Cells, tissues and reagents
Four NPC cell lines (C17, C666, NPC43-ve and NPC43+ve), kindly provided by Professor George Tsao were cultured with RPMI1640 medium (Invitrogen) supplemented with 10 % FBS, 1 % P/S and 4 µM Y27632 ROCK inhibitor (Enzo Life Sciences,. ALX-270-333). NPC tissue samples used in this study were obtained from patients admitted to Queen Mary Hospital, the University of Hong Kong. Tissues were fixed and subjected to histological examination. The study has been approved by the Institutional Review Board of The University of Hong Kong/Hospital Authority Hong Kong West Cluster (HKU/HA HKW IRB, UW16-428).
IDX (provided by Noxopharm Limited, Australia) was suspended in DMSO at 40 mg/mL (stock solution) and stored at –80 °C. Serial dilutions of the stock solution were freshly prepared in complete medium and kept for less than 4 weeks at -20 °C. In all cultures, the final concentration of DMSO in the medium was ≤0.1%.