[Effect of combined application of psoralen and ultraviolet A for inducing NB4 cell apoptosis and its impact on Fas/FasL gene expressions].
OBJECTIVE
To explore the effect of combined application of psoralen (PSO, an extract from psoralea) and ultraviolet A (UVA) for inducing the apoptosis of human leukemic cell line NB4 and its impact on the Fas/FasL gene expressions.


METHODS
According to factorial design, changes of apoptosis rate and ultrastructure of NB4 cells, as well as the gene and protein expressions of Fas/FasL were observed after cells were treated with PSO in different concentrations and irradiated by UVA of 360 nm wavelength for different times, using flow cytometry, transmission electron microscopy and quantitative polymerase chain reaction (PCR), and the outcomes were treated with variable analysis.


RESULTS
(1) After treatment of PSO in concentration of 10, 20, 40, 80 microg/mL combined with a 5-min exposure of UVA, the NB4 cells apoptosis rate induced were 26.57% +/- 0.42%, 30.67% +/- 0.11%, 34.90% +/- 0.30% and 24.63% +/- 0.38% respectively. The effects were dose- and time-dependent, and an interaction was shown between the two actors. (2) After being treated by PSO plus UVA, obvious ultrastructure changes with apoptosis characteristics were shown in NB4 cell under electron microscope. (3) PSO plus UVA showed up-regulatory effect on gene and protein expressions of Fas, and down-regulatory effect on gene and protein expressions of FasL in a dose- and time-dependent manner, with the interaction between the two actors in altering Fas gene expression, also in altering FasL gene and protein expressions.


CONCLUSIONS
Combined application of PSO and UVA can induce the apoptosis of NB4 cells, and the Fas/FasL system is one of the pathways for apoptosis inducing.
Xiang
Yang
Y
Department of Traditional Chinese Medicine & Hematology, The 210th Hospital of PLA, Liaoning 116021.
Huang
Shi-lin
SL
Chen
Nan-nan
NN
D017209:Apoptosis / Q000187:drug effects* / Q000528:radiation effects*; D045744:Cell Line, Tumor; D053222:Fas Ligand Protein / Q000378:metabolism*; D005363:Ficusin / Q000494:pharmacology*; D015870:Gene Expression; D015973:Gene Expression Regulation, Leukemic; D006801:Humans; D014466:Ultraviolet Rays; D019014:fas Receptor / Q000378:metabolism*
C491901:FAS protein, human; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D019014:fas Receptor; D005363:Ficusin