CYB5R3 functions as a tumor suppressor by inducing ER stress-mediated apoptosis in lung cancer cells via the PERK-ATF4 and IRE1α-JNK pathways.

Cytochrome b5 reductase 3 (CYB5R3) is involved in various cellular metabolic processes, including fatty acid synthesis and drug metabolism. However, the role of CYB5R3 in cancer development remains poorly understood. Here, we show that CYB5R3 expression is downregulated in human lung cancer cell lines and tissues. Adenoviral overexpression of CYB5R3 suppresses lung cancer cell growth in vitro and in vivo. However, CYB5R3 deficiency promotes tumorigenesis and metastasis in mouse models. Transcriptome analysis revealed that apoptosis- and endoplasmic reticulum (ER) stress-related genes are upregulated in CYB5R3-overexpressing lung cancer cells. Metabolomic analysis revealed that CYB5R3 overexpression increased the production of nicotinamide adenine dinucleotide (NAD+) and oxidized glutathione (GSSG). Ectopic CYB5R3 is mainly localized in the ER, where CYB5R3-dependent ER stress signaling is induced via activation of protein kinase RNA-like ER kinase (PERK) and inositol-requiring enzyme 1 alpha (IRE1α). Moreover, NAD+ activates poly (ADP-ribose) polymerase16 (PARP16), an ER-resident protein, to promote ADP-ribosylation of PERK and IRE1α and induce ER stress. In addition, CYB5R3 induces the generation of reactive oxygen species and caspase-9-dependent intrinsic cell death. Our findings highlight the importance of CYB5R3 as a tumor suppressor for the development of CYB5R3-based therapeutics for lung cancer.

Design, Synthesis and Biological Evaluation of Novel MDH Inhibitors Targeting Tumor Microenvironment.

MDH1 and MDH2 enzymes play an important role in the survival of lung cancer. In this study, a novel series of dual MDH1/2 inhibitors for lung cancer was rationally designed and synthesized, and their SAR was carefully investigated. Among the tested compounds, compound 50 containing a piperidine ring displayed an improved growth inhibition of A549 and H460 lung cancer cell lines compared with LW1497. Compound 50 reduced the total ATP content in A549 cells in a dose-dependent manner; it also significantly suppressed the accumulation of hypoxia-inducible factor 1-alpha (HIF-1α) and the expression of HIF-1α target genes such as GLUT1 and pyruvate dehydrogenase kinase 1 (PDK1) in a dose-dependent manner. Furthermore, compound 50 inhibited HIF-1α-regulated CD73 expression under hypoxia in A549 lung cancer cells. Collectively, these results indicate that compound 50 may pave the way for the development of next-generation dual MDH1/2 inhibitors to target lung cancer.

DDIAS, DNA damage-induced apoptosis suppressor, is a potential therapeutic target in cancer.

Increasing evidence indicates that DNA damage-induced apoptosis suppressor (DDIAS) is an oncogenic protein that is highly expressed in a variety of cancers, including colorectal cancer, lung cancer, breast cancer, and hepatocellular carcinoma (HCC). The discovery of DDIAS as a novel therapeutic target and its role in human cancer biology is fascinating and noteworthy. Recent studies have shown that DDIAS is involved in tumorigenesis, metastasis, DNA repair and synthesis, and drug resistance and that it plays multiple roles with distinct binding partners in several human cancers. This review focuses on the function of DDIAS and its regulatory proteins in human cancer as potential targets for cancer therapy, as well as the development and future prospects of DDIAS inhibitors.

DNA methylome and single-cell transcriptome analyses reveal CDA as a potential druggable target for ALK inhibitor-resistant lung cancer therapy.

Acquired resistance to inhibitors of anaplastic lymphoma kinase (ALK) is a major clinical challenge for ALK fusion-positive non-small-cell lung cancer (NSCLC). In the absence of secondary ALK mutations, epigenetic reprogramming is one of the main mechanisms of drug resistance, as it leads to phenotype switching that occurs during the epithelial-to-mesenchymal transition (EMT). Although drug-induced epigenetic reprogramming is believed to alter the sensitivity of cancer cells to anticancer treatments, there is still much to learn about overcoming drug resistance. In this study, we used an in vitro model of ceritinib-resistant NSCLC and employed genome-wide DNA methylation analysis in combination with single-cell (sc) RNA-seq to identify cytidine deaminase (CDA), a pyrimidine salvage pathway enzyme, as a candidate drug target. CDA was hypomethylated and upregulated in ceritinib-resistant cells. CDA-overexpressing cells were rarely but definitively detected in the naïve cell population by scRNA-seq, and their abundance was increased in the acquired-resistance population. Knockdown of CDA had antiproliferative effects on resistant cells and reversed the EMT phenotype. Treatment with epigenome-related nucleosides such as 5-formyl-2'-deoxycytidine selectively ablated CDA-overexpressing resistant cells via accumulation of DNA damage. Collectively, our data suggest that targeting CDA metabolism using epigenome-related nucleosides represents a potential new therapeutic strategy for overcoming ALK inhibitor resistance in NSCLC.

Synaptotagmin 11 scaffolds MKK7-JNK signaling process to promote stem-like molecular subtype gastric cancer oncogenesis.

BACKGROUND: Identifying biomarkers related to the diagnosis and treatment of gastric cancer (GC) has not made significant progress due to the heterogeneity of tumors. Genes involved in histological classification and genetic correlation studies are essential to develop an appropriate treatment for GC. METHODS: In vitro and in vivo lentiviral shRNA library screening was performed. The expression of Synaptotagmin (SYT11) in the tumor tissues of patients with GC was confirmed by performing Immunohistochemistry, and the correlation between the expression level and the patient's survival rate was analyzed. Phospho-kinase array was performed to detect Jun N-terminal kinase (JNK) phosphorylation. SYT11, JNK, and MKK7 complex formation was confirmed by western blot and immunoprecipitation assays. We studied the effects of SYT11 on GC proliferation and metastasis, real-time cell image analysis, adhesion assay, invasion assay, spheroid formation, mouse xenograft assay, and liver metastasis. RESULTS: SYT11 is highly expressed in the stem-like molecular subtype of GC in transcriptome analysis of 527 patients with GC. Moreover, SYT11 is a potential prognostic biomarker for histologically classified diffuse-type GC. SYT11 functions as a scaffold protein, binding both MKK7 and JNK1 signaling molecules that play a role in JNK1 phosphorylation. In turn, JNK activation leads to a signaling cascade resulting in cJun activation and expression of downstream genes angiopoietin-like 2 (ANGPTL2), thrombospondin 4 (THBS4), Vimentin, and junctional adhesion molecule 3 (JAM3), which play a role in epithelial-mesenchymal transition (EMT). SNU484 cells infected with SYT11 shRNA (shSYT11) exhibited reduced spheroid formation, mouse tumor formation, and liver metastasis, suggesting a pro-oncogenic role of SYT11. Furthermore, SYT11-antisense oligonucleotide (ASO) displayed antitumor activity in our mouse xenograft model and was conferred an anti-proliferative effect in SNU484 and MKN1 cells. CONCLUSION: SYT11 could be a potential therapeutic target as well as a prognostic biomarker in patients with diffuse-type GC, and SYT11-ASO could be used in therapeutic agent development for stem-like molecular subtype diffuse GC.

TNF-α Secreted from Macrophages Increases the Expression of Prometastatic Integrin αV in Gastric Cancer.

The tumor microenvironment comprising blood vessels, fibroblasts, immune cells, and the extracellular matrix surrounding cancer cells, has recently been targeted for research in cancer therapy. We aimed to investigate the effect of macrophages on the invasive ability of gastric cancer cells, and studied their potential mechanism. In transcriptome analysis, integrin αV was identified as a gene increased in AGS cells cocultured with RAW264.7 cells. AGS cells cocultured with RAW264.7 cells displayed increased adhesion to the extracellular matrix and greater invasiveness compared with AGS cells cultured alone. This increased invasion of AGS cells cocultured with RAW264.7 cells was inhibited by integrin αV knockdown. In addition, the increase in integrin αV expression induced by tumor necrosis factor-α (TNF-α) or by coculture with RAW264.7 cells was inhibited by TNF receptor 1 (TNFR1) knockdown. The increase in integrin αV expression induced by TNF-α was inhibited by both Mitogen-activated protein kinase (MEK) inhibitor and VGLL1 S84 peptide treatment. Finally, transcription of integrin αV was shown to be regulated through the binding of VGLL1 and TEAD4 to the promoter of integrin αV. In conclusion, our study demonstrated that TNFR1-ERK-VGLL1 signaling activated by TNF-α secreted from RAW264.7 cells increased integrin αV expression, thereby increasing the adhesion and invasive ability of gastric cancer cells.

DGG-100629 inhibits lung cancer growth by suppressing the NFATc1/DDIAS/STAT3 pathway.

DNA damage-induced apoptosis suppressor (DDIAS) promotes the progression of lung cancer and hepatocellular carcinoma through the regulation of multiple pathways. We screened a chemical library for anticancer agent(s) capable of inhibiting DDIAS transcription. DGG-100629 was found to suppress lung cancer cell growth through the inhibition of DDIAS expression. DGG-100629 induced c-Jun NH(2)-terminal kinase (JNK) activation and inhibited NFATc1 nuclear translocation. Treatment with SP600125 (a JNK inhibitor) or knockdown of JNK1 restored DDIAS expression and reversed DGG-100629-induced cell death. In addition, DGG-100629 suppressed the signal transducer and activator of transcription (STAT3) signaling pathway. DDIAS or STAT3 overexpression restored lung cancer cell growth in the presence of DGG-100629. In a xenograft assay, DGG-100629 inhibited tumor growth by reducing the level of phosphorylated STAT3 and the expression of STAT3 target genes. Moreover, DGG-100629 inhibited the growth of lung cancer patient-derived gefitinib-resistant cells expressing NFATc1 and DDIAS. Our findings emphasize the potential of DDIAS blockade as a therapeutic approach and suggest a novel strategy for the treatment of gefitinib-resistant lung cancer.

VGLL1 phosphorylation and activation promotes gastric cancer malignancy via TGF-ß/ERK/RSK2 signaling.

We previously reported that vestigial-like 1 (VGLL1), a cofactor of transcriptional enhanced associate domain 4 (TEAD4), is transcriptionally regulated by PI3K and ß-catenin signaling and is involved in gastric cancer malignancy. However, the precise mechanism underlying the regulation of VGLL1 activation remains unknown. Therefore, we aimed to investigate the molecular mechanism underlying the transforming growth factor-ß (TGF-ß)-mediated activation of VGLL1 and the VGLL1-TEAD4 interaction in gastric cancer cells. We showed that TGF-ß enhanced VGLL1 phosphorylation and that this phosphorylated VGLL1 functioned as a transcription cofactor of TEAD4 in NUGC3 cells. TGF-ß also increased the phosphorylation of ERK and ribosomal S6 kinase 2 (RSK2) in NUGC3 cells, thereby triggering the translocation of phosphorylated RSK2 to the nucleus. Site-directed mutagenesis and immunoprecipitation experiments revealed that RSK2 phosphorylated VGLL1 at S84 in the presence of TGF-ß. Mutation of VGLL1 at S84 suppressed VGLL1-TEAD4 binding and the subsequent transcriptional activation of matrix metalloprotease 9 (MMP9). Moreover, VGLL1 peptide containing S84 suppressed the TGF-ß-induced MMP9 expression and reduced the invasion and proliferation of gastric cancer cells, whereas VGLL1 peptide containing S84A did not. Furthermore, suppression of expression or activation of VGLL1 enhances the therapeutic effects of lapatinib. Collectively, these results indicate that VGLL1 phosphorylation via TGF-ß/ERK/RSK2 signaling plays a crucial role in MMP9-mediated malignancy of gastric cancer. In addition, our study highlights the therapeutic potential of the peptide containing VGLL1 S84 for the treatment of gastric cancer.

Transglutaminase 2 Depletion Attenuates α-Synuclein Mediated Toxicity in Mice.

α-Synuclein (α-Syn) is a key pathogenic protein in α-synucleinopathies including Parkinson disease (PD) and Dementia with Lewy Bodies. The aggregation of α-Syn is believed to be deleterious and a critical step leading to neuronal dysfunction and death. One of the factors that may contribute to the initial steps of this aggregation is crosslinking through transglutaminase 2 (TG2). We previously demonstrated that overexpression of TG2 exacerbates α-Syn toxicity in mice and yeast by increasing the higher-order species of α-Syn. Herein, we investigated whether deletion of the TG2 encoding gene could mitigate the toxicity of α-Syn in vivo. Compared with α-Syn transgenic (SynTg) mice, TG2 null /α-Syn transgenic mice (TG2KO/SynTg) exhibited a reduced amount of phosphorylated α-Syn aggregates and fewer proteinase K-resistant α-Syn aggregates in sections of brain tissue. Neuritic processes that are depleted in SynTg mice compared to wild-type mice were preserved in double TG2KO/SynTg mice. Additionally, the neuroinflammatory reaction to α-Syn was attenuated in TG2KO/SynTg animals. These neuropathological markers of diminished α-Syn toxicity in the absence of TG2 were associated with better motor performance on the rotarod and balance beam. These results suggest that deleting TG2 reduces the toxicity of α-Syn in vivo and improves the behavioral performance of SynTg mice. Accordingly, these findings collectively support pharmacological inhibition of TG2 as a potential disease modifying therapeutic strategy for α-synucleinopathies.

Miconazole inhibits signal transducer and activator of transcription 3 signaling by preventing its interaction with DNA damage-induced apoptosis suppressor.

DNA damage-induced apoptosis suppressor (DDIAS) facilitates the survival of lung cancer by suppressing apoptosis. Moreover, DDIAS promotes tyrosine phosphorylation of signal transducer and activator of transcription 3 (STAT3) via their interaction. Here, we identified miconazole as an inhibitor of DDIAS/STAT3 interaction by screening a chemical library using a yeast two-hybrid assay. Miconazole inhibited growth, migration and invasion of lung cancer cells. Furthermore, miconazole suppressed STAT3 tyrosine Y705 phosphorylation and the expression of its target genes, such as cyclin D1, survivin and snail but had no suppressive effect on the activation of ERK1/2 or AKT, which is involved in the survival of lung cancer. As expected, no interaction between DDIAS and STAT3 occurred in the presence of miconazole, as confirmed by immunoprecipitation assays. Mouse xenograft experiments showed that miconazole significantly suppressed both tumor size and weight in an NCI-H1703 mouse model. Tyrosine phosphorylation of STAT3 at Y705 and expression of its targets, such as cyclin D1, survivin and snail, were decreased in miconazole-treated tumor tissues, as compared with those in vehicle-treated tumor tissues. These data suggest that miconazole exerts an anti-cancer effect by suppressing STAT3 activation through inhibiting DDIAS/STAT3 binding.

DDIAS promotes STAT3 activation by preventing STAT3 recruitment to PTPRM in lung cancer cells.

DNA damage-induced apoptosis suppressor (DDIAS) regulates cancer cell survival. Here we investigated the involvement of DDIAS in IL-6-mediated signaling to understand the mechanism underlying the role of DDIAS in lung cancer malignancy. We showed that DDIAS promotes tyrosine phosphorylation of signal transducer and activator of transcription 3 (STAT3), which is constitutively activated in malignant cancers. Interestingly, siRNA protein tyrosine phosphatase (PTP) library screening revealed protein tyrosine phosphatase receptor mu (PTPRM) as a novel STAT3 PTP. PTPRM knockdown rescued the DDIAS-knockdown-mediated decrease in STAT3 Y705 phosphorylation in the presence of IL-6. However, PTPRM overexpression decreased STAT3 Y705 phosphorylation. Moreover, endogenous PTPRM interacted with endogenous STAT3 for dephosphorylation at Y705 following IL-6 treatment. As expected, PTPRM bound to wild-type STAT3 but not the STAT3 Y705F mutant. PTPRM dephosphorylated STAT3 in the absence of DDIAS, suggesting that DDIAS hampers PTPRM/STAT3 interaction. In fact, DDIAS bound to the STAT3 transactivation domain (TAD), which competes with PTPRM to recruit STAT3 for dephosphorylation. Thus we show that DDIAS prevents PTPRM/STAT3 binding and blocks STAT3 Y705 dephosphorylation, thereby sustaining STAT3 activation in lung cancer. DDIAS expression strongly correlates with STAT3 phosphorylation in human lung cancer cell lines and tissues. Thus DDIAS may be considered as a potential biomarker and therapeutic target in malignant lung cancer cells with aberrant STAT3 activation.

PI3K/AKT/ß-Catenin Signaling Regulates Vestigial-Like 1 Which Predicts Poor Prognosis and Enhances Malignant Phenotype in Gastric Cancer.

Although gastric cancer is a common cause of cancer mortality worldwide, its biological heterogeneity limits the available therapeutic options. Therefore, identifying novel therapeutic targets for developing effective targeted therapy of gastric cancer is a pressing need. Here, we investigate molecular function and regulatory mechanisms of Vestigial-like 1 (VGLL1) in gastric cancer. Microarray analysis of 556 gastric cancer tissues revealed that VGLL1 was a prognostic biomarker that correlated with PI3KCA and PI3KCB. VGLL1 regulates the proliferation of gastric cancer cells, as shown in live cell imaging, sphere formation, and in vivo xenograft model. Tail vein injection of NUGC3 cells expressing shVGLL1 resulted in less lung metastasis occurring when compared to the control. In contrast, larger metastatic lesions in lung and liver were detected in the VGLL1-overexpressing NUGC3 cell xenograft excision mouse model. Importantly, VGLL1 expression is transcriptionally regulated by the PI3K-AKT-ß-catenin pathway. Subsequently, MMP9, a key molecule in gastric cancer, was explored as one of target genes that were transcribed by VGLL1-TEAD4 complex, a component of the transcription factor. Taken together, PI3K/AKT/ß-catenin signaling regulates the transcription of VGLL1, which promotes the proliferation and metastasis in gastric cancer. This finding suggests VGLL1 as a novel prognostic biomarker and a potential therapeutic target.

Bcl-2-dependent synthetic lethal interaction of the IDF-11774 with the V0 subunit C of vacuolar ATPase (ATP6V0C) in colorectal cancer.

BACKGROUND: The IDF-11774, a novel clinical candidate for cancer therapy, targets HSP70 and inhibits mitochondrial respiration, resulting in the activation of AMPK and reduction in HIF-1α accumulation. METHODS: To identify genes that have synthetic lethality to IDF-11774, RNA interference screening was conducted, using pooled lentiviruses expressing a short hairpin RNA library. RESULTS: We identified ATP6V0C, encoding the V0 subunit C of lysosomal V-ATPase, knockdown of which induced a synergistic growth-inhibitory effect in HCT116 cells in the presence of IDF-11774. The synthetic lethality of IDF-11774 with ATP6V0C possibly correlates with IDF-11774-mediated autolysosome formation. Notably, the synergistic effect of IDF-11774 and the ATP6V0C inhibitor, bafilomycin A1, depended on the PIK3CA genetic status and Bcl-2 expression, which regulates autolysosome formation and apoptosis. Similarly, in an experiment using conditionally reprogramed cells derived from colorectal cancer patients, synergistic growth inhibition was observed in cells with low Bcl-2 expression. CONCLUSIONS: Bcl-2 is a biomarker for the synthetic lethal interaction of IDF-11774 with ATP6V0C, which is clinically applicable for the treatment of cancer patients with IDF-11774 or autophagy-inducing anti-cancer drugs.

DDIAS suppresses TRAIL-mediated apoptosis by inhibiting DISC formation and destabilizing caspase-8 in cancer cells.

DNA damage-induced apoptosis suppressor (DDIAS) has an anti-apoptotic function during DNA damage in lung cancer. However, the anti-apoptotic mechanism of DDIAS in cancer cells under other conditions has not been reported. We report here that DDIAS protects cancer cells from tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis by two distinct mechanisms in non-small cell lung cancer (NSCLC) and hepatocellular carcinoma (HCC) cells. DDIAS depletion sensitized NSCLC and HCC cells to TRAIL-mediated apoptosis, an effect that was abrogated by pharmacological or genetic inhibition of caspase-8 and was independent of caspase-9, p53, or mitogen-activated protein kinase signaling. Interestingly, we found that the N terminus of DDIAS interacted with the death effector domain of Fas-associated protein death domain (FADD) and prevented its recruitment to the death-inducing signaling complex (DISC), thereby blocking caspase-8 activation. DDIAS knockdown also suppressed epidermal growth factor-induced phosphorylation of p90 ribosomal S6 kinase (RSK) 2 and stabilized caspase-8 by preventing its ubiquitination and proteasomal degradation. This effect was abolished by RSK2 overexpression. Taken together, DDIAS has dual functions in inhibiting DISC formation as well as in destabilizing caspase-8, thereby suppressing TRAIL-mediated apoptosis of cancer cells. Thus, we suggest that DDIAS can serve as an effective therapeutic target in the treatment of NSCLC and HCC.

Stability of the cancer target DDIAS is regulated by the CHIP/HSP70 pathway in lung cancer cells.

DNA damage-induced apoptosis suppressor (DDIAS) rescues lung cancer cells from apoptosis in response to DNA damage. DDIAS is transcriptionally activated by NFATc1 and EGF-mediated ERK5/MEF2B, leading to cisplatin resistance and cell invasion. Therefore, DDIAS is suggested as a therapeutic target for lung cancer. Here, we report that DDIAS stability is regulated by E3 U-box ubiquitin ligase carboxyl terminus of HSP70-interacting protein (CHIP)-mediated proteasomal degradation. We first isolated CHIP as an interacting partner of DDIAS by yeast two-hybrid screening. CHIP physically associated with both the N- and C-terminal regions of DDIAS, targeting it for proteasomal degradation and reducing the DDIAS half-life. CHIP overexpression analyses indicated that the tetratrico peptide repeat (TPR) domain and the U-box are required for DDIAS ubiquitination. It is likely that HSP70-bound DDIAS is recruited to the CHIP E3 ligase via the TPR domain, suggesting DDIAS as a client protein of HSP70. In addition, CHIP overexpression in lung cancer cells expressing high DDIAS levels induced significant growth inhibition by enhancing DDIAS degradation. Furthermore, simultaneous CHIP overexpression and DNA damage agent treatment caused a substantial increase in the apoptosis of lung cancer cells. Taken together, these findings indicate that the stability of the DDIAS protein is regulated by CHIP/HSP70-mediated proteasomal degradation and that CHIP overexpression stimulates the apoptosis of lung cancer cells in response to DNA-damaging agents.

Data on the transcriptional regulation of DNA damage induced apoptosis suppressor (DDIAS) by ERK5/MEF2B pathway in lung cancer cells.

The data included in this article are associated with the article entitled "DNA-damage-induced apoptosis suppressor (DDIAS) is upregulated via ERK5/MEF2B signaling and promotes ß-catenin-mediated invasion" (J.Y. Im, S.H. Yoon, B.K. Kim, H.S. Ban, K.J. Won, K.S. Chung, K.E. Jung, M. Won) [1]. Quantitative RT-PCR data revealed that genetic or pharmacological inhibition of extracellular signal-regulated kinase 5 (ERK5) suppresses DDIAS transcription in response to epidermal growth factor (EGF) in Hela cells. p300 did not interact with myocyte enhancer factor 2B (MEF2B), a downstream target of ERK5 and affect transcription of DDIAS. Moreover, DDIAS transcription is activated by ERK5/MEF2B signaling on EGF exposure in the non-small cell lung cancer cells (NSCLC) NCI-H1703 and NCI-H1299. DDIAS knockdown suppresses lung cancer cell invasion by decreasing ß-catenin protein level on EGF exposure.

DNA damage induced apoptosis suppressor (DDIAS) is upregulated via ERK5/MEF2B signaling and promotes ß-catenin-mediated invasion.

DNA damage induced apoptosis suppressor (DDIAS) is an anti-apoptotic protein that promotes cancer cell survival. We previously reported that DDIAS is transcriptionally activated by nuclear factor of activated T cells 2 (NFATc1). However, the upstream regulation of DDIAS expression by growth factors has not been studied. Here, we demonstrate that DDIAS expression is induced by extracellular signal-regulated kinase 5 (ERK5) and myocyte enhancer factor 2B (MEF2B) in response to epidermal growth factor (EGF) and that it positively regulates ß-catenin signaling in HeLa cells. The genetic or pharmacological inhibition of ERK5 suppressed DDIAS induction following EGF exposure and the overexpression of constitutively active MEK5 (CA-MEK5) enhanced DDIAS expression. In chromatin immunoprecipitation assays, MEF2B, a downstream target of ERK5, exhibited sequence-specific binding to a MEF2 binding site in the DDIAS promoter following treatment with EGF. The overexpression of MEF2B increased the EGF-mediated induction of DDIAS expression, whereas the knockdown of MEF2B impaired this effect. Furthermore, DDIAS promoted invasion by increasing ß-catenin expression at the post-translational level in response to EGF, suggesting that DDIAS plays a crucial role in the metastasis of cancer cells by regulating ß-catenin expression. It is unlikely that MEF2B and NFATc1 cooperatively regulate DDIAS transcription in response to EGF. Collectively, EGF activates the ERK5/MEF2 pathway, which in turn induces DDIAS expression to promote cancer cell invasion by activating ß-catenin target genes.

Shikonin induces apoptosis of lung cancer cells via activation of FOXO3a/EGR1/SIRT1 signaling antagonized by p300.

Shikonin derivatives exert powerful cytotoxic effects including induction of apoptosis. Here, we demonstrate the cytotoxic efficacy of shikonin in vivo in xenograft models, which did not affect body weight as well as its reduction of cell viability in vitro using several non-small cell lung cancer (NSCLC) cell lines. We found that inhibition of AKT by shikonin activated the forkhead box (FOX)O3a/early growth response protein (EGR)1 signaling cascade and enhanced the expression of the target gene Bim, leading to apoptosis in lung cancer cells. Overexpression of wild-type or a constitutively active mutant of FOXO3a enhanced shikonin-induced Bim expression. The NAD+-dependent histone deacetylase sirtuin (SIRT)1 amplified the pro-apoptotic effect by deacetylating FOXO3a, which induced EGR1 binding to the Bim promoter and activated Bim expression. Meanwhile, PI3K/AKT activity was enhanced, whereas that of FOXO3a was reduced and p300 was upregulated by treatment with a sublethal dose of shikonin. FOXO3a acetylation was enhanced by p300 overexpression, while shikonin-induced Bim expression was suppressed by p300 overexpression, which promoted cell survival. FOXO3a acetylation was increased by p300 overexpression and treatment with SIRT1 inhibitor, improving cell survival. In addition, shikonin-induced FOXO3a nuclear localization was blocked by AKT activation and SIRT1 inhibition, which blocked Bim expression and conferred resistance to the cytotoxic effects of shikonin. The EGR1 increase induced by shikonin was restored by pretreatment with SIRT1 inhibitor. These results suggest that shikonin induces apoptosis in some lung cancer cells via activation of FOXO3a/EGR1/SIRT1 signaling, and that AKT and p300 negatively regulate this process via Bim upregulation.

DNA damage-induced apoptosis suppressor (DDIAS), a novel target of NFATc1, is associated with cisplatin resistance in lung cancer.

In a previous study, we reported that DNA damage induced apoptosis suppressor (DDIAS; hNoxin), a human homolog of mouse Noxin, functions as an anti-apoptotic protein in response to DNA repair. Here we reveal that DDIAS is a target gene of nuclear factor of activated T cells 2 (NFATc1) and is associated with cisplatin resistance in lung cancer cells. In the DDIAS promoter analysis, we found that NFATc1 activated the transcription of DDIAS through binding to NFAT consensus sequences in the DDIAS promoter. In addition, tissue array immunostaining revealed a correlation between DDIAS and NFATc1 expression in human lung tumors. NFATc1 knockdown or treatment with the NFAT inhibitor cyclosporine A induced apoptosis and led to growth inhibition of lung cancer cells, indicating the functional relevance of both the proteins. In contrast, DDIAS overexpression overcame this NFATc1 knockdown-induced growth inhibition, supporting the cancer-specific role of DDIAS as a target gene of NFATc1. NFATc1 or DDIAS inhibition clearly enhanced apoptosis induced by cisplatin in NCI-H1703 and A549 cells. Conversely, DDIAS overexpression rescued NCI-H1703 cells from cisplatin-mediated cell death and caspase-3/7 activation. These results suggest that NFATc1-induced DDIAS expression contributes to cisplatin resistance, and targeting DDIAS or NFATc1 impairs the mechanism regulating cisplatin resistance in lung cancer cells. Taken together, DDIAS is a target of NFATc1 and is associated with cisplatin resistance in lung cancer cells.

Apoptosis signal-regulating kinase 1 modulates the phenotype of α-synuclein transgenic mice.

α-Synuclein is a key pathogenic protein in α-synucleinopathies including Parkinson's disease, and its overexpression and aggregation in model systems are associated with a neuroinflammatory response and increased oxidative stress. Apoptosis signal-regulating kinase 1 (ASK1) is activated upon stress signaling events such as oxidative stress and is a central player linking oxidative stress with neuroinflammation. Here, we demonstrate that overexpression of human α-synuclein activates ASK1 in both PC12 cells and in the brains of α-synuclein transgenic mice. Deleting ASK1 in mice mitigates the neuronal damage and neuroinflammation induced by α-synuclein and improves performance of the animals on the rotarod. ASK1 deletion does not impact the aggregation profile or phosphorylation state of α-synuclein in the mouse brain. These results collectively implicate ASK1 in the cascade of events triggered by α-synuclein overexpression, likely because of the inflammatory response and oxidative stress that lead to ASK1 activation. These conclusions raise the possibility that potent antioxidants and anti-inflammatory agents may ameliorate the phenotype of α-synucleinopathies.