Ets1 mediates sorafenib resistance by regulating mitochondrial ROS pathway in hepatocellular carcinoma

Abstract

The incidence and mortality of hepatocellular carcinoma (HCC) are on a rise in the Western countries including US, attributed mostly to late detection. Sorafenib has been the first-line FDA-approved drug for advanced unresectable HCC for almost a decade, but with limited efficacy due to the development of resistance. More recently, several other multi-kinase inhibitors (lenvatinib, cabozantinib, regorafenib), human monoclonal antibody (ramucirumab), and immune checkpoint inhibitors (nivolumab, pembrolizumab) have been approved as systemic therapies. Despite this, the median survival of patients is not significantly increased. Understanding of the molecular mechanism(s) that govern HCC resistance is critically needed to increase efficacy of current drugs and to develop more efficacious ones in the future. Our studies with sorafenib-resistant (soraR) HCC cells using transcription factor RT2 Profiler PCR Arrays revealed an increase in E26 transformation–specific-1 (Ets-1) transcription factor in all soraR cells. HCC TMA studies showed an increase in Ets-1 expression in advanced HCC compared to the normal livers. Overexpression or knocking down Ets-1 modulated sorafenib resistance-related epithelial–mesenchymal transition (EMT), migration, and cell survival. In addition, the soraR cells showed a significant reduction of mitochondrial damage and mitochondrial reactive oxygen species (mROS) generation, which were antagonized by knocking down Ets-1 expression. More in-depth analysis identified GPX-2 as a downstream mediator of Ets-1-induced sorafenib resistance, which was down-regulated by Ets-1 knockdown while other antioxidant pathway genes were not affected. Interestingly, knocking down GPX2 expression significantly increased sorafenib sensitivity in the soraR cells. Our studies indicate the activation of a novel Ets-1–GPX2 signaling axis in soraR cells, targeting which might successfully antagonize resistance and increase efficacy.

Drug resistance mechanism of kinase inhibitors in the treatment of hepatocellular carcinoma

“…It has been shown that the transcription factor E26 transformation–specific-1(Ets-1), which is commonly increased in sorafenib-resistant tumor cells, promotes key EMT gene expression ( Gluck et al, 2019 ). Further studies by Vishnoi et al (2022) identified antioxidant protein GPX2 as a downstream mediator of Ets-1 induced sorafenib resistance, and knockdown of GPX2 expression significantly increased the sensitivity of sorafenib resistant cells to sorafenib ( Vishnoi et al, 2022 ). The results indicate the activation of a novel Ets-1-GPX2 signaling axis in sorafenib resistant cells, targeting which might successfully antagonize resistance ( Vishnoi et al, 2022 ).…”

“…Further studies by Vishnoi et al (2022) identified antioxidant protein GPX2 as a downstream mediator of Ets-1 induced sorafenib resistance, and knockdown of GPX2 expression significantly increased the sensitivity of sorafenib resistant cells to sorafenib ( Vishnoi et al, 2022 ). The results indicate the activation of a novel Ets-1-GPX2 signaling axis in sorafenib resistant cells, targeting which might successfully antagonize resistance ( Vishnoi et al, 2022 ). Tan et al (2019) found that tumor necrosis factor (TNF-α), a key cellular inflammatory factor, can promote sorafenib resistance in HCC cells by inducing EMT through activating the TNF-α/NF-κB/EMT pathway, and inhibition of TNF-α expression using ulinastatin significantly enhanced the anti-tumor effect of sorafenib in HCC cells with high TNF-α expression.…”

TPX2 enhances the transcription factor activation of PXR and enhances the resistance of hepatocellular carcinoma cells to antitumor drugs

“…At present, it is generally believed that unlike NSCLC, mutations in TKIs (such as sorafenib) targets, which include receptor tyrosine kinases (RTKs, such as vascular endothelial growth factor receptor [VEGFR], platelet-derived growth factor [PDGFR], or c-kit or the kinase associated with the mitogen-activated protein kinase/phosphoinositide 3 kinase protein kinase B [MAPK/PI3K-AKT pathway]) in HCC cells are not the main mechanism for the difference in sensitivity or resistance to sorafenib in HCC patients [ 37 , 38 ]. Correspondingly, various mechanisms of HCC cell resistance to sorafenib include several possibilities: (1) Notch, mammalian target of rapamycin [mTOR], and other cell pro-survival, anti-apoptosis-related pathways can lead to up-regulation of cell resistance to TKIs [ 39 ]; (2) the epithelial–mesenchymal transition (EMT) process can reduce the polarity of HCC cells and induce the resistance of HCC cells to sorafenib and other TKIs [ 40 – 42 ]; (3) HCC-related cancer stem cells and HCC cells are closely associated with sorafenib resistance [ 43 ]; and (4) the mutual compensation between different signaling pathways (such as c-MET can induce resistance to multiple TKIs, including sorafenib) [ 44 ]. Our group has conducted many studies on the resistance of HCC to molecularly targeted drugs and found that the PXR can also be an important mechanism for the resistance of HCC cells to sorafenib [ 19 , 20 ].…”

Transcriptional regulation of NDUFA4L2 by NFIB induces sorafenib resistance by decreasing reactive oxygen species in hepatocellular carcinoma

“…The production of ROS in a variety of cancers has been proven to be a “double‐edged sword.” Low levels of ROS can promote the survival and metastasis of cancer cells, while excessive ROS accumulation inhibits cancer cells by inducing G2/M cell cycle arrest and apoptosis to inhibit the growth of cells 40,41 . Sorafenib can induce excessive accumulation of ROS in HCC cells, leading to the release of cytochrome C from mitochondria into the cytoplasm, triggering programmed cell death and thereby killing HCC cells 40,42 . ROS scavengers can reduce the killing effect of sorafenib on HCC cells, 43,44 which shows that sorafenib is at least partly dependent on ROS production to kill HCC cells.…”

“…40,41 Sorafenib can induce excessive accumulation of ROS in HCC cells, leading to the release of cytochrome C from mitochondria into the cytoplasm, triggering programmed cell death and thereby killing HCC cells. 40,42 ROS scavengers can reduce the killing effect of sorafenib on HCC cells, 43,44 which shows that sorafenib is at least partly dependent on ROS production to kill HCC cells. We found that NFIB could reduce the accumulation of ROS in HCC cells caused by sorafenib.…”