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) and resistant A(549)/DDP cells to the Cis-dichlorodiammine platinum (Cisplatin) were performed by measurements of fluorescence and flow cytometry approaches using fluorescence dyes of DPH, N-AS and Merocyanine 540 (MC 540) respectively. Fatty acids of membrane lipid of the two cell lines were analyzed by gas chromatography. The results indicated clearly that fluorescence polarization (P) of the DPH probe is 0.169 for the sensitive A(549) cell and 0.194 for the resistant A(549)/DDP cells. Statistical analysis showed significant 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 the resistant A(549)/DDP cells respectively, but there is no significant difference of the polarization of 12-AS between the two cell lines. This shows that alterations of the membrane fluidity of both cells were mainly located 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 detected by MC540 probe indicated that lipid packing of A(549) cell membranes was looser than that of the A(549)/DDP cells. And unsaturation degree of plasma 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 membrane lipid biophysical state may be involved in the resistance of A(549)/DDP cells to cisplatin.