Enhancing Effects of Theanine Liposomes as Chemotherapeutic Agents for Tumor Therapy

Chemotherapy is one of the most effective methods of treating tumors in clinical study currently, but drug side effects usually are unbearable to the patient, which also makes it difficult to continue chemotherapy. Enhanced drug efficacy and reduced drug side effects are the main strategies for tumor therapy. Herein, based on biochemical regulation, theanine liposomes were designed to adjuvant doxorubicin (DOX) therapy, which can reduce the adverse reactions and enhance the effect of DOX. Stigmasterol was applied instead of traditional cholesterol for reducing the risk of cardiovascular disease. The as-prepared theanine liposomes by two methods had optimal sizes (154.8 and 169.0 nm), which can effectively accumulate in tumor tissues. In vitro experiments demonstrated that the theanine liposomes had a good effect of sustaining drug release. Cell uptake indicated that the presence of theanine can effectively inhibit glutathione (GSH) levels in cells and increase the uptake of DOX. In tumor bearing mice experiments, the combination of the theanine liposomes and DOX showed a better tumor inhibitory effect with a smaller tumor volume (2.7 fold) compared with that of the free DOX group. Meanwhile, under the mediation of theanine, the amount of doxorubicin was greatly reduced to achieve the same therapeutic effect, and the side effects of the drug were largely inhibited. Therefore, theanine liposomes have great application potential in tumor chemotherapy.