Finally, 3R-US will use the data derived from the ex vivo and de novo approaches to establish and validate in silico tumor models that reliably predict the pharmacokinetics and therapy response to anti-cancer drugs.

https://www.verbund.uni-stuttgart.de/3r-biomedicus/3r-research/3r-us/  

The Rho GTPase activating (GAP) protein Deleted in Liver Cancer 1 (DLC1) has emerged as an important tumor suppressor, whose downregulation in various types of cancer may be as common as that of p53. Our work has shown that DLC1 loss facilitates the aberrant migration of breast cancer cells, whereas expression of the family member DLC3 is crucial for the establishment and maintenance of cell polarity and cell-cell adhesions. While Rho signaling is regulated negatively by GAP proteins on the one hand, it is regulated positively by GEF proteins on the other.  We are especially interested in unraveling how specific GEF-GAP networks regulate spatiotemporal Rho signaling and how dysregulation contributes to the metastatic behavior of cancer cells. As partner within the H2020 SECRET Innovative Training Network, we aim to identify drug vulnerabilities of cancer cells with DLC downregulation.

The ErbB family of receptor tyrosine kinases (RTKs) plays a well-established role in cancer development and progression. ErbB2/HER2, for example, is amplified and/or overexpressed in approximately 25% of breast cancer patients, correlating with poor clinical prognosis, whereas EGFR/ErbB1 expression is elevated in 70% of triple-negative breast cancers. Although these receptors are prime targets for pharmacological intervention in the clinic, cancer cells are often non-responsive or become resistant to treatment. In collaboration with the lab of Prof. Roland Kontermann we are developing novel RTK-based targeted approaches for personalized treatment of solid cancers.

Triple-negative breast cancer (TNBC) is an especially aggressive form of breast cancer for which targeted therapies are still in their infancy. We identified the serine-threonine kinase PKD3 to be upregulated in TNBC where it drives proliferation, cell motility and cancer stem cell survival. By mapping the PKD3 interactome and kinome our goal is to identify druggable signaling nodes for this cancer type.

Loss of tumor suppressors and activation of oncogenes are key events in cancer development. While these events can spontaneously occur in multiple cells, only a subset of these cells will eventually contribute to tumor formation or promote metastasis. The conditions that facilitate this, particularly in 3D environments in which cells typically grow within tissues, are poorly understood. This interdisciplinary project tackles this topic by combining state of the art CRISPR/Cas9 epigenetic editing, cancer cell biology and biophysical methodologies. This project is performed in close collaboration with the Guo lab of cell mechanics (MIT) and is funded by the MISTI Global Seed Fund – University of Stuttgart program.

More than 70% of breast cancer associated deaths hail from the metastatic spread of the disease to distant organs. Interestingly, most breast cancer metastases affect the bones, the mechanisms involved in this tissue-specific enrichment being still poorly understood. In particular, the role of biophysical cues such as tissue topography and stiffness in this process are not clear. In this interdisciplinary project we will develop high resolution bone mimetic scaffolds to assay the metastatic colonization process. This work is performed together with the Heymann and Hörning groups from the IBBS. The initiative is funded by the Research Seed Capital Program (MWK Baden-Württemberg & University of Stuttgart).

We are pleased to announce the publication of a new research article from the Olayioye group in the journal Cell Death & Disease. The study, “BCL-xL as a therapeutic target in cetuximab-refractory colorectal cancer”, identifies inhibition of the anti-apoptotic protein BCL-xL as a promising strategy to induce tumor cell death in colorectal cancers that have developed resistance to cetuximab. The work represents a close collaborative effort within our institute and with external partners at the Bosch Health Campus, Charles River Laboratories, and the University of Freiburg, highlighting the strength of interdisciplinary and interinstitutional cooperation within the regional research landscape. Importantly, the study is strongly aligned with the 3R principles (Replacement, Reduction, and Refinement), relying extensively on advanced in vitro systems and ex vivo patient-derived tumor tissue models to investigate therapeutic vulnerabilities while minimizing animal experimentation.

The underlying PhD project was conducted within the 3R-US network, funded by the Ministry of Science, Research and the Arts (MWK) Baden-Württemberg. This network laid the foundation for the Stuttgart Research Initiative 3R-BioMedicUS, making the publication a notable example of the initiative’s long-term scientific impact.

Read the full article: https://www.nature.com/articles/s41419-026-08434-5 

We are pleased to announce that Merih Özverin, doctoral researcher in our group and member of the SECRET Marie Skłodowska-Curie Actions (MSCA) Innovative Training Network (ITN), has successfully defended her PhD! Her work culminates not only in the completion of her doctoral degree but also in a significant scientific contribution published as a co-first author in PLOS Computational Biology.  

Merih’s research, conducted within the framework of the SECRET MSCA Doctoral Network, investigated the complex process of epithelial-mesenchymal transition (EMT) — a fundamental biological program with critical roles in development, tissue repair, and cancer progression.  

The publication titled “Integrated mathematical and experimental modeling uncovers enhanced EMT plasticity upon loss of the DLC1 tumor suppressor” (co-first authored by Sebastian Höpfl from the Radde group) combines mathematical modeling with experimental data to reveal how the tumor suppressor protein DLC1 regulates EMT dynamics. Their findings demonstrate that loss of DLC1 leads to increased cellular plasticity and a partial EMT phenotype, shedding light on mechanisms that may contribute to tumor progression and metastasis.  

Merih’s PhD work is an example of the interdisciplinary training fostered by the SECRET-ITN network, which brings together early career researchers across Europe to explore secretory pathway regulation in cancer and develop novel computational and experimental approaches to complex biological problems.  

We warmly congratulate Florian Meyer on the successful defense of his doctoral thesis, “A Molecular and Imaging-Based Analysis of Actin-Driven Processes in Cancer Cells,” which he completed in the Olayioye lab.

Florian’s academic journey is closely linked to our institute: after completing both his Bachelor’s and Master’s studies in the Olayioye lab, he has now also concluded his PhD research here. Over the years, he has developed into a highly valued member of the institute and a recognized expert in imaging and image analysis, contributing substantially to method development and data interpretation across multiple projects.

During his doctoral studies, Florian was involved in five scientific publications, including one first-author paper published in iScience (10.1016/j.isci.2025.112618). His collaborative work also contributed to publications in Traffic, iScience, Communications Biology, as well as a recent collaborative work with the group of Prof. Ming Guo (MIT, Department of Medical Engineering) in PRX Life (10.1111/tra.12880; 10.1016/j.isci.2024.110203; 10.1038/s42003-024-05990-4; 10.1103/PRXLife.2.043010).

We congratulate Florian on this outstanding achievement and wish him all the best in his scientific career. 

Cristiana Lungu was selected to give a talk at the recent EMBL/EMBO “Cell Biology of the Nucleus”conference in Heidelberg, where she presented the research she led on how the spatial organization of epigenetic enzymes influences the behaviour of triple-negative breast cancer cells.

The conference brought together researchers from across the field to highlight the cell-biological mechanisms that define the nucleus as an organelle. Topics included nuclear architecture, nuclear envelope remodeling, nucleocytoplasmic transport, nuclear mechanics, molecular machines, nuclear division, evolutionary perspectives, and the biophysics of the nucleus.

Link to research paper / Link to conference program

In their new article published in Cell Reports, Pelzer et al., investigated the spatial organization of Polycomb Repressive Complex 2 (PRC2), a master chromatin regulator, in triple-negative breast cancer (TNBC) cells.

Through the use of in situ subcellular proteomics, high-resolution imaging, and functional genomics, PHF19was identified as a sub-stoichiometric PRC2 component that acts as a spatial organizer, driving the formation of micron-sized PRC2 clusters within TNBC nuclei. These clusters were shown to structure gene-silencing domains and to enhance cancer cell motility.

In summary, a previously unrecognized architectural layer of epigenetic regulation was uncovered, demonstrating that the 3D nuclear arrangement of chromatin regulators can directly influence cancer cell behaviour.

Read the full article here: PHF19 drives the formation of PRC2 clusters to enhance motility in TNBC cells - ScienceDirect

The prize was awarded for her outstanding contribution to the manuscript: Repeat DNA methylation is modulated by adherens junction signaling., published in Communications Biology (Nature Portfolio).

The work is a collaborative achievement by researchers from the Olayioye group (IZI), Jeltsch group (Institute of Biochemistry, IBC), and the Massachusetts Institute of Technology (Department of Mechanical Engineering).

Since 2018, the University of Stuttgart has honored excellent scientific publications from each of its ten faculties as part of its annual Day of Research event. Each award is endowed with €2,500.

On July 9 starting at 4 PM, the awardees from the faculties will present their publications in short, entertaining talks.
Where? Campus Vaihingen, Room 38.02, Universitätsstraße 38, 70569 Stuttgart.

Optional: Want to know more about the interface between Cell Signaling and Epigenetics, check out our recently funded EpiSignal graduate college (GRK).

Integrated mathematical and experimental modeling uncovers enhanced EMT plasticity upon loss of the DLC1 tumor suppressor

Sebastian Höpfl, Merih Özverin, Helena Nowack, Raluca Tamas, Andrew G. Clark, Nicole Radde, Monilola A. Olayioye

Abstract

Reciprocal regulation of Solo and Src orchestrates Src trafficking to promote mesenchymal cell migration

Florian Meyer, Cristiana Lungu, Bettina Noll, David Benz, Felix Fränkle, Miguel Â. Ferreira, Raluca Tamas, Monilola A. Olayioye

Highlights:

• Solo expression is increased in breast cancer cells with high EMT signatures.
• Solo promotes breast cancer cell migration in a RhoGEF-dependent manner.
• Src phosphorylates Solo at Y242 and cooperates with Solo to promote cell migration.
• Loss of Solo disrupts Src trafficking and focal adhesion signaling dynamics.

Summary

Rho GTPases are key regulators of cell motility and membrane trafficking, influencing critical processes such as epithelial-mesenchymal transition (EMT). Among them, the small GTPase RhoB plays a pivotal role, but the mechanisms underlying its regulation remain largely unclear. We have previously identified the Rho guanine nucleotide exchange factor (RhoGEF) Solo (ARHGEF40) as a regulator of endosomal RhoB in epithelial cells. Here, we find that Solo is upregulated in breast cancer cells with high EMT scores and promotes cell motility through its RhoGEF activity. Solo’s ability to enhance migration is further regulated by phosphorylation at tyrosine 242, mediated by the proto-oncogene Src. By combining high-resolution imaging with photoconversion assays, we further demonstrate that Solo regulates Src trafficking dynamics, localization, and consequently signaling at focal adhesions. Together, our data identify Solo as a novel feedback regulator of Src and a key driver of the motility of breast cancer cells with mesenchymal characteristics.

Congratulations to Lisa Brenner on the successful defense of her PhD thesis! Using a powerful combination of CRISPR/Cas9, high-resolution imaging, and cell biology, Lisa uncovered a novel pathway that bridges epigenetics and cell signaling. Her research revealed that in confluent breast epithelial cell monolayers, DNA methylation of α-satellite repeats is reduced compared to low-density cultures—a change linked with increased transcriptional activity. She also demonstrated that the junctional protein E-cadherin is essential for transmitting signals via the actin cytoskeleton into the nucleus. Notably, this pathway is disrupted in cancer cells lacking E-cadherin, opening new avenues to explore how the loss of contact inhibition contributes to tumor development.

For more details, check out our recent publication in Communications Biology: Repeat DNA methylation is modulated by adherens junction signaling | Communications Biology

and the accompanying “Behind the Paper” blog post on Springer Nature’s Research Communities:  Research Communities by Springer Nature

We applaud Lisa’s achievements and wish her every success as she embarks on her new role as Scientific Project Manager at the Center for Personalized Medicine, University Hospital Tübingen.

Does that sound like an exciting research topic? We are looking for talent to join our teams within the newly funded EpiSignal graduate school: https://www.grk3112.uni-stuttgart.de/

Dr. Cristiana Lungu has been invited to give a presentation at Cell Bio 2024, the joint meeting of the ASCB and EMBO, taking place in San Diego from December 14–18, 2024. The talk will showcase the use of opts-proteomics, an advanced spatial proteomics technology, to obtain insights into the misregulation of epigenetic proteins in cancer cells.

Cell Bio 2024 is a premier event in the field of cell biology, bringing together leading researchers to explore foundational and interdisciplinary topics: https://www.ascb.org/cellbio2024/program/