RHNO1 disruption inhibits cell proliferation and induces mitochondrial apoptosis via PI3K/Akt pathway in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) represents one of the primary liver malignancies with poor prognosis. RHNO1, which implicated in the ATR-CHK1 signaling pathway thus functions in the DNA replication stress response. However, the role and molecular mechanisms of RHNO1 in HCC remain largely elusive. Here, we imply that RHNO1 is elevated in HCC tumor tissues and that high expression of RHNO1 predicts poor prognosis of HCC patients. Moreover, RHNO1 mRNA, especially protein levels were significantly increased in most HCC cells. Knockdown of RHNO1 through small interfering RNAs (siRNAs) inhibited the proliferation and triggered cell apoptosis of HCC cells both in vitro and in vivo. Specifically, we find that RHNO1 deficiency confers apoptosis via mitochondrial-mediated pathway. Mechanistically, silencing of RHNO1 impeded HCC proliferation and induced apoptosis by inactivating the PI3K/Akt pathway. Overall, these findings unravel that RHNO1 functions as an oncogene in HCC, and involved in regulating mitochondrial apoptosis to promote HCC thus may serve as a therapeutic and diagnostic target for HCC.

Targeting Mitochondrial Metabolic Reprogramming as a Potential Approach for Cancer Therapy.

Abnormal energy metabolism is a characteristic of tumor cells, and mitochondria are important components of tumor metabolic reprogramming. Mitochondria have gradually received the attention of scientists due to their important functions, such as providing chemical energy, producing substrates for tumor anabolism, controlling REDOX and calcium homeostasis, participating in the regulation of transcription, and controlling cell death. Based on the concept of reprogramming mitochondrial metabolism, a range of drugs have been developed to target the mitochondria. In this review, we discuss the current progress in mitochondrial metabolic reprogramming and summarized the corresponding treatment options. Finally, we propose mitochondrial inner membrane transporters as new and feasible therapeutic targets.

The comprehensive landscape of miR-34a in cancer research.

MicroRNA-34 (miR-34) plays central roles in human diseases, especially cancers. Inactivation of miR-34 is detected in cancer cell lines and tumor tissues versus normal controls, implying its potential tumor-suppressive effect. Clinically, miR-34 has been identified as promising prognostic indicators for various cancers. In fact, members of the miR-34 family, especially miR-34a, have been convincingly proved to affect almost the whole cancer progression process. Here, a total of 512 (miR-34a, 10/21), 85 (miR-34b, 10/16), and 114 (miR-34c, 10/14) putative targets of miR-34a/b/c are predicted by at least ten miRNA databases, respectively. These targets are further analyzed in gene ontology (GO), KEGG pathway, and the Reactome pathway dataset. The results suggest their involvement in the regulation of signal transduction, macromolecule metabolism, and protein modification. Also, the targets are implicated in critical signaling pathways, such as MAPK, Notch, Wnt, PI3K/AKT, p53, and Ras, as well as apoptosis, cell cycle, and EMT-related pathways. Moreover, the upstream regulators of miR-34a, mainly including transcription factors (TFs), lncRNAs, and DNA methylation, will be summarized. Meanwhile, the potential TF upstream of miR-34a/b/c will be predicted by PROMO, JASPAR, Animal TFDB 3.0, and GeneCard databases. Notably, miR-34a is an attractive target for certain cancers. In fact, miR-34a-based systemic delivery combined with chemotherapy or radiotherapy can more effectively control tumor progression. Collectively, this review will provide a panorama for miR-34a in cancer research.

Opportunities and challenges of patient-derived models in cancer research: patient-derived xenografts, patient-derived organoid and patient-derived cells.

BACKGROUND: As reported, preclinical animal models differ greatly from the human body. The evaluation model may be the colossal obstacle for scientific research and anticancer drug development. Therefore, it is essential to propose efficient evaluation systems similar to clinical practice for cancer research. MAIN BODY: While it has emerged for decades, the development of patient-derived xenografts, patient-derived organoid and patient-derived cell used to be limited. As the requirements for anticancer drug evaluation increases, patient-derived models developed rapidly recently, which is widely applied in basic research, drug development, and clinical application and achieved remarkable progress. However, there still lack systematic comparison and summarize reports for patient-derived models. In the current review, the development, applications, strengths, and challenges of patient-derived models in cancer research were characterized. CONCLUSION: Patient-derived models are an indispensable approach for cancer research and human health.

Alterations of housekeeping proteins in human aged and diseased hearts.

Pathological remodeling includes alterations of ion channel function and calcium homeostasis and ultimately cardiac maladaptive function during the process of disease development. Biochemical assays are important approaches for assessing protein abundance and post-translational modification of ion channels. Several housekeeping proteins are commonly used as internal controls to minimize loading variabilities in immunoblotting protein assays. Yet, emerging evidence suggests that some housekeeping proteins may be abnormally altered under certain pathological conditions. However, alterations of housekeeping proteins in aged and diseased human hearts remain unclear. In the current study, immunoblotting was applied to measure three commonly used housekeeping proteins (ß-actin, calsequestrin, and GAPDH) in well-procured human right atria (RA) and left ventricles (LV) from diabetic, heart failure, and aged human organ donors. Linear regression analysis suggested that the amounts of linearly loaded total proteins and quantified intensity of total proteins from either Ponceau S (PS) blot-stained or Coomassie Blue (CB) gel-stained images were highly correlated. Thus, all immunoblotting data were normalized with quantitative CB or PS data to calibrate potential loading variabilities. In the human heart, ß-actin was reduced in diabetic RA and LV, while GAPDH was altered in aged and diabetic RA but not LV. Calsequestrin, an important Ca2+ regulatory protein, was significantly changed in aged, diabetic, and ischemic failing hearts. Intriguingly, expression levels of all three proteins were unchanged in non-ischemic failing human LV. Overall, alterations of human housekeeping proteins are heart chamber specific and disease context dependent. The choice of immunoblotting loading controls should be carefully evaluated. Usage of CB or PS total protein analysis could be a viable alternative approach for some complicated pathological specimens.

TUBA1C expression promotes proliferation by regulating the cell cycle and indicates poor prognosis in glioma.

Gliomas are the major type of primary brain tumors. Accumulating research has demonstrated that tubulin is connected with the development and malignant progression of tumors. TUBA1C is a subtype of α-tubulin and is linked to prognosis in multiple cancers. In this study, the prognosis-related gene TUBA1C in glioma was identified and analyzed by bioinformatic approaches such as Kaplan-Meier (KM) survival time analysis, univariate and multivariate Cox analysis, receiver operating characteristic (ROC) analysis and functional enrichment analysis. Based on the above analyses, we found that glioma tissues had significantly higher expression of TUBA1C than normal brain tissues, and high expression of TUBA1C has worse prognosis in glioma. Gene set enrichment analysis (GSEA) revealed the signaling pathways related to the cell cycle. Furthermore, knockdown of TUBA1C also inhibited proliferation and migration and caused apoptosis and G2/M phase arrest in glioma cells. This study demonstrated that high TUBA1C expression correlated with poor outcomes in glioma patients and that knocking down TUBA1C suppressed glioma cell proliferation via cell cycle arrest. In addition, TUBA1C might be a therapeutic biomarker for gliomas.

Causal roles of stress kinase JNK2 in DNA methylation and binge alcohol withdrawal-evoked behavioral deficits.

Excessive binge alcohol intake is a common drinking pattern in humans, especially during holidays. Cessation of the binge drinking often leads to aberrant withdrawal behaviors, as well as serious heart rhythm abnormalities (clinically diagnosed as Holiday Heart Syndrome (HHS)). In our HHS mouse model with well-characterized binge alcohol withdrawal (BAW)-induced heart phenotypes, BAW leads to anxiety-like behaviors and cognitive impairment. We have previously reported that stress-activated c-Jun NH(2)-terminal kinase (JNK) plays a causal role in BAW-induced heart phenotypes. In the HHS brain, we found that activation of JNK2 (but not JNK1 and JNK3) in the prefrontal cortex (PFC), but not hippocampus and amygdala, led to anxiety-like behaviors and impaired cognition. DNA methylation mediated by a crucial DNA methylation enzyme, DNA methyltransferase1 (DNMT1), is known to be critical in alcohol-associated behavioral deficits. In HHS mice, JNK2 in the PFC (but not hippocampus and amygdala) causally enhanced total genomic DNA methylation via increased DNMT1 expression, which was regulated by enhanced binding of JNK downstream transcriptional factor c-JUN to the DNMT1 promoter. JNK2-specific inhibition either by an inhibitor JNK2I or JNK2 knockout completely offset c-JUN-regulated DNMT1 upregulation and restored the level of DNA methylation in HHS PFC to the baseline levels seen in sham controls. Strikingly, either JNK2-specific inhibition or genetic JNK2 depletion or DNMT1 inhibition (by an inhibitor 5-Azacytidine) completely abolished BAW-evoked behavioral deficits. In conclusion, our studies revealed a novel mechanism by which JNK2 drives BAW-evoked behavioral deficits through a DNMT1-regulated DNA hypermethylation. JNK2 could be a novel therapeutic target for alcohol withdrawal treatment and/or prevention.

Sepiapterin reductase: Characteristics and role in diseases.

Sepiapterin reductase, a homodimer composed of two subunits, plays an important role in the biosynthesis of tetrahydrobiopterin. Furthermore, sepiapterin reductase exhibits a wide distribution in different tissues and is associated with many diseases, including brain dysfunction, chronic pain, cardiovascular disease and cancer. With regard to drugs targeting sepiapterin reductase, many compounds have been identified and provide potential methods to treat various diseases. However, the underlying mechanism of sepiapterin reductase in many biological processes is unclear. Therefore, this article summarized the structure, distribution and function of sepiapterin reductase, as well as the relationship between sepiapterin reductase and different diseases, with the aim of finding evidence to guide further studies on the molecular mechanisms and the potential clinical value of sepiapterin reductase. In particular, the different effects induced by the depletion of sepiapterin reductase or the inhibition of the enzyme suggest that the non-enzymatic activity of sepiapterin reductase could function in certain biological processes, which also provides a possible direction for sepiapterin reductase research.

The structure and regulation of the E3 ubiquitin ligase HUWE1 and its biological functions in cancer.

E3 ligases are a class of critical enzymes that can catalyse the transfer of ubiquitin (Ub) from an E2 enzyme to the substrate and are essential to cellular processes. The E3 ligase HUWE1 (also known as ARF-BP1, HECTH9, HSPC272, Ib772, LASU1, MULE, URE-B1, UREB1, and HECT, UBA and WWE domain-containing E3 ubiquitin protein ligase 1) is encoded by the huwe1 gene. HUWE1 is a key regulator of the DNA damage response, transcription, autophagy, apoptosis and metabolism in a variety of cancers. Due to its pivotal role in conferring substrate specificity, HUWE1 has attracted enormous attention as a promising anticancer drug target. In this review, we indicate the specific molecular structure of HUWE1 and its role in various cellular signalling pathways and highlight new insights into HUWE1 in cancer. Finally, we discuss outstanding questions regarding HUWE1 in oncology and highlight its limitations in drug development and clinical guidance to better define the role of HUWE1 in multiple cancers.

Synergistic combination of DT-13 and Topotecan inhibits aerobic glycolysis in human gastric carcinoma BGC-823 cells via NM IIA/EGFR/HK II axis.

DT-13 combined with topotecan (TPT) showed stronger antitumour effects in mice subcutaneous xenograft model compared with their individual effects in our previous research. Here, we further observed the synergistically effect in mice orthotopic xenograft model. Metabolomics analysis showed DT-13 combined with TPT alleviated metabolic disorders induced by tumour and synergistically inhibited the activity of the aerobic glycolysis-related enzymes in vivo and in vitro. Mechanistic studies revealed that the combination treatment promoted epidermal growth factor receptor (EGFR) degradation through non-muscle myosin IIA (NM IIA)-induced endocytosis of EGFR, further inhibited the activity of hexokinase II (HK II), and eventually promoted the aerobic glycolysis inhibition activity more efficiently compared with TPT or DT-13 monotherapy. The combination therapy also inhibited the specific binding of HK II to mitochondria. When using the NM II inhibitor (-)002Dblebbistatin or MYH-9 shRNA, the synergistic inhibition effect of DT-13 and TPT on aerobic glycolysis was eliminated in BGC-823 cells. Immunohistochemical analysis revealed selective up-regulation of NM IIA while specific down-regulation of p-CREB, EGFR, and HK II by the combination therapy. Collectively, these findings suggested that this regimen has significant clinical implications, warranted further investigation.

Tumor-secreted PAI-1 promotes breast cancer metastasis via the induction of adipocyte-derived collagen remodeling.

BACKGROUND: Breast cancer cells recruit surrounding stromal cells, such as cancer-associated fibroblasts (CAFs), to remodel collagen and promote tumor metastasis. Adipocytes are the most abundant stromal partners in breast tissue, local invasion of breast cancer leads to the proximity of cancer cells and adipocytes, which respond to generate cancer-associated adipocytes (CAAs). These cells exhibit enhanced secretion of extracellular matrix related proteins, including collagens. However, the role of adipocyte-derived collagen on breast cancer progression still remains unclear. METHODS: Adipocytes were cocultured with breast cancer cells for 3D collagen invasion and collagen organization exploration. Breast cancer cells and adipose tissue co- implanted mouse model, clinical breast cancer samples analysis were used to study the crosstalk between adipose and breast cancer cells in vivo. A combination of proteomics, enzyme-linked immunosorbent assay, loss of function assay, qPCR, western blot, database analysis and chromatin immunoprecipitation assays were performed to study the mechanism mediated the activation of PLOD2 in adipocytes. RESULTS: It was found that CAAs remodeled collagen alignment during crosstalk with breast cancer cells in vitro and in vivo, which further promoted breast cancer metastasis. Tumor-derived PAI-1 was required to activate the expression of the intracellular enzyme procollagen-lysine, 2-oxoglutarate 5-dioxygenase 2 (PLOD2) in CAAs. Pharmacologic blockade of PAI-1 or PLOD2 disrupted the collagen reorganization in CAAs. Mechanistically, it was observed that PI3K/AKT pathway was activated in adipocytes upon co-culturing with breast cancer cells or treatment with recombinant PAI-1, which could promote the translocation of transcription factor FOXP1 into the nucleus and further enhanced the promoter activity of PLOD2 in CAAs. In addition, collagen reorganization at the tumor-adipose periphery, as well as the positive relevance between PAI-1 and PLOD2 in invasive breast carcinoma were confirmed in clinical specimens of breast cancer. CONCLUSION: In summary, our findings revealed a new stromal collagen network that favors tumor invasion and metastasis establish between breast cancer cells and surrounding adipocytes at the tumor invasive front, and identified PLOD2 as a therapeutic target for metastatic breast cancer treatment.

Adipocyte-derived IL-6 and leptin promote breast Cancer metastasis via upregulation of Lysyl Hydroxylase-2 expression.

BACKGROUND: Adipocytes make up the major component of breast tissue, accounting for 90% of stromal tissue. Thus, the crosstalk between adipocytes and breast cancer cells may play a critical role in cancer progression. Adipocyte-breast cancer interactions have been considered important for the promotion of breast cancer metastasis. However, the specific mechanisms underlying these interactions are unclear. In this study, we investigated the mechanisms of adipocyte-mediated breast cancer metastasis. METHODS: Breast cancer cells were cocultured with mature adipocytes for migration and 3D matrix invasion assays. Next, lentivirus-mediated loss-of-function experiments were used to explore the function of lysyl hydroxylase (PLOD2) in breast cancer migration and adipocyte-dependent migration of breast cancer cells. The role of PLOD2 in breast cancer metastasis was further confirmed using orthotopic mammary fat pad xenografts in vivo. Clinical samples were used to confirm that PLOD2 expression is increased in tumor tissue and is associated with poor prognosis of breast cancer patients. Cells were treated with cytokines and pharmacological inhibitors in order to verify which adipokines were responsible for activation of PLOD2 expression and which signaling pathways were activated in vitro. RESULTS: Gene expression profiling and Western blotting analyses revealed that PLOD2 was upregulated in breast cancer cells following coculture with adipocytes; this process was accompanied by enhanced breast cancer cell migration and invasion. Loss-of-function studies indicated that PLOD2 knockdown suppressed cell migration and disrupted the formation of actin stress fibers in breast cancer cells and abrogated the migration induced by following coculture with adipocytes. Moreover, experiments performed in orthotopic mammary fat pad xenografts showed that PLOD2 knockdown could reduce metastasis to the lung and liver. Further, high PLOD2 expression correlated with poor prognosis of breast cancer patients. Mechanistically, adipocyte-derived interleukin-6 (IL-6) and leptin may facilitate PLOD2 upregulation in breast cancer cells and promote breast cancer metastasis in tail vein metastasis assays. Further investigation revealed that adipocyte-derived IL-6 and leptin promoted PLOD2 expression through activation of the JAK/STAT3 and PI3K/AKT signaling pathways. CONCLUSIONS: Our study reveals that adipocyte-derived IL-6 and leptin promote PLOD2 expression by activating the JAK/STAT3 and PI3K/AKT signaling pathways, thus promoting breast cancer metastasis.

[Effects and mechanisms of Xiao-Ai-Ping injection on angiogenesis].

This study was designed to investigate the effect of Xiao-Ai-Ping injection on cancer angiogenesis. CCK8 assay and Brd U incorporation immunofluorescence assay were used to detect the effect of Xiao-Ai-Ping injection on HUVECs proliferation; wound healing assay and transwell assay were employed to test the effect of Xiao-Ai-Ping injection on HUVECs migration. The anti-angiogenic effect of Xiao-Ai-Ping injection was examined by tube formation assay, rat aortic ring assay and chicken chorioallantoic membrane(CAM) assay. ELISA assay was used to measure the secretion of vascular endothelial growth factor(VEGF); and the activation of vascular endothelial growth factor receptor 2(VEGFR2) protein and its downstream signaling pathways were examined by Western blot. Our data demonstrated that Xiao-Ai-Ping injection inhibited HUVECs proliferation in a time- and dose-dependent manner, and the IC(50) (mg·m L(-1)) values for 24, 48 and 72 h were 48.7 ± 7.14, 29.1 ±2.25 and 22.0 ± 4.53, individually. Xiao-Ai-Ping injection inhibited HUVECs DNA synthesis and migration. Xiao-Ai-Ping injection suppressed HUVECs tube formation, and reduced microvessel sprouting from rat aortic rings and vessel growth in CAMs. Furthermore, Xiao-Ai-Ping injection attenuated the secretion of VEGF, and inhibited the expression of p-VEGFR2 and phosphorylation of protein kinase B(p-AKT). We conclude that Xiao-Ai-Ping injection inhibits angiogenesis by down-regulation of VEGF signaling and AKT pathway.

p85α mediates NFAT3-dependent VEGF induction in the cellular UVB response.

Exposure to solar ultraviolet B (UVB) radiation is known to induce several pathological reactions in the skin. In these processes, upregulation of VEGF expression has been demonstrated to be important in angiogenesis-associated photodamage and even skin cancers. However, the signaling events that are responsible for VEGF induction under UVB exposure have not been fully defined. Here, we demonstrate that the regulatory subunit of the phosphoinositide 3-kinase (PI3K), p85α, plays a role in mediating UVB-induced VEGF expression in mouse embryonic fibroblasts (MEFs) and mouse epithermal cells, the effect of which is unrelated to the PI3K activity. The transcriptional factor NFAT3 functions as a downstream target of p85α to mediate the induction of VEGF expression in the UVB response. Although lacking NFAT3-binding ability, p85α is required for the recruitment of NFAT3 to the NFAT-response element within the vegf promoter. Furthermore, by identifying the adjacent NFAT- and AP-1-binding sites within the vegf promoter, we also found an induced interaction between NFAT3 and one of the AP-1 components, c-Fos, after UVB irradiation. Without the aid of c-Fos, NFAT3 lost its vegf-promoter-binding ability. Taken together, our results reveal a novel PI3K-independent role for p85α in controlling VEGF induction during the cellular UVB response by regulating NFAT3 activity. Targeting p85α might be helpful for preventing UVB-induced angiogenesis and the associated photodamage.

(+)- and (-)-liriodenol, a pair of novel enantiomeric lignans from Liriodendron hybrid.

(+)- and (-)-liriodenol, a pair of unprecedented enantiomeric lignans bearing a 1,1-disubstituted olefinic group, were isolated from the barks of Liriodendron hybrid. The structure and relative configurations were determined by comprehensive analysis of MS and NMR spectroscopy. The cytotoxicity of these three lignans ((±)-, (+)-, and (-)-liriodenol) was evaluated in vitro against four selected human tumor cell lines, where (+)-liriodenol showed more significant cytotoxic effects than the (±)- and (-)-liriodenol enantiomers.

Ribosomal protein S7 regulates arsenite-induced GADD45α expression by attenuating MDM2-mediated GADD45α ubiquitination and degradation.

The stress-responding protein, GADD45α, plays important roles in cell cycle checkpoint, DNA repair and apoptosis. In our recent study, we demonstrate that GADD45α undergoes a dynamic ubiquitination and degradation in vivo, which process can be blocked by the cytotoxic reagent, arsenite, resulting in GADD45α accumulation to activate JNKs cell death pathway, thereby revealing a novel mechanism for the cellular GADD45α functional regulation. But the factors involved in GADD45α stability modulations are unidentified. Here, we demonstrated that MDM2 was an E3 ubiquitin ligase for GADD45α. One of MDM2-binding partner, ribosomal protein S7, interacted with and stabilized GADD45α through preventing the ubiquitination and degradation of GADD45α mediated by MDM2. This novel function of S7 is unrelated to p53 but seems to depend on S7/MDM2 interaction, for the S7 mutant lacking MDM2-binding ability lost its function to stabilize GADD45α. Further investigations indicated that arsenite treatment enhanced S7-MDM2 interaction, resulting in attenuation of MDM2-dependent GADD45α ubiquitination and degradation, thereby leading to GADD45α-dependent cell death pathway activation. Silencing S7 expression suppressed GADD45α-dependent cytotoxicity induced by arsenite. Our findings thus identify a novel function of S7 in control of GADD45α stabilization under both basal and stress conditions and its significance in mediating arsenite-induced cellular stress.

The extract, LXB-1, from the barks of Liriodendron × hybrid, induced apoptosis via Akt, JNK and ERK1/2 pathways in A549 lung cancer cells.

The effect of LXB-1, an extract from Liriodendron × hybrid, was determined on A549 human lung adenocarcinoma cell lines. Growth inhibition of LXB-1 was analyzed by MTT assay. Cancer cell cycle was measured by flow cytometry. To verify the apoptosis effect of LXB-1 on A549 cells, annexin V/PI double staining assay was performed. The expression levels of proapoptotic proteins were also measured by western blot. The potential mechanisms of LXB-1 inducing apoptosis - the expression and phosphorylation of ERK, p38, JNK and Akt - were investigated by western blot. The IC50 values of LXB-1 on A549 for 24, 48 and 72 h treatment were determined to be 12.97±1.53 µg/mL, 9.55±1.42 µg/mL, and 5.90±0.74 µg/mL, respectively. LXB-1 induced an obvious G2/M cell cycle arrest in A549 cells and resulted in significant cell apoptosis. LXB-1 also increased the cleavage of both caspase-3 and caspase-9, and greatly decreased the protein levels of Bcl-2. Moreover, LXB-1 increased the expression of phosphorylated JNK but decreased the levels of phosphorylated ERK1/2 and Akt. These results suggest that that LXB-1 induced apoptosis through JNK, ERK1/2, and Akt pathways in A549 cells.

IKKα contributes to UVB-induced VEGF expression by regulating AP-1 transactivation.

Exposure to ultraviolet B (UVB) irradiation from sunlight induces the upregulation of VEGF, a potent angiogenic factor that is critical for mediating angiogenesis-associated photodamage. However, the molecular mechanisms related to UVB-induced VEGF expression have not been fully defined. Here, we demonstrate that one of the catalytic subunits of the IκB kinase complex (IKK), IKKα, plays a critical role in mediating UVB-induced VEGF expression in mouse embryonic fibroblasts (MEFs), which requires IKKα kinase activity but is independent of IKKß, IKKγ and the transactivation of NF-κB. We further show that the transcriptional factor AP-1 functions as the downstream target of IKKα that is responsible for VEGF induction under UVB exposure. Both the accumulation of AP-1 component, c-Fos and the transactivation of AP-1 by UVB require the activated IKKα located within the nucleus. Moreover, nuclear IKKα can associate with c-Fos and recruit to the vegf promoter regions containing AP-1-responsive element and then trigger phosphorylation of the promoter-bound histone H3. Thus, our results have revealed a novel independent role for IKKα in controlling VEGF expression during the cellular UVB response by regulating the induction of the AP-1 component and phosphorylating histone H3 to facilitate AP-1 transactivation. Targeting IKKα shows promise for the prevention of UVB-induced angiogenesis and the associated photodamage.

AP-1 activation attenuates the arsenite-induced apoptotic response in human bronchial epithelial cells by up-regulating HO-1 expression.

Arsenite is a cytotoxic reagent that has been used clinically to treat certain cancers. Although the cytotoxic mechanisms of arsenite have been investigated, the cellular mechanisms that act against arsenite damage are poorly understood. Heme oxygenase 1 (HO-1) has been implicated in cellular survival under other multiple stress conditions. Here, we show that a significant induction of HO-1 expression is present in human bronchial epithelial cells (Beas-2B) treated with lethal doses of arsenite treatment. This induction depends on the known ERK/AP1 signaling pathway. As expected, HO-1 RNAi knockdown, or ERK/AP1 inhibition, renders the Beas-2B cells more sensitive to arsenite damage. Our data thus suggest that transcriptional upregulation of HO-1 expression via a putative ERK/AP-1 pathway constitutes an inherent mechanism by which arsenite-induced apoptosis is attenuated.

The influence of YS-1 on the Dll4-Notch1 signaling pathway.

In this study, we investigated the role and molecular mechanism of p43 and YS-1 (recombinant human p43 protein) in Dll4-Notch1 signaling pathway. Active, small interfering RNA and recombinant plasmid targeting of p43 protein were used to infect human umbilical vein endothelial cells (HUVECs). Three-dimensional sprouting model, endothelial cell migration assay, and sprouting and tube formation assay were used to deduce the function of p43 and YS-1 in angiogenesis. Semi-quantitative reverse transcription-polymerase chain reaction and western blot analysis were performed to detect the efficiency of p43 in Dll4-Notch1 signaling in HUVECs. It was found that silencing and overexpression of p43 could upregulate Dll4-Notch and stimulate angiogenesis. p43 plays a complex role in angiogenesis. When the concentration is under 100 nM, it promotes angiogenesis; instead, when the concentration is over 100 nM, it inhibits angiogenesis. In this study, we found that the expression level of p43 was under 60 nM. However, recombinant human p43 protein, YS-1, inhibited endothelial cell sprouting, and 500 µg/ml of YS-1 attenuated the activation of Dll4-Notch1 signaling. These results suggested that YS-1 could directly inhibit angiogenesis through Dll4-Notch1 signal transduction pathway, while p43 plays a modulating role in this signaling pathway.