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Berlin Brandenburg

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  • Article  (12)
  • Kent Academic Repository (University of Kent)  (12)
  • 1
    In: Löschmann, Nadine and Michaelis, Martin and Rothweiler, Florian and Voges, Yvonne and Balónová, Barbora and Blight, Barry A. and Cinatl, Jindrich (2016) ABCB1 as predominant resistance mechanism in cells with acquired SNS-032 resistance. Oncotarget, 7 (36). pp. 58051-58064.
    Description: The CDK inhibitor SNS-032 had previously exerted promising anti-neuroblastoma activity via CDK7 and 9 inhibition. ABCB1 expression was identified as major determinant of SNS-032 resistance. Here, we investigated the role of ABCB1 in acquired SNS-032 resistance. In contrast to ABCB1-expressing UKF-NB-3 sub-lines resistant to other ABCB1 substrates, SNS-032-adapted UKF-NB-3 (UKF-NB-3rSNS- 032300nM) cells remained sensitive to the non-ABCB1 substrate cisplatin and were completely re-sensitized to cytotoxic ABCB1 substrates by ABCB1 inhibition. Moreover, UKF-NB-3rSNS-032300nM cells remained similarly sensitive to CDK7 and 9 inhibition as UKF-NB-3 cells. In contrast, SHEPrSNS-0322000nM, the SNS-032-resistant sub-line of the neuroblastoma cell line SHEP, displayed low level SNS-032 resistance also when ABCB1 was inhibited. This discrepancy may be explained by the higher SNS-032 concentrations that were used to establish SHEPrSNS-0322000nM cells, since SHEP cells intrinsically express ABCB1 and are less sensitive to SNS-032 (IC50 912 nM) than UKF-NB-3 cells (IC50 153 nM). In conclusion, we show that ABCB1 expression represents the primary (sometimes exclusive) resistance mechanism in neuroblastoma cells with acquired resistance to SNS-032. Thus, ABCB1 inhibitors may increase the SNS-032 efficacy in ABCB1-expressing cells and prolong or avoid resistance formation.
    Keywords: RM Therapeutics. Pharmacology
    ISSN: 1949-2553
    Source: University of Kent
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  • 2
    In: Ahmad, Aamir and Sarin, Navin and Engel, Florian and Kalayda, Ganna V. and Mannewitz, Mareike and Cinatl, Jindrich and Rothweiler, Florian and Michaelis, Martin and Saafan, Hisham and Ritter, Christoph A. and Jaehde, Ulrich and Frötschl, Roland (2017) Cisplatin resistance in non-small cell lung cancer cells is associated with an abrogation of cisplatin-induced G2/M cell cycle arrest. PLOS ONE, 12 (7). e0181081.
    Description: The efficacy of cisplatin-based chemotherapy in cancer is limited by the occurrence of innate and acquired drug resistance. In order to better understand the mechanisms underlying acquired cisplatin resistance, we have compared the adenocarcinoma-derived non-small cell lung cancer (NSCLC) cell line A549 and its cisplatin-resistant sub-line A549rCDDP2000 with regard to cisplatin resistance mechanisms including cellular platinum accumulation, DNA-adduct formation, cell cycle alterations, apoptosis induction and activation of key players of DNA damage response. In A549rCDDP2000 cells, a cisplatin-induced G2/M cell cycle arrest was lacking and apoptosis was reduced compared to A549 cells, although equitoxic cisplatin concentrations resulted in comparable platinum-DNA adduct levels. These differences were accompanied by changes in the expression of proteins involved in DNA damage response. In A549 cells, cisplatin exposure led to a significantly higher expression of genes coding for proteins mediating G2/M arrest and apoptosis (mouse double minute 2 homolog (MDM2), xeroderma pigmentosum complementation group C (XPC), stress inducible protein (SIP) and p21) compared to resistant cells. This was underlined by significantly higher protein levels of phosphorylated Ataxia telangiectasia mutated (pAtm) and p53 in A549 cells compared to their respective untreated control. The results were compiled in a preliminary model of resistance-associated signaling alterations. In conclusion, these findings suggest that acquired resistance of NSCLC cells against cisplatin is the consequence of altered signaling leading to reduced G2/M cell cycle arrest and apoptosis.
    ISSN: 1932-6203
    Source: University of Kent
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  • 3
    In: Schneider, Constanze and Oellerich, Thomas and Baldauf, Hanna-Mari and Schwarz, Sarah-Marie and Thomas, Dominique and Flick, Robert and Bohnenberger, Hanibal and Kaderali, Lars and Stegmann, Lena and Cremer, Anjali and Martin, Margarethe and Lohmeyer, Julian and Michaelis, Martin and Hornung, Veit and Schliemann, Christoph and Berdel, Wolfgang E and Hartmann, Wolfgang and Wardelmann, Eva and Comoglio, Federico and Hansmann, Martin-Leo and Yakunin, Alexander F and Geisslinger, Gerd and Ströbel, Philipp and Ferreirós, Nerea and Serve, Hubert and Keppler, Oliver T and Cinatl, Jindrich (2016) SAMHD1 is a biomarker for cytarabine response and a therapeutic target in acute myeloid leukemia. Nature medicine, 23 (2). pp. 250-255.
    Description: The nucleoside analog cytarabine (Ara-C) is an essential component of primary and salvage chemotherapy regimens for acute myeloid leukemia (AML). After cellular uptake, Ara-C is converted into its therapeutically active triphosphate metabolite, Ara-CTP, which exerts antileukemic effects, primarily by inhibiting DNA synthesis in proliferating cells. Currently, a substantial fraction of patients with AML fail to respond effectively to Ara-C therapy, and reliable biomarkers for predicting the therapeutic response to Ara-C are lacking. SAMHD1 is a deoxynucleoside triphosphate (dNTP) triphosphohydrolase that cleaves physiological dNTPs into deoxyribonucleosides and inorganic triphosphate. Although it has been postulated that SAMHD1 sensitizes cancer cells to nucleoside-analog derivatives through the depletion of competing dNTPs, we show here that SAMHD1 reduces Ara-C cytotoxicity in AML cells. Mechanistically, dGTP-activated SAMHD1 hydrolyzes Ara-CTP, which results in a drastic reduction of Ara-CTP in leukemic cells. Loss of SAMHD1 activity-through genetic depletion, mutational inactivation of its triphosphohydrolase activity or proteasomal degradation using specialized, virus-like particles-potentiates the cytotoxicity of Ara-C in AML cells. In mouse models of retroviral AML transplantation, as well as in retrospective analyses of adult patients with AML, the response to Ara-C-containing therapy was inversely correlated with SAMHD1 expression. These results identify SAMHD1 as a potential biomarker for the stratification of patients with AML who might best respond to Ara-C-based therapy and as a target for treating Ara-C-refractory AML.
    Keywords: RM Therapeutics. Pharmacology
    ISSN: 1078-8956
    Source: University of Kent
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  • 4
    In: Isono, Makoto and Hoffmann, Michèle J and Pinkerneil, Maria and Sato, Akinori and Michaelis, Martin and Cinatl, Jindrich and Niegisch, Günter and Schulz, Wolfgang A (2017) Checkpoint kinase inhibitor AZD7762 strongly sensitises urothelial carcinoma cells to gemcitabine. Journal of experimental & clinical cancer research : CR, 36 (1). p. 1.
    Description: BACKGROUND More effective chemotherapies are urgently needed for bladder cancer, a major cause of morbidity and mortality worldwide. We therefore explored the efficacy of the combination of gemcitabine and AZD7762, a checkpoint kinase 1/2 (CHK1/2) inhibitor, for bladder cancer. METHODS Viability, clonogenicity, cell cycle distribution and apoptosis were assessed in urothelial cancer cell lines and various non-malignant urothelial cells treated with gemcitabine and AZD7762. DNA damage was assessed by γH2A.X and 53-BP1 staining and checkpoint activation was followed by Western blotting. Pharmacological inhibition of CHK1 and CHK2 was compared to downregulation of either CHK1 or CHK2 using siRNAs. RESULTS Combined use of gemcitabine and AZD7762 synergistically reduced urothelial carcinoma cell viability and colony formation relative to either single treatment. Non-malignant urothelial cells were substantially less sensitive to this drug combination. Gemcitabine plus AZD7762 inhibited cell cycle progression causing cell accumulation in S-phase. Moreover, the combination induced pronounced levels of apoptosis as indicated by an increase in the fraction of sub-G1 cells, in the levels of cleaved PARP, and in caspase 3/7 activity. Mechanistic investigations showed that AZD7762 treatment inhibited the repair of gemcitabine-induced double strand breaks by interference with CHK1, since siRNA-mediated depletion of CHK1 but not of CHK2 mimicked the effects of AZD7762. CONCLUSIONS AZD7762 enhanced sensitivity of urothelial carcinoma cells to gemcitabine by inhibiting DNA repair and disturbing checkpoints. Combining gemcitabine with CHK1 inhibition holds promise for urothelial cancer therapy.
    Keywords: RM Therapeutics. Pharmacology
    ISSN: 1756-9966
    Source: University of Kent
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  • 5
    In: Sarin, Navin and Engel, Florian and Kalayda, Ganna V and Frötschl, Roland and Cinatl, Jindrich and Rothweiler, Florian and Michaelis, Martin and Fröhlich, Holger and Jaehde, Ulrich (2016) Knowledge-based approach to identify key determinants of cisplatin sensitivity . International journal of clinical pharmacology and therapeutics, .
    Keywords: RM Therapeutics. Pharmacology
    ISSN: 0946-1965
    Source: University of Kent
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  • 6
    In: Das, Chandan Kanta and Linder, Benedikt and Bonn, Florian and Rothweiler, Florian and Dikic, Ivan and Michaelis, Martin and Cinatl, Jindrich and Mandal, Mahitosh and Kögel, Donat (2018) BAG3 Overexpression and Cytoprotective Autophagy Mediate Apoptosis Resistance in Chemoresistant Breast Cancer Cells. Neoplasia, 20 (3). pp. 263-279.
    Description: Target-specific treatment modalities are currently not available for triple-negative breast cancer (TNBC), and acquired chemotherapy resistance is a primary obstacle for the treatment of these tumors. Here we employed derivatives of BT-549 and MDA-MB-468 TNBC cell lines that were adapted to grow in the presence of either 5-Fluorouracil, Doxorubicin or Docetaxel in an aim to identify molecular pathways involved in the adaptation to drug-induced cell killing. All six drug-adapted BT-549 and MDA-MB-468 cell lines displayed cross resistance to chemotherapy and decreased apoptosis sensitivity. Expression of the anti-apoptotic co-chaperone BAG3 was notably enhanced in two thirds (4/6) of the six resistant lines simultaneously with higher expression of HSP70 in comparison to parental controls. Doxorubicin-resistant BT-549 (BT-549DOX) and 5-Fluorouracil-resistant MDA-MB-468 (MDA-MB-4685-FU) cells were chosen for further analysis with the autophagy inhibitor Bafilomycin A1 and lentiviral depletion of ATG5, indicating that enhanced cytoprotective autophagy partially contributes to increased drug resistance and cell survival. Stable lentiviral BAG3 depletion was associated with a robust down-regulation of Mcl-1, Bcl-2 and Bcl-xL, restoration of drug-induced apoptosis and reduced cell adhesion in these cells, and these death-sensitizing effects could be mimicked with the BAG3/Hsp70 interaction inhibitor YM-1 and by KRIBB11, a selective transcriptional inhibitor of HSF-1. Furthermore, BAG3 depletion was able to revert the EMT-like transcriptional changes observed in BT-549DOX and MDA-MB-4685-FU cells. In summary, genetic and pharmacological interference with BAG3 is capable to resensitize TNBC cells to treatment, underscoring its relevance for cell death resistance and as a target to overcome therapy resistance of breast cancer.
    Keywords: RM Therapeutics. Pharmacology
    ISSN: 1476-5586
    Source: University of Kent
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  • 7
    In: Vallo, Stefan and Rutz, Jochen and Kautsch, Miriam and Winkelmann, Ria and Michaelis, Martin and Wezel, Felix and Bartsch, Georg and Haferkamp, Axel and Rothweiler, Florian and Blaheta, Roman A and Cinatl, Jindrich (2017) Blocking integrin β1 decreases adhesion in chemoresistant urothelial cancer cell lines. Oncology letters, 14 (5). pp. 5513-5518.
    Description: Treatment failure in metastatic bladder cancer is commonly caused by acquisition of resistance to chemotherapy in association with tumor progression. Since alterations of integrins can influence the adhesive and invasive behaviors of urothelial bladder cancer cell lines, the present study aimed to evaluate the role of integrins in bladder cancer cells with acquired resistance to standard first-line chemotherapy with gemcitabine, and cisplatin. Therefore, four gemcitabine- and four cisplatin-resistant sublines out of a panel of four parental urothelial bladder cancer cell lines (TCC-SUP, HT1376, T24, and 5637) were used. Expression of integrin subunits α3, α5, α6, β1, β3, and β4 was detected using flow cytometry. Adhesion and chemotaxis were analyzed. For functional assays, integrin β1 was attenuated with a blocking antibody. In untreated cells, chemotaxis was upregulated in 3/4 gemcitabine-resistant sublines. In cisplatin-resistant cells, chemotaxis was enhanced in 2/4 cell lines. Acquired chemoresistance induced the upregulation of integrin β1 in all four tested gemcitabine-resistant sublines, as well as an upregulation in 3/4 cisplatin-resistant sublines compared with parental cell lines. Following the inhibition of integrin β1, adhesion to extracellular matrix components was downregulated in 3/4 gemcitabine-resistant sublines and in all four tested cisplatin-resistant sublines. Since integrin β1 is frequently upregulated in chemoresistant urothelial cancer cell lines and inhibition of integrin β1 may influence adhesion, further studies are warranted to evaluate integrin β1 as a potential therapeutic target for bladder cancer.
    Keywords: RM Therapeutics. Pharmacology
    ISSN: 1792-1074
    Source: University of Kent
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  • 8
    In: Vallo, Stefan and K�pp, Raoul and Michaelis, Martin and Rothweiler, Florian and Bartsch, Georg and Brandt, Maximilian and Gust, Kilian and Wezel, Felix and Blaheta, Roman and Haferkamp, Axel and Cinatl, Jindrich (2017) Resistance to nanoparticle albumin-bound paclitaxel is mediated by ABCB1 in urothelial cancer cells. Oncology Letters, 13 (6).
    Description: Nanoparticle albumin‑bound (nab)-paclitaxel appears to exhibit better response rates in patients with metastatic urothelial cancer of the bladder whom are pretreated with nab-paclitaxel compared with conventional paclitaxel. Paclitaxel may induce multidrug resistance in patients with cancer, while the mechanisms of resistance against paclitaxel are manifold. These include reduced function of pro‑apoptotic proteins, mutations of tubulin and overexpression of the drug transporter adenosine 5'‑triphosphate‑binding cassette transporter subfamily B, member 1 (ABCB1). To evaluate the role of ABCB1 in nab‑paclitaxel resistance in urothelial cancer cells, the bladder cancer cell lines T24 and TCC‑SUP, as well as sub‑lines with acquired resistance against gemcitabine (T24rGEMCI20 and TCC‑SUPrGEMCI20) and vinblastine (T24rVBL20 and TCC‑SUPrVBL20) were examined. For the functional inhibition of ABCB1, multi-tyrosine kinase inhibitors with ABCB1‑inhibiting properties, including cabozantinib and crizotinib, were used. Additional functional assessment was performed with cell lines stably transduced with a lentiviral vector encoding for ABCB1, and protein expression was determined by western blotting. It was indicated that cell lines overexpressing ABCB1 exhibited similar resistance profiles to nab‑paclitaxel and paclitaxel. Cabozantinib and crizotinib sensitized tumor cells to nab‑paclitaxel and paclitaxel in the same dose‑dependent manner in cell lines overexpressing ABCB1, without altering the downstream signaling of tyrosine kinases. These results suggest that the overexpression of ABCB1 confers resistance to nab‑paclitaxel in urothelial cancer cells. Additionally, small molecules may overcome resistance to anticancer drugs that are substrates of ABCB1.
    ISSN: 1792-1074
    Source: University of Kent
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  • 9
    In: Sarin, Navin and Engel, Florian and Rothweiler, Florian and Cinatl, Jindrich and Michaelis, Martin and Frötschl, Roland and Fröhlich, Holger and Kalayda, Ganna V (2018) Key Players of Cisplatin Resistance: Towards a Systems Pharmacology Approach. International Journal of Molecular Sciences, 19 (3). pp. 767-785.
    Description: The major obstacle in the clinical use of the antitumor drug cisplatin is inherent and acquired resistance. Typically, cisplatin resistance is not restricted to a single mechanism demanding for a systems pharmacology approach to understand a whole cell’s reaction to the drug. In this study, the cellular transcriptome of untreated and cisplatin-treated A549 non-small cell lung cancer cells and their cisplatin-resistant sub-line A549rCDDP2000 was screened with a whole genome array for relevant gene candidates. By combining statistical methods with available gene annotations and without a previously defined hypothesis HRas, MAPK14 (p38), CCL2, DOK1 and PTK2B were identified as genes possibly relevant for cisplatin resistance. These and related genes were further validated on transcriptome (qRT-PCR) and proteome (Western blot) level to select candidates contributing to resistance. HRas, p38, CCL2, DOK1, PTK2B and JNK3 were integrated into a model of resistance-associated signalling alterations describing differential gene and protein expression between cisplatin-sensitive and -resistant cells in reaction to cisplatin exposure.
    ISSN: 1422-0067
    Source: University of Kent
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  • 10
    In: Voges, Yvonne and Michaelis, Martin and Rothweiler, Florian and Schaller, Torsten and Schneider, Constanze and Politt, Katharina and Mernberger, Marco and Nist, Andrea and Stiewe, Thorsten and Wass, Mark N. and Rödel, Franz and Cinatl, Jindrich (2016) Effects of YM155 on survivin levels and viability in neuroblastoma cells with acquired drug resistance. Cell death & disease, 7 (10). e2410.
    Description: Resistance formation after initial therapy response (acquired resistance) is common in high-risk neuroblastoma patients. YM155 is a drug candidate that was introduced as a survivin suppressant. This mechanism was later challenged, and DNA damage induction and Mcl-1 depletion were suggested instead. Here we investigated the efficacy and mechanism of action of YM155 in neuroblastoma cells with acquired drug resistance. The efficacy of YM155 was determined in neuroblastoma cell lines and their sublines with acquired resistance to clinically relevant drugs. Survivin levels, Mcl-1 levels, and DNA damage formation were determined in response to YM155. RNAi-mediated depletion of survivin, Mcl-1, and p53 was performed to investigate their roles during YM155 treatment. Clinical YM155 concentrations affected the viability of drug-resistant neuroblastoma cells through survivin depletion and p53 activation. MDM2 inhibitor-induced p53 activation further enhanced YM155 activity. Loss of p53 function generally affected anti-neuroblastoma approaches targeting survivin. Upregulation of ABCB1 (causes YM155 efflux) and downregulation of SLC35F2 (causes YM155 uptake) mediated YM155-specific resistance. YM155-adapted cells displayed increased ABCB1 levels, decreased SLC35F2 levels, and a p53 mutation. YM155-adapted neuroblastoma cells were also characterized by decreased sensitivity to RNAi-mediated survivin depletion, further confirming survivin as a critical YM155 target in neuroblastoma. In conclusion, YM155 targets survivin in neuroblastoma. Furthermore, survivin is a promising therapeutic target for p53 wild-type neuroblastomas after resistance acquisition (neuroblastomas are rarely p53-mutated), potentially in combination with p53 activators. In addition, we show that the adaptation of cancer cells to molecular-targeted anticancer drugs is an effective strategy to elucidate a drug's mechanism of action.
    Keywords: RM Therapeutics. Pharmacology
    ISSN: 2041-4889
    Source: University of Kent
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