Cytotoxic effects of mistletoe (Viscum album L.) in head and neck squamous cell carcinoma cell lines

Head and neck squamous cell carcinoma is a complex disease with several etiologic factors and different molecular changes that may trigger certain events; it is also globally one of the most common malignancies in this topography. Extracts from Viscum album L. (VA) (mistletoe) have been used as adjuvant therapies with promising results in several types of cancer, mainly in European countries. In vitro studies have demonstrated that various types of VA may have cytotoxicity in carcinoma cells, activating the apoptotic cascade or leading cells to necrosis. This study aimed to verify the effects of three types of VA extracts (Iscador Qu Spezial, Iscador P and Iscador M) in squamous cell carcinoma of the tongue cell lines SCC9 and SCC25, not previously studied. A concentration of 0.3 mg/ml (IC50) of the drugs induced apoptosis, affecting gene expression and protein levels of AKT, PTEN and CYCLIN D1. It was concluded that VA extracts have a cytotoxic effect on SCC9 and SCC25 cell lines, but while SCC9 cell line was more resistant to the action of the drugs, Iscador Qu Spezial and Iscador M have higher cytotoxic potential in both cell lines compared to Iscador P.