Endoscopic Aortic Valve Replacement: Initial Outcomes of Isolated and Concomitant Surgery.

BACKGROUND: The applicability of totally endoscopic surgical aortic valve replacement (AVR) in multivalve operations is unknown. This study describes an approach and perioperative outcomes of totally endoscopic isolated and concomitant AVR using various valve types. METHODS: A total of 216 patients (114 male; mean age, 71.3 ± 11.3 years) underwent totally endoscopic AVR from May 2017 to October 2022 in a tertiary care center. The 3-port technique was used: a 3- to 4-cm main port without rib spreading, a 10-mm 3-dimensional endoscopic port, and a 5-mm left-hand port with femoral cannulations. Sutures were hand tied with a knot pusher. Descriptive analyses compared perioperative outcomes between patients with or without concomitant procedures. RESULTS: Of 216 patients, concomitant surgery was performed in 33 (15.2%) patients. Of the 33, 21 (63.6%) had a concomitant mitral procedure. A stented bioprosthesis was implanted in 165 (76.3%) patients, a mechanical valve in 22 (10.2%) patients, and a rapid deployment or sutureless valve in 29 (13.4%) patients. Median operation time and aortic cross-clamp time were 175 minutes (interquartile range; 150-194 minutes) and 78 minutes (interquartile range; 67-92 minutes) for isolated AVR, respectively. Thirty-day mortality occurred in 1 patient (0.5%). Two patients (0.9%) had conversion to sternotomy. Major neurologic events occurred in 3 patients (1.4%). The major adverse event rate was similar between patients with or without concomitant procedures. CONCLUSIONS: Endoscopic AVR can safely address concomitant valve diseases.

Midterm results after seamless patch mitral reconstruction.

Objectives: Some pathologies, including infective endocarditis or sclerotic changes of the mitral leaflet, make the conventional mitral valve repair challenging. Our previously described technique for reconstruction with a seamless pericardial patch makes the repair feasible in some of such difficult pathologies. However, the extent of mitral leaflet segments that could be safely repaired using this technique remains unknown. We investigated the association between the midterm outcome and the extent of mitral leaflet segments replaced by a pericardial patch. Methods: From January 2009 to January 2022, patients who underwent mitral valve repair with the seamless 1-patch reconstruction technique were included. The glutaraldehyde-treated pericardium was trimmed and anchored at the papillary muscle. The edge was sewn to the leaflet and the annulus. Results: A total of 49 patients (aged 60 ± 15 years) underwent mitral valve repair with this technique. The totally endoscopic approach was used in 27 patients (55%). No patient's repair was converted to valve replacement. No operative mortality or disabling stroke was observed during the early postoperative period. In the midterm follow-up, redo surgery was required in 9 patients (18%). Freedom from mitral valve reintervention rates at 1, 5, and 10 years were 84%, 82%, and 82% for all patients, respectively. Freedom from reoperation at 5 years was 100%, 92%, and 46% for commissural lesion, 1- to 2-segment involvement, and 3-segment involvement, respectively. There was a significant difference among the 3 groups with regard to mitral valve reoperation rate (P = .002). Conclusions: Mitral valve seamless patch reconstruction provides excellent midterm results if applied to commissural lesions or lesions involving up to 2 segments.

Compulsory drainage of inferior vena cava to obtain bloodless field in minimally invasive mitral valve surgery.

Gaining bloodless field in minimally invasive mitral valve surgery is crucial for a successful surgery. We here demonstrate a simple method to obtain bloodless field in minimally invasive mitral valve surgery with only single venous cannula through the femoral vein. A dual-stage venous cannula is inserted through the femoral vein, with its tip located deep in superior vena cava. After establishing full flow, the inferior vena cava (IVC) was snared. Returning blood from the IVC was blocked at the snare, and drained through the side holes at the midportion of the cannula. This technique collapsed the right atrium, and made the left atrium almost bloodless. Pressures of the femoral vein measured in 28 patients were 9.5 ± 4.1 mmHg before bypass, 6.8 ± 4.8 mmHg before snaring IVC, and 7.2 ± 4.8 mmHg after snaring. By blocking returning blood from the lower body, venous congestion of the lower body did not occur.

Shoot base responds to root-applied glutathione and functions as a critical region to inhibit cadmium translocation from the roots to shoots in oilseed rape (Brassica napus).

Glutathione (GSH) is a tripeptide involved in controlling heavy metal movement in plants. Our previous study showed that GSH, when site-specifically applied to plant roots, inhibits Cd translocation from the roots to shoots in hydroponically cultured oilseed rape (Brassica napus) plants. A factor that led to this inhibitory effect was the activation of Cd efflux from root cells. To further investigate the molecular mechanism triggered by root-applied GSH, Cd movement was non-invasively monitored using a positron-emitting tracer imaging system. The Cd absorption and efflux process in the roots were visualized successfully. The effects of GSH on Cd efflux from root cells were estimated by analyzing imaging data. Reanalysis of image data suggested that GSH applied to roots, at the shoot base, activated Cd return. Cutting the shoot base significantly inhibited Cd efflux from root cells. These experimental results demonstrate that the shoot base plays an important role in distributing Cd throughout the plant body. Furthermore, microarray analysis revealed that about 400 genes in the roots responded to root-applied GSH. Among these, there were genes for transporter proteins related to heavy metal movement in plants and proteins involved in the structure modification of cell walls.

Role for phagocytosis in the prevention of neoplastic transformation in Drosophila.

Immunity is considered to be involved in the prevention of cancer. Although both humoral and cellular immune reactions may participate, underlying mechanisms have yet to be clarified. The present study was conducted to clarify this issue using a Drosophila model, in which neoplastic transformation was induced through the simultaneous inhibition of cell-cycle checkpoints and apoptosis. We first determined the location of hemocytes, blood cells of Drosophila playing a role of immune cells, in neoplasia-induced and normal larvae, but there was no significant difference between the two groups. When gene expression pattern in larval hemocytes was determined, the expression of immunity-related genes including those necessary for phagocytosis was reduced in the neoplasia model. We then asked the involvement of phagocytosis in the prevention of neoplasia examining animals where the expression of engulfment receptors instead of apoptosis was retarded. We found that the inhibition of engulfment receptor expression augmented the occurrence of neoplasia induced by a defect in cell-cycle checkpoints. This suggested a role for phagocytosis in the prevention of neoplastic transformation in Drosophila.

Identification of Radiation-Dose-Dependent Expressive Genes in Individuals Exposed to External Ionizing Radiation.

For victims of radiological accidents, rapid dose estimation and damage prediction are essential. Administering the gold-standard biodosimetry chromosome aberration assay requires highly skilled individuals and several days of labor; consequently, rapid turnaround is an important concern. Identification of new dose estimation markers and damage-predicting in vivo molecules to replace the chromosome aberration assay is crucial to improving the delivery time of medical treatment. Here, we investigated the applicability of mRNA levels using a mouse model. Female C57BL/6J mice were X-ray irradiated at various doses, and a DNA microarray was then performed to identify differentially expressed mRNAs in whole blood. The microarray analysis identified 14 radioresponsive mRNAs with more than fourfold differences by pattern matching in the expression at 24 h postirradiation. In particular, mRNA expression of Slfn4, Itgb5, Smim3, Tmem40, Litaf, Gp1bb and Cxx1c was significantly increased in a radiation-dose-dependent manner, as validated by reverse transcription quantitative polymerase chain reaction. We also performed an analysis using the cBioPortal for Cancer Genomics and found that the overall survival of ovarian adenocarcinoma patients with alterations in Smim3 and that of thymoma patients with alterations in Cxx1c had a worse prognosis than patients without these alterations. These findings suggest that the expression of several genes in whole blood was a sensitive and specific biomarker of radiation exposure and can be used as a rapid and reliable prospective molecular biomarker in radiological emergencies.

A maple syrup extract alleviates liver injury in type 2 diabetic model mice.

A recent study showed that 54% of type 2 diabetes (T2D) patients have nonalcoholic fatty liver disease, which is a risk factor for aggravation diabetic symptoms. Previous studies suggested components in maple syrup alleviated liver injury and found polyphenols as food components to improve the symptoms and complications of diabetes. Therefore, we hypothesized that a polyphenol fraction in maple syrup improves the symptoms and complications of diabetes. To address the hypothesis, we investigated the effects of a polyphenol-rich maple syrup extract (MSE) on a T2D model mice. KK-Ay mice were fed a normal or 0.1% MSE-supplemented diet for 43 days. The results showed that the levels of serum alanine aminotransferase and aspartate aminotransferase were significantly reduced in mice that ingested MSE. Hepatic genes related to lipogenesis and lipolysis were down- and upregulated, respectively, in mice that ingested MSE. These results suggest that MSE intake alleviates liver injury and suppresses lipid accumulation in the livers of T2D mice.

Foliar-applied glutathione activates zinc transport from roots to shoots in oilseed rape.

Glutathione is a tripeptide involved in diverse aspects of plant metabolism. We investigated how the reduced form of glutathione, GSH, applied site-specifically to plants, affects zinc (Zn) distribution and behavior in oilseed rape plants (Brassica napus) cultured hydroponically. Foliar-applied GSH significantly increased the Zn content in shoots and the root-to-shoot Zn translocation ratio; furthermore, this treatment raised the Zn concentration in the cytosol of root cells and substantially enhanced Zn xylem loading. Notably, microarray analysis revealed that the gene encoding pectin methylesterase was upregulated in roots following foliar GSH treatment. We conclude that certain physiological signals triggered in response to foliar-applied GSH were transported via sieve tubes and functioned in root cells, which, in turn, increased Zn availability in roots by releasing Zn from their cell wall. Consequently, root-to-shoot translocation of Zn was activated and Zn accumulation in the shoot was markedly increased.

Dose-Dependent Increase of Nrf2 Target Gene Expression in Mice Exposed to Ionizing Radiation.

Nuclear factor-erythroid-2-related factor 2 transcription factor (Nrf2) is activated by reactive oxygen species (ROS) and binds to antioxidant response elements in the promoter regions of its target genes involved in redox regulation and antioxidative functions. In this study, we elucidated the relationship between radiation dose and the expression response of Nrf2 target genes involved in oxidative stress, such as heme oxygenase 1, ferritin heavy polypeptide 1 ( Fth1), NADPH dehydrogenase quinone 1, glutamate-cysteine ligase catalytic subunit, glutamate-cysteine ligase modifier subunit, glutathione reductase ( Gsr) and thioredoxin reductase 1 genes, in peripheral blood from X-ray irradiated mice. Whole-body radiation doses ranged from 0.5 to 3 Gy, and gene expressions were analyzed using reverse transcription quantitative polymerase chain reaction. A significant relationship was observed only for one gene: a statistically significant positive correlation between radiation dose and Fth1 mRNA expression was detected. However, Fth1 did not show any correlations with the biological damages induced by radiation tested in this study. Furthermore, while Gsr expression was significantly associated with spleen weight loss, splenic cell number reduction and bone marrow cell death apoptosis, no significant correlation was observed between Gsr expression and radiation dose. Together these results indicate that Nrf2 target gene expression is closely related to radiation dose and its level may reflect biological damages induced by ionizing radiation. These findings suggest the possibility for application of these target genes as a bio-dosimeter and/or damage marker in individuals exposed to ionizing radiation.

Comprehensive DNA microarray expression profiles of tumors in tenascin-C-knockout mice.

Tenascin-C (TNC), an extracellular matrix glycoprotein, plays a pivotal role in tumor growth. However, the mechanism whereby TNC affects tumor biology remains unclear. To investigate the exact role of TNC in primary tumor growth, a mouse mammary tumor cell line, GLMT1, was first developed. Subsequently, global gene expression in GLMT1-derived tumors was compared between wild-type (WT) and TNC-knockout (TNKO) mice. Tumors in WT mice were significantly larger than those in TNKO mice. DNA microarray analysis revealed 447 up and 667 downregulated in the tumors inoculated into TNKO mice as compared to tumors in WT mice. Validation by quantitative gene expression analysis showed that Tnc, Cxcl1, Cxcl2, and Cxcr2 were significantly upregulated in WT mice. We hypothesize that TNC stimulates the CXCL1/2-CXCR2 pathway involved in cancer cell proliferation.

Signaling pathway for phagocyte priming upon encounter with apoptotic cells.

The phagocytic elimination of cells undergoing apoptosis is an evolutionarily conserved innate immune mechanism for eliminating unnecessary cells. Previous studies showed an increase in the level of engulfment receptors in phagocytes after the phagocytosis of apoptotic cells, which leads to the enhancement of their phagocytic activity. However, precise mechanisms underlying this phenomenon require further clarification. We found that the pre-incubation of a Drosophila phagocyte cell line with the fragments of apoptotic cells enhanced the subsequent phagocytosis of apoptotic cells, accompanied by an augmented expression of the engulfment receptors Draper and integrin αPS3. The DNA-binding activity of the transcription repressor Tailless was transiently raised in those phagocytes, depending on two partially overlapping signal-transduction pathways for the induction of phagocytosis as well as the occurrence of engulfment. The RNAi knockdown of tailless in phagocytes abrogated the enhancement of both phagocytosis and engulfment receptor expression. Furthermore, the hemocyte-specific RNAi of tailless reduced apoptotic cell clearance in Drosophila embryos. Taken together, we propose the following mechanism for the activation of Drosophila phagocytes after an encounter with apoptotic cells: two partially overlapping signal-transduction pathways for phagocytosis are initiated; transcription repressor Tailless is activated; expression of engulfment receptors is stimulated; and phagocytic activity is enhanced. This phenomenon most likely ensures the phagocytic elimination of apoptotic cells by stimulated phagocytes and is thus considered as a mechanism to prime phagocytes in innate immunity.

Identification of BCL11B as a regulator of adipogenesis.

The differentiation of preadipocytes into adipocytes is controlled by several transcription factors, including peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα), which are known as master regulators of adipogenesis. BCL11B is a zinc finger-type transcription factor that regulates the development of the skin and central nervous and immune systems. Here, we found that BCL11B was expressed in the white adipose tissue (WAT), particularly the subcutaneous WAT and that BCL11B(-/-) mice had a reduced amount of subcutaneous WAT. During adipogenesis, BCL11B expression transiently increased in 3T3-L1 preadipocytes and mouse embryonic fibroblasts (MEFs). The ability for adipogenesis was reduced in BCL11B knockdown 3T3-L1 cells and BCL11B(-/-) MEFs, whereas the ability for osteoblastogenesis was unaffected in BCL11B(-/-) MEFs. Luciferase reporter gene assays revealed that BCL11B stimulated C/EBPß activity. Furthermore, the expression of downstream genes of the Wnt/ß-catenin signaling pathway was not suppressed in BCL11B(-/-) MEFs during adipogenesis. Thus, this study identifies BCL11B as a novel regulator of adipogenesis, which works, at least in part, by stimulating C/EBPß activity and suppressing the Wnt/ß-catenin signaling pathway.

Searching for novel ATF4 target genes in human hepatoma cells by microarray analysis.

Activating transcription factor 4 (ATF4) is a transcription factor with an important biological activity. ATF4 is induced by various stresses, such as endoplasmic reticulum stress, through the phosphorylation of eukaryotic translation initiation factor 2α. ATF4 is also involved in lipid metabolism. In the present study, we performed a microarray experiment to identify new ATF4 target genes, particularly those involved in lipid metabolism, and identified C12orf39, CSTA, and CALCB as novel ATF4 target genes. An amino acid response element (AARE) as an ATF4-binding site is present in the promoter regions of these genes. In a detailed analysis using luciferase assay, we showed that ATF4 activated C12orf39 promoter activity and that this activation was diminished by deletion or mutation of the AARE sequence in the promoter region. Our results suggest that C12orf39, CSTA, and CALCB are novel ATF4 target genes and that C12orf39 promoter activity is activated by ATF4 through AARE.

Broccoli sprout extract induces detoxification-related gene expression and attenuates acute liver injury.

AIM: To investigate the effects of broccoli sprout extract (BSEx) on liver gene expression and acute liver injury in the rat. METHODS: First, the effects of BSEx on liver gene expression were examined. Male rats were divided into two groups. The Control group was fed the AIN-76 diet, and the BSEx group was fed the AIN-76 diet containing BSEx. After a 10-d feeding period, rats were sacrificed and their livers were used for DNA microarray and real-time reverse transcription-polymerase chain reaction (RT-PCR) analyses. Next, the effects of BSEx on acute liver injury were examined. In experiments using acute liver injury models, 1000 mg/kg acetaminophen (APAP) or 350 mg/kg D-galactosamine (D-GalN) was used to induce injury. These male rats were divided into four groups: Control, BSEx, Inducer (APAP or D-GalN), and Inducer+BSEx. The feeding regimens were identical for the two analyses. Twenty-four hours following APAP administration via p.o. or D-GalN administration via i.p., rats were sacrificed to determine serum aspartate transaminase (AST) and alanine transaminase (ALT) levels, hepatic glutathione (GSH) and thiobarbituric acid-reactive substances accumulation and glutathione-S-transferase (GST) activity. RESULTS: Microarray and real-time RT-PCR analyses revealed that BSEx upregulated the expression of genes related to detoxification and glutathione synthesis in normal rat liver. The levels of AST (70.91 ± 15.74 IU/mL vs 5614.41 ± 1997.83 IU/mL, P < 0.05) and ALT (11.78 ± 2.08 IU/mL vs 1297.71 ± 447.33 IU/mL, P < 0.05) were significantly suppressed in the APAP + BSEx group compared with the APAP group. The level of GSH (2.61 ± 0.75 nmol/g tissue vs 1.66 ± 0.59 nmol/g tissue, P < 0.05) and liver GST activity (93.19 ± 16.55 U/g tissue vs 51.90 ± 16.85 U/g tissue, P < 0.05) were significantly increased in the APAP + BSEx group compared with the APAP group. AST (4820.05 ± 3094.93 IU/mL vs 12465.63 ± 3223.97 IU/mL, P < 0.05) and ALT (1808.95 ± 1014.04 IU/mL vs 3936.46 ± 777.52 IU/mL, P < 0.05) levels were significantly suppressed in the D-GalN + BSEx group compared with the D-GalN group, but the levels of AST and ALT in the D-GalN + BSEx group were higher than those in the APAP + BSEx group. The level of GST activity was significantly increased in the D-GalN + BSEx group compared with the D-GalN group (98.04 ± 15.75 U/g tissue vs 53.15 ± 8.14 U/g tissue, P < 0.05). CONCLUSION: We demonstrated that BSEx protected the liver from various types of xenobiotic substances through induction of detoxification enzymes and glutathione synthesis.

Administered chrysanthemum flower oil attenuates hyperuricemia: mechanism of action as revealed by DNA microarray analysis.

We applied Chrysanthemum flower oil (CFO) to a hyperuricemia model by feeding rats a hyperuricemia-inducing diet (HID) and investigated its effect on serum uric acid (SUA) levels and its mode of action. CFO is the oily fraction that contains polyphenols derived from chrysanthemum flowers. Oral administration of CFO to HID-fed rats significantly decreased their SUA levels. It also inhibited xanthine oxidase activities in the liver and increased urine uric acid levels. The effects of CFO on the renal gene expressions that accompanied the induction of hyperuricemia were comprehensively confirmed by DNA microarray analysis. The analysis showed up-regulation of those genes for uric acid excretion by CFO administration. These results suggest that CFO suppresses the increase in SUA levels via two mechanisms: suppression of uric acid production by inhibition of xanthine oxidase in the liver and acceleration of its excretion by up-regulation of uric acid transporter genes in the kidney.

Inhibition of malignant phenotypes of human osteosarcoma cells by a gene silencer, a pyrrole-imidazole polyamide, which targets an E-box motif.

Gene amplification and/or overexpression of the transcription factor c-MYC, which binds to the E-box sequence (5'-CACGTG-3'), has been observed in many human tumors. In this study, we have designed 5 pyrrole-imidazole (PI) polyamides recognizing E-box, and found that, among them, Myc-6 significantly suppresses malignant phenotypes of human osteosarcoma MG63 cells both in vitro and in vivo. Intriguingly, knockdown of the putative Myc-6 target MALAT1 encoding long noncoding RNA remarkably impaired cell growth of MG63 cells. Collectively, our present findings strongly suggest that Myc-6 exerts its tumor-suppressive ability at least in part through the specific down-regulation of MALAT1.

Post-exercise impact of ingested whey protein hydrolysate on gene expression profiles in rat skeletal muscle: activation of extracellular signal-regulated kinase 1/2 and hypoxia-inducible factor-1α.

We have previously shown that whey protein hydrolysate (WPH) causes a greater increase in muscle protein synthesis than does a mixture of amino acids that is identical in amino acid composition. The present study was conducted to investigate the effect of WPH on gene expression. Male Sprague-Dawley rats subjected to a 2 h swimming exercise were administered either a carbohydrate-amino acid diet or a carbohydrate-WPH diet immediately after exercise. At 1 h after exercise, epitrochlearis muscle mRNA was sampled and subjected to DNA microarray analysis. We found that ingestion of WPH altered 189 genes after considering the false discovery rate. Among the up-regulated genes, eight Gene Ontology (GO) terms were enriched, which included key elements such as Cd24, Ccl2, Ccl7 and Cxcl1 involved in muscle repair after exercise. In contrast, nine GO terms were enriched in gene sets that were down-regulated by the ingestion of WPH, and these GO terms fell into two clusters, 'regulation of ATPase activity' and 'immune response'. Furthermore, we found that WPH activated two upstream proteins, extracellular signal-regulated kinase 1/2 (ERK1/2) and hypoxia-inducible factor-1α (HIF-1α), which might act as key factors for regulating gene expression. These results suggest that ingestion of WPH, compared with ingestion of a mixture of amino acids with an identical amino acid composition, induces greater changes in the post-exercise gene expression profile via activation of the proteins ERK1/2 and HIF-1α.

Influence of a short-term iron-deficient diet on hepatic gene expression profiles in rats.

Iron is an essential mineral for the body, and iron deficiency generally leads to anemia. However, because non-anemic iron deficiency can exist, we performed a comprehensive transcriptome analysis of the liver to define the effects of this condition on the body. Four-week-old male rats were fed a low-iron diet (approximately 3 ppm iron) for 3 days and compared with those fed a normal diet (48 ppm iron) by pair feeding as a control. The rats in the iron-deficient diet group developed a non-anemic iron-deficient state. DNA microarray analysis revealed that during this short time, this state conferred a variety of effects on nutrient metabolism in the liver. In comparison with long-term (17 days) iron-deficiency data from a previous study, some of the changed genes were found to be common to both short- and long-term iron deficiency models, some were specific to the short-term iron deficiency model, and the others were oppositely regulated between the two feeding terms. Taken together, these data suggest that although the blood hemoglobin level itself remains unchanged during non-anemic iron deficiency, a variety of metabolic processes involved in the maintenance of the energy balance are altered.

Effect of Lactobacillus brevis KB290 on the cell-mediated cytotoxic activity of mouse splenocytes: a DNA microarray analysis.

Lactic acid bacteria confer a variety of health benefits. Here, we investigate the mechanisms by which Lactobacillus brevis KB290 (KB290) enhances cell-mediated cytotoxic activity. Female BALB/c mice aged 9 weeks were fed a diet containing KB290 (3 × 10(9) colony-forming units/g) or starch for 1 d. The resulting cytotoxic activity of splenocytes against YAC-1 cells was measured using flow cytometry and analysed for gene expression using DNA microarray technology. KB290 enhanced the cell-mediated cytotoxic activity of splenocytes. DNA microarray analysis identified 327 up-regulated and 347 down-regulated genes that characterised the KB290 diet group. The up-regulated genes were significantly enriched in Gene Ontology terms related to immunity, and, especially, a positive regulation of T-cell-mediated cytotoxicity existed among these terms. Almost all the genes included in the term encoded major histocompatibility complex (MHC) class I molecules involved in the presentation of antigen to CD8(+) cytotoxic T cells. Marco and Signr1 specific to marginal zone macrophages (MZM), antigen-presenting cells, were also up-regulated. Flow cytometric analysis confirmed that the proportion of MZM was significantly increased by KB290 ingestion. Additionally, the over-represented Kyoto Encyclopedia of Genes and Genomes pathways among the up-regulated genes were those for natural killer (NK) cell-mediated cytotoxicity and antigen processing and presentation. The results for the selected genes associated with NK cells and CD8(+) cytotoxic T cells were confirmed by quantitative RT-PCR. These results suggest that enhanced cytotoxic activity could be caused by the activation of NK cells and/or of CD8(+) cytotoxic T cells stimulated via MHC class I presentation.

PRAS40 is a functionally critical target for EWS repression in Ewing sarcoma.

Ewing sarcoma family tumors (ESFT) are highly aggressive and highly metastatic tumors caused by a chromosomal fusion between the Ewing sarcoma protein (EWS) with the transcription factor FLI-1. However, expression of the EWS/FLI-1 chimeric oncogene by itself is insufficient for carcinogenesis, suggesting that additional events are required. Here, we report the identification of the Akt substrate PRAS40 as an EWS target gene. EWS negatively regulates PRAS40 expression by binding the 3' untranslated region in PRAS40 mRNA. ESFT cell proliferation was suppressed by treatment with an Akt inhibitor, and ESFT cell proliferation and metastatic growth were suppressed by siRNA-mediated PRAS40 knockdown. Furthermore, PRAS40 knockdown was sufficient to reverse an increased cell proliferation elicited by EWS knockdown. In support of a pathologic role for PRAS40 elevation in EFST, we documented inverse protein levels of EWS and PRAS40 in ESFT cells. Together, our findings suggest that PRAS40 promotes the development of ESFT and might therefore represent a novel therapeutic target in this aggressive disease.