Antitumour effect of odoroside A and its derivative on human leukaemia cells through the ROS/JNK pathway

Abstract

Oleandrigenin‐3‐O‐β‐D‐diginoside (a derivative of odoroside A), isolated and purified by our group, has seldom been explored for its pharmacological activity. This study aimed at clarifying the mechanisms towards the leukaemia‐suppressive role of odoroside A (compound #1) and its derivative, oleandrigenin‐3‐O‐β‐D‐diginoside (compound #2) isolated from Nerium oleander. Viability and nuclear morphology change were assessed by CCK‐8 assay and fluorescence microscope, respectively. Then, the cell apoptosis and autophagy induced by the compounds were detected by flow cytometry and Western blot. Xenograft model of nude mice was also applied to measure the leukaemia‐suppressive effects of compound #2 in vivo. The result displayed that compound #1 and compound #2 inhibited the proliferation of HL60 and K562 cells and stronger effects were found in HL60 than K562 cells. Both of the compounds induced a dose‐dependent apoptosis and autophagy in HL60 cells, where compound #2 was more potent than compound #1. Compound #2 also demonstrated a time‐dependent apoptosis and autophagy in HL60 cells. Furthermore, ROS generation and JNK phosphorylation occurred in a dose‐dependent manner in the cells treated with compound #2. Mitochondria also played critical role, proved by the decrease of Bcl‐2, the release of cyto c to cytosol and the activation of caspase‐3 and caspase‐9. Moreover, the antitumour effects of compound #2 were validated in the nude mouse xenograft model in vivo. Odoroside A and its derivative inhibited the growth of leukaemia by inducing apoptosis and autophagy through the activation of ROS/JNK pathway. These results suggest that the compounds can serve as potential antitumour agents against leukaemia, especially acute myeloid leukaemia (AML).

The mechanistic role of cardiac glycosides in DNA damage response and repair signaling

“…2 , blue highlight). As demonstrated by the activity of the two compounds, oleandrin displays a better cancer proliferation inhibitory activity than odoroside A [ 13 ]. The difference in activity of these two compounds can also be attributed to the difference in stereochemistry of the sugar moiety (Fig.…”

“…2 , orange highlight). Additionally, the presence of the acetate group can increase the lipid solubility of the compound that consequently results in an enhanced chemical penetration through cellular membranes [ 13 ].…”

“…The increased levels of ROS and the induced DNA damage as an effect of CG treatment resulted in activation of the JNK signaling pathway [ 36 ]. In their work, Hu and co-workers demonstrated that CGs (odoroside A and oleandrin) suppress the growth of acute myeloid leukemia (AML) cells by increasing the production of ROS which activates the phosphorylation of JNK [ 13 ]. This, consequently, triggered light chain 3B (LC3B) and caspase-9/caspase-3 that induce autophagy and apoptosis, respectively.…”

“…The role of CGs in the ROS formation and activity in apoptosis and autophagy has been extensively reported [ 13 , 71 – 73 ]. Calderón-Montaño et al reported that a Nerium oleander extract (NOE)-induced levels of ROS were significantly higher than the basal levels [ 21 ].…”

“…Since then, the anti-cancer properties of CGs have generated considerable interest [ 8 – 12 ]. This includes a dramatic increase in the number of in vitro and in vivo studies evaluating the effects of cardiac glycosides on the inhibition of various types of cancer, demonstrating the ability to block cancer cell proliferation and subsequently cause cell death [ 13 – 17 ].…”