Background: Miltefosine, an alkylphosphocholine, affects lipid metabolism and cell signaling by interacting with cell membranes. In this study, we aim to demonstrate the effect of miltefosine (hexadecylphosphocholine (HePC)) on the alterations of the membrane lipid content of human lung adenocarcinoma (A549) cells and normal human umbilical vein endothelial cells (HUVECs) in respect to the reduction of their membrane fluidity and metastatic potential of the cancer cells.

Methods: To study lateral diffusion in cell membranes, we employed membrane labeling with fusogenic liposomes followed by fluorescence recovery after photobleaching (FRAP) analysis. Cell viability was examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay; total cholesterol and sphingomyelin were measured using commercially available kits.

Results: Miltefosine inhibited cell growth and increased the total cholesterol in both cell lines (p < 0.05 for HUVEC and p < 0.01 for A549). Sphingomyelin levels were not significantly altered in A549 cells, but in HUVECs HePC caused a decrease in sphingomyelin (p < 0.05). Miltefosine treatment of A549 cells reduced the membrane diffusion coefficient (p < 0.001), which was associated with an increased half-time of fluorescent recovery (p < 0.05) measured by FRAP. These changes reflect a significant reduction in membrane fluidity in the cancer cells. In contrast, miltefosine induced a milder response in HUVECs, attenuating the diffusion coefficient (p < 0.05) but not affecting the half-time of fluorescent recovery. As a result, the reduction in membrane fluidity in HUVECs was less pronounced.

Conclusion: Miltefosine induces a decrease in membrane fluidity of cancer cells, and this effect was related to decreased cell viability and total cholesterol levels. Miltefosine may be an effective antitumor agent and has great potential as an adjuvant therapy in the future.