Src mediates extracellular signal‐regulated kinase 1/2 activation and autophagic cell death induced by cardiac glycosides in human non‐small cell lung cancer cell lines

Abstract

Aberrant Na(+) /K(+) -ATPases (NKA) expression is closely related to the incidence and development of cancer, making NKA targeted cancer therapy more intriguing. Cardiac glycosides (CGs) belong to NKA inhibitors and possess potent anti-cancer properties in many cancers. Our previous work demonstrates that CGs family member digoxin or ouabain induces autophagic cell death in human non-small cell lung cancer (NSCLC) cell lines through regulation of both mammalian target of rapamycin and extracellular signal-regulated kinase 1/2 (ERK1/2) pathway. However, what acts as an upstream regulator of ERK1/2 activation during autophagy induction remains obscure. In the present study, the role of Src in the ERK1/2 signaling pathway as well as autophagic cell death induced by either digoxin or ouabain was examined in A549 and H460 cells. Src is significantly activated simultaneously with mitogen-activated protein kinase kinase 1/2 (MEK1/2) and ERK1/2 activation upon the drug treatment. Moreover, Src inhibitor PP2 could block either drug induced MEK1/2 and ERK1/2 phosphorylation, together with autophagic phenotypes in the cells. Knockdown of Src with siRNA causes the similar effect as PP2, both of which markedly alleviate the drugs' cytotoxicity. In addition, increased levels of intracellular reactive oxygen species (ROS) are found to be involved in Src mediated autophagy. Together, this work provides evidences showing that Src mediates MEK1/2 and ERK1/2 pathway as well as ROS generation, and regulates autophagic cell death induced by the cardiac glycosides. These observations may further help understand the molecular mechanisms of autophagy induced by NKA inhibitors in NSCLC cells.

A new semisynthetic cardenolide analog 3β-[2-(1-amantadine)- 1-on-ethylamine]-digitoxigenin (AMANTADIG) affects G2/M cell cycle arrest and miRNA expression profiles and enhances proapoptotic survivin-2B expression in renal cell carcinoma cell lines

“…Our data showed the unchanged expression levels of MAPK1 mRNA and protein but significant increase of phosphorylated MAPK1 (pMAPK1), which is the functionally active form of MAPK1. This result is in agreement with previous publications that cardiac glycoside (ouabain) does not change total MAPK1 (ERK2) but increases pMAPK1 protein expression in rat renal epithelial cells, neuroblastoma cells and lung cancer cells [43–45]. …”

Liver cancer cells are sensitive to Lanatoside C induced cell death independent of their PTEN status

“…Cardiac glycosides have been reported to activate apoptosis or autophagy-induced cell death in a tissue-specific manner (Wang et al 2014;Xie and Cai 2003). In this study, we characterized liver cancer cell death as apoptosis.…”

CXCL1 Inhibits Airway Smooth Muscle Cell Migration through the Decoy Receptor Duffy Antigen Receptor for Chemokines

“…Using Western blotting, we could not detect b-arrestin 2 protein expression in ASMCs with or without CXCL1 stimulation (data not shown), suggesting that b-arrestin 2 is unlikely to mediate CXCL1/DARC-induced ERK-1/2 MAPK pathway activation. Moreover, neither inhibition of src nor blockade of epidermal growth factor receptor, two pathways known to mediate ERK-1/2 MAPK pathway activation (67) using the pharmacological inhibitor PP2 (68) and PD153035 (69), was able to inhibit CXCL1/ DARC-mediated ERK-1/2 MAPK pathway activation (data not shown), suggesting that they may not be involved in this activation. Instead, we chose to examine the effect of HSP90, a chaperone protein that was found to be involved in the activation of ERK1/2 MAPK pathway in vascular smooth muscle cells through direct association with phospho-ERK1/2 (46).…”