Study On The Regulatory Mechanism Of Schisandrin B On Tumor Sensitivity Of Non-small-cell Lung Cancer Cells

Fructus Schisandrae Chinensis belongs to the Schisandra chinensis(Turcz.)Baill.Fructus Schisandrae Chinensis has been traditionally used in China for the treatment of dyspnea,cough,mouth spontaneous diaporesis,nocturnal diaphoresis,nocturnal emission,dysentery,insomnia and amnesia.Recent research indicates that the extraction of Fructus Schisandrae Chinensis,especially the lignans of Schisandra has anti-tumor effects.The research that lignans of Schisandra enhances tumor cell sensitivity to chemotherapy has become anew hotspot.TRAIL is an anti-tumor agent with high selectivity for tumor cells as opposed to normal cells.Although many studies have indicated that TRAIL could induce a variety of human or murine tumor cell apoptosis,a lot of primary tumor exhibits higher resistance to TRAIL,and the non-small-cell lung carcinoma(A549)is one of those.It is discovered in study at present that lignans of Schisandra combined with TRAIL could significantly increase the sensitivity of A549 to TRAIL.In this article,a research on the active constituent from lignans of Schisandra which increases the sensitivity of A549 to TRAIL and mechanism of action will be proceed on the basis of previous research.Firstly,the research was screened the efficacious components which could increase the sensitivity of A549 cells to TRAIL from lignans of Schisandra.The results show that TRAIL or lignans of Schisandra had no effects on A549 cells,whereas Deoxyschizandrin,Schizandrin B or Schisandrol B combined with TRAIL could decrease the viability and livability of A549 cells.The Schizandrin B was the most effective.A549 cells survival rate was 65.3%by treated with Schizandrin B(50μmol/L)combined with TRAIL(100 ng/ml)for 18h..The survival rate was hightened with the increase of Schizandrin B dose,A549 cells were inhibited proliferation by treated with Schizandrin B(50μmol/L)combined with TRAIL(100 ng/ml)for 12h.Then the death mode of A549 cells was definited by analyzing of the related index of apoptosis.The results show that schisandrin B could inhance TRAIL-induced apoptosis by exciting eversion of PS,increasing hypodiploid apex and activating caspase 3.Secondly,the effect of TRAIL and schisandrin B on TRAIL death receptor was studyed.The resuilts showed that the expression of DR4 mRNA and DR5 mRNA were up-regulated with the increase of Schizandrin B dose and action time.The effect was evident by treated with schisandrin B(30-50μmol/L)for 6h.Schisandrin B could significantly stimulate the distribution of DR4 and DR5 receptor on cell membrane.The effect of apoptosis by TRAIL combinded with Schisandrin B was restrained after inhibiting the DR4 and DR5.Thirdly,the effect of schisandrin B on inhibitor of apoptosis protein FLIP was studyed.It was found that schisandrin B could dose-dependently reduced FLIP1 and FLIPS expression.At the same time,schisandrin B combined with TRAIL synergism greatly suppressed by over expression of FLIP1 and FLIPS.The study on influence of TRAIL combinded with schisandrin B for gene in lung cancer cells through GeneChip.The results indicated that only 4 genes were up-regulated by TRAIL,14 genes were up-regulated by Sch B(10 mol/L)and 19 genes were down-regulated.when concentration of Sch B was 50 mol/L,57 genes were up-regulated and 17 genes were down-regulated.The expression of 80 genes was significantly higher and 31 genes was lower by treated with TRAIL combinded with Schisandrin B(50 mol/L).The most obviously up-regulated were CHOP and CHAC1,the most obviously down-regulated was PLK2.Finally,mechanism of endoplasmic reticulum stress on effect of schisandrin B inhance TRAIL-induced apoptosis in lung cance cells was inspected.The results showed that schisandrin B could dependently stimulanted CHOP mRNA and protein expression,and stimulation of CHOP transcription.schisandrin B sensitivity response elements located in the CHOP promoter(-649,-280).At the same time,CHOP is also involved in schisandrin B on DR5 up-regulation effect.In addition,the Chac1 was an important downstream genes of CHOP.The apoptosis of A549cells by TRAIL combinded with Schisandrin B was restrained after inhibiting the Chac 1.In conclusion,schisandrin B had enhanced lung cancer cell sensitivity to TRAIL via many signal transduction pathways.On the one hand schisandrin B showed inhibition of the apoptosis protein FLIP degradation,on the other hand,activation of CHOP by endoplasmic reticulum stress.Then CHOP promote DR5 transcriptional activation and Chac1 expression.The research established foundation for further studying application of Schisandra lignans on anti-tumor.