Alteration of membrane lipid biophysical properties and resistance of human lung adenocarcinoma A(549) cells to cisplatin

Alterations of membrane lipid biophysical properties of sensitive A(549) an d resistant A(549)/DDP cells to the Cis-dichlorodiammine platinum (Cisplati n) were performed by measurements of fluorescence and flow cytometry approa ches using fluorescence dyes of DPH, N-AS and Merocyanine 540 (MC 540) resp ectively. Fatty acids of membrane lipid of the two cell lines were analyzed by gas chromatography. The results indicated clearly that fluorescence pol arization (P) of the DPH probe is 0.169 for the sensitive A549 cell and 0.1 94 for the resistant A(549)/DDP cells. Statistical analysis showed signific ant difference between the two cell lines. The polarizations of 2-AS and 7- AS which reflect the fluidity of surface and middle of lipid bilayer are 0. 134 and 0.144 for the sensitive A549 cells as well as 0.171 and 0.178 for t he resistant A(549)/DDP cells respectively, but there is no significant dif ference of the polarization of 12-AS between the two cell lines. This shows that alterations of the membrane fluidity of both cells were mainly locate d on the surface and middle of the lipid bilayer. In addition, the packing density of phospholipid molecules in the membrane of the two cell lines det ected by MC540 probe indicated that lipid packing of A549 cell membranes wa s looser than that of the A(549)-DDP cells. And unsaturation degree of plas ma membrane fatty acids of the A(549)/DDP cells was also lower than that of A(549) cells. Taken together, it was proposed that the alteration of membr ane lipid biophysical state may be involved in the resistance of A(549)/DDP cells to cisplatin.