Investigating the Effect of Lippia Citriodora Leaf Hydro-Ethanolic Extract on Two Prostate Cancer Cell Lines PC-3 and LNCaP Alone and in Combination with Docetaxel

Abstract

Background: Prostate cancer is the most common cancer in men. Docetaxel is the most important drug for prostate cancer, but drug resistance reduces its effectiveness. One of the important strategies to increase the drug efficacy is the use of combination therapy. This study investigated toxic effect of Lippia citriodora leaf extract on two prostate cancer cell lines and its effect on docetaxel cytotoxicity.

Methods: Cytotoxicity of Lippia citriodora leaf extract was evaluated individually or in combination with docetaxel. Cells were cultured in 96-well plates. After treating cells with different concentrations of extracts and drugs, their survival was measured by MTT assay.

Results: Lippia citriodora leaf extract showed a highly toxic effect on prostate cancer cells. The extract at the highest concentration, decreased the percentage of viable cells to 18.01 ± 1.37 in PC-3 cells and to 20.80 ± 1.06 in LNCaP cells. The IC50 value of the extract was 78.14 mg/ml for PC-3 cells and 88.76 mg/ml for LNCaP cells. In addition, the extract increased the cytotoxicity of docetaxel. In the maximum increasing effect, the percentage of survival in PC-3 and LNCaP cells decreased from 50.87 ± 2.46 to 26.48 ± 1.12 and from 54.13 ± 1.83 to
28.84 ± 1.69, respectively.

Conclusion: Lippia citriodora leaf extract had a remarkable toxic effect on prostate cancer cells in vitro and increased docetaxel cytotoxicity. The antitumor effects of the extract can be further evaluated in vivo and clinical trials.