The Effect Of JNK On The Expression Of MRP1in A549and A549/DDP

AIM: To study the the expression of p-JNK that an active form of c-Jun N-terminalkinase (JNK) phosphorylation and multidrug resistant protein1(MRP1) in lung cancercells,as well as the effect of JNK on the expression of MRP1gene and the drug-resistant inA549/DDP.METHODS: The lung cancer cells A549and resistant strains A549/DDP as the researchobject,firstly,the expression of JNK, MRP1mRNA in A549and A549/DDP was assayed byreal-time fluorescent quantitative PCR. The expression of JNK，p-JNK，MRP1protein wasassayed by western blot.Afterwards, added JNK specificity inhibitor SP600125to A549andA549/DDP respectively, the influence of JNK to the expression of MRP1gene was assayedby real-time fluorescent quantitative PCR. the influence of JNK to the expression of MRP1protein was assayed by western blot. The efflux function of MRP1was detected by Flowcytometry.The chemosensitivity of A549and A549/DDP was determined by the MTTmethod.RESULTS: The results of real-time fluorescent quantitative PCR showed that therelative expression level of JNK mRNA in A549and A549/DDP were26.06±0.42%，36.85±0.84%，and that of MRP1mRNA were24.51±0.38%，54.72±0.09%；The results ofwestern blot show that MRP1/β-actin，P-JNK/β-actin，JNK/β-actin of A549respectivelywere5.64±0.13，2.33±0.05，0.14±0.01, and that of A549/DDP respectively was7.77±0.09，2.74±0.02，0.16±0.01.After adding JNK specificity inhibitor SP600125to A549and A549/DDP respectively, the results of real-time fluorescent quantitative PCR showed thatthe relative expression level of JNK mRNA decreased respectively from36.85±0.84%to22.07±0.65%(P<0.05),and that of MRP1mRNA decreased respectively from54.72±0.09%to39.50±0.49%(P<0.05) in A549/DDP. The results of western blot show that the expressionlevel of JNK,p-JNK,MRP1protein decreased respectively from2.82±0.09，2.15±0.72，10.71±0.22to1.83±0.12，1.09±0.34，8.67±0.10(P<0.05). The results of Flow cytometryshow that the efflux function of MRP1in the two cells decreased in different degree. Theresults of MTT show that The chemosensitivity of A549and A549/DDP increased in differentdegree.CONCLUSIONS: MRP1,p-JNK and JNK all express in A549and A549/DDP, and thatis higher in A549/DDP than that in A549. Restrain JNK phosphorylation,the relative expression level of MRP1gene and protein both decreased in A549and A549/DDP.So thedrug resistance of the cells reversed.