Cytotoxicity and radiosensitizing effect of wogonin, an extract from Scutellaria litwinowii, in head and neck squamous cell carcinoma line HN5

Background: Radiotherapy is one of the most prominent techniques used in cancer therapy. However, efforts for finding new effective radiosensitizers in improvement of radiotherapy efficacy have been continued yet. Wogonin is a natural flavonoid from Scutellaria litwinowii with known cytotoxic effects in some cancer cells. Objective: To determine the potential of radiosensitizer effects of wogonin in a head and neck cancer cell line (HN5). Methods: This study was carried out in Omid Hospital and Herbal Medicine Research Center (Mashhad, Iran). HN5 cells were cultured in DMEM medium and incubated with different concentrations of wogonin (25-500 μg/ml) and were exposed to (2-10 Gray [Gy]) γ-rays. Cell viability was quantified by MTT assay in wogonin cytotoxicity assay after 24, 48 and 72 hours and in coincident radiation and wogonin therapy after 72 hours. Data were analyzed by performing one-way ANOVA in SPSS (V.16). P-value ≤ 0.05 was considered significant. Results: Wogonin decreased cell viability in HN5 cells as a timeand concentration-dependent manner. Wogonin could also enhance radiation-induced toxicity. For instance, while cell viability percentage in separate administration of wogonin (100 μM) and radiation (2 Gy) was significantly decreased to 53.98±2.76 and 74.97±1.05 respectively (p<0.001), wogonin 100 μM concurrent with 2 Gy radiation decreased the percentage of cell viability to 33.29±1.76 (p<0.001). Conclusion: Concurrent use of wogonin and radiation increased radiation sensitivity and cell death in HN5 cells. Therefore, wogonin is a good radiosensitizer candidate for more study.