towards improved death receptor targeted therapy for ... - TI Pharma
towards improved death receptor targeted therapy for ... - TI Pharma towards improved death receptor targeted therapy for ... - TI Pharma
Chapter 6 The novel thymidylate synthase inhibitor Trifluorothymidine (TFT) and TRAIL synergistically eradicate non‐small cell lung cancer cells Kaamar Azijli, Ingrid van Roosmalen, Jorn Smit, Saravanan Yuvaraj, Masakazu Fukushima, Steven de Jong, Godefridus J. Peters, Irene V. Bijnsdorp, Frank A.E. Kruyt Submitted for publication
Chapter 6 ABSTRACT TRAIL is a tumor selective anti‐cancer agent that may be used for the treatment of non‐ small cell lung cancer (NSCLC). However, TRAIL resistance is frequently encountered. Here, the combined use of TRAIL with TFT, a thymidylate synthase inhibitor that causes DNA damage, was examined for sensitizing NSCLC cells to TRAIL. Interactions between TRAIL and TFT were studied in NSCLC cell culture models using growth inhibition and apoptosis assays. Western blotting and flow cytometry were used to investigate underlying mechanisms of tumor cell eradication. The combined treatment of TFT and TRAIL showed synergistic cytotoxicity in A549, H292, H322 and H460 cells. For synergistic activity the sequence of administration was important; TFT treatment followed by TRAIL exposure did not show sensitization. Combined TFT and TRAIL treatment for 24 h followed by 48 h of TFT alone was synergistic in all cell lines, with combination index (CI) values below 0.9. The treatments affected cell cycle progression, with TRAIL inducing a G1 arrest and TFT a G2/M arrest. TFT activated Chk2 and reduced Cdc25c levels known to cause G2/M arrest. TRAIL‐induced caspase‐dependent apoptosis was enhanced by TFT, whereas TFT alone mainly induced caspase‐independent death. Further analyses showed that TFT enhanced the expression of p53 and p21/WAF1, and p53 was involved in the increase of TRAIL‐R2 surface expression. TFT also caused down‐regulation of cFLIP and XIAP and increased Bax expression. TFT enhances TRAIL‐induced apoptosis in NSCLC cells by sensitizing the apoptotic machinery at different levels in the TRAIL pathway. Our findings suggest a possible therapeutic benefit of the combined use of TFT and TRAIL in NSCLC. Key Words: TRAIL, TFT, synergy, apoptosis, NSCLC ‐ 100 ‐
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Chapter 6<br />
The novel thymidylate synthase inhibitor<br />
Trifluorothymidine (TFT) and TRAIL synergistically<br />
eradicate non‐small cell lung cancer cells<br />
Kaamar Azijli, Ingrid van Roosmalen, Jorn Smit, Saravanan Yuvaraj,<br />
Masakazu Fukushima, Steven de Jong, Godefridus J. Peters, Irene V.<br />
Bijnsdorp, Frank A.E. Kruyt<br />
Submitted <strong>for</strong> publication
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