Mortality rate after coronary revascularization in heart failure patients with coronary artery disease.

AIMS: Coronary artery disease (CAD) is a common cause of heart failure (HF). It remains unclear who, when and why to direct towards coronary revascularization. The outcomes of coronary revascularization in HF patients are still a matter of debate nowadays. This study aims to evaluate the effect of revascularization strategy on all-cause of death in the context of ischaemic HF. METHODS AND RESULTS: An observational cohort was conducted on 692 consecutive patients who underwent coronary angiography at the University Hospital of Toulouse between January 2018 and December 2021 for either a recent diagnosis of HF or a decompensated chronic HF, and in whom coronary angiograms showed at least 50% obstructive coronary lesion. The study population was divided into two groups according to the performance or not of a coronary revascularization procedure. The living status (alive or dead) of each of the study's participants was observed by April 2022. Seventy-three per cent of the study population underwent coronary revascularization either by percutaneous coronary intervention (66.6%) or coronary artery bypass grafting (6.2%). Baseline characteristics including age, sex and cardiovascular risk factors did not differ between the invasive and conservative groups, respectively. Death occurred in 162 study participants resulting in an all-cause mortality rate of 23.5%; 26.7% of observed deaths have occurred in the conservative group versus 22.2% in the invasive group (P = 0.208). No difference in survival outcomes has been observed over a mean follow-up period of 2.5 years (P = 0.140) even after stratification by HF categories (P = 0.132) or revascularization modalities (P = 0.366). CONCLUSIONS: Findings from the present study showed comparable all-cause mortality rates between groups. Coronary revascularization does not modify short-term survival outcomes in HF patients compared with optimal medical therapy alone outside the setting of acute coronary syndrome.

[Retracted] Effects of nutrients on matrix metalloproteinases in human T­lymphotropic virus type 1 positive and negative malignant T­lymphocytes.

Subsequently to the publication of the above article, a concerned reader drew to the attention of the Editorial Office and the authors that certain pairings of the GAPDH western blotting control bands in Fig. 4 appeared to be strikingly similar to adjacent pairings of bands within the same gel slices; moreover, data bands featured in the HuT­2, C91­PL and Jurkat zymography blots in Fig. 5 also appeared to be remarkably similar, both comparing the bands within a given gel slice (as in the case of the Jurkat cell experiment in Fig. 5) or comparing between gel slices (as in the case of the Hut­2 cells compared with the C910PL cells in Fig. 5). The Editorial Office independently investigated these concerns, and reached the conclusion that the bands did appear strikingly similar; too similar for the appearance of the bands within these figures to have arisen by chance. Moreover, the application of a software analysis program revealed that certain of the data in Fig. 6 had also appeared in another paper published by several of the same authors in another journal at around the same time. As a result of this investigation, the Editor of International Journal of Oncology has decided that this paper should be retracted from the journal on account of a lack of confidence in the authenticity of the presented data. The authors were asked for an explanation to account for these concerns, but the Editorial Office did not receive a satisfactory reply. The Editor apologizes to the readership for any inconvenience caused. [International Journal of Oncology 45: 2159­2166, 2014; DOI: 10.3892/ijo.2014.2638].

Retrospective Study of 573 Patients with Heart Failure Evaluated for Coronary Artery Disease at Toulouse University Center, France.

BACKGROUND Heart failure (HF) most commonly occurs due to ischemic heart disease from stenotic coronary artery disease (CAD). HF is classified into 3 groups based on the percentage of the ejection fraction (EF): reduced (HFrEF), mid-range (HFmrEF), and preserved (HFpEF). This retrospective study included 573 patients who presented with HF based on the evaluation of EF and were evaluated for CAD by coronary angiography before undergoing coronary angioplasty at a single center in Toulouse, France. MATERIAL AND METHODS This retrospective observational study included patients recently diagnosed with HF or acute decompensation of chronic HF and referred for coronary angiography at Toulouse University Hospital between January 2019 and May 2020. RESULTS Significant CAD was found in 55.8%, 55%, and 55% of the whole population, HFpEF, and HFrEF groups, respectively. Older age, male sex, and diabetes mellitus were the main risk factors for ischemic HF. Except for age and sex, patients with ischemic HFpEF were comparable to those with non-ischemic HFpEF, unlike the ischemic HFrEF group, which had more common cardiovascular risk factors than the non-ischemic HFrEF group. The ischemic HFpEF group had an older age and higher rate of dyslipidemia than the ischemic HFrEF group. CONCLUSIONS At our center, CAD was diagnosed in more than half of patients who presented with heart failure with preserved or reduced EF. Older age and male sex were the common risk factors in patients with HFpEF and HFrEF.

Evaluation of Mitral and Aortic Valvular Disease and Left Ventricular Dysfunction in a Lebanese Population: Retrospective Single-Center Experience.

BACKGROUND Recently, new therapeutic approaches have revolutionized the management of left ventricular dysfunction (LVD) and valvular heart disease (VHD), which are a growing public health problem. In parallel, there are no available epidemiological data about LVD and VHD in developing countries, especially in the Mediterranean area. This retrospective study was conducted at a single center and aimed to evaluate the associations between mitral and aortic valvular disease and left ventricle systolic and diastolic dysfunction in the Lebanese population. MATERIAL AND METHODS A retrospective study was conducted of 4520 consecutive patients aged >18 years who were referred to the Cardiovascular Department of Notre Dame de Secours-University Hospital in Jbeil-Lebanon for transthoracic echocardiography between December 2016 and December 2019. The study population was divided into different groups based on types of LVD and VHD. Left ventricle systolic dysfunction was defined as a left ventricle ejection fraction (EF) ≤40%. Statistical analysis was carried out using SPSS software version 20. RESULTS VHD and systolic dysfunction were more common in men, whereas diastolic dysfunction was more common in women. Being older than age 65 years and smoking were significantly associated with heart failure with preserved EF, whereas female sex was a significant preventive factor against heart failure with reduced EF. Systemic hypertension was correlated with mitral stenosis and tricuspid regurgitation, whereas diabetes mellitus was associated with tricuspid regurgitation (TR). Smoking and older age also appeared to be associated with aortic stenosis. CONCLUSIONS Mitral valve disease (regurgitation and stenosis) was significantly correlated with systolic dysfunction, whereas aortic and mitral regurgitation were associated with diastolic dysfunction. Better monitoring of cardiovascular disease risk factors may lead to a reduced burden of LVD and VHD.

Cyclin A2 maintains colon homeostasis and is a prognostic factor in colorectal cancer.

To clarify the function of cyclin A2 in colon homeostasis and colorectal cancer (CRC), we generated mice deficient for cyclin A2 in colonic epithelial cells (CECs). Colons of these mice displayed architectural changes in the mucosa and signs of inflammation, as well as increased proliferation of CECs associated with the appearance of low- and high-grade dysplasias. The main initial events triggering those alterations in cyclin A2-deficient CECs appeared to be abnormal mitoses and DNA damage. Cyclin A2 deletion in CECs promoted the development of dysplasia and adenocarcinomas in a murine colitis-associated cancer model. We next explored the status of cyclin A2 expression in clinical CRC samples at the mRNA and protein levels and found higher expression in tumors of patients with stage 1 or 2 CRC compared with those of patients with stage 3 or 4 CRC. A meta-analysis of 11 transcriptome data sets comprising 2239 primary CRC tumors revealed different expression levels of CCNA2 (the mRNA coding for cyclin A2) among the CRC tumor subtypes, with the highest expression detected in consensus molecular subtype 1 (CMS1) and the lowest in CMS4 tumors. Moreover, we found high expression of CCNA2 to be a new, independent prognosis factor for CRC tumors.

Inhibition of Proliferation and Induction of Apoptosis by Thymoquinone via Modulation of TGF Family, p53, p21 and Bcl-2α in Leukemic Cells.

INTRODUCTION: Adult T-cell leukemia (ATL) is an aggressive form of malignancy caused by human T- cell lymphotropic virus 1 (HTLV-1). Currently, there is no effective treatment for ATL. Thymoquinone has been reported to have anti-cancer properties. OBJECTIVE: The aim of this study is to investigatthe effects of TQ on proliferation, apoptosis induction and the underlying mechanism of action in both HTLV-1 positive (C91-PL and HuT-102) and HTLV-1 negative (CEM and Jurkat) malignant T-lymphocytes. MATERIALS AND METHODS: Cells were incubated with different thymoquinone concentrations for 24h. Cell cytotoxicity was assayed using the CytoTox 96® Non-Radioactive Cytotoxicity Assay Kit. Cell proliferation was determined using CellTiter 96® Non-Radioactive Cell Proliferation. Cell cycle analysis was performed by staining with propidium iodide. Apoptosis was assessed using cell death ELISA kit. The effect of TQ on p53, p21, Bcl-2 protein expression was determined using Western blot analysis while TGF mRNA expression was determined by RT-PCR. RESULTS: At non-cytotoxic concentrations of TQ, it resulted in the inhibition of proliferation in a dose dependent manner. Flow cytometric analysis revealed a shift in the cell cycle distribution to the PreG1 phase which is a marker of apoptosis. Also TQ increase DNA fragmentation. TQ mediated its anti-proliferative effect and apoptosis induction by an up-regulation of TGFß1, p53 and p21 and a down-regulation of TGF-α and Bcl-2α. CONCLUSION: Thymoquinone presents antiproliferative and proapoptotic effects in ATL cells. For this reason, further research is required to investigate its possible application in the treatment of ATL.

The importance of blood culture and serology for Brucellosis diagnosis and treatment.

INTRODUCTION: Brucellosis is a zoonotic endemic disease in Lebanon. It is caused by direct transmission of Brucella from contaminated animal products to humans. If left untreated brucellosis might lead to several complications and a chronic disease state. The prompt diagnosis of brucellosis has the ability to limit the progression of the disease, especially if the correct treatment is administered for the adequate amount of time. The aim of this study is to determine the optimal diagnostic tool and to assess Brucella burden in Lebanon. METHODOLOGY: This retrospective study was performed by reviewing the medical charts of 46 brucellosis patients from three Lebanese hospitals. Brucellosis diagnostic tests were compared and sensitivity of each test was calculated, as well as, the level of agreement with other standard diagnostic tools. Data retrieved were analyzed for relevance and statistical significance using the statistical package for social sciences version 23. RESULTS: Sensitivity results of the diagnostic tests were: Rose Bengal test (RBT) 94.7%, blood culture 65.6%, standard agglutination test (SAT) melitensis 95.1% and SAT abortus 97.6%. The level of agreement between RBT and SAT melitensis as well as abortus is 98% and 90.18%, respectively. While the level of agreement between Blood culture and SAT melitensis as well as abortus is 66.88% and 64.5%, respectively. DISCUSSION: Culture techniques require further optimization in order to find the best diagnostic tool for brucellosis. Meanwhile, Blood Rose Bengal test held a significant potential for identifying Brucella infection in a highly sensitive, cost effective and time saving manner.

Effects of Ascorbic Acid on Tax, NF-κB and MMP-9 in Human T-cell Lymphotropic Virus Type 1 Positive Malignant T-Lymphocytes.

BACKGROUND: HTLV1 is a retrovirus that infects CD4-positive cells and leads to Adult T-cell leukemia by constitutive activation of nuclear factor kappa B. Ascorbic acid (AA) is an essential nutrient that possess anti-proliferative and pro-apoptotic activity against a number of malignant cell lines. This study delineates the effect of AA on Tax protein expression as well as NF-κB and MMP9 activity in two HTLV1-positive leukemia cells (HuT-102 and C91-PL). METHODS: The cytotoxic and antiproliferative effect of AA were studied by LDH release and MTT tests, respectively. The proteins expression level was assessed by western blotting. RT-PCR was used to study mRNAs level. Finally, ELISA/EMSA and Zymography were used to evaluate NF-κB and MMP-9 activities, respectively. RESULTS: Cell lines were treated with non-cytotoxic concentrations of AA for 48h and 96h, which resulted in a significant inhibition of proliferation at a concentration of 50µg/ml at 96h in both cell lines. The same concentration inhibited Tax protein expression as well as the NF-κB nuclearization and DNA binding activity. The inhibitory effect of AA on MMP9 protein expression and activity started at 100µg/ml and 50µg/ml in HuT-102 and C91-PL cells respectively, with no effect at the transcriptional levels of MMP-9 in either one of the two cell lines. CONCLUSION: These results indicated that while AA exerted its anti-proliferative effect on the NF- κB activation pathway by suppressing Tax expression, its effects on MMP9 seemed to be independent of this mechanism and follow a different approach.

Downregulation of sphingosine kinase-1 induces protective tumor immunity by promoting M1 macrophage response in melanoma.

The infiltration of melanoma tumors by macrophages is often correlated with poor prognosis. However, the molecular signals that regulate the dialogue between malignant cells and the inflammatory microenvironment remain poorly understood. We previously reported an increased expression of sphingosine kinase-1 (SK1), which produces the bioactive lipid sphingosine 1-phosphate (S1P), in melanoma. The present study aimed at defining the role of tumor SK1 in the recruitment and differentiation of macrophages in melanoma. Herein, we show that downregulation of SK1 in melanoma cells causes a reduction in the percentage of CD206highMHCIIlow M2 macrophages in favor of an increased proportion of CD206lowMHCIIhigh M1 macrophages into the tumor. This macrophage differentiation orchestrates T lymphocyte recruitment as well as tumor rejection through the expression of Th1 cytokines and chemokines. In vitro experiments indicated that macrophage migration is triggered by the binding of tumor S1P to S1PR1 receptors present on macrophages whereas macrophage differentiation is stimulated by SK1-induced secretion of TGF-ß1. Finally, RNA-seq analysis of human melanoma tumors revealed a positive correlation between SK1 and TGF-ß1 expression. Altogether, our findings demonstrate that melanoma SK1 plays a key role in the recruitment and phenotypic shift of the tumor macrophages that promote melanoma growth.

Berberis libanotica extract targets NF-κB/COX-2, PI3K/Akt and mitochondrial/caspase signalling to induce human erythroleukemia cell apoptosis.

The aim of this study was to describe and understand the relationship between cyclooxygenase-2 (COX-2) expression and apoptosis rate in erythroleukemia cells after apoptosis induction by Berberis libanotica (Bl) extract. To achieve this goal we used erythroleukemia cell lines expressing COX­2 (HEL cell line) or not (K562 cell line). Moreover, we made use of COX­2 cDNA to overexpress COX­2 in K562 cells. In light of the reported chemopreventive and chemosensitive effects of natural products on various tumor cells and animal models, we postulated that our Bl extract may mediate their effects through apoptosis induction with suppression of cell survival pathways. Our study is the first report on the specific examination of intrinsic apoptosis and Akt/NF-κB/COX­2 pathways in human erythroleukemia cells upon Bl extract exposure. Even if Bl extract induced apoptosis of three human erythroleukemia cell lines, a dominant effect of Bl extract treatment on K562 cells was observed resulting in activation of the late markers of apoptosis with caspase-3 activation, PARP cleavage and DNA fragmentation. Whereas, we showed that Bl extract reduced significantly expression of COX­2 by a dose-dependent manner in HEL and K562 (COX­2+) cells. Furthermore, in regard to our results, it is clear that the simultaneous inhibition of Akt and NF-κB signalling can significantly contribute to the anticancer effects of Bl extract in human erythroleukemia cells. We observed that the Bl extract is clearly more active than the berberine alone on the induction of DNA fragmentation in human erythro-leukemia cells.

Expression of eukaryotic initiation factor 4E and 4E binding protein 1 in colorectal carcinogenesis.

Cap dependent translation is mainly regulated at the level of the eukaryotic initiation factor 4E (eIF4E), the activity of which is controlled by phosphorylation and sequestration by its well established regulator, 4E binding protein 1 (4E-BP1). Both eIF4E and 4E-BP1 have been shown to be involved in the malignant progression of multiple human cancers, including colorectal cancer. However, the data on determining the expression of eIF4E, 4E-BP1 and their phosphorylated forms simultaneously in a single patient with colorectal cancer is lacking. Therefore the aim of our study was to explore the roles of these factors in colorectal carcinogenesis by immunohistostaining colorectal tissues (normal, low grade adenoma, high grade adenoma, and adenocarcinoma). Our results showed that the expression levels of eIF4E increased steadily as the cancer progressed from the case of benign dysplasia to an adenocarcinoma; all the while maintaining an unphosphorylated form. On the other hand, total expression levels of 4E-BP1 increased only in the premalignant state of the disease and decreased (but highly phosphorylated or inactivated) or abolished upon malignancy. Taken together, our findings suggest that strong correlations exist between the expression of eIF4E (not p-eIF4E) and tumor grade providing evidence that eIF4E expression plays a pivotal role in the malignant progression of colorectal cancer. Moreover, 4E-BP1 showed a bi-phasic level of expression during carcinogenesis, which is expressed only in hyperplasic or dysplastic tissues as an endogenous tumor suppressor molecule.

pecific nutrient combination effects on tax, NF- κB and MMP-9 in human T-cell lymphotropic virus -1 positive malignant T-lymphocytes.

BACKGROUND: Adult T-cell Leukemia (ATL) is a disease with no known cure. The disease manifests itself as an aggressive proliferation of CD4+ cells with the human T-cell Lymphotropic virus type 1 (HTLV-1). The leukemogenesis of the virus is mainly attributed to the viral oncoprotein. Tax activates the Nuclear Factor kappa B (NF-κB) which stimulates the activity and expression of the matrix metalloproteinase-9 (MMP-9). The objective of this study was to investigate the efficacy of a specific nutrient synergy (SNS) on proliferation, Tax expression, NF-κB levels as well as on MMP-9 activity and expression both at the transcriptional and translational levels in two HTLV-1 positive cell lines, HuT-102 and C91-PL at 48h and 96h of incubation. Cytotoxicity of Epigallocatechin-3-gallate (EGCG) was assayed using CytoTox 96 Non-radioactive and proliferation was measured using Cell Titer96TM Nonradioactive Cell Proliferation kit (MTT- based assay). Enzyme linked immunosorbant assay (ELISA) and electrophoretic mobility shift assay (EMSA) were used to assess the effect of SNS on NF-κB mobility. Zymography was used to determine the effects of SNS on the activity and secretion of MMP-9. The expression of MMP-9 was done using RT-PCR at the translational level and Immunoblotting at the transcriptional level. RESULTS: A significant inhibition of proliferation was seen in both cell lines starting at a concentration of 200µg/ml and in a dose dependent manner. SNS induced a dose dependent decrease in Tax expression, which was paralleled by a down-regulation of the nuclearization of NF-κB. This culminated in the inhibition of the activity of MMP-9 and their expression both at the transcriptional and translational levels. CONCLUSIONS: The results of this study indicate that a specific nutrient synergy targeted multiple levels pertinent to the progression of ATL. Its activity was mediated through the NF-κB pathway, and hence has the potential to be integrated in the treatment of this disease as a natural potent anticancer agent.

Effects of nutrients on matrix metalloproteinases in human T-lymphotropic virus type 1 positive and negative malignant T-lymphocytes.

Experimental and clinical studies have revealed the effectiveness of a specific nutrient synergy (SNS) mixture composed of ascorbic acid (AA), lysine, proline, arginine, epigallocatechin gallate (EGCG) and other micronutrients in targeting crucial physiological mechanisms involved in cancer progression and metastasis. HTLV-1 causes adult T-cell leukemia (ATL). The spread and metastases of ATL as well as other tumors has been associated with matrix metalloproteinases, especially the gelatinases MMP-2 and MMP-9. The objective of this study was to investigate whether SNS, AA and EGCG affects the gelatinolytic activity of MMP-2 and its transcriptional and translational levels in HTLV-1-positive and -negative malignant T-cells. The results indicated that SNS and EGCG caused a dose-dependent decline in the activity, transcription and translation of MMP-2 after treatment with SNS and EGCG, while AA was only able to inhibit the activity at maximum doses tested and to some extent, the protein expression levels of MMP-2, without affecting their transcriptional levels. The highest activity was noted in the case of SNS which is likely to be due to a synergistic effect of the different constituents in the formulation. These results point towards the potential integration of SNS in the anti-invasive treatment of ATL and related diseases.

Epigallocatechin-3-gallate inhibits tax-dependent activation of nuclear factor kappa B and of matrix metalloproteinase 9 in human T-cell lymphotropic virus-1 positive leukemia cells.

Epigallocatechin-3-gallate (EGCG) is the most abundant polyphenol molecule from green tea and is known to exhibit antioxidative as well as tumor suppressing activity. In order to examine EGCG tumor invasion and suppressing activity against adult T-cell leukemia (ATL), two HTLV-1 positive leukemia cells (HuT-102 and C91- PL) were treated with non-cytotoxic concentrations of EGCG for 2 and 4 days. Proliferation was significantly inhibited by 100 µM at 4 days, with low cell lysis or cytotoxicity. HTLV-1 oncoprotein (Tax) expression in HuT- 102 and C91-PL cells was inhibited by 25 µM and 125 µM respectively. The same concentrations of EGCG inhibited NF-kB nuclearization and stimulation of matrix metalloproteinase-9 (MMP-9) expression in both cell lines. These results indicate that EGCG can inhibit proliferation and reduce the invasive potential of HTLV-1- positive leukemia cells. It apparently exerted its effects by suppressing Tax expression, manifested by inhibiting the activation of NF-kB pathway and induction of MMP-9 transcription in HTLV-1 positive cells.

Contribution of HIF-1α in 4E-BP1 gene expression.

The eukaryotic translation initiation factor 4E (eIF4E) is necessary for the translation of capped mRNAs into proteins. Cap-dependent mRNA translation can be however inhibited by the eIF4E-binding protein 1 (4E-BP1). The hypophosphorylated forms of 4E-BP1 indeed sequester eIF4E and thus block translation initiation and consequent protein synthesis. Different reports indicate that, in addition to hypophosphorylation, 4E-BP1 function can be also regulated at the level of protein expression. This is the case in contact-inhibited cells or in cells exposed to hypoxia. The molecular mechanisms responsible for 4E-BP1 protein accumulation in these conditions remain however unknown. In the present study, we found that 4E-BP1 gene promoter contains a hypoxia-responsive element (HRE) that mediates 4E-BP1 gene upregulation via the hypoxia-inducible factor-1 alpha (HIF-1α) transcription factor. Gene reporter assays then revealed that the presence of such HRE in the promoter of 4E-BP1 gene is involved in 4E-BP1 accumulation in contact-inhibited cells and in cells exposed to hypoxia. We also reveal that the TGF-ß-dependent transcription factor SMAD4 cooperates with HIF-1α to fully activate 4E-BP1 gene transcription under hypoxia. These data therefore suggest that HIF-1α contributes to 4E-BP1 gene expression under different conditions.

Medication prescribing errors: data from seven Lebanese hospitals.

INTRODUCTION: Medication prescribing errors are made all over the world. However, exact data about them are lacking in Lebanon. Our objective was to describe medication errors, including drug-drug interactions in medication orders given to patients admitted to Lebanese hospitals. METHODS: A prospective study was carried out on 313 patients taken from seven Lebanese hospitals; 1826 medication orders were assessed for errors and 456 drug-drug interactions were found. Data was entered and analyzed on SPSS. RESULTS: Around 40% of medication orders were judged to comprise at least one prescribing error, mainly no ordering of parameters monitoring (20%), unnecessary medication (9%), and no indication (7%). Errors occurred mainly in the pediatrics (50%) and internal medicine wards (40%). Having an infectious or gastrointestinal problem almost doubled the risk of medication prescribing error. Antiulcer agents, NSAIDs, antibiotics and steroidal agents were the medications mainly involved. Meanwhile, 12 adverse medication events were reported, with an odds ratio of association to a medication error of 7.4 (p = 0.004). As for drug-drug interaction (DDI), prescriptions comprised zero to 29 interactions, involving medications with low margin of safety such as acenocoumarol, amiodarone and valproate. Pharmacodynamic interactions were mainly found (60%). The majority of DDI were of high clinical significance and well documented (80%), with moderate (59%) to major (17%) severity. CONCLUSION: These results highlight the urgency of an intervention to improve patients' outcomes and avoid deleterious impact of inadequate medication use in Lebanon. The presence of a clinical pharmacist, the inclusion of computerized systems and the application of drug management policies are suggested to decrease medication prescribing errors and enhance the physician attention to DDI.

Control of contact-inhibition by 4E-BP1 upregulation.

Although contact inhibition is a fundamental process for multicellular organisms, how proliferation is inhibited at high cellular densities remains poorly characterized. Here we show that 4E-BP1, one major repressor of cap-dependent translation, plays a critical role in density-mediated cell cycle arrest. 4E-BP1 promoter is activated and 4E-BP1 protein amount increases as cells reach confluence. Conversely, a much less marked density-dependent inhibition of cell proliferation is observed upon 4E-BP1 silencing. We further show that at high density, progression through the G1 phase of the cell cycle is faster and Cyclin D1 protein is induced in different cell types where 4E-BP1 has been either downregulated (stable shRNA expression or transient siRNA transfection) or removed (knock-out). Thus 4E-BP1 appears as an important mediator of contact inhibition.

4E-BP1 is a target of Smad4 essential for TGFbeta-mediated inhibition of cell proliferation.

Assembly of the multi-subunit eukaryotic translation initiation factor-4F (eIF4F) is critical for protein synthesis and cell growth and proliferation. eIF4F formation is regulated by the translation-inhibitory protein 4E-BP1. While proliferation factors and intracellular pathways that impinge upon 4E-BP1 phosphorylation have been extensively studied, how they control 4E-BP1 expression remains unknown. Here, we show that Smad4, a transcription factor normally required for TGFbeta-mediated inhibition of normal cell proliferation, enhances 4E-BP1 gene-promoter activity through binding to a conserved element. 4E-BP1 expression is specifically modulated by treatment with TGFbeta and by manipulations of the natural Smad4 regulators (co-Smads) in cells isolated from Smad4(+/+) human tumours, whereas no response is observed in cells isolated from Smad4(-/-) human tumours or in cells where Smad4 has been knocked down by specific siRNAs. In addition, cells where 4E-BP1 has been knocked down (inducible shRNAs in human pancreatic cancer cells or siRNAs in non-malignant human keratinocytes) or has been knocked out (mouse embryonic fibroblasts isolated from 4E-BP1(-/-) mice) proliferate faster and are resistant to the antiproliferative effect of TGFbeta. Thus, 4E-BP1 gene appears critical for TGFbeta/Smad4-mediated inhibition of cell proliferation.

Fibroblast growth factor 1 induced during myogenesis by a transcription-translation coupling mechanism.

Fibroblast growth factor 1 (FGF1) is involved in muscle development and regeneration. The FGF1 gene contains four tissue-specific promoters allowing synthesis of four transcripts with distinct leader regions. Two of these transcripts contain internal ribosome entry sites (IRESs), which are RNA elements allowing mRNA translation to occur in conditions of blockade of the classical cap-dependent mechanism. Here, we investigated the function and the regulation of FGF1 during muscle differentiation and regeneration. Our data show that FGF1 protein expression is induced in differentiating myoblasts and regenerating mouse muscle, whereas siRNA knock-down demonstrated FGF1 requirement for myoblast differentiation. FGF1 induction occurred at both transcriptional and translational levels, involving specific activation of both promoter A and IRES A, whereas global cap-dependent translation was inhibited. Furthermore, we identified, in the FGF1 promoter A distal region, a cis-acting element able to activate the IRES A-driven translation. These data revealed a mechanism of molecular coupling of mRNA transcription and translation, involving a unique process of IRES activation by a promoter element. The crucial role of FGF1 in myoblast differentiation provides physiological relevance to this novel mechanism. This finding also provides a new insight into the molecular mechanisms linking different levels of gene expression regulation.

Overexpression of high molecular weight FGF-2 forms inhibits glioma growth by acting on cell-cycle progression and protein translation.

In order to clarify the role of HMW FGF-2 in glioma development and angiogenesis, we over-expressed different human FGF-2 isoforms in C6 rat glioma cell line using a tetracycline-regulated expression system. Phenotypic modifications were analyzed in vitro and compared to untransfected cells or to cells over-expressing 18 kDa FGF-2 or all FGF-2 isoforms. In particular, we demonstrate that HMW FGF-2 has unique features in inhibiting glioma cell proliferation. HMW FGF-2 expressing cells showed a cell-cycle arrest at the G2M, demonstrating a role of HMW FGF-2 in controlling the entry in mitosis. Moreover, hydroxyurea was ineffective in blocking cells at the G1S boundary when HMW FGF-2 was expressed. We also show that the HMW FGF-2 isoforms inhibit 4E-BP1 phosphorylation at critical sites restoring the translation inhibitory activity of 4E-BP1. In vivo, inhibition of tumor growth was observed when cells expressed HMW FGF-2. This indicates that HMW FGF-2 inhibits tumor growth in glioma cells by acting on cell-cycle progression and protein translation.