Background: Every year there are several hundred thousand new cases of oral cancer worldwide. Clinical oncology is still challenged by toxicity and side effects of multimodal therapy strategies in which is associated with poor prognosis for patients. There is an urgent necessity to develop novel therapy strategies. As the majority of anticancer drugs are of natural origin, natural products represent a valuable source for the identification and development of novel treatment options for cancer. The aim of this investigation was to study the cytotoxicity of Salvia officinalis L. (sage) essential oil.
Methods: Salvia officinalis essential oil was gained by aqueous extraction from plant material and subsequently analyzed by gas chromatography. The cytotoxicity of the essential oil on the squamous human cell carcinoma cell line of the oral cavity (UMSCC1) was assessed with the XTT assay. These experiments revealed the half maximal inhibitory concentration (IC(50)) of the essential oil. It was used in the microarray-based analysis of gene expression of UMSSC1 cells. The results were submitted to a signaling pathway analysis.
Results: The main constituents of Salvia officinalis essential oil include the monoterpenes thujone, β-pinene, and 1,8-cineol. Low concentrations of the essential oil increased vitality of the UMSCC1 cells. Beyond the concentration of the IC(50) of 135 µg/ml, sage essential oil reduced UMSSC1 cells viability to a minimum. In the microarray gene expression analysis, genes involved in cancer, cellular growth and proliferation, cell death, cell morphology, cell cycle, gene expression, and DNA repair were the most prominent. The three most significantly regulated pathways by sage were aryl hydrocarbon receptor signaling, cell cycle (G1/S checkpoint) regulation, and p53 signaling.
Conclusion: To the best of our knowledge, this study suggests for the first time the ability of Salvia officinalis essential oil to inhibit human HNSCC cell growth. The therapeutic potential of sage essential oil might exceed that of its common use in otorhinolaryngology.