Increased ATF2 expression predicts poor prognosis and inhibits sorafenib-induced ferroptosis in gastric cancer.

Sorafenib, a tyrosine kinase inhibitor, has an important antitumor effect as a ferroptosis inducer in multiple cancers, including gastric cancer (GC). However, the status of sorafenib as a ferroptosis inducer has recently been questioned. There is very limited information about the relationship between ferroptosis and ATF2, and the role of ATF2 in sorafenib-induced ferroptosis has not been studied. In this study, we investigated the role and underlying molecular mechanisms of ATF2 in sorafenib-induced ferroptosis in GC. We found that ATF2 was significantly upregulated in GC tissues and predicted a poor clinical prognosis. Silencing ATF2 significantly inhibited the malignant phenotype of GC cells. In addition, we observed that ATF2 was activated during sorafenib-induced ferroptosis in GC cells. ATF2 knockdown promoted sorafenib-induced ferroptosis, while ATF2 overexpression showed the opposite results in GC cells. Using ChIP-Seq and RNA-Seq, we identified HSPH1 as a target of ATF2 and further validated it by ChIP‒qPCR analysis. HSPH1 can interact with SLC7A11 (cystine/glutamate transporter) and increase its protein stability. Importantly, knockdown of HSPH1 partly reversed the effects caused by ATF2 overexpression on sorafenib-induced ferroptosis in GC cells. In addition, the results from the tumor xenograft model showed that ATF2 knockdown can effectively enhance sorafenib sensitivity in vivo. Collectively, our study reveals a novel mechanism by which sorafenib induces ferroptosis in GC.

Nuciferine attenuates lipopolysaccharide-stimulated inflammatory responses by inhibiting p38 MAPK/ATF2 signaling pathways.

Nuciferine, isolated from Nelumbo nucifera (commonly known as lotus) leaves, has been shown to have beneficial effects, including antioxidant, anti-obesity, anti-diabetic, and anti-inflammatory properties. However, little is known about the mechanism of nuciferine action on the inflammatory response. This study aimed to investigate the anti-inflammatory effects of nuciferine and its underlying molecular mechanisms in lipopolysaccharide (LPS)-stimulated murine macrophages. In this study, nuciferine reduced LPS-induced nitric oxide (NO) and prostaglandin E2 (PGE2) production and mRNA expression levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2. Nuciferine also decreased the production of pro-inflammatory cytokines such as interleukin (IL)-1ß, IL-6, and tumor necrosis factor (TNF)-α. Furthermore, nuciferine inhibited the LPS-mediated transcriptional activity of nuclear factor (NF)-κB and activator protein (AP)-1, and the nuclear translocation of NF-κB p65 and activating transcription factor 2 (ATF2), an AP-1 subunit. Nuciferine also decreased the phosphorylation of IκB kinase (IKK), inhibitor of NF-κB (IκB), NF-κB, mitogen-activated protein kinase 3 (MKK3), MKK6, p38 mitogen-activated protein kinase (MAPK), and ATF2. Overall, our findings suggest that nuciferine may exert anti-inflammatory effects in LPS-induced macrophages by inhibiting the NF-κB and p38 MAPK/ATF2 signaling pathways.

Chemogenetic inhibition of corticostriatal circuits reduces cued reinstatement of methamphetamine seeking.

Methamphetamine (meth) causes enduring changes within the medial prefrontal cortex (mPFC) and the nucleus accumbens (NA). Projections from the mPFC to the NA have a distinct dorsal-ventral distribution, with the prelimbic (PL) mPFC projecting to the NAcore, and the infralimbic (IL) mPFC projecting to the NAshell. Inhibition of these circuits has opposing effects on cocaine relapse. Inhibition of PL-NAcore reduces cued reinstatement of cocaine seeking and IL-NAshell inhibition reinstates cocaine seeking. Meth, however, exhibits a different profile, as pharmacological inhibition of either the PL or IL decrease cued reinstatement of meth-seeking. The potentially opposing roles of the PL-NAcore and IL-NAshell projections remain to be explored in the context of cued meth seeking. Here we used an intersectional viral vector approach that employs a retrograde delivery of Cre from the NA and Cre-dependent expression of DREADD in the mPFC, in both male and female rats to inhibit or activate these parallel pathways. Inhibition of the PL-NAcore circuit reduced cued reinstatement of meth seeking under short and long-access meth self-administration and after withdrawal with and without extinction. Inhibition of the IL-NAshell also decreased meth cued reinstatement. Activation of the parallel circuits was without an effect. These studies show that inhibition of the PL-NAcore or the IL-NAshell circuits can inhibit reinstated meth seeking. Thus, the neural circuitry mediating cued reinstatement of meth seeking is similar to cocaine in the dorsal, but not ventral, mPFC-NA circuit.

CREB, ATF, and AP-1 transcription factors regulate IFN-gamma secretion by human T cells in response to mycobacterial antigen.

IFN-gamma production by T cells is pivotal for defense against many pathogens, and the proximal promoter of IFN-gamma, -73 to -48 bp upstream of the transcription start site, is essential for its expression. However, transcriptional regulation mechanisms through this promoter in primary human cells remain unclear. We studied the effects of cAMP response element binding protein/activating transcription factor (CREB/ATF) and AP-1 transcription factors on the proximal promoter of IFN-gamma in human T cells stimulated with Mycobacterium tuberculosis. Using EMSA, supershift assays, and promoter pulldown assays, we demonstrated that CREB, ATF-2, and c-Jun, but not cyclic AMP response element modulator, ATF-1, or c-Fos, bind to the proximal promoter of IFN-gamma upon stimulation, and coimmunoprecipitation indicated the possibility of interaction among these transcription factors. Chromatin immunoprecipitation confirmed the recruitment of these transcription factors to the IFN-gamma proximal promoter in live Ag-activated T cells. Inhibition of ATF-2 activity in T cells with a dominant-negative ATF-2 peptide or with small interfering RNA markedly reduced the expression of IFN-gamma and decreased the expression of CREB and c-Jun. These findings suggest that CREB, ATF-2, and c-Jun are recruited to the IFN-gamma proximal promoter and that they up-regulate IFN-gamma transcription in response to microbial Ag. Additionally, ATF-2 controls expression of CREB and c-Jun during T cell activation.