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Berlin Brandenburg

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  • 2017  (4)
  • Kent Academic Repository (University of Kent)  (4)
  • 1
    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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  • 2
    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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  • 3
    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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  • 4
    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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