Nuclear translocation regulated by phosphorylation is a key step in providing activated mitogen-activated protein kinases (MAPKs) access to their nuclear targets; however, the mechanisms linking MAPK-induced nuclear translocation and target gene expression mediating oncologic activity remain obscure. Here, we show that the MAPK extracellular signal-regulated kinase (ERK) 1, but not ERK2, phosphorylated intestine-specific homeobox (ISX), leading to its nuclear translocation and downstream oncogenic signaling. Mechanistically, ERK1 phosphorylated serine 183 of ISX, facilitating its nuclear translocation and downstream target gene expression. In contrast, dominant-negative ERK1 expression in hepatoma cells inhibited the nuclear translocation of ISX and the expression of downstream genes involved in cell proliferation, malignant transformation, and epithelial-mesenchymal transition in vitro and in vivo. An activating mutation in ISX (S183D) exhibited a constitutive nuclear localization and resistance to sorafenib. Additionally, in 576 paired clinical hepatocellular carcinoma (HCC) samples and adjacent normal tissues, ERK1 and ISX were co-expressed in a tumor-specific manner at mRNA and protein levels, while their mRNA levels showed significant correlation with survival duration, tumor size, number, and stage. These results highlight the significance of ERK1/ISX signaling in HCC progression and its potential as a prognostic and therapeutic target in HCC.

Background: Dysregulation of eicosanoids is associated with asthma and a composite of oxylipins, including exhaled LTB4, but their potential utility in monitoring the therapeutic outcomes has not been comprehensively assessed. Objectives: We aimed to examine the levels of major eicosanoids representing different metabolic pathways in exhaled breath condensates (EBCs) of children with asthma during exacerbation and after treatment. Methods: Levels of 6 exhaled eicosanoid species in asthmatic children and healthy subjects were evaluated using ELISA. Results: In addition to those previously reported, including LTB4, LTE4, LXA4 and PGE2, the levels of exhaled 15-HETE, but not TXB2, showed significant difference between asthmatics (N=318) and healthy controls (N=97). When the asthmatic population was stratified into different severity groups, the severe group was characterized by significantly lower levels of 15-HETE and 15-HETE/LTB4 ratio, as compared to the mild and control groups. Receiver Operating Characteristic (ROC) analyses revealed similar distinguishing power for the level of exhaled 15-HETE and those of FEV1 and FeNO. Analysis of asthmatics (N=75) during exacerbation and convalescence showed significant improvement in lung function (FEV1; p<0.001), but not FeNO, concomitant with significantly increased levels of 15-HETE (p<0.001) and reduced levels of TXB2 (p<0.05) after therapy, particularly for those who at the top 30% level during exacerbation. Further, decreased LTB4 and LXA4 at convalescence were noted only in those at the top 30 percentile during exacerbation. Conclusion: The exhaled 15-HETE was found to discriminate childhood asthma while decreased levels of exhaled TXB2 and increased levels of 15-HETE were prominent after treatment.

Background: Dysregulation of eicosanoids is associated with asthma and a composite of oxylipins, including exhaled LTB4, characterizes childhood asthma. While FeNO has been used as the standard for monitoring steroid responsiveness, the potential utility of eicosanoids in monitoring the therapeutic outcomes remains unclear. We aimed to examine the levels of major eicosanoids representing different metabolic pathways in exhaled breath condensates (EBCs) of children with asthma during exacerbation and after treatment. Methods: Levels of 6 exhaled eicosanoid species in asthmatic children and healthy subjects were evaluated using ELISA. Results: In addition to those previously reported, including LTB4, the levels of exhaled 15-HETE, but not TXB2, showed significant difference between asthmatics (N=318) and healthy controls (N=97), particularly the severe group showed the lowest levels of exhaled 15-HETE. Receiver Operating Characteristic (ROC) analyses revealed similar distinguishing power for the levels of 15-HETE, FEV1 and FeNO, whilethe 15-HETE/LTB4 ratio was significantly lower in subjects with severe asthma (p<0.01). Analysis of asthmatics (N=75) during exacerbation and convalescence showed significant improvement in lung function (FEV1; p<0.001), but not FeNO, concomitant with significantly increased levels of 15-HETE (p<0.001) and reduced levels of TXB2 (p<0.05) after therapy, particularly for those who at the top 30% level during exacerbation. Further, decreased LTB4 and LXA4 at convalescence were noted only in those at the top 30 percentile during exacerbation. Conclusion: The exhaled 15-HETE was found to discriminate childhood asthma while decreased levels of exhaled TXB2 and increased levels of 15-HETE were prominent after treatment.

Background: We have previously demonstrated that benzo(a)pyrene (BaP) co-exposure with dermatophagoides group 1 allergen (Der f 1) can potentiate Der f 1-induced airway inflammation. We sought to investigate the molecular mechanisms underlying the potentiation of BaP exposure on Der f 1-induced airway inflammation. Methods: BaP co-exposure with Der f 1-induced activation of TGFβ1 signaling was analyzed in airway epithelial cells (HBECs) and in asthma mouse model. The role of aryl hydrocarbon receptor (AhR) and RhoA in BaP co-exposure-induced TGFβ1 signaling was investigated. AhR binding sites in RhoA were predicted and experimentally confirmed by luciferase reporter assays. The role of RhoA in BaP co-exposure-induced airway hyper-responsiveness (AHR) and allergic inflammation was examined. Results: BaP co-exposure potentiates Der f 1-induced TGFβ1 signaling activation in HBECs and in the airways of asthma mouse model. The BaP co-exposure-induced the activation of TGFβ1 signaling was attenuated by either AhR antagonist CH223191 or AhR knockdown in HBECs. Furthermore, AhR knockdown led to the reduction of BaP co-exposure-induced active RhoA. Inhibition of RhoA signaling with fasudil, a RhoA/ROCK inhibitor, suppressed BaP co-exposure-induced TGFβ1 signaling activation. This was further confirmed in HBECs expressing constitutively active RhoA (RhoA-L63) or dominant negative RhoA (RhoA-N19). Luciferase reporter assays showed prominently increased promoter activities for the AhR binding sites in the promoter region of RhoA. Inhibition of RhoA suppressed co-exposure-induced AHR, Th2-associated airway inflammation and TGFβ1 signaling activation in asthma. Conclusions: Our studies identified a functional axis of AhR-RhoA that regulates TGFβ1 signaling activation, leading to allergic airway inflammation and asthma.