Cardiac glycoside sensitized hepatocellular carcinoma cells to TRAIL via ROS generation, p38MAPK, mitochondrial transition, and autophagy mediation

Abstract

A major concern in the clinical application of tumor necrosis factor related apoptosis‐inducing ligand (TRAIL) in tumors is the development of resistance. Therefore, agents that can potentially restore TRAIL sensitivity are important therapeutic targets for cancer treatment. Herein, we evaluated lanatoside c and digoxin, both of which are widely used cardiac glycosides (CGs), for their ability to sensitize human hepatocellular carcinoma cells (Huh‐7 and HepG2) through TRAIL‐induced apoptosis. CGs functionalize TRAIL as shown by its effect on intracellular reactive oxygen species (ROS) generation, which damages mitochondrial integrity and thereby confers intrinsic apoptotic caspase cascade during combined treatment. Caspase activation is dependent on ROS as shown by the ability of CGs to generate ROS and the ROS‐N‐acetylcysteine (NAC) relationship, which inhibits apoptosis during cotreatment by preventing the formation of caspase‐8 and ‐3. Furthermore, CGs triggered p38MAPK phosphorylation and NAC pre‐exposure blocked p38MAPK phosphorylation, which demonstrated that p38MAPK was dependent upon ROS generation. Additionally, CGs were found to be potent inducers of AMPK‐mediated protective autophagy as pharmacological and genetic autophagy inhibition reached the higher threshold of TRAIL‐mediated apoptosis. Finally, CGs downregulated the expression of the antiapoptotic protein Bcl‐2 and increased the translocation of proapoptotic protein cytochrome c, thereby inducing apoptosis. Collectively, these results indicate that CGs potentiate the enhanced cytotoxic capacity to TRAIL through ROS generation, p38MAPK phosphorylation, cell survival protein downregulation, and protective autophagy inhibition.

Cardiac Glycoside Ouabain Exerts Anticancer Activity via Downregulation of STAT3

“…Ouabain treatment could induce apoptosis through the decrease of intracellular K + and increase of intracellular Na + and Ca 2+ (30)(31)(32), and the suppression of anti-apoptotic and pro-survival genes by STAT3 inactivation could synergistically promote these apoptosis-inducing effects. In addition, it has been shown digoxin and lanatoside C upregulated the ROS generation in hepatocellular carcinoma cells (33), and our data also revealed similar effects in ouabaintreated cancer cells. Ouabain was able to inhibit DNA damage repair directly by the Fanconi anemia/BRCA pathway (34) or indirectly by STAT3 inactivation (35)(36)(37), thus ouabain treatment could remarkably induce DNA double-strand breaks.…”

Metabolomic approach to characterize the metabolic phenotypes and varied response to ouabain of diffuse large B-cell lymphoma cells

“…These data indicated that hypoxanthine and guanine degradation were increased or hypoxanthine and guanine synthesis were blocked in Su-DHL4 cells, while level of NADPH for anti-oxidant was elevated in OCI-Ly3 cells. It is well documented that enhanced ROS level is related to apoptosis (Figure 5(A)) [35][36][37][38]. As showed, ROS generation was significantly elevated in Su-DHL4 cells with ouabain rather than in OCI-Ly3 cells (Figured 5(B)).…”

“…The catabolism of hypoxanthine and guanine into uric acid produces much ROS [33,34]. Moreover, previous studies showed that ouabain induced cell apoptosis by promoting ROS generation [35][36][37][38]. So we speculated that different antioxidant capacity may contribute to differential apoptosis rate induced by ouabain.…”

cRGDyK‑modified procaine liposome inhibits the proliferation and motility of glioma cells via the ERK/p38MAPK pathway

“…The involvement of the ERK/p38 MAPK pathway in the progression of several types of cancer, including glioma, has already been revealed (14). Several oncogenes have been shown to affect the progression and metastasis of multiple types of cancer, including breast, lung and gastric cancer, through this pathway, and numerous drugs targeting the ERK/p38MAPK pathway have been developed or are in clinical trials (15).…”