Evaluation of apoptotic and cytotoxic effect of robinin in TPC-1 and SW1736 human thyroid cancer cells

Background: During the past few years, thyroid cancer (TC) has increased in terms of rate of morbidity and mortality. Plant flavonoids have shown positive effect in regulating thyroid tumorigenesis via inhibition of apoptosis. Robinin is a natural flavone glycoside isolated from Vinca erecta with potent pharmacological activities. Materials and Methods: In this study, we aimed to explore the apoptotic and cytotoxic activity of robinin against TPC-1 and SW1736 cells. Results: Robinin (20 μM/mL) significantly suppressed the growth and cell proliferation and induced apoptotic activity in TC cells. According to the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test, TPC-1 and SW1736 cancer cells revealed 100% cell viability. Robinin inhibited growth of TC cells in a dose-dependent manner. It was found that reactive oxygen species (ROS) generation in TPC-1 and SW1736 cancer cells was decreased; however, robinin (20 μM/mL) enhanced ROS formation. The study of apoptosis in TPC-1 and SW1736 cells revealed morphological changes and damaged nuclei. Robinin (20 μM/mL) triggered a powerful apoptosis signal and caused loss of membrane integrity in TC cells. It also increased the activity of caspases 8 and 9. Robinin (20 μM/mL) decreased the levels of Bcl-2, c-Myc, and cyclin-D1 and increased the levels of Bax and caspase-3 when compared to control and robinin-treated cells. It exhibited potent antiproliferative and apoptotic activity in TC cells. Conclusion: Robinin can be useful in the treatment of thyroid cancer.