ABSTRACT
Objective@#To understand the mechanism of chemotherapy resistance in nasopharyngeal carcinoma under hypoxic conditions through the perspective of protein SUMOylation modification.@*Methods@#Cobalt chloride (CoCl2) was used to establish the hypoxic model of human nasopharyngeal carcinoma CNE1 cells. Then, the cell cycle was detected by flow cytometry, and the expression level of small ubiquitin-related modifier(SUMO) and cyclin-dependent kinase 6 (CDK6) proteins were detected by western blotting. MTT assay was used to determine the median lethal dose (IC50) of cancer cells against cisplatin, and enzyme-linked immunosorbent assay (ELISA) was used to determine lactate dehydrogenase (LDH) level.@*Results@#The cell cycle of CNE1 induced by hypoxia was arrested in G0/G1 phase.The results of Western blot showed that the protein expression level of CDK6 in CNE1 cells was lower than that in the control group (0.83±0.25 vs. 0.43±0.21, t=14.67, P=0.003). The protein level of conjugated SUMO1 was significantly lower than that in the control group (2.69±0.48 vs. 1.38±0.31, t=17.22, P=0.001), while the level of free SUMO1 protein was significantly higher than that in the control group (2.01±0.43 vs. 2.60±0.59, t=15.45, P=0.002).The LC50 of CNE1 cells in the control group was significantly lower than that in the hypoxic group (29.44 μg/ml vs. 97.72 μg/ml, t=12.79, P=0.001). After CNE1 cells received 50 μg/ml cisplatin for 48 h, the LDH content in the supernatant of the control group was significantly higher than that in the hypoxic group ((541.49±64.59) ng/ml vs. (234.67±41.03) ng/ml, t=11.94, P=0.007)). The apoptosis rate of CNE1 cells in the control group was significantly higher than that in the hypoxic group ((76.64±5.37)% vs. (32.84±4.77) ng/ml, t=8.49, P=0.003)).@*Conclusion@#Hypoxia can dissociate the covalent modification of CDK6 and SUMO1, inhibit cell cycle and increase the chemotherapy resistance of nasopharyngeal carcinoma.
ABSTRACT
Objective To establish a method for detecting the chemical compositions of “decocted first and defoamed” of Ephedra Herba by UPLC-DAD-TOF/MS coupled with HPLC-UV, so as to clarify the difference of chemical constituents among them. Methods The analysis was performed on an ACQUITY UPLC® BEH C18 column (50 mm × 2.1 mm, 1.7 μm ) by UPLC-DAD-TOF/MS with gradient elution. The mobile phase consists of methanol and 0.1% formic acid-water at a flow rate of 0.3 mL/min. The column temperature was 40 ℃. The information of compounds was acquired on positive and negative mode. Similarly, HPLC-UV was applied for measuring the content of alkaloids respectively. The C18 column was used, the mobile phase was acetonitrile-0.1% phosphoric acid (containing 0.05% triethylamine) (99 : 1) at the flow rate of 1 mL/min, the detective wavelength was set up at 210 nm, and the column temperature was 30 ℃. Results There were less content in the upper foam, and the chemical components in the lower liquid and the whole liquid were basically same. Five alkaloids and one carboxylic acid (4-hydroxy-7-methoxyl-2-quinoline carboxylic acid) was identified from all kinds of liquids. However, the content of alkaloids in the upper foam was very low, and the content of three alkaloids in the whole solution was slightly higher than that in the lower liquid. Conclusion The defoamed method may not be related to the chemical compositions of alkaloids, but it still needs further research and verification.