Macrophage interleukin-1ß mediates atrial fibrillation risk in diabetic mice.

Diabetes mellitus (DM) is an independent risk factor for atrial fibrillation (AF). The mechanisms underlying DM-associated AF are unclear. AF and DM are both related to inflammation. We investigated whether DM-associated inflammation contributed to AF risk. Mice were fed with high fat diet to induce type II DM and were subjected to IL-1ß antibodies, macrophage depletion by Clodronate liposomes, a mitochondrial antioxidant (mitoTEMPO), or a cardiac ryanodine receptor (RyR2) stabilizer (S107). All tests were performed at 36-38 weeks of age. DM mice presented with increased AF inducibility, enhanced mitochondrial reactive oxygen species (mitoROS) generation, and activated innate immunity in the atria as evidenced by enhanced monocyte chemoattractant protein-1 (MCP-1) expression, macrophage infiltration, and IL-1ß levels. Signs of aberrant RyR2 Ca2+ leak were observed in the atria of DM mice. IL-1ß neutralization, macrophage depletion, mitoTEMPO, and S107 significantly ameliorated the AF vulnerability in DM mice. Atrial overexpression of MCP-1 increased AF occurrence in normal mice through the same mechanistic signaling cascade as observed in DM mice. In conclusion, macrophage-mediated IL-1ß contributed to DM-associated AF risk through mitoROS modulation of RyR2 Ca2+ leak.

Lysosomal Ca2+ flux modulates automaticity in ventricular cardiomyocytes and correlates with arrhythmic risk.

Automaticity involves Ca2+ handling at the cell membrane and sarcoplasmic reticulum (SR). Abnormal or acquired automaticity is thought to initiate ventricular arrhythmias associated with myocardial ischemia. Ca2+ flux from mitochondria can influence automaticity, and lysosomes also release Ca2+. Therefore, we tested whether lysosomal Ca2+ flux could influence automaticity. We studied ventricular human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs), hiPSC 3D engineered heart tissues (EHTs), and ventricular cardiomyocytes isolated from infarcted mice. Preventing lysosomal Ca2+ cycling reduced automaticity in hiPSC-CMs. Consistent with a lysosomal role in automaticity, activating the transient receptor potential mucolipin channel (TRPML1) enhanced automaticity, and two channel antagonists reduced spontaneous activity. Activation or inhibition of lysosomal transcription factor EB (TFEB) increased or decreased total lysosomes and automaticity, respectively. In adult ischemic cardiomyocytes and hiPSC 3D EHTs, reducing lysosomal Ca2+ release also inhibited automaticity. Finally, TRPML1 was up-regulated in cardiomyopathic patients with ventricular tachycardia (VT) compared with those without VT. In summary, lysosomal Ca2+ handling modulates abnormal automaticity, and reducing lysosomal Ca2+ release may be a clinical strategy for preventing ventricular arrhythmias.

Inflammatory Macrophage Interleukin-1ß Mediates High-Fat Diet-Induced Heart Failure With Preserved Ejection Fraction.

Diabetes mellitus (DM) is a main risk factor for diastolic dysfunction (DD) and heart failure with preserved ejection fraction. High-fat diet (HFD) mice presented with diabetes mellitus, DD, higher cardiac interleukin (IL)-1ß levels, and proinflammatory cardiac macrophage accumulation. DD was significantly ameliorated by suppressing IL-1ß signaling or depleting macrophages. Mice with macrophages unable to adopt a proinflammatory phenotype were low in cardiac IL-1ß levels and were resistant to HFD-induced DD. IL-1ß enhanced mitochondrial reactive oxygen species (mitoROS) in cardiomyocytes, and scavenging mitoROS improved HFD-induced DD. In conclusion, macrophage-mediated inflammation contributed to HFD-associated DD through IL-1ß and mitoROS production.

miR-448 regulates potassium voltage-gated channel subfamily A member 4 (KCNA4) in ischemia and heart failure.

BACKGROUND: MicroRNA miR-448 mediates some of the effects of ischemia on arrhythmic risk. Potassium voltage-gated channel subfamily A member 4 (KCNA4) encodes a Kv1.4 current that opens in response to membrane depolarization and is essential for regulating the action potential duration in heart. KCNA4 has a miR-448 binding site. OBJECTIVE: We investigated whether miR-448 was involved in the regulation of KCNA4 messenger RNA expression in ischemia. METHODS: Quantitative real-time reverse-transcriptase polymerase chain reaction was used to investigate the expression of KCNA4 and miR-448. Pull-down assays were used to examine the interaction between miR-448 and KCNA4. miR-448 decoy and binding site mutation were used to examine the specificity of the effect for KCNA4. RESULTS: The expression of KCNA4 is diminished in ischemia and human heart failure tissues with ventricular tachycardia. Previously, we have shown that miR-448 is upregulated in ischemia and inhibition can prevent arrhythmic risk after myocardial infarction. The 3'-untranslated region of KCNA4 has a conserved miR-448 binding site. miR-448 bound to this site directly and reduced KCNA4 expression and the transient outward potassium current. Inhibition of miR-448 restored KCNA4. CONCLUSION: These findings showed a link between Kv1.4 downregulation and miR-448-mediated upregulation in ischemia, suggesting a new mechanism for the antiarrhythmic effect of miR-448 inhibition.

Reduced sarcoplasmic reticulum Ca2+ pump activity is antiarrhythmic in ischemic cardiomyopathy.

BACKGROUND: We have described an arrhythmic mechanism seen only in cardiomyopathy that involves increased mitochondrial Ca2+ handling and selective transfer of Ca2+ to the sarcoplasmic reticulum (SR). Modeling suggested that mitochondrial Ca2+ transfer to the SR via type 2a sarco/endoplasmic reticulum Ca2+-ATPase (SERCA2a) is a crucial element of this arrhythmic mechanism. OBJECTIVE: We tested the role of SERCA2a in arrhythmias during ischemic cardiomyopathy. METHODS: Myocardial infarction (MI) was induced in wild-type (Wt) and SERCA2a heterozygous knockdown (SERCA+/-) mice. RESULTS: Compared with Wt MI mice, SERCA2a heterozygous knockdown (SERCA+/-) MI mice had a substantially lower mortality after 3 weeks of MI without a significant change in MI area. Aside from a significant delay of the cytoplasmic Ca2+ transient decay existed in SERCA+/- compared with Wt, SERCA+/- did not affect cardiac systolic and diastolic function at the whole organ or single cell levels either before or after MI. After MI, SERCA+/- mice had reduced SERCA2a expression in the MI border zone compared with Wt MI mice. SERCA+/- mice had significantly decreased corrected QT intervals and less ventricular tachycardia compared with Wt MI mice. SERCA+/- cardiomyocytes from MI mice showed a reduced action potential duration and reduced triggered activity compared with Wt MI cardiomyocytes. Reduction in arrhythmic risk was accompanied by reduced diastolic SR Ca2+ sparks, reduced SR Ca2+ content, reduced oxidized ryanodine receptor, and increased calsequestrin 2 in SERCA+/- MI mice. CONCLUSION: SERCA2a knockdown was antiarrhythmic after MI without affecting overall systolic performance. Possible antiarrhythmic mechanisms included reduced SR free Ca2+ and reduced diastolic SR Ca2+ release.

PRR16/Largen Induces Epithelial-Mesenchymal Transition through the Interaction with ABI2 Leading to the Activation of ABL1 Kinase.

Advanced or metastatic breast cancer affects multiple organs and is a leading cause of cancer-related death. Cancer metastasis is associated with epithelial-mesenchymal metastasis (EMT). However, the specific signals that induce and regulate EMT in carcinoma cells remain unclear. PRR16/Largen is a cell size regulator that is independent of mTOR and Hippo signalling pathways. However, little is known about the role PRR16 plays in the EMT process. We found that the expression of PRR16 was increased in mesenchymal breast cancer cell lines. PRR16 overexpression induced EMT in MCF7 breast cancer cells and enhances migration and invasion. To determine how PRR16 induces EMT, the binding proteins for PRR16 were screened, revealing that PRR16 binds to Abl interactor 2 (ABI2). We then investigated whether ABI2 is involved in EMT. Gene silencing of ABI2 induces EMT, leading to enhanced migration and invasion. ABI2 is a gene that codes for a protein that interacts with ABL proto-oncogene 1 (ABL1) kinase. Therefore, we investigated whether the change in ABI2 expression affected the activation of ABL1 kinase. The knockdown of ABI2 and PRR16 overexpression increased the phosphorylation of Y412 in ABL1 kinase. Our results suggest that PRR16 may be involved in EMT by binding to ABI2 and interfering with its inhibition of ABL1 kinase. This indicates that ABL1 kinase inhibitors may be potential therapeutic agents for the treatment of PRR16-related breast cancer.

Preventing unfolded protein response-induced ion channel dysregulation to treat arrhythmias.

Cardiomyopathies are associated with arrhythmias and cardiac ion channel downregulation. This downregulation is arrhythmogenic. Paradoxically, antiarrhythmic therapies are based on ion channel-blocking drugs that further downregulate these channels and exhibit proarrhythmic risk. Recent studies have shown that inhibition of the protein kinase RNA-like ER kinase (PERK) arm of the unfolded protein response (UPR) prevents select cardiac ion channel downregulation and plays a protective role against arrhythmias. Prevention of ion channel downregulation represents as a novel therapeutic strategy to treat arrhythmias in myocardial infarction and heart failure.

Loss of EMP2 Inhibits Melanogenesis of MNT1 Melanoma Cells via Regulation of TRP-2.

Melanogenesis is the production of melanin from tyrosine by a series of enzyme-catalyzed reactions, in which tyrosinase and DOPA oxidase play key roles. The melanin content in the skin determines skin pigmentation. Abnormalities in skin pigmentation lead to various skin pigmentation disorders. Recent research has shown that the expression of EMP2 is much lower in melanoma than in normal melanocytes, but its role in melanogenesis has not yet been elucidated. Therefore, we investigated the role of EMP2 in the melanogenesis of MNT1 human melanoma cells. We examined TRP-1, TRP-2, and TYR expression levels during melanogenesis in MNT1 melanoma cells by gene silencing of EMP2. Western blot and RT-PCR results confirmed that the expression levels of TYR and TRP-2 were decreased when EMP2 expression was knocked down by EMP2 siRNA in MNT1 cells, and these changes were reversed when EMP2 was overexpressed. We verified the EMP2 gene was knocked out of the cell line (EMP2 CRISPR/Cas9) by using a CRISPR/Cas9 system and found that the expression levels of TRP-2 and TYR were significantly lower in the EMP2 CRISPR/Cas9 cell lines. Loss of EMP2 also reduced migration and invasion of MNT1 melanoma cells. In addition, the melanosome transfer from the melanocytes to keratinocytes in the EMP2 KO cells cocultured with keratinocytes was reduced compared to the cells in the control coculture group. In conclusion, these results suggest that EMP2 is involved in melanogenesis via the regulation of TRP-2 expression.

Resolvin D1 Suppresses H2O2-Induced Senescence in Fibroblasts by Inducing Autophagy through the miR-1299/ARG2/ARL1 Axis.

ARG2 has been reported to inhibit autophagy in vascular endothelial cells and keratinocytes. However, studies of its mechanism of action, its role in skin fibroblasts, and the possibility of promoting autophagy and inhibiting cellular senescence through ARG2 inhibition are lacking. We induced cellular senescence in dermal fibroblasts by using H2O2. H2O2-induced fibroblast senescence was inhibited upon ARG2 knockdown and promoted upon ARG2 overexpression. The microRNA miR-1299 suppressed ARG2 expression, thereby inhibiting fibroblast senescence, and miR-1299 inhibitors promoted dermal fibroblast senescence by upregulating ARG2. Using yeast two-hybrid assay, we found that ARG2 binds to ARL1. ARL1 knockdown inhibited autophagy and ARL1 overexpression promoted it. Resolvin D1 (RvD1) suppressed ARG2 expression and cellular senescence. These data indicate that ARG2 stimulates dermal fibroblast cell senescence by inhibiting autophagy after interacting with ARL1. In addition, RvD1 appears to promote autophagy and inhibit dermal fibroblast senescence by inhibiting ARG2 expression. Taken together, the miR-1299/ARG2/ARL1 axis emerges as a novel mechanism of the ARG2-induced inhibition of autophagy. Furthermore, these results indicate that miR-1299 and pro-resolving lipids, including RvD1, are likely involved in inhibiting cellular senescence by inducing autophagy.

LW1497, an Inhibitor of Malate Dehydrogenase, Suppresses TGF-ß1-Induced Epithelial-Mesenchymal Transition in Lung Cancer Cells by Downregulating Slug.

LW1497 suppresses the expression of the hypoxia-inducing factor (HIF)-1α inhibiting malate dehydrogenase. Although hypoxia and HIF-1α are known to be important in cancer, LW1497 has not been therapeutically applied to cancer yet. Thus, we investigated the effect of LW1497 on the epithelial-mesenchymal transition (EMT) of lung cancer cells. A549 and H1299 lung cancer cells were induced to undergo via TGF-ß1 treatment, resulting in the downregulation of E-cadherin and upregulation of N-cadherin and Vimentin concurrently with increases in the migration and invasion capacities of the cells. These effects of TGF-ß1 were suppressed upon co-treatment of the cells with LW1497. An RNA-seq analysis revealed that LW1497 induced differential expression of genes related to hypoxia, RNA splicing, angiogenesis, cell migration, and metastasis in the A549 lung cancer cell lines. We confirmed the differential expression of Slug, an EMT-related transcription factor. Results from Western blotting and RT-PCR confirmed that LW1497 inhibited the expression of EMT markers and Slug. After orthotopically transplanting A549 cancer cells into mice, LW1497 was administered to examine whether the lung cancer progression was inhibited. We observed that LW1497 reduced the area of cancer. In addition, the results from immunohistochemical analyses showed that LW1497 downregulated EMT markers and Slug. In conclusion, LW1497 suppresses cancer progression through the inhibition of EMT by downregulating Slug.

Inhibition of the unfolded protein response reduces arrhythmia risk after myocardial infarction.

Ischemic cardiomyopathy is associated with an increased risk of sudden death, activation of the unfolded protein response (UPR), and reductions in multiple cardiac ion channels. When activated, the protein kinase-like ER kinase (PERK) branch of the UPR reduces protein translation and abundance. We hypothesized that PERK inhibition could prevent ion channel downregulation and reduce arrhythmia risk after myocardial infarct (MI). MI induced in mice by coronary artery ligation resulted in reduced ion channel levels, ventricular tachycardia (VT), and prolonged corrected intervals between the Q and T waves on the ECGs (QTc). Protein levels of major cardiac ion channels were decreased. MI cardiomyocytes showed significantly prolonged action potential duration and decreased maximum upstroke velocity. Cardiac-specific PERK KO reduced electrical remodeling in response to MI, with shortened QTc intervals, fewer VT episodes, and higher survival rates. Pharmacological PERK inhibition had similar effects. In conclusion, we found that activated PERK during MI contributed to arrhythmia risk by the downregulation of select cardiac ion channels. PERK inhibition prevented these changes and reduced arrhythmia risk. These results suggest that ion channel downregulation during MI is a fundamental arrhythmia mechanism and that maintenance of ion channel levels is antiarrhythmic.

Magnesium Deficiency Causes a Reversible, Metabolic, Diastolic Cardiomyopathy.

Background Dietary Mg intake is associated with a decreased risk of developing heart failure, whereas low circulating Mg level is associated with increased cardiovascular mortality. We investigated whether Mg deficiency alone could cause cardiomyopathy. Methods and Results C57BL/6J mice were fed with a low Mg (low-Mg, 15-30 mg/kg Mg) or a normal Mg (nl-Mg, 600 mg/kg Mg) diet for 6 weeks. To test reversibility, half of the low-Mg mice were fed then with nl-Mg diet for another 6 weeks. Low-Mg diet significantly decreased mouse serum Mg (0.38±0.03 versus 1.14±0.03 mmol/L for nl-Mg; P<0.0001) with a reciprocal increase in serum Ca, K, and Na. Low-Mg mice exhibited impaired cardiac relaxation (ratio between mitral peak early filling velocity E and longitudinal tissue velocity of the mitral anterior annulus e, 21.1±1.1 versus 15.4±0.4 for nl-Mg; P=0.011). Cellular ATP was decreased significantly in low-Mg hearts. The changes were accompanied by mitochondrial dysfunction with mitochondrial reactive oxygen species overproduction and membrane depolarization. cMyBPC (cardiac myosin-binding protein C) was S-glutathionylated in low-Mg mouse hearts. All these changes were normalized with Mg repletion. In vivo (2-(2,2,6,6-tetramethylpiperidin-1-oxyl-4-ylamino)-2-oxoethyl)triphenylphosphonium chloride treatment during low-Mg diet improved cardiac relaxation, increased ATP levels, and reduced S-glutathionylated cMyBPC. Conclusions Mg deficiency caused a reversible diastolic cardiomyopathy associated with mitochondrial dysfunction and oxidative modification of cMyBPC. In deficiency states, Mg supplementation may represent a novel treatment for diastolic heart failure.

Ethacrynic acid, a loop diuretic, suppresses epithelial-mesenchymal transition of A549 lung cancer cells via blocking of NDP-induced WNT signaling.

Lung cancer is one of the leading causes of death in cancer patients. Epithelial-mesenchymal transition (EMT) plays an important role in lung cancer progression. Therefore, for lung cancer treatment, it is crucial to find substances that inhibit EMT. Ethacrynic acid (ECA) is a diuretic that inhibits cellular ion flux and exerts anticancer effects. However, the effects of ECA on EMT in lung cancer remain unclear. We examined the effects of ECA on sphingosylphosphorylcholine (SPC) or TGF-ß1-induced EMT process in A549 and H1299 cells via reverse transcription polymerase chain reaction and Western blotting. We found that ECA inhibited SPC-induced EMT and SPC-induced WNT signalling in EMT. We observed that SPC induces the expression of NDP [Norrie disease protein] and WNT-2, whereas ECA suppressed their expression. SPC-induced WNT activation, EMT, migration, and invasion were suppressed by NDP small-interfering RNA (siNDP), but NDP overexpression (pNDP) enhanced these events in A549 and H1299 cells. Accordingly, NDP expression may influence lung cancer prognosis. In summary, our results revealed that ECA inhibited SPC or TGF-ß1-induced EMT in A549 and H1299 lung cancer cells by downregulating NDP expression and inhibiting WNT activation. Therefore, ECA might be a new drug candidate for lung cancer treatment.

Therapeutic Effects of Specialized Pro-Resolving Lipids Mediators on Cardiac Fibrosis via NRF2 Activation.

Heart disease is the number one mortality disease in the world. In particular, cardiac fibrosis is considered as a major factor causing myocardial infarction and heart failure. In particular, oxidative stress is a major cause of heart fibrosis. In order to control such oxidative stress, the importance of nuclear factor erythropoietin 2 related factor 2 (NRF2) has recently been highlighted. In this review, we will discuss the activation of NRF2 by docosahexanoic acid (DHA), eicosapentaenoic acid (EPA), and the specialized pro-resolving lipid mediators (SPMs) derived from polyunsaturated lipids, including DHA and EPA. Additionally, we will discuss their effects on cardiac fibrosis via NRF2 activation.

MIR448 antagomir reduces arrhythmic risk after myocardial infarction by upregulating the cardiac sodium channel.

Cardiac ischemia is associated with arrhythmias; however, effective therapies are currently limited. The cardiac voltage-gated sodium channel α subunit (SCN5A), encoding the Nav1.5 current, plays a key role in the cardiac electrical conduction and arrhythmic risk. Here, we show that hypoxia reduces Nav1.5 through effects on a miR, miR-448. miR-448 expression is increased in ischemic cardiomyopathy. miR-448 has a conserved binding site in 3'-UTR of SCN5A. miR-448 binding to this site suppressed SCN5A expression and sodium currents. Hypoxia-induced HIF-1α and NF-κB were major transcriptional regulators for MIR448. Moreover, hypoxia relieved MIR448 transcriptional suppression by RE1 silencing transcription factor. Therefore, miR-448 inhibition reduced arrhythmic risk after myocardial infarction. Here, we show that ischemia drove miR-448 expression, reduced Nav1.5 current, and increased arrhythmic risk. Arrhythmic risk was improved by preventing Nav1.5 downregulation, suggesting a new approach to antiarrhythmic therapy.

SARNP, a participant in mRNA splicing and export, negatively regulates E-cadherin expression via interaction with pinin.

Triple-negative breast cancer (TNBC) is associated with a high mortality rate, which is related to the insufficient number of appropriate biomarkers and targets. Therefore, there is an urgent need to discover appropriate biomarkers and targets for TNBC. SARNP (Hcc-1 and CIP29) is highly expressed in several cancers. It binds to UAP56, an RNA helicase component of the TREX complex in messenger RNA (mRNA) splicing and export. However, the role of SARNP in mRNA splicing and export and in the progression of breast cancer, especially of TNBC, remains unknown. Therefore, we examined the role of SARNP in mRNA splicing and export and progression of TNBC. We confirmed that SARNP binds to UAP56 and Aly and that SARNP overexpression enhances mRNA splicing, whereas its knockdown suppressed mRNA export. The SARNP overexpression induced the proliferation of MCF7 cells, whereas its knockdown induced E-cadherin expression and downregulated vimentin and N-cadherin expressions in SK-BR-3 and MDA-MB-231 cells. SARNP downregulates E-cadherin expression by interaction with pinin. Mice injected with MDA-MB-231shSARNP cells exhibited a significant reduction in tumor growth and lung metastasis compared with those injected with MDA-MB-231shCon cells in vivo. These findings suggested that SARNP is involved in mRNA splicing and export. SARNP maintains mesenchymal phenotype by escaping from inhibitory interaction with pinin leading to the downregulation of E-cadherin expression.

YDJC Induces Epithelial-Mesenchymal Transition via Escaping from Interaction with CDC16 through Ubiquitination of PP2A.

Lung cancer is the number 1 cause of cancer-related casualties in the world. Appropriate diagnostic markers and novel targets for lung cancer are needed. Chitooligosaccharide deacetylase homolog (YDJC) catalyzes the deacetylation of acetylated carbohydrates; however, the role of YDJC in lung cancer progression has yet to be studied. A549 lung cancer orthotopic mouse model was used for mice experiments. We found that YDJC overexpression contributes to lung cancer progression in an orthotopic mouse model. Long-term treatment (48 h) induces YDJC expression in sphingosylphosphorylcholine (SPC)-induced epithelial-mesenchymal transition (EMT). Gene silencing of YDJC (siYDJC) reduced N-cadherin expression and increased E-cadherin expression in SPC-induced EMT. Overexpression of YDJC reverses them but overexpression of the deacetylase deficient mutant YDJCD13A could not. Interestingly, overexpression of CDC16, a YDJC binding partner, suppressed EMT. ERK2 is activated in siCDC16-induced EMT. YDJC overexpression reduces expression of protein phosphatase 2A (PP2A), whereas CDC16 overexpression induces PP2A expression. YDJC overexpression induced ubiquitination of PP2A but YDJCD13A could not. CDC16 overexpression increased the ubiquitination of YDJC. These results suggest that YDJC contributes to the progression of lung cancer via enhancing EMT by inducing the ubiquitination of PP2A. Therefore, YDJC might be a new target for antitumor therapy against lung cancer.

Over-activation of AKT signaling leading to 5-Fluorouracil resistance in SNU-C5/5-FU cells.

Here, we investigated whether over-activation of AKT pathway is important in the resistance to 5-fluorouracil (5-FU) in SNU-C5/5-FU cells, 5-FU-resistant human colon cancer cells. When compared to wild type SNU-C5 cells (WT), SNU-C5/5-FU cells showed over-activation of PI3K/AKT pathway, like increased phosphorylation of AKT, mTOR, and GSK-3ß, nuclear localization of ß-catenin, and decreased E-cadherin. Moreover, E-cadherin level was down-regulated in recurrent colon cancer tissues compared to primary colon cancer tissues. Gene silencing of AKT1 or treatment of LY294002 (PI3 kinase inhibitor) increased E-cadherin, whereas decreased phospho-GSK-3ß. LY294002 also reduced protein level of ß-catenin with no influence on mRNA level. PTEN level was higher in SNU-C5/WT than SNU-C5/5-FU cells, whereas the loss of PETN in SNU-C5/WT cells induced characteristics of SNU-C5/5-FU cells. In SNU-C5/5-FU cells, NF-κB signaling was activated, along with the overexpression of COX-2 and stabilization of survivin. However, increased COX-2 contributed to the stabilization of survivin, which directly interacts with cytoplasmic procaspase-3, while the inhibition of AKT reduced this cascade. We finally confirmed that combination treatment with 5-FU and LY294002 or Vioxx could induce apoptosis in SNU-C5/5-FU cells. These data suggest that inhibition of AKT activation may overcome 5-FU-resistance in SNU-C5/5-FU cells. These findings provide evidence that over-activation of AKT is crucial for the acquisition of resistance to anticancer drugs and AKT pathway could be a therapeutic target for cancer treatment.

YdjC chitooligosaccharide deacetylase homolog induces keratin reorganization in lung cancer cells: involvement of interaction between YDJC and CDC16.

Lung cancer is a fatal disease with a high mortality rate. The perinuclear reorganization of keratin 8 (K8) is an important biochemical phenomenon reflecting changes in the physical properties of metastatic cancer. However, there is not much of information about the regulatory molecules involved in phosphorylation and perinuclear reorganization of K8. In this study, we investigated the role and molecular mechanisms of YdjC chitooligosaccha- ride deacetylase homolog (YDJC) in sphingosylphosphorylcholine (SPC)-induced phosphorylation and reorganization of K8, and migration and invasion (SPC-induced events). SPC induced expression of YDJC in a dose- and time-dependent manner. Gene silencing of YDJC suppressed SPC-induced events. YDJC overexpression induced the SPC-induced events. YDJC deacetylase dominant negative mutant (YDJCD13A) did not induce SPC-induced events. YDJC siRNA reduced ERK activation and overexpression of YDJC induced ERK activation. The siRNA of ERK1 or ERK2 suppressed YDJC-induced phosphorylation and reorganization of K8, and migration and invasion. Co-immunoprecipitation revealed that YDJC binds to CDC16. Interestingly, CDC16 siRNA induced SPC-induced events. Overexpression of CDC16 blocked SPC-induced events. KMPLOT analysis based on public microarray data revealed the poor prognosis of lung cancer patients with high expression of YDJC compared with patients with low expression of YDJC. The collective results indicate that YDJC is involved in SPC-induced events in A549 lung cancer cells by interacting with CDC16. YDJC overexpression might be involved in the progression of lung cancer. These results also suggest that suppression of YDJC or boosting of CDC16 interaction with YDJC might be a novel way to prevent progression of lung cancer.