The Effect of Vaccination against COVID-19 in Cancer Patients: Final Results of the COICA Trial.

Background: The COICA study is an ambispective, observational trial that was conceived to assess the clinical course of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in cancer patients. A recently published, population-based, case-control study reported a reduced vaccine efficacy at 3-6 months in cancer patients compared to individuals without cancer. Objectives: The aim of the study was to describe coronavirus disease 19 (COVID-19) outcomes in cancer patients and analyze differences in SARS-CoV-2 outcomes between vaccinated and unvaccinated patients. Methods: Descriptive statistics and frequency counts were used to summarize characteristics of the study population. χ2 test and the log-rank test were used to compare outcomes between vaccinated and unvaccinated patients. Results: A total of 141 cancer patients (80 males, 61 females) were recruited at two participating Institutions from March 2020 until April 2022 and observed from the time of positive SARS-CoV-2 test to the time of negativization or death. Approximately 35% of patients had been vaccinated at the time of infection with 2 (16 patients) or 3 (33 patients) vaccine doses. Vaccinated patients consistently and significantly showed improved COVID-19 outcomes compared to unvaccinated patients, with CT-diagnosed pneumonia, hospitalization, O2 therapy, and death reported in 0% versus 48.6%, 2.0% versus 15.2%, 0% versus 14.1%, and 0% versus 7.6%, respectively, of assessable patients (p < 0.05). Vaccinated versus unvaccinated patients showed a significantly shorter time to negativization, with a median (95% confidence interval) time of 12 (10-14) versus 20 (17-23) days, respectively (p < 0.001). Conclusions: Vaccination consistently improved all COVID-19 outcomes. No death was recorded among vaccinated patients. Additional research is especially warranted to establish optimal timing and patient selection for administration of the fourth vaccination dose.

The Impact of Routine Molecular Screening for SARS-CoV-2 in Patients Receiving Anticancer Therapy: An Interim Analysis of the Observational COICA Study.

Introduction: Cancer aggravates COVID-19 prognosis. Nosocomial transmission of SARS-CoV-2 is particularly frequent in cancer patients, who need to attend hospitals regularly. Since March 2020, all cancer patients having access to the Oncology Unit at the "Andrea Tortora" Hospital (Pagani, Salerno - referred to as "the Hospital") as inpatients or outpatients receiving intravenous therapy have been screened for SARS-CoV-2 using RT-PCR nasal swab. The ongoing COICA (COVID-19 infection in cancer patients) study is an ambispective, multicenter, observational study designed to assess the prognosis of SARS-CoV-2 infection in cancer patients. The aim of the study presented here was to explore potential differences in COVID-19-related outcomes among screening-detected versus nonscreening-detected SARS-CoV-2-infected patients. Methods: The COICA study enrolled cancer patients who had received any anticancer systemic therapy within 3 months since the day they tested positive for SARS-CoV-2 on RT-PCR. The target accrual is 128 patients, and the study was approved by the competent Ethics Committee. Only the subgroup of patients enrolled at the Hospital was considered in this unplanned interim analysis. Logistic regression analysis was used to evaluate the association of screening-based versus nonscreening-based diagnosis. Results: Since March 15, 2020, until August 15, 2021, a total of 931 outpatients and 230 inpatients were repeatedly screened for SARS-CoV-2 using RT-PCR nasal swab at the Hospital. Among these, 71 asymptomatic patients were positive on routine screening and 5 patients were positive for SARS-CoV-2 outside the institutional screening. Seven patients died because of COVID-19. At univariate analysis, nonscreening- versus screening-detected SARS-CoV-2 infection was associated with significantly higher odds of O2 therapy (OR = 16.2; 95% CI = 2.2-117.1; p = 0.006), hospital admission (OR = 31.5; 95% CI = 3.1-317.8; p = 0.003), admission to ICU (OR = 23.0; 95% CI = 2.4-223.8; p = 0.007), and death (OR = 8.8; 95% CI = 1.2-65.5; p = 0.034). Conclusion: Routine screening with RT-PCR may represent a feasible and effective strategy in reducing viral circulation and possibly COVID-19 mortality in patients with active cancer having repeated access to hospital facilities.

Hematological Toxicity During Concomitant Treatment With Ruxolitinib and Avelumab for Merkel Cell Carcinoma.

Background: Merkel cell carcinoma (MCC) is a rare neuroendocrine skin cancer. It frequently emerges in the presence of immunosuppression states such as myeloproliferative syndrome (MS). MS is treated with ruxolitinib, a selective JAK1 and JAK2 inhibitor. Avelumab, an anti PDL-1 inhibitor, is the standard treatment for MCC. To date it is unknown if avelumab and ruxolitinib have a synergistic or antagonistic effect when used together. Methods: We have identified all patients diagnosed with MCC, treated with avelumab, concomitant ruxolitinib, belonging to Tortora Hospital, Pagani and Santa Maria La Pietà Hospital, Nola, Italy between June 1 2019 and April 1 2020. Results: Among six MCC patients, we have found two patients in treatment with concomitant drugs. Both patients were being treated with ruxolitinib for MS as a standard regimen without suffering any hematological side effects. After starting doses of avelumab, we found thrombocytopenia, leukopenia, and anemia after cycle 1 and cycle 4, respectively, and decided to suspend both treatments. Following the suspension, the hematological values improved allowing us to restart treatment with avelumab without the need to resume ruxolitinib treatment. Conclusions: The combined treatment of ruxolitinib and avelumab demonstrated severe toxicity. Modifying the schedule or reducing the dose of both drugs needs to be studied in order to be able to treat both pathologies.

Clinical Characteristics of Metastatic Prostate Cancer Patients Infected with COVID-19 in South Italy.

BACKGROUND: To date, the clinical characteristics of coronavirus disease 19 (COVID-19)-infected urologic cancer patients are unknown. METHODS: We have analyzed all patients with prostate cancer undergoing hormonal or chemotherapy treatment and receiving telephone and in person pre-triage between March 1 and 27, 2020, at the Tortora Hospital, Pagani, Italy. RESULTS: Among 72 patients, 48 and 24 were hormone-sensitive (HS) and castration-resistant prostate cancer (CRPC), respectively; 0 HS and 2 (8.3%) CRPC (p < 0.05) were positive for COVID-19. Both patients were receiving LHRH agonist therapy, and 1 patient was receiving enzalutamide. Urgent intensive care unit admission was required due to clinical worsening. Blood tests showed severe lymphopenia, anemia, and an increase in platelets. Retroviral therapy, antibiotics, heparin, and chloroquine were prescribed at the beginning. One patient also received tocilizumab as a salvage treatment. After 3 weeks of hospitalization, the patients were discharged from the hospital. Both patients suffered from an aggressive COVID-19 course due to concomitant comorbidities. CONCLUSIONS: Investigating whether hormonal therapy, especially in advanced disease, acts as a protective factor or a risk factor during COVID-19 could be useful.

COVID 19 therapies and anti-cancer drugs: A systematic review of recent literature.

BACKGROUND: It is reasonable to think that cancer patients undergoing chemotherapy, targeted therapy or immunotherapy could have a more aggressive course if positive for Coronavirus disease CoV-2 (COVID- 19). METHODS: We conducted a literature review on https://www.ncbi.nlm.nih.gov/pubmed/, https://scholar.google.com, www.arxiv.org, www.biorxiv.org, of all articles published using the keywords COVID-19 therapy or treatment and cancer until May 2, 2020. A total of 205 articles were identified and 53 were included in this review. RESULTS: We describe the ongoing COVID-19 therapies that should be known by oncologists and highlight the potential interactions with antineoplastic drugs, commonly used in clinical practice. The main drug interactions were found with tocilizumab, ruxolitinib and colchicine. CONCLUSIONS: The literature provides an inconclusive picture on potential preferred treatments for COVID-19 and their interactions with antineoplastic agents. Future clinical trials are needed to better understand the interactions between different drugs in the context of COVID-19 pandemic.

T Cell Leukemia/Lymphoma 1A is essential for mouse epidermal keratinocytes proliferation promoted by insulin-like growth factor 1.

T Cell Leukemia/Lymphoma 1A is expressed during B-cell differentiation and, when over-expressed, acts as an oncogene in mouse (Tcl1a) and human (TCL1A) B-cell chronic lymphocytic leukemia (B-CLL) and T-cell prolymphocytic leukemia (T-PLL). Furthermore, in the murine system Tcl1a is expressed in the ovary, testis and in pre-implantation embryos, where it plays an important role in blastomere proliferation and in embryonic stem cell (ESC) proliferation and self-renewal. We have also observed that Tcl1-/- adult mice exhibit alopecia and deep ulcerations. This finding has led us to investigate the role of TCL1 in mouse skin and hair follicles. We have found that TCL1 is expressed in the proliferative structure (i.e. the secondary hair germ) and in the stem cell niche (i.e. the bulge) of the hair follicle during regeneration phase and it is constitutively expressed in the basal layer of epidermis where it is required for the correct proliferative-differentiation program of the keratinocytes (KCs). Taking advantage of the murine models we have generated, including the Tcl1-/- and the K14-TCL1 transgenic mouse, we have analysed the function of TCL1 in mouse KCs and the molecular pathways involved. We provide evidence that in the epidermal compartment TCL1 has a role in the regulation of KC proliferation, differentiation, and apoptosis. In particular, the colony-forming efficiency (CFE) and the insulin-like growth factor 1 (IGF1)-induced proliferation are dramatically impaired, while apoptosis is increased, in KCs from Tcl1-/- mice when compared to WT. Moreover, the expression of differentiation markers such as cytokeratin 6 (KRT6), filaggrin (FLG) and involucrin (IVL) are profoundly altered in mutant mice (Tcl1-/-). Importantly, by over-expressing TCL1A in basal KCs of the K14-TCL1 transgenic mouse model, we observed a significant rescue of cell proliferation, differentiation and apoptosis of the mutant phenotype. Finally, we found TCL1 to act, at least in part, via increasing phospho-ERK1/2 and decreasing phospho-P38 MAPK. Hence, our data demonstrate that regulated levels of Tcl1a are necessary for the correct proliferation and differentiation of the interfollicular KCs.

Intracardiac metastasis originated from chondrosarcoma.

Primary cardiac tumors are extremely rare. By comparison, metastatic involvement of the heart is over 20 times more common and has been reported in autopsy series in up to one in five patients dying of cancer. Cardiac metastasis of chondrosarcoma is absolutely not frequent. In the recent literature, a cardiac metastasis from chondrosarcoma has never been described. We report the case of an 18-year-old man with a diagnosis of cardiac metastasis that originated from a left scapular chondrosarcoma. Chondrosarcoma is a skeletal tumor with various grades of malignancy, rapidly evolving, and with a strong tendency to metastasize, with low responsiveness to chemotherapy. The onset of characteristic systemic symptoms in the late stage of the disease led to the diagnosis of a mass localized in the right atrium. Management and differential diagnosis of infective heart lesions were also very complex in a rapidly evolving life-threatening condition.

Endothelial cell adhesion to soluble vascular endothelial growth factor receptor-1 triggers a cell dynamic and angiogenic phenotype.

The aim of this study was to identify the molecular signals produced in human endothelial cells (ECs) by the interaction of α5ß1 integrin with soluble vascular endothelial growth factor receptor-1 (sVEGFR-1) present in the extracellular matrix. We generated a gene expression profile of ECs adhering to sVEGFR-1 or to fibronectin, the classic extracellular matrix ligand for α5ß1 integrin or in a nonadhering condition. Several biological pathways were differently modulated, 3 protein kinase C substrates [adducin, myristoylated alanine-rich protein kinase C substrate (MARCKS), and radixin] were differently expressed and phosphorylated when cells adhering to sVEGFR-1 were compared with those adhering to fibronectin. Rac1 activation and Gα13 protein involvement through the interaction with radixin were also detected after attachment to sVEGFR-1, and these responses depended on active VEGFR-2 signaling. On sVEGFR-1, ECs exhibited a motile phenotype that was consistent with the abundant presence of MARCKS, a stabilizer of dynamic adhesions. Moreover, ECs silenced for radixin expression no longer responded to the proangiogenic VEGFR-1-derived peptide 12. We propose that the presence of sVEGFR-1 in the EC microenvironment directs α5ß1 integrin signaling to generate a dynamic, motile phenotype. Our findings also provide new insights into the mechanism of action of proangiogenic peptide 12, relevant to a therapeutic perspective.

Detection, monitoring, and management of trastuzumab-induced left ventricular dysfunction: an actual challenge.

The antibody trastuzumab, targeted to inhibit the signalling of ErbB2, a tyrosine kinase receptor overexpressed in 20-30% of breast cancers, improves the prognosis in women affected by this tumour, but produces cardiotoxicity, since ErbB2 is also involved in myocardial homeostasis. In this review, we discuss the pathophysiology of trastuzumab cardiomyopathy and the complex interplay between ErbB2 inhibition and anthracyclines, and we focus on the actual challenges of detecting, monitoring, and managing trastuzumab cardiotoxicity: the research of new, sensitive markers of early trastuzumab toxicity, before the ejection fraction is reduced, is an active field of research.

Intracellular targets of RGDS peptide in melanoma cells.

BACKGROUND: RGD-motif acts as a specific integrins-ligand and regulates a variety of cell-functions via extracellular action affecting cell-adhesion properties. However, increasing evidence identifies additional RGDS-functions at intracellular level. Previous reports show RGDS-internalization in endothelial cells, cardiomyocytes and lymphocytes, indicating intracellular targets such as caspase-8 and caspase-9, and suggest RGDS specific activity at cytoplasmic level. Given the role RGDS-peptides play in controlling proliferation and apoptosis in several cell types, investigating intracellular targets of RGDS in melanoma cells may un-reveal novel molecular targets and key pathways, potentially useful for a more effective approach to melanoma treatment. RESULTS: In the present study we show for the first time that RGDS-peptide is internalized in melanoma cells in a time-dependent way and exerts strong anti-proliferative and pro-apoptotic effects independently from its extracellular anti-adhesive action. RGES control-peptide did not show biological effects, as expected; nevertheless it is internalized, although with slower kinetics. Survivin, a known cell-cycle and survival-regulator is highly expressed in melanoma cells. Co-immunoprecipitation assays in cell lysates and overlay assays with the purified proteins showed that RGDS interacts with survivin, as well as with procaspase-3, -8 and -9. RGDS-peptide binding to survivin was found to be specific, at high affinity (Kd 27.5 muM) and located at the survivin C-terminus. RGDS-survivin interaction appeared to play a key role, since RGDS lost its anti-mitogenic effect in survivin-deprived cells with a specific siRNA. CONCLUSIONS: RGDS inhibits melanoma growth with an adhesion-independent mechanism; it is internalized in melanoma cells and specifically interacts with survivin. The present data may indicate a novel role of RGDS-containing peptides physiologically released from the extracellular matrix and may suggest a possible novel anti-proliferation strategy in melanoma.

Women survive breast cancer but fall victim to heart failure: the shadows and lights of targeted therapy.

In many cases, early-stage breast cancer is now curable, and metastatic disease can be chronic consequent to the advent of new therapeutic tools. Unfortunately, some treatments have been associated with adverse cardiovascular effects. Indeed, in many breast cancer survivors, the risk of cardiovascular disease is higher than the risk of cancer recurrence. The clinical challenge of preventing cardiovascular complications in patients undergoing antineoplastic treatment has two aims, more effective life-saving treatment of patients, and prevention of morbidity and cardiovascular mortality in the short term and long term. The aim of the present study is to review the rapidly evolving therapeutic strategies designed to treat early-stage breast cancer. The review highlights the need for more data on the impact of new biological drugs (targeted therapy) on the cardiovascular apparatus. Finally, given the complexity of targeted and other novel treatments, cancer patients are best managed through a multidisciplinary approach.

Nitric oxide deficiency determines global chromatin changes in Duchenne muscular dystrophy.

The present study provides evidence that abnormal patterns of global histone modification are present in the skeletal muscle nuclei of mdx mice and Duchenne muscular dystrophy (DMD) patients. A combination of specific histone H3 modifications, including Ser-10 phosphorylation, acetylation of Lys 9 and 14, and Lys 79 methylation, were found enriched in muscle biopsies from human patients affected by DMD and in late-term fetuses, early postnatal pups, or adult mdx mice. In this context, chromatin immunoprecipitation experiments showed an enrichment of these modifications at the loci of genes involved in proliferation or inflammation, suggesting a regulatory effect on gene expression. Remarkably, the reexpression of dystrophin induced by gentamicin treatment or the administration of nitric oxide (NO) donors reversed the abnormal pattern of H3 histone modifications. These findings suggest an unanticipated link between the dystrophin-activated NO signaling and the remodeling of chromatin. In this context, the regulation of class IIa histone deacetylases (HDACs) 4 and 5 was found altered as a consequence of the reduced NO-dependent protein phosphatase 2A activity, indicating that both NO and class IIa HDACs are important for satellite cell differentiation and gene expression in mdx mice. In conclusion, this work provides the first evidence of a role for NO as an epigenetic regulator in DMD.

Differentiation-dependent progesterone synthesis and metabolism in NT2-N human neurons.

Human embryonic teratocarcinoma-derived Ntera2/cl.D1 (NT2) cells recapitulate many features of embryonic neuronal progenitor cells. Upon retinoic acid (RA) treatment they terminally differentiate into post-mitotic neuron-like cells (NT2-N), akin to human fetal neurons, thus representing an in vitro model of human neuron terminal differentiation. Experimental evidence also indicate NT2-N cultures as a potential source for cell transplantation therapy. The neurosteroids progesterone and its metabolite 3alpha-hydroxy-5alpha-pregnan-20-one (3alpha,5alpha-THP) promote neurogenesis and show anti-neurodegenerative properties. This study's aim was to assess the neurosteroidogenic competence of NT2 cells during RA-induced neuronal differentiation. Radioimmunoassay measurements revealed progesterone only in NT2-N cultures (4 week RA). Accordingly, progesterone synthesis from (3)H-pregnenolone was absent in NT2 cells and increased during RA exposure, being highest in NT2-N. [(3)H]-pregnenolone metabolism, yielding [(3)H]-progesterone and [(3)H]-5alpha-dihydroprogesterone ([(3)H]-5alpha-DHP), was time-dependent and inhibited by trilostane, a 3beta-hydroxysteroid-dehydrogenase (3beta-HSD) inhibitor. Conversely, (3)H-progesterone metabolism, which yielded [(3)H]-5alpha-DHP > [(3)H]-3beta,5alpha-THP > [(3)H]-3alpha,5alpha-THP, occurred at all time points examined, though showing a nadir in cultures treated with RA for 1 and 2 weeks. The differentiation-dependent increase of progesterone accumulation matched 3beta-HSD type I mRNA expression and 3beta-HSD immunoreactivity, that co-localized with Map2a/b- and GAD67 in NT2-N. Hence, in vitro differentiated human neurons, while retaining progesterone metabolic activity, also become competent in progesterone synthesis. These findings suggest an autocrine/paracrine role of neuronal progesterone, either on its own or through its 5alpha-reduced metabolites, in fetal brain development and allow speculation that NT2-N-produced neurosteroids may contribute to the encouraging results of NT2-N transplants in animal models of neurodegenerative diseases.

HDAC2 blockade by nitric oxide and histone deacetylase inhibitors reveals a common target in Duchenne muscular dystrophy treatment.

The overlapping histological and biochemical features underlying the beneficial effect of deacetylase inhibitors and NO donors in dystrophic muscles suggest an unanticipated molecular link among dystrophin, NO signaling, and the histone deacetylases (HDACs). Higher global deacetylase activity and selective increased expression of the class I histone deacetylase HDAC2 were detected in muscles of dystrophin-deficient MDX mice. In vitro and in vivo siRNA-mediated down-regulation of HDAC2 in dystrophic muscles was sufficient to replicate the morphological and functional benefits observed with deacetylase inhibitors and NO donors. We found that restoration of NO signaling in vivo, by adenoviral-mediated expression of a constitutively active endothelial NOS mutant in MDX muscles, and in vitro, by exposing MDX-derived satellite cells to NO donors, resulted in HDAC2 blockade by cysteine S-nitrosylation. These data reveal a special contribution of HDAC2 in the pathogenesis of Duchenne muscular dystrophy and indicate that HDAC2 inhibition by NO-dependent S-nitrosylation is important for the therapeutic response to NO donors in MDX mice. They also define a common target for independent pharmacological interventions in the treatment of Duchenne muscular dystrophy.

Estrogen receptor-alpha and endothelial nitric oxide synthase nuclear complex regulates transcription of human telomerase.

We report that in endothelial cells, the angiogenic effect of 17beta-estradiol (E2) is inhibited by the estrogen receptor (ER) antagonist ICI or the NO synthase (NOS) inhibitor 7-nitroindazole via downregulation of hTERT, the telomerase catalytic subunit, suggesting that E2 and NO are involved in controlling hTERT transcription. Quantitative Real-Time PCR and chromatin immunoprecipitations in E2-treated human umbilical vein endothelial cells, showed recruitment of ERs on the hTERT promoter and concomitant enrichment in histone 3 methylation at Lysine 79, a modification associated with transcription-competent chromatin. Confocal microscopy and re-chromatin immunoprecipitations revealed that on E2 induction, endothelial (e)NOS rapidly localized into the nucleus and associated with ERalpha on the hTERT promoter. Transfections of a constitutively active eNOS mutant (S1177D) strongly induced the hTERT promoter, indicating a direct role of the protein in hTERT transcriptional regulation. Mutation of the estrogen response element in the promoter abolished response to both ERs and active eNOS, demonstrating that the estrogen response element integrity is required for hTERT regulation by these factors. To investigate this novel regulation in a reduced NO environment, pulmonary endothelial cells were isolated from eNOS(-/-) mice and grown with/without E2. In wild-type cells, E2 significantly increased telomerase activity. In eNOS(-/-) cells, basal telomerase activity was rescued by exogenous eNOS or an NO donor, whereas responsiveness to E2 demanded the active protein. In conclusion, we document the novel findings of a combinatorial eNOS/ERalpha complex at the hTERT estrogen response element site and that active eNOS and ligand-activated ERs cooperate in regulating hTERT expression in the endothelium.

AKT is activated in an ataxia-telangiectasia and Rad3-related-dependent manner in response to temozolomide and confers protection against drug-induced cell growth inhibition.

The phosphatidylinositol 3-kinase/AKT pathway is activated frequently in human cancer, and it has been implicated in tumor cell proliferation, survival, and chemoresistance. In this study, we addressed the role of AKT in cellular responses to the therapeutic methylating agent temozolomide (TMZ), and we investigated the possible link between TMZ-induced modulation of AKT function and activation of ataxia-telangiectasia and Rad3-related (ATR)- and ataxia telangiectasia mutated (ATM)-dependent signaling pathways. We found that clinically relevant concentrations of TMZ caused activation of endogenous AKT in lymphoblastoid cells, and in colon and breast cancer cells, and that this molecular event required a functional mismatch repair system. Transfection of a dominant-negative kinase-dead form of AKT1 into breast cancer cells abrogated TMZ-induced activation of endogenous AKT, and it markedly enhanced cell sensitivity to the drug. Likewise, exposure of the MMR-proficient cell lines to the AKT inhibitor D-3-deoxy-2-O-methyl-myo inositol 1-[(R)-2-methoxy-3-(octadecyloxy)-propyl hydrogen phosphate] (SH-5) impaired AKT phosphorylation in response to TMZ, and it significantly increased cell chemosensitivity. Furthermore, small interfering RNA (siRNA)-mediated reduction of AKT1 expression in colon cancer cells potentiated the growth inhibitory effects of TMZ. Inhibition of ATM expression in colon cancer cells by siRNA did not impair TMZ-induced activation of AKT, whereas siRNA-mediated inhibition of ATR prevented AKT activation in response to the drug and increased cell chemosensitivity. These results strongly support the hypothesis that clinical benefit could be obtained by combining TMZ with inhibitors of the AKT pathway. Moreover, they provide the first evidence of a novel function of ATR as an upstream activator of AKT in response to DNA damage induced by O(6)-guanine-methylating agents.

Control of gcm RNA stability is necessary for proper glial cell fate acquisition.

The control of RNA stability is an important post-transcriptional event. While neural development is known to require proteins that bind AU-rich elements (ARE) and affect RNA half-life, the role of specific RNA stability in this process remains elusive. In the Drosophila embryo, glial fate acquisition is triggered by glial cells missing (gcm) master gene, which is transiently expressed in all gliogenic stem cells and submitted to tight transcriptional regulation. By using in vitro and in vivo site directed mutagenesis, we have discovered that gcm RNA is unstable and that its 3'UTR confers labile properties to RNA due to the presence of an ARE motif. Moreover, we show that the gliogenic potential of Gcm transcription factor increases when ARE is abolished and demonstrate the importance of gcm RNA stability in the acquisition of the glial fate. Thus, control of a single RNA half-life is crucial for nervous system differentiation.

Nitric oxide modulates chromatin folding in human endothelial cells via protein phosphatase 2A activation and class II histone deacetylases nuclear shuttling.

Nitric oxide (NO) modulates important endothelial cell (EC) functions and gene expression by a molecular mechanism which is still poorly characterized. Here we show that in human umbilical vein ECs (HUVECs) NO inhibited serum-induced histone acetylation and enhanced histone deacetylase (HDAC) activity. By immunofluorescence and Western blot analyses it was found that NO induced class II HDAC4 and 5 nuclear shuttling and that class II HDACs selective inhibitor MC1568 rescued serum-dependent histone acetylation above control level in NO-treated HUVECs. In contrast, class I HDACs inhibitor MS27-275 had no effect, indicating a specific role for class II HDACs in NO-dependent histone deacetylation. In addition, it was found that NO ability to induce HDAC4 and HDAC5 nuclear shuttling involved the activation of the protein phosphatase 2A (PP2A). In fact, HDAC4 nuclear translocation was impaired in ECs expressing small-t antigen and exposed to NO. Finally, in cells engineered to express a HDAC4-Flag fusion protein, NO induced the formation of a macromolecular complex including HDAC4, HDAC3, HDAC5, and an active PP2A. The present results show that NO-dependent PP2A activation plays a key role in class II HDACs nuclear translocation.

Heterodimerization of FGF-receptor 1 and PDGF-receptor-alpha: a novel mechanism underlying the inhibitory effect of PDGF-BB on FGF-2 in human cells.

Previous evidence has shown that platelet-derived growth factor-BB (PDGF-BB) and fibroblast growth factor-2 (FGF-2) directly interact with high affinity, leading to potent reciprocal inhibitory effects on bovine endothelial cells and rat vascular smooth muscle cells. In this study, we report that PDGF-BB inhibits a series of FGF-2-induced events, such as proliferation of human umbilical vein endothelial cells (HUVECs), FGF-2 cellular internalization, phosphorylation of intracellular signaling factors including p38, rac1/cdc42, MKK4, and MKK3/6, and phosphorylation of FGF-receptor 1 (FGF-R1). PDGF-receptor-alpha (PDGF-Ralpha) was found to mediate PDGF-BB inhibitory effects because its neutralization fully restored FGF-2 mitogenic activity and internalization. Additional biochemical analyses, coimmunoprecipitation experiments, and FRET analysis showed that FGF-R1 and PDGF-Ralpha directly interact in vitro and in vivo and that this interaction is somehow increased in the presence of the corresponding ligands FGF-2 and PDGF-BB. These results suggest that FGF-R1/PDGF-Ralpha heterodimerization may represent a novel endogenous mechanism to modulate the action of these receptors and their ligands and to control endothelial cell function.