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We report on whole-exome sequencing (WES) of 213 melanomas. Our analysis established NF1, encoding a negative regulator of RAS, as the third most frequently mutated gene in melanoma, after BRAF and NRAS. Inactivating NF1 mutations were present in 46% of melanomas expressing wild-type BRAF and RAS, occurred in older patients and showed a distinct pattern of co-mutation with other RASopathy genes, particularly RASA2. Functional studies showed that NF1 suppression led to increased RAS activation in most, but not all, melanoma cases. In addition, loss of NF1 did not predict sensitivity to MEK or ERK inhibitors. The rebound pathway, as seen by the induction of phosphorylated MEK, occurred in cells both sensitive and resistant to the studied drugs. We conclude that NF1 is a key tumor suppressor lost in melanomas, and that concurrent RASopathy gene mutations may enhance its role in melanomagenesis. [ABSTRACT FROM AUTHOR]

Learning and memory require orchestrated regulation of both structural and functional synaptic plasticity in the hippocampus. While a neuropeptide alpha-melanocyte-stimulating hormone, a-MSH, has been implicated in memory acquisition and retention, the functional role of its cognate receptor, melanocortin-4 receptor (MC4R), in hippocampal-dependent synaptic plasticity has not been explored. In this study, we report that activation of MC4R enhances synaptic plasticity through the regulation of dendritic spine morphology and abundance of AMPA receptors. We show that activation of postsynaptic MC4R increases the number of mature dendritic spines and enhances surface expression of AMPA receptor subunit GluAl, resulting in synaptic accumulation of GluAl-containing AMPA receptors. Moreover, MC4R stimulates surface GluAl trafficking through phosphorylation of GluAl at Ser845 in a Gas-cAMP/PKA-dependent manner. Blockade of protein kinase A (PKA) signaling abolishes the MC4R-mediated enhancement of neurotransmission and hippocampal long-term potentiation. Importantly, in vivo application of MC4R agonists increases LTP in the mouse hippocampal CAI region. These findings reveal that MC4R in the hippocampus plays a critical role in the regulation of structural and functional plasticity. [ABSTRACT FROM AUTHOR]

BRAFV600E/K is a frequent mutationally active tumor-specific kinase in melanomas that is currently targeted for therapy by the specific inhibitor PLX4032. Our studies with melanoma tumor cells that are BRAFV600E/K and BRAFWT showed that, paradoxically, while PLX4032 inhibited ERK1/2 in the highly sensitive BRAFV600E/K, it activated the pathway in the resistant BRAFWT cells, via RAF1 activation, regardless of the status of mutations in NRAS or PTEN. The persistently active ERK1/2 triggered downstream effectors in BRAFWT melanoma cells and induced changes in the expression of a wide-spectrum of genes associated with cell cycle control. Furthermore, PLX4032 increased the rate of proliferation of growth factor-dependent NRAS Q61L mutant primary melanoma cells, reduced cell adherence and increased mobility of cells from advanced lesions. The results suggest that the drug can confer an advantage to BRAFWT primary and metastatic tumor cells in vivo and provide markers for monitoring clinical responses. [ABSTRACT FROM AUTHOR]

Decitabine, an epigenetic modifier that reactivates genes otherwise suppressed by DNA promoter methylation, is effective for some, but not all cancer patients, especially those with solid tumors. It is commonly recognized that to overcome resistance and improve outcome, treatment should be guided by tumor biology, which includes genotype, epigenotype, and gene expression profile. We therefore took an integrative approach to better understand melanoma cell response to clinically relevant dose of decitabine and identify complementary targets for combined therapy. We employed eight different melanoma cell strains, determined their growth, apoptotic and DNA damage responses to increasing doses of decitabine, and chose a low, clinically relevant drug dose to perform whole-genome differential gene expression, bioinformatic analysis, and protein validation studies. The data ruled out the DNA damage response, demonstrated the involvement of p21Cip1 in a p53-independent manner, identified the TGFb pathway genes CLU and TGFBI as markers of sensitivity to decitabine and revealed an effect on histone modification as part of decitabine-induced gene expression. Mutation analysis and knockdown by siRNA implicated activated b-catenin/MITF, but not BRAF, NRAS or PTEN mutations as a source for resistance. The importance of protein stability predicted from the results was validated by the synergistic effect of Bortezomib, a proteasome inhibitor, in enhancing the growth arrest of decitabine in otherwise resistant melanoma cells. Our integrative analysis show that improved therapy can be achieved by comprehensive analysis of cancer cells, identified biomarkers for patient's selection and monitoring response, as well as targets for improved combination therapy. [ABSTRACT FROM AUTHOR]

Background In 2003 the National Institute of Clinical Excellence published guidelines recommending the use of brain natriuretic peptipe (BNP) and the electrocardiogram (ECG) as part of the diagnostic work up of individuals with heart failure. However, the guideline did not address whether one test was superior to the other or whether performing both tests was superior to performing single tests. Aim To investigate the relative test accuracy of the ECG, BNP, N terminal-pro brain natriuretic peptide (NT-proBNP) and combinations of two or more tests in the diagnosis of left ventricular systolic dysfunction (LVSD) in the primary care setting. Design of study Cohort studies making within-subject comparisons of intervention diagnostic test(s) with reference standard results. Method Standard systematic review methodology was followed. Results Thirty-two primary studies met the review inclusion criteria. Studies were of variable quality and highly clinically heterogeneous, therefore restricting the use of meta-analysis. Within these limitations BNP, NT-proBNP and the ECG all had similar test sensitivity (>80% in the majority of studies). Specificity of the three tests was not as good. Three studies directly comparing BNP and the ECG found no difference in sensitivity and limited support for improved specificity of BNP. Two studies found no difference in sensitivity and limited evidence for an improvement in specificity for the combination of the ECG and BNP compared to single tests. Conclusion On the basis of existing evidence, the ECG, BNP and NT-proBNP are useful in excluding a diagnosis of LVSD (good sensitivity). However, use of abnormal test results to select individuals for echocardiography may overwhelm services. There is currently no evidence to justify the use of one test over another or the use of tests in combination. The additional cost of BNP is not self-evidently justified by improved test accuracy. Further research is needed to directly compare the diagnostic performance of these tests in homogeneous, representative primary care populations. [ABSTRACT FROM AUTHOR]

Focuses on the loss of tyrosinase, the key enzyme in melanin synthesis, in malignant melanocytes. Investigation of proteolytic degradation as a basis for the loss of tyrosinase; Methods and materials used in the study; Results and discussion.

Activating mutations in BRAF kinase are common in melanomas. Clinical trials with PLX4032, the mutant-BRAF inhibitor, show promising preliminary results in patients selected for the presence of V600E mutation. However, activating V600K mutation is the other most common mutation, yet patients with this variant are currently excluded from the PLX4032 trials. Here we present evidence that a patient bearing the BRAF V600K mutation responded remarkably to PLX4032, suggesting that clinical trials should include all patients with activating BRAF V600E/K mutations. [ABSTRACT FROM AUTHOR]