Abstract
The water extract of Gracilaria tenuistipitata have been found to be protective against oxidative stress-induced cellular DNA damage, but the biological function of the ethanolic extracts of G. tenuistipitata (EEGT) is still unknown. In this study, the effect of EEGT on oral squamous cell cancer (OSCC) Ca9-22 cell line was examined in terms of the cell proliferation and oxidative stress responses. The cell viability of EEGT-treated OSCC cells was significantly reduced in a dose-response manner (p < 0.0001). The annexin V intensity and pan-caspase activity of EEGT-treated OSCC cells were significantly increased in a dose-response manner (p < 0.05 to 0.0001). EEGT significantly increased the reactive oxygen species (ROS) level (p < 0.0001) and decreased the glutathione (GSH) level (p < 0.01) in a dose-response manner. The mitochondrial membrane potential (MMP) of EEGT-treated OSCC cells was significantly decreased in a dose-response manner (p < 0.005). In conclusion, we have demonstrated that EEGT induced the growth inhibition and apoptosis of OSCC cells, which was accompanied by ROS increase, GSH depletion, caspase activation, and mitochondrial depolarization. Therefore, EEGT may have potent antitumor effect against oral cancer cells.
Highlights
Oral squamous cell cancer (OSCC) has high morbidity and mortality rates across the world because it is frequently found in advanced stages before therapy [1,2]
We found that the water extracts of G. tenuistipitata (AEGT) reduced hydrogen peroxide-induced oxidative DNA damage [9]
We have found that AEGT has more vitamin C content than ethanolic extracts of G. tenuistipitata (EEGT) and it may contribute to the higher anti-oxidative activity of AEGT
Summary
Oral squamous cell cancer (OSCC) has high morbidity and mortality rates across the world because it is frequently found in advanced stages before therapy [1,2]. Novel, effective therapy for OSCC treatment is still needed. Gracilaria algae have been cultivated in Taiwan for at least 50 years [7] and are abundant and cheap and used in natural medicines. Many species of Gracilaria algae are well established to be a potential source for drug discovery in natural medicines due to their antibacterial, antiviral, antifungal, antihypertensive, cytotoxic, spermicidal, embriotoxic, and anti-inflammatory effects [8]. We were interested in the biological effects of different extracts of G. tenuistipitata. The cellular response to the ethanol extracts of G. tenuistipitata (EEGT) was still unknown. In this study the biological effects for ethanolic extracts of EEGT on oral cancer cells were examined. We evaluated the possible antiproliferative effects against OSCC (Ca9-22) cells by EEGT as well as its possible mechanism involving apoptosis and oxidative stress
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