Proscillaridin A induces apoptosis and suppresses non-small-cell lung cancer tumor growth via calcium-induced DR4 upregulation

Abstract

Non-small-cell lung cancer (NSCLC) is the predominant histological type of lung cancer and is characterized by the highest mortality and incidence rates among these types of malignancies. Cardiac glycosides, a class of natural products, have been identified as a potential type of chemotherapeutic agent. This study aims to investigate the anti-cancer effects and the mechanisms of action of Proscillaridin A (P.A) in NSCLC cells. In vitro sodium–potassium pump (Na+/K+ ATPase) enzyme assays indicated that P.A is a direct Na+/K+ ATPase inhibitor. P.A showed potent cytotoxic effects in NSCLC cells at nanomolar levels. Treatment mechanism studies indicated that P.A elevated Ca2+ levels, activated the AMPK pathway and downregulated phosphorylation of ACC and mTOR. Subsequently, P.A increased death receptor 4 (DR4) expression and downregulated NF–κB. Interestingly, P.A selectively suppressed EGFR activation in EGFR mutant cells but not in EGFR wild-type cells. In vivo, P.A significantly suppressed tumor growth in nude mice compared to vehicle-treated mice. Compared with the Afatinib treatment group, P.A displayed less pharmaceutical toxicity, as the body weight of mice treated with P.A did not decrease as much as those treated with Afatinib. Consistent changes in protein levels were obtained from western blotting analysis of tumors and cell lines. Immunohistochemistry analysis of the tumors from P.A-treated mice showed a significant suppression of EGFR phosphorylation (Tyr 1173) and reduction of the cell proliferation marker Ki-67. Taken together, our results suggest that P.A is a promising anti-cancer therapeutic candidate for NSCLC.

Ouabain impairs cancer metabolism and activates AMPK-Src signaling pathway in human cancer cell lines

“…This discrepancy may result from the large differences with regard to the drug concentration and cellular contexts in the two studies, given that CGs are well known to initiate diverse signaling and biological effects at various concentrations in many cell types. Consistent with our data, other compounds in the CGs family, such as proscillaridin A, bufalin, and digitoxin, have been reported to induce AMPK activation at the nanomolar level in either cancer cell lines or normal human foreskin fibroblast cells, contributing to apoptosis or autophagy [ 26 – 29 ]. Interestingly, AMPK activation by proscillaridin A has been suggested to be correlated with the elevation of the intracellular Ca 2+ level, as the interruption of the NKA pump activity by CGs normally stimulates Na + /Ca 2+ exchange, leading to an increase in the calcium ion level [ 26 ].…”

“…Consistent with our data, other compounds in the CGs family, such as proscillaridin A, bufalin, and digitoxin, have been reported to induce AMPK activation at the nanomolar level in either cancer cell lines or normal human foreskin fibroblast cells, contributing to apoptosis or autophagy [ 26 – 29 ]. Interestingly, AMPK activation by proscillaridin A has been suggested to be correlated with the elevation of the intracellular Ca 2+ level, as the interruption of the NKA pump activity by CGs normally stimulates Na + /Ca 2+ exchange, leading to an increase in the calcium ion level [ 26 ]. The increased Ca 2+ concentration can consequently stimulate calmodulin-dependent kinase kinase β, which is another positive upstream regulator of AMPK [ 12 ].…”

Dysbiosis of the Salivary Microbiome Is Associated With Non-smoking Female Lung Cancer and Correlated With Immunocytochemistry Markers

“…These bacteria may shed different microbial bioactive molecules and affect the host ( 69 ). It is known that apoptosis is highly regulated and plays an important role in immune response and tumorigenesis ( 70 , 71 ). The p53 signaling pathway is recognized as a potential risk factor in lung adenocarcinoma tumorigenesis and survival ( 72 ).…”

Inhibition of JNK-Mediated Autophagy Promotes Proscillaridin A- Induced Apoptosis via ROS Generation, Intracellular Ca+2 Oscillation and Inhibiting STAT3 Signaling in Breast Cancer Cells

“…As indicated in Figure 3C , we noticed significant decrease in MMP in both MCF-7 and MDA-MB-231 cells. In previous studies, it has been shown that PSD-A increases intracellular Ca +2 level ( Li et al., 2018 ). Therefore, we determined the effect of PSD-A in MCF-7 and MDA-MB-231 cells by using Fluo-3AM.…”