Effect of Carboplatin and Methotrexate on Lipid Levels in the Plasma Membrane of MCF-7 Cells and their Association with Cell Motility.

Aim: We examine in this study the effect of two antitumor drugs metothrexate (MTX) and carboplatin (CPT) on the phospholipid content of plasma membrane of MCF-7 breast cancer cells. MTX is a folate analog that inhibit dihydrofolate reductase. CPT is a platinum-containing antineoplastic drug that inter-chelates DNA and inhibits replication. Methods: MCF-7 breast cancer cells were treated with different concentrations of CPT or MTX. Plasma membranes were purified and their protein contents were measured with and without drug treatment. We extracted the lipids from plasma membranes of drug-treated and control MCF-7 cells, quantitated, and separated by HPLC using a C18 reverse-phase column. The ability of both drugs to affect cell movement was studied using a motility assay. Results: MTX induced 50% cell death at concentrations ranging from 50 to 100 mM. No further decrease in viability was seen above this concentration even at 1 mM. CPT induced 50% cell death at 5 mM. It also showed a range concentration that gives a 50% cell death after 24 hrs of incubation. Protein levels in plasma membranes of treated cells doubled compared to control. Lipid levels in plasma membranes decrease insignificantly after drug treatment. No changes in separation pattern of lipid extracted from membranes were seen after CPT treatment compared to control; however, MTX treatment showed to a single change in elution pattern in peak at 4.36 min. Both drugs had little effect on cell motility causing a decrease of 13.3% and 17.4% with CPT and MTX respectively compared to control. Conclusions: Our results show that both drugs did not affect the amount of lipids but lead to doubling in the protein concentration in the plasma membranes of MCF-7 breast cancer cells. These drugs did not lead to a significant decrease in cell motility compared to control.