Inhibition of anticancer growth in Retinoblastoma cells by naturally occurring sesquiterpene nootkatone is mediated via autophagy, endogenous ROS production, cell cycle arrest and inhibition of NF-κB signalling pathway.

PURPOSE: The main aim of the present study was to determine the antiproliferative effects induced by nootkatone-a plant sesquiterpene ketone along with determining its effects on autophagy, reactive oxygen species (ROS) production, cell cycle, cell migration and NF-κB signalling pathway.
METHODS: Cell proliferation of HXO-Rb44 human retinoblastoma cell line was evaluated by CCK-8 assay, while autophagic effects were evaluated by electron microscopy and western blot. Effects on cell cycle and ROS production were evaluated by flow cytometry. In vitro wound healing assay was used to determine the effects on cell migration.
RESULTS: The results indicated that nootkatone induced significant and dose-dependent cytotoxicity in HXO-Rb44 retinoblastoma cells with an IC50 value of 10.2 μM. Electron microscopy and western blot showed that nootkatone could induce autophagy as autophagosomes and vacuoles were seen to develop after nootkatone treatment. Autophagy was confirmed by observing the expression levels of LC3B-II, LC3B-I and p62. Nootkatone led to an increase of LC3B-II and LC3B-I but also led to inhibition of p62 expression. Nootkatone also led to increase of ROS production dose-dependently along with inducing S-phase cell cycle arrest. Nootkatone also led to inhibition of cell migration along with inhibiting NF-κB signalling pathway.
CONCLUSIONS: In conclusion, nootkatone molecule inhibits retinoblastoma by inhibiting Nf-κB signalling pathway and cell migration, autophagy induction, ROS generation and S-phase cell cycle arrest.