20( S )-ginsenoside Rh2 induces caspase-dependent promyelocytic leukemia-retinoic acid receptor A degradation in NB4 cells via Akt/Bax/caspase9 and TNF- /caspase8 signaling cascades

Background: Acute promyelocytic leukemia (APL) is a hematopoietic malignancy driven by promyelocyticleukemiaeretinoic acid receptor A (PML-RARA) fusion gene. The therapeutic drugs currently used totreat APL have adverse effects. 20(S)-ginsenoside Rh2 (GRh2) is an anticancer medicine with higheffectiveness and low toxicity. However, the underlying anticancer mechanisms of GRh2-induced PMLRARAdegradation and apoptosis in human APL cell line (NB4 cells) remain unclear. Methods: Apoptosis-related indicators and PML-RARA expression were determined to investigate theeffect of GRh2 on NB4 cells. Z-VAD-FMK, LY294002, and C 87, as inhibitors of caspase, and the phosphatidylinositol3-kinase (PI3K) and tumor necrosis factor-a (TNF-a ) pathways were used to clarify therelationship between GRh2-induced apoptosis and PML-RARA degradation. Results: GRh2 dose- and time-dependently decreased NB4 cell viability. GRh2-induced apoptosis, cellcycle arrest, and caspase3, caspase8, and caspase9 activation in NB4 cells after a 12-hour treatment. GRh2-induced apoptosis in NB4 cells was accompanied by massive production of reactive oxygen species,mitochondrial damage and upregulated Bax/Bcl-2 expression. GRh2 also induced PML/PML-RARAdegradation, PML nuclear bodies formation, and activation of the downstream p53 pathway in NB4cells. Z-VAD-FMK inhibited caspase activation and significantly reversed GRh2-induced apoptosis andPML-RARA degradation. GRh2 also upregulated TNF-a expression and inhibited Akt phosphorylation. LY294002, an inhibitor of the PI3K pathway, enhanced the antitumor effects of GRh2, and C 87, an inhibitorof the TNF-a pathway, reversed NB4 cell viability, and GRh2-mediated apoptosis in a caspase-8-dependent manner. Conclusion: GRh2 induced caspase-dependent PML-RARA degradation and apoptosis in NB4 cells via theAkt/Bax/caspase9 and TNF-a/caspase8 pathways. KCI Citation Count: 12