Methyl eugenol induces potent anticancer effects in RB355 human retinoblastoma cells by inducing autophagy, cell cycle arrest and inhibition of PI3K/mTOR/Akt signalling pathway

Purpose: Retinoblastoma is one of the lethal malignancies in children. Approximately half of the children that are diagnosed with retinoblastoma die of this disease. Enucleation is commonly used for the treatment of retinoblastoma but this leads to loss of vision. Therefore there is an urgent need to look for viable chemotherapeutic agents for the treatment of retinoblastoma. Consistent with this, natural products can produce efficient anticancer agents and in the present study a plant-derived phenylpropene methyl eugenol (ME) was evaluated against retinoblastoma RB355 cells. Methods: The cytotoxic activity of this molecule was evaluated by MTT cell viability assay, while autophagic effects were evaluated by flow cytometry using acridine orange (AO)/monodansylcadaverine (AO/MDC) staining dyes. The effects on the cell cycle progression were analyzed by flow cytometry while the effects on mTOR/PI3K/Akt signalling pathway were assessed by western blot method. Results: The results indicated that ME exhibited an IC50 value of 50 mu M and exerted its cytotoxic effects in a dosedependent manner in RB355 cells. Moreover, it was observed that the ME lessens the cell viability and triggers G2/M cell cycle arrest. It was also observed that ME induced autophagy dose-dependently in retinoblastoma RB355 cells. Western blot analysis revealed that ME could modulate the mTOR/PI3K/Akt signalling pathway in RB355 cells at the IC50 concentration. Conclusions: The above results clearly indicate that ME is a potent anticancer agent and may be developed further as a possible anticancer lead molecule against retinoblastoma provided further in depth in vivo studies are carried out.