Does Verapamil Reverse The Drug-resistance Of Lung Adenocarcinoma Cell Line A549/T To Taxol Through Gap Junction Intercellular Communication Changes?

Objective: To study how Verapamil (one drug resistance reverser) change the state of gap junction intercellular communication and intracellular calcium between the lung adenocarcinoma cell line A549 and its drug resistance cell ling A549/T, and exploring the mechanisms.Methods: Firstly we choose identified drug resistance reverser-Verapamil , which could be testified to change the characterization of lung adenocarcinoma cell line A549/T resistance to Taxol by MTT-way. Secondly we examine expression of connexin43 and MRP1 of these two cell lines through flow cytometry at different times and different concentration of verapamil. Finally we use the confocal laser scanning microscope to detect the concentration changes of calium of two cell lines;and use fluorescence redistribution after photobleaching to examine gap junction intercellular communication. Results:Part I:The drug resistance of A549/T cell line to Taxol is as 50-80 times as A549 cell line . After we give different concentration ofVerapamil,we can find A549/T lose its characterization of drug resistance.Part II:The expression of MRP1 of A549/T is much higher than A549 cell line(65.22±1.74%Vs 1.69±0.32%, P<0.01) , but if verapamil is given the MRP1 expression is reduced obviously. The level of expression of CX43 of A549/T is lower than A549 cell line (4.11±0.41% vs 12.49±0.37%,P<0.05).When given Verapamil, the level of CX43 on A549/T get higher as time goes and the concertration climb. The dependability analysis show the negative correlation between these two indexes. PartIII:The concentration of intracellular calcium([Ca]i) are quite different between these two cell lines(A549 vs A549/T 25.90±2.06 vs 13.91±1.91, P<0.01) , and the level are improved when they are given by verapamil. But in these two cell lines , the change of [Ca]I between 10-20ug/ml have no significance, on the other hand, both of these two cell lines have dysfunctional GJIC, and verapamil have no effect on them. The dependability analysis show the negative correlation between [Ca]I and expression of MRP1 (r=-0.768,P=0.044) , the positivecorrelation between [Ca]I and expression of CX43 (r=0.916,P=0.004) in A549/T cell lines.Conclusion: The mechanism of verapamil to reverse drug resistancein lung adenocarcinoma cell line have some relationship with calcium change in cell, but it could not reverse drug resistance through GJIC.