@misc{BrauneKruegerGengeKammereretal., author = {Braune, Steffen and Kr{\"u}ger-Genge, Anne and Kammerer, Sarah and Jung, Friedrich and K{\"u}pper, Jan-Heiner}, title = {Phycocyanin from Arthrospira platensis as Potential Anti-Cancer Drug: Review of In Vitro and In Vivo Studies}, series = {Life}, volume = {11}, journal = {Life}, number = {2}, doi = {10.3390/life11020091}, pages = {91}, language = {en} } @misc{Kammerer, author = {Kammerer, Sarah}, title = {Three-Dimensional Liver Culture Systems to Maintain Primary Hepatic Properties for Toxicological Analysis In Vitro}, series = {International Journal of Molecular Sciences}, volume = {22}, journal = {International Journal of Molecular Sciences}, number = {19}, issn = {1422-0067}, doi = {10.3390/ijms221910214}, language = {en} } @misc{JungKammererBrandensteinetal., author = {Jung, Ernst Michael and Kammerer, Sarah and Brandenstein, M. and Putz, F. J. and Stroszczynski, Christian and Jung, Friedrich}, title = {High resolution flow (HR Flow) and Glazing Flow in cases of hepatic flow changes: Comparison to color-coded doppler sonography (CCDS)}, series = {Clinical Hemorheology and Microcirculation}, volume = {79}, journal = {Clinical Hemorheology and Microcirculation}, number = {1}, issn = {1875-8622}, doi = {10.3233/CH-219102}, pages = {3 -- 17}, abstract = {AIM: To evaluate the possibilities of flow detection using high resolution flow (HR Flow) and Glazing Flow technique in patients with liver parenchymal changes and flow changes in comparison to color-coded Doppler sonography (CCDS). MATERIAL AND METHODS: All examinations were performed using a multi frequency matrix convex probe with high resolution technique (SC6-1U/Resona7, Mindray, Shenzhen, China) by one experienced examiner to evaluate the venous, portal venous and arterial liver flow with digital documentation of the dynamic flow parameters like peak systolic flow, end-diastolic flow and resistance index. For liver parenchymal stiffness changes shear wave elastography was performed with at least 10 measurements. By two independent readers an elevation was performed to evaluate the image quality and the degree of flow artefacts, from 0 = not available to 5 points with excellent image quality without flow artefacts. RESULTS: All 40 patients (24 men, 16 women, age 27-83 years, mean 56±5 years) showed morphology changes from B-Mode of the liver parenchyma to inhomogeneous tissue with higher stiffness evaluated by the shear wave elastography (1.45 m/s up to 2.79 m/s±1.79 m/s, considering F1 up to F4 fibrosis) and in 15 cases histopathologically proven liver cirrhosis. In 9 cases after non-acute thrombosis flow reduction of the portal vein was the reason for the diameter less than 5 mm. Flow parameters for the venous flow were between 8 cm/s up to 29 cm/s, mean 14±4 cm/s, for the hepatic portal vein 5 cm/s up to 57 cm/s, mean 17±5 cm/s, for the hepatic artery systolic flow between 50 cm/s up to 127±33 cm/s, end-diastolic flow from 22 cm/s up to 47±8 cm/s. Resistance index for the hepatic artery was between 0.41 up to 0.73, mean 0.67±0.25. The image quality for CCDS over all cases was evaluated for CCDS between 1 up to 4. The mean quality was 2.5±0.5, for HR Flow in combination with Glazing Flow 3±0.5, with significant differences for the 2 readers (P < 0.01). CONCLUSION: Combination of HR Flow with Glazing Flow could be helpful to evaluate morphological und hemodynamic changes of liver arterial flow, portal venous and venous flow. Reduction of flow artefacts in combination with a higher image quality could be helpful for optimizing the digital measurements also for follow up examinations.}, language = {en} } @misc{VagiannisZhangBudagagaetal., author = {Vagiannis, Dimitrios and Zhang, Yu and Budagaga, Youssif and Novotna, Eva and Skarka, Adam and Kammerer, Sarah and K{\"u}pper, Jan-Heiner and Hofman, Jakub}, title = {Alisertib shows negligible potential for perpetrating pharmacokinetic drug-drug interactions on ABCB1, ABCG2 and cytochromes P450, but acts as dual-activity resistance modulator through the inhibition of ABCC1 transporter}, series = {Toxicology and Applied Pharmacology}, volume = {Vol. 434}, journal = {Toxicology and Applied Pharmacology}, issn = {0041-008X}, doi = {10.1016/j.taap.2021.115823}, pages = {13}, language = {en} } @misc{VagiannisBudagagaMorelletal., author = {Vagiannis, Dimitrios and Budagaga, Youssif and Morell, Anselm and Zhang, Yu and Novotna, Eva and Skarka, Adam and Kammerer, Sarah and K{\"u}pper, Jan-Heiner and Hanke, Ivo and Rozkoš, Tom{\´a}š and Hofman, Jakub}, title = {Tepotinib Inhibits Several Drug Efflux Transporters and Biotransformation Enzymes: The Role in Drug-Drug Interactions and Targeting Cytostatic Resistance In Vitro and Ex Vivo}, series = {International Journal of Molecular Sciences}, volume = {22}, journal = {International Journal of Molecular Sciences}, number = {21}, issn = {1422-0067}, doi = {10.3390/ijms222111936}, language = {en} } @misc{KruegerGengeKoehlerLaubeetal., author = {Kr{\"u}ger-Genge, Anne and K{\"o}hler, Susanne and Laube, Markus and Haileka, Vanessa and Lemm, Sandy and Majchrzak, Karolina and Kammerer, Sarah and Schulz, Christian and Storsberg, Joachim and Pietzsch, Jens and K{\"u}pper, Jan-Heiner and Jung, Friedrich}, title = {Anti-Cancer Prodrug Cyclophosphamide Exerts Thrombogenic Effects on Human Venous Endothelial Cells Independent of CYP450 Activation—Relevance to Thrombosis}, series = {Cells}, volume = {12}, journal = {Cells}, number = {15}, issn = {2073-4409}, doi = {10.3390/cells12151965}, abstract = {Cancer patients are at a very high risk of serious thrombotic events, often fatal. The causes discussed include the detachment of thrombogenic particles from tumor cells or the adverse effects of chemotherapeutic agents. Cytostatic agents can either act directly on their targets or, in the case of a prodrug approach, require metabolization for their action. Cyclophosphamide (CPA) is a widely used cytostatic drug that requires prodrug activation by cytochrome P450 enzymes (CYP) in the liver. We hypothesize that CPA could induce thrombosis in one of the following ways: (1) damage to endothelial cells (EC) after intra-endothelial metabolization; or (2) direct damage to EC without prior metabolization. In order to investigate this hypothesis, endothelial cells (HUVEC) were treated with CPA in clinically relevant concentrations for up to 8 days. HUVECs were chosen as a model representing the first place of action after intravenous CPA administration. No expression of CYP2B6, CYP3A4, CYP2C9 and CYP2C19 was found in HUVEC, but a weak expression of CYP2C18 was observed. CPA treatment of HUVEC induced DNA damage and a reduced formation of an EC monolayer and caused an increased release of prostacyclin (PGI2) and thromboxane (TXA) associated with a shift of the PGI2/TXA balance to a prothrombotic state. In an in vivo scenario, such processes would promote the risk of thrombus formation.}, language = {en} } @misc{KammererNowakMantkeetal., author = {Kammerer, Sarah and Nowak, Elisabeth and Mantke, Ren{\´e} and Jung, Friedrich and K{\"u}pper, Jan-Heiner}, title = {In vitro simulation of the liver first-pass effect with biotransformation-competent HepG2 cells to study effects of MG-132 on liver and cancer cells}, series = {Clinical Hemorheology and Microcirculation}, volume = {86}, journal = {Clinical Hemorheology and Microcirculation}, number = {1-2}, issn = {1386-0291}, doi = {10.3233/CH-238108}, pages = {159 -- 168}, abstract = {BACKGROUND: Liver biotransformation is the major route for drug metabolism in humans, often catalysed by cytochrome P450 (CYP) enzymes. This first-pass effect can lead to hepatotoxicity and influences the bioavailability of drugs. OBJECTIVE: We aimed to establish in vitro culture systems simulating the liver first-pass to study effects of the proteasome inhibitor MG-132 simultaneously on hepatocytes and cancer cells. METHODS: The first-pass effect was simulated by conditioned medium transfer (CMT) from pre-treated HepG2 CYP3A4-overexpressing cells to either pancreatic cancer cell line PANC-1 or primary colon cancer cells, and by indirect co-culture (CC) of liver and cancer cells in a shared medium compartment. Experimental proteasome inhibitor MG-132 was used as test substance as it is detoxified by CYP3A4. RESULTS: Cancer cells showed higher viabilities in the first-pass simulation by CMT and CC formats when compared to monocultures indicating effective detoxification of MG-132 by HepG2 CYP3A4-overexpressing cells. HepG2-CYP3A4 cells showed reduced viabilites after treatment with MG-132. CONCLUSIONS: We successfully established two different culture systems to simulate the liver first-pass effect in vitro. Such systems easily allow to study drug effects simultaneously on liver and on target cancer cells. They are of great value in pre-clinical cancer research, pharmaceutical research and drug development.}, language = {en} } @misc{StockHoferLochmannetal., author = {Stock, Valentina and Hofer, Rebecca and Lochmann, Franziska and Spanke, Vera and Liedl, Klaus R. and Troppmair, Jakob and Langer, Thierry and Gstach, Hubert and Dank, Christian and Mayhew, Chris A. and Kammerer, Sarah and Ruzsanyi, Veronika}, title = {Tolterodine is a novel candidate for assessing CYP3A4 activity through metabolic volatiles to predict drug responses}, series = {Scientific reports}, volume = {15}, journal = {Scientific reports}, number = {1}, publisher = {Nature Publishing Group UK}, address = {London}, issn = {2045-2322}, doi = {10.1038/s41598-025-86450-9}, pages = {1 -- 12}, abstract = {Cytochrome P450 (CYP) 3A4 plays a major role in drug metabolism. Its activity could be determined by non-invasive and cost-effective assays, such as breath analysis, for the personalised monitoring of drug response. For the first time, we identify an isotopically unlabelled CYP3A4 substrate, tolterodine that leads to the formation of a non-toxic volatile metabolite, acetone, which could potentially be applied to monitor CYP3A4 activity in humans. In vitro biotransformation of tolterodine by HepG2 cells overexpressing CYP3A4, CYP2D6 or CYP2C9 was investigated by LC-MS analysis of cell culture supernatant for the non-volatile metabolite, N-dealkylated tolterodine, and PTR-ToF-MS analysis of the headspace for acetone. The highest level of the N-dealkylated metabolite was produced by HepG2-CYP3A4. Concentration dependent effects of tolterodine were analysed, resulting in TC50 values of 414 µM and 375 µM for HepG2-CYP3A4 and reference cells, respectively. Acetone and N-dealkylated tolterodine levels increased continuously over 24 h in HepG2-CYP3A4. Treatment with either a pan-CYP inhibitor, 1-aminobenzotriazole, or a CYP3A4 inhibitor, ketoconazole, considerably reduced the production of both metabolites in HepG2-CYP3A4 cells. These findings pave the way for the further development of non-invasive breath tests using unlabelled precursors to determine CYP enzyme activity in individuals.}, language = {en} } @misc{StockHoferSpankeetal., author = {Stock, Valentina and Hofer, Rebecca and Spanke, Vera A. and Liedl, Klaus R. and Troppmair, Jakob and Langer, Thierry and Dank, Christian and Gstach, Hubert and Kammerer, Sarah and Ruzsanyi, Veronika}, title = {Diisopromine as a non-labelled CYP3A4 substrate : implications for breath test development}, series = {Bioorganic chemistry}, volume = {163}, journal = {Bioorganic chemistry}, number = {6}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {0045-2068}, doi = {10.1016/j.bioorg.2025.108772}, pages = {1134 -- 1146}, abstract = {Breath tests for the prediction of patient-specific drug response require suitable substrates that when metabolised in the human body yield specific, unlabelled volatile metabolites. This study explores diisopromine as a potential substrate due to its structural similarity to tolterodine, the first identified non-labelled CYP3A4 substrate producing a volatile metabolite. In contrast to tolterodine, diisopromine contains a phenyl-group instead of p-cresol. During biotransformation, both compounds undergo N-dealkylation, forming acetone, though their non-volatile metabolites differ. Mass spectrometric techniques such as PTR-ToF-MS and LC-MS were used to determine volatile and non-volatile metabolites, respectively. A design of experiments was used to determine the optimal reaction time and substrate concentration of diisopromine to maximise the production of the non-volatile metabolite while maintaining high cell viability. The specificity for diisopromine was investigated with three different CYP isoforms using HepG2 clones that overexpress the respective isoform. As expected, highest levels of N-dealkylated diisopromine were obtained by CYP3A4, with minor contributions from CYP2D6 and CYP2C9. The absence of a stereocenter in diisopromine (i) enhances its biotransformation efficiency (yielding 1.5 times more N-dealkylated metabolite and 1.4 times more acetone than tolterodine), (ii) shifts its metabolism more towards N-dealkylation and (iii) decreases the toxicity to the cells (with TC50 values of almost 1000 μM). The production of both metabolites in HepG2-CYP3A4 cells was significantly inhibited following treatment with either 1-aminobenzotriazole or ketoconazole. These findings highlight that the minor structural modification in diisopromine enhances the biotransformation efficiency, paving the way for its potential development for a (non-) invasive CYP assay.}, language = {en} } @misc{StockHoferLiedletal., author = {Stock, Valentina and Hofer, Rebecca and Liedl, Klaus R. and Troppmair, Jakob and Langer, Thierry and Gstach, Hubert and Dank, Christian and Kammerer, Sarah and Ruzsanyi, Veronika}, title = {Towards the use of metabolic volatiles in breath for determining drug response : gstachamine as an unlabeled substrate to measure CYP3A4 activity}, series = {ChemMedChem : an official journal of the EFMC}, volume = {20}, journal = {ChemMedChem : an official journal of the EFMC}, number = {18}, publisher = {Wiley}, address = {Weinheim}, issn = {1860-7179}, doi = {10.1002/cmdc.202500492}, pages = {1134 -- 1146}, abstract = {Breath analysis is a promising noninvasive diagnostic tool, but the clinical applicability of breath tests depends on several factors. A salient criterion pertains to the presence of substrates with the ability to produce detectable volatile metabolites during the metabolism. In this work, we evaluated the potential of two candidate compounds, namely gstachidine and gstachamine, for their use in metabolic breath analysis. Both substrates were evaluated for their toxicity and metabolic conversion in HepG2 cell clones overexpressing CYP3A4. Gstachidine was found to be toxic and did not produce any volatile metabolite. In contrast, gstachamine successfully generated butanone as a volatile metabolite, making it the first substrate to yield a stable VOC detectable exclusively at low ppbV levels in breath. To characterize its biotransformation, we conducted time-dependent analyses, as well as CYP specificity, toxicity, and inhibition investigations regarding the production of N-dealkylated gstachamine or butanone. The results demonstrated that gstachamine had a high metabolic turnover and a strong CYP3A4-dependency in the production of the specific N-dealkylated metabolite. Furthermore, a substantial reduction in the production of both metabolites was observed in HepG2-CYP3A4 cells following treatment with CYP inhibitors 1-aminobenzotriazole or ketoconazole. The results suggest that gstachamine has potential for noninvasive CYP3A4 metabolism monitoring.}, language = {en} } @misc{JansenAlAssarafetal., author = {Jansen, Gerrit and Al, Marjon and Assaraf, Yehuda G. and Kammerer, Sarah and van Meerloo, Johan and Ossenkoppele, Gert J. and Cloos, Jacqueline and Peters, Godefridus J.}, title = {Statins markedly potentiate aminopeptidase inhibitor activity against (drug-resistant) human acute myeloid leukemia cells}, series = {Cancer drug resistance}, volume = {6}, journal = {Cancer drug resistance}, number = {2}, publisher = {OAE Publishing Inc.}, issn = {2578-532X}, doi = {10.20517/cdr.2023.20}, pages = {430 -- 446}, abstract = {Aim: This study aimed to decipher the molecular mechanism underlying the synergistic effect of inhibitors of the mevalonate-cholesterol pathway (i.e., statins) and aminopeptidase inhibitors (APis) on APi-sensitive and -resistant acute myeloid leukemia (AML) cells. Methods: U937 cells and their sublines with low and high levels of acquired resistance to (6S)-[(R)-2-((S)-Hydroxy-hydroxycarbamoyl-methoxy-methyl)-4-methyl-pentanoylamino]-3,3 dimethyl-butyric acid cyclopentyl ester (CHR2863), an APi prodrug, served as main AML cell line models. Drug combination effects were assessed with CHR2863 and in vitro non-toxic concentrations of various statins upon cell growth inhibition, cell cycle effects, and apoptosis induction. Mechanistic studies involved analysis of Rheb prenylation required for mTOR activation. Results: A strong synergy of CHR2863 with the statins simvastatin, fluvastatin, lovastatin, and pravastatin was demonstrated in U937 cells and two CHR2863-resistant sublines. This potent synergy between simvastatin and CHR2863 was also observed with a series of other human AML cell lines (e.g., THP1, MV4-11, and KG1), but not with acute lymphocytic leukemia or multiple solid tumor cell lines. This synergistic activity was: (i) specific for APis (e.g., CHR2863 and Bestatin), rather than for other cytotoxic agents; and (ii) corroborated by enhanced induction of apoptosis and cell cycle arrest which increased the sub-G1 fraction. Consistently, statin potentiation of CHR2863 activity was abrogated by co-administration of mevalonate and/or farnesyl pyrophosphate, suggesting the involvement of protein prenylation; this was experimentally confirmed by impaired Rheb prenylation by simvastatin. Conclusion: These novel findings suggest that the combined inhibitory effect of impaired Rheb prenylation and CHR2863-dependent mTOR inhibition instigates a potent synergistic inhibition of statins and APis on human AML cells.}, language = {en} }