Background:
Levels of cellular Reactive Oxygen Species (ROS) influence the oxidized/reduced
states of cellular proteins, and create redox-signaling pathways that can activate transcription factors, kinases,
and phosphatases. ROS levels can be increased radically by external factors, including ionizing and UV radiation or
exposure to chemical compounds. These increased ROS levels can, in turn, lead to oxidative damage of DNA.
Natural plant treatments against cancer can modulate these processes by inducing or decreasing ROS production.
Methods:
Here we report new observations that squamous carcinoma (SCC-25) cells, exposed to 24 hours of
combined resveratrol and berberine treatment, contain increased ROS levels. Using flow cytometry, for drug
activity characteristics, an accumulation of ROS was observed. A combination of different dyes, CellROX
Green (Life Technologies) and DCFH-DA (Sigma), allowed for flow cytometric estimation of levels of cellular
ROS as well as cellular localization.
Results:
Live staining and microscopic observations confirmed the accumulation of ROS in SCC-25 cells following
a combination treatment at concentrations of 10μg/ml. Additionally, the cytotoxicity of the compounds
was significantly improved after their combined application. Additive effects were observed for doses lower
than the calculated IC50 of berberine [IC50=23µg/ml] and resveratrol [IC50=9µg/ml]. Viability (MTS) assays and
analysis of isobolograms revealed a significant impact on cell viability upon combination treatment.
Conclusion:
These results suggest that administration of berberine, in the presence of resveratrol, could be
decreased even to 50% (half the IC50 for berberine) for cancer treatment.