Biology subjects

Behrmann, I.

Publications and source records attributed to Behrmann, I..

4 recordsLinked to original sources

bioRxiv2024

Targeting the energy metabolism of melanoma cells: FX-11 acts as a mitochondrial uncoupler

In a compound screen on melanoma cells, which included different microenvironmental contexts aiming at better representing the environmental and growth characteristics of tumours, we identified several drugs efficiently suppressing cell viability. Here we focus on results obtained with FX-11, reported to be an inhibitor of lactate dehydrogenase (LDH). FX-11 dose-dependently inhibited growth of 624Mel and Wm3248 melanoma cells grown in a modular physiologic medium (MPM). Importantly, FX-11 was able to reduce the growth of the corresponding drug-resistant melanoma sublines equipotently. When testing the on-target activity of FX-11, the results were unexpected: in contrast to other LDH inhibitors (used as positive controls), FX-11 did not decrease the NAD+/NADH ratio, the glucose uptake, or the lactate secretion of melanoma cells. However, in seahorse assays, FX-11 increased the oxygen consumption rate as well as the extracellular acidification rate of cells, behaving like the mitochondrial uncouplers FCCP and Bam15. Treatment with FX-11, FCCP, or Bam15 induced an increase in acetyl-CoA carboxylase phosphorylation and a decrease in serine 65 phosphorylation of the eukaryotic initiation factor 4E-binding protein 1, indicative of AMPK activation by a decreased ATP/ADP ratio. Importantly, FX-11 and Bam15 drastically decreased the mitochondrial membrane potential in contrast to the LDH inhibitors LDH-IN-I and GNE-140. Taken together, we provide evidence that FX-11 effectively inhibits the growth of melanoma cells, including drug-resistant ones. FX-11 profoundly affects their energy metabolism, although it does not seem to act as other LDH inhibitors, but as a mitochondrial uncoupler.

cancer biology↗

bioRxiv2024

Metabolism-oriented compound screen in physiological culture conditions identifies a NAMPT inhibitor highly effective against drug-naive and -resistant melanoma cells

Many melanoma patients do not respond to therapy or rapidly develop resistance to MAPK pathway inhibitors and immune checkpoint blockade treatments, highlighting the urgent need for additional therapeutic strategies for these patients. To identify compounds that target drug-naive and -resistant melanoma cells (Encorafenib/Binimetinib-resistant), we performed a screen using a metabolism-oriented compound library in different cell culture media and growth conditions (2D and 3D). The efficacy of several compounds varied considerably under changing test conditions, but importantly, we also detected compounds that work across all tested conditions. In general, drug activity was reduced under hypoxia and in 3D spheroids. Thorough validation was performed for drugs showing potency in all conditions with a focus on efficacy in 3D spheroids grown in an in- house physiological culture medium. Using hydrogel matrix-embedded multi-cell type 3D models, we found that FK866, a nicotinamide phosphoribosyltransferase (NAMPT) inhibitor, is very potently suppressing melanoma cell growth while not affecting the growth of healthy cells such as fibroblasts and endothelial cells.

cancer biology↗

bioRxiv2024

Ferroptosis susceptibility of melanoma cells: dependence on cell-type, acquired drug resistance, and medium composition

Resistance of melanoma cells to targeted therapy (BRAF and MEK inhibitors) is a major clinical problem and alternative treatments are sought. We describe the establishment of modular physiologic medium (MPM) and Mel-MPM (which contains additional supplements and sustains the 3D growth of melanoma cells, fibroblasts (NHDFs) and HMEC-1 endothelial cells) as novel resources for melanoma and combine them with a multi-cell-type matrix-embedded 3D culture model to investigate melanoma cell vulnerabilities in a more physiological setting. We made use of the modular nature of MPM to interrogate NEAA dependencies in melanoma cells and we found them to be particularly sensitive to the depletion of C/C. We additionally describe that melanoma cells are less sensitive to ferroptosis inducing compounds when cultured in MPM compared to RPMI and we could attribute this to different components of MPM and Mel-MPM (selenite, B27). Cell death induced by the glutathione peroxidase 4 inhibitor, ML162, had characteristics of ferroptosis or apoptosis depending on cell type, its drug resistance status and the culture medium. Cystine/cysteine starvation and ML162 treatment combinations increased melanoma cell death in 2D, 3D, and also in the complex matrix embedded multi-cell-type-3D system in OrganoplatesTM. This underlines the potential of combining metabolism-oriented drug treatments with amino acid starvation conditions, which is of interest in view of future therapeutic approaches to combat melanoma and other cancer types.

cancer biology↗

bioRxiv2024

Complement-Activating Multimeric Immunotherapeutic Complexes for HER2-breast cancer immunotherapy

BackgroundDirecting selective complement activation towards tumor cells is an attractive strategy to promote their elimination. We have generated Complement-activating Multimeric immunotherapeutic compleXes (CoMiX) that selectively stimulate the alternative pathway using Factor H Related protein 4 (FHR4) or the classical complement pathways using triple Fc dimers on HER2-expressing tumor cells. MethodsWe used the C4bp C-terminal--/{beta}-chain multimerising scaffolds to generate CoMiX-FHR4 and CoMiX-Fc with 2 different VHH anti-HER2, VHH(T) and VHH(P), recognising trastuzumab-or pertuzumab-competing HER2 epitopes, respectively: FHR4/VHH(T), FHR4/VHH(P), VHH(T)/Fc, VHH(P)/Fc. The different CoMiX were compared in vitro for C3b and C5b9 depositions, complement-dependent cytotoxicity, and their ability to activate NK cells and phagocytosis by macrophages using one-way ANOVA and post-hoc Tukeys tests. We further explored their therapeutic efficacy in vivo on human BT474 breast cancer xenografts established in NUDE mice, when used individually or in combination, as compared to trastuzumab or pertuzumab. ResultsFHR4/VHH(T) and FHR4/VHH(P) led to the highest C3b and C5b9 depositions and CDC, both individually and in combinations on BT474 tumor cells (p< 0.0001) surpassing the very low complement activating capacity of trastuzumab and pertuzumab. CoMiX-Fc showed NK cell activation and complement-mediated BT474 phagocytosis by M2 macrophages. In the xenograft model, CoMiX-FHR4 molecules reduced the tumor volume by a factor of 7.33 compared to the PBS control. VHH(T)/Fc had no effect on tumor growth, while VHH(P)/Fc led to a 2.75-times tumor volume reduction that was higher than pertuzumab (p< 0.01). Trastuzumab and its combination with pertuzumab remained the most potent regimen, alone or in combination, to completely inhibit tumor growth. CoMiX-FHR4, CoMiX-Fc and C3b deposition were visualized as soon as one hour after injection resulting in a massive homogeneous complement deposit 6 hours after injection. Interestingly, CoMiX-FHR4 significantly reduced the growth of trastuzumab-resistant cancer cells in contrast to trastuzumab and induced a large NK cell infiltration into the tumor. ConclusionsCoMiX-FHR4 and CoMiX VHH(P)/Fc significantly inhibit tumor growth through complement activation, NK cells infiltration, and phagocytosis by macrophages. CoMiX-FHR4 proteins delay xenograft growth of BT474 cells resistant to trastuzumab and could thus be an attractive approach when resistance to antibody emerges. Key messagesO_ST_ABSWhat is already known on this topicC_ST_ABSComplement activation represents a substantial part of the overall biological activity of few therapeutic antibodies used in cancer immunotherapy. Factor H-related protein 4 can activate complement by serving as a platform for the assembly of alternative pathway C3 convertase by competing with factor H for C3b binding. We previously showed that multimeric recombinant proteins displaying the FHR4 complement effector moiety and a nanobody anti-HER2 targeting moiety selectively direct the activation of the complement alternative pathway on HER2-expressing tumor cells, leading to subsequent cell destruction through direct cell lysis or through the activation of host effector cells. What this study addsWe used in the current work a novel complement-directed tumor cell distruction strategy in vivo. We showed that CoMiX-FHR4 and CoMiX-Fc (based on triple Fc dimers), targeting HER2-positive breast tumor cells, inhibit tumor growth in a model of BT474 xenograft in NUDE mice by stimulating complement activation, BT474 death, NK cell activation, and phagocytosis of tumor cells by macrophages. CoMiX-FHR4 remain efficient in xenografts of BT474 cells resistant to trastuzumab. How this study might affect research, practice or policyWe demonstrate for the first time that directed complement activation on tumor cells is an alternative to therapeutic antibodies which is particularly promising when resistance to standard-of-care treatment occurs.

immunology↗