Jair Bar1, Ivan Gorn-Hondermann2, Patricia Moretto1, Theodore J Perkins3, Nima Niknejad2, David J Stewart1, Glenwood D Goss1, Jim Dimitroulakos4. 1. Division of Medical Oncology, University of Ottawa Faculty of Medicine and The Ottawa Hospital Cancer Centre, Ottawa, Ontario, Canada. 2. Centre for Cancer Therapeutics, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada. 3. Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada; Department of Biochemistry, University of Ottawa Faculty of Medicine, Ottawa, Ontario, Canada. 4. Centre for Cancer Therapeutics, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada; Department of Biochemistry, University of Ottawa Faculty of Medicine, Ottawa, Ontario, Canada. Electronic address: jdimitroulakos@ohri.ca.
Abstract
UNLABELLED: To identify the mechanisms of cisplatin resistance, global microRNA (miR) expression was tested. The expression of miR-145 was consistently higher in resistant cells. The expression of cyclin-dependent kinase 6 (CDK6), a potential target of miR-145, was lower in resistant cells, and inhibition of CDK4/6 protected cells from cisplatin. Cell cycle inhibition, currently being tested in clinical trials, might be antagonistic to cisplatin and other cytotoxic drugs. BACKGROUND: Non-small-cell lung cancer (NSCLC) is the leading cause of cancer-related death. Platinum-based chemotherapeutic drugs are the most active agents in treating advanced disease. Resistance to these drugs is common and multifactorial; insight into the molecular mechanisms involved will likely enhance efficacy. MATERIALS AND METHODS: A set of NSCLC platinum-resistant sublines was created from the Calu6 cell line. Cell viability was quantified using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Differentially expressed microRNAs (miRs) in these lines were identified using Affymetrix miR arrays. The potential genes targeted by these miRs were searched using the TargetScan algorithm. The expression levels of miRs and mRNA were tested using real-time polymerase chain reaction. RESULTS: miR-145 was reproducibly elevated in all the resistant sublines tested; however, modulation of miR-145 levels alone in these cells did not affect their response to cisplatin. A potential target of miR-145 is cyclin-dependent kinase 6 (CDK6), an important regulator of cell proliferation. The mRNA and protein levels of CDK6 were both downregulated in the resistant sublines. An inhibitor of CDK4/6 (PD0332991) protected parental NSCLC cells from cisplatin cytotoxicity. CONCLUSION: In the present study, we identified miRs differentially expressed in cisplatin-resistant cell lines, including miR-145. A predicted target of miR-145 is CDK6, and its expression was found to be downregulated in the resistant sublines, although not directly by miR-145. Inhibition of CDK6 antagonizes cisplatin-induced NSCLC cell cytotoxicity, suggesting that agents that inhibit CDK6 should be avoided during cisplatin therapy.
UNLABELLED: To identify the mechanisms of cisplatin resistance, global microRNA (miR) expression was tested. The expression of miR-145 was consistently higher in resistant cells. The expression of cyclin-dependent kinase 6 (CDK6), a potential target of miR-145, was lower in resistant cells, and inhibition of CDK4/6 protected cells from cisplatin. Cell cycle inhibition, currently being tested in clinical trials, might be antagonistic to cisplatin and other cytotoxic drugs. BACKGROUND:Non-small-cell lung cancer (NSCLC) is the leading cause of cancer-related death. Platinum-based chemotherapeutic drugs are the most active agents in treating advanced disease. Resistance to these drugs is common and multifactorial; insight into the molecular mechanisms involved will likely enhance efficacy. MATERIALS AND METHODS: A set of NSCLCplatinum-resistant sublines was created from the Calu6 cell line. Cell viability was quantified using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Differentially expressed microRNAs (miRs) in these lines were identified using Affymetrix miR arrays. The potential genes targeted by these miRs were searched using the TargetScan algorithm. The expression levels of miRs and mRNA were tested using real-time polymerase chain reaction. RESULTS:miR-145 was reproducibly elevated in all the resistant sublines tested; however, modulation of miR-145 levels alone in these cells did not affect their response to cisplatin. A potential target of miR-145 is cyclin-dependent kinase 6 (CDK6), an important regulator of cell proliferation. The mRNA and protein levels of CDK6 were both downregulated in the resistant sublines. An inhibitor of CDK4/6 (PD0332991) protected parental NSCLC cells from cisplatincytotoxicity. CONCLUSION: In the present study, we identified miRs differentially expressed in cisplatin-resistant cell lines, including miR-145. A predicted target of miR-145 is CDK6, and its expression was found to be downregulated in the resistant sublines, although not directly by miR-145. Inhibition of CDK6 antagonizes cisplatin-induced NSCLC cell cytotoxicity, suggesting that agents that inhibit CDK6 should be avoided during cisplatin therapy.
Authors: Chellappagounder Thangavel; Ettickan Boopathi; Yi Liu; Christopher McNair; Alex Haber; Maryna Perepelyuk; Anshul Bhardwaj; Sankar Addya; Adam Ertel; Sunday Shoyele; Ruth Birbe; Joseph M Salvino; Adam P Dicker; Karen E Knudsen; Robert B Den Journal: Clin Cancer Res Date: 2018-01-08 Impact factor: 12.531
Authors: Florian Bellutti; Anca-Sarmiza Tigan; Sofie Nebenfuehr; Marlies Dolezal; Markus Zojer; Reinhard Grausenburger; Svenja Hartenberger; Sebastian Kollmann; Eszter Doma; Michaela Prchal-Murphy; Iris Z Uras; Alexander Höllein; Donna S Neuberg; Benjamin L Ebert; Anna Ringler; Andre C Mueller; Joanna I Loizou; Philip W Hinds; Claus Vogl; Gerwin Heller; Stefan Kubicek; Johannes Zuber; Marcos Malumbres; Matthias Farlik; Andreas Villunger; Karoline Kollmann; Veronika Sexl Journal: Cancer Discov Date: 2018-06-13 Impact factor: 39.397