Alcohol increases the risk of
carcinoma originated from oral epithelium, but the biological effects of ultra-low doses of
ethanol on existing
carcinoma cells in combination with natural substances are still unclear. A role for
ethanol (EtOH), taken in small amounts as an ingredient of some beverages or
mouthwashes to change the growth behavior of established
squamous cell carcinoma, has still not been examined sufficiently. We designed an in vitro study to determine the effect of
caffeic acid (CFA) on viability and migration ability of malignant oral epithelial keratinocytes, exposed to ultra-low concentrations (maximum 100 mmol/L) EtOH. MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-dimethyltetrazolium
bromide) and LDH (
lactate dehydrogenase) assays were used to assess the cytotoxic effect of EtOH/CFA and the viability of
squamous carcinoma SCC-25 cells (ATCC CRL-1628, mobile part of the tongue). Tested EtOH concentrations were: 2.5, 5, 10, 25, 50, and 100 mmol/L, along with an equal CFA concentration of 50 μmol/L.
Carcinoma cells' migration was investigated by monolayer "wound" healing assay. We demonstrated that very low concentrations of EtOH ranging between 2.5 and 10 mmol/L may induce the viability of
oral squamous cell carcinoma cells, while the results following addition of CFA reveal an antagonistic effect, attenuating pro-proliferative EtOH activity. The migration rate of oral
squamous carcinoma cells can be significantly inhibited by the biological activity of
caffeic acid.