Novel loss-of-function variant in DENND5A impedes melanosomal cargo transport and predisposes to familial cutaneous melanoma

PurposeMore than half of the familial cutaneous melanomas have unknown genetic predisposition. This study aims at characterizing a novel melanoma susceptibility gene.MethodsWe performed exome and targeted sequencing in melanoma-prone families without any known melanoma susceptibility genes. We analyzed the expression of candidate gene DENND5A in melanoma samples in relation to pigmentation and UV signature. Functional studies were carried out using microscopic approaches and zebrafish model.ResultsWe identified a novel DENND5A truncating variant that segregated with melanoma in a Swedish family and 2 additional rare DENND5A variants, 1 of which segregated with the disease in an American family. We found that DENND5A is significantly enriched in pigmented melanoma tissue. Our functional studies show that loss of DENND5A function leads to decrease in melanin content in vitro and pigmentation defects in vivo. Mechanistically, harboring the truncating variant or being suppressed leads to DENND5A losing its interaction with SNX1 and its ability to transport the SNX1-associated vesicles from melanosomes. Consequently, untethered SNX1-premelanosome protein and redundant tyrosinase are redirected to lysosomal degradation by default, causing decrease in melanin content.ConclusionOur findings provide evidence of a physiological role of DENND5A in the skin context and link its variants to melanoma susceptibility.     

Alterations in pain processing circuitries in episodic migraine

BackgroundThe precise underlying mechanisms of migraine remain unknown. Although we have previously shown acute orofacial pain evoked changes within the brainstem of individuals with migraine, we do not know if these brainstem alterations are driven by changes in higher cortical regions. The aim of this investigation is to extend our previous investigation to determine if higher brain centers display altered activation patterns and connectivity in migraineurs during acute orofacial noxious stimuli.MethodsFunctional magnetic resonance imaging was performed in 29 healthy controls and 25 migraineurs during the interictal and immediately (within 24-h) prior to migraine phases. We assessed activation of higher cortical areas during noxious orofacial heat stimulation using a thermode device and assessed whole scan and pain-related changes in connectivity.ResultsDespite similar overall pain intensity ratings between all three groups, migraineurs in the group immediately prior to migraine displayed greater activation of the ipsilateral nucleus accumbens, the contralateral ventrolateral prefrontal cortex and two clusters in the dorsolateral prefrontal cortex (dlPFC). Reduced whole scan dlPFC [Z + 44] connectivity with cortical/subcortical and brainstem regions involved in pain modulation such as the putamen and primary motor cortex was demonstrated in migraineurs. Pain-related changes in connectivity of the dlPFC and the hypothalamus immediately prior to migraine was also found to be reduced with brainstem pain modulatory areas such as the rostral ventromedial medulla and dorsolateral pons.ConclusionsThese data reveal that the modulation of brainstem pain modulatory areas by higher cortical regions may be aberrant during pain and these alterations in this descending pain modulatory pathway manifests exclusively prior to the development of a migraine attack.     

Has hyperglycemia a different prognostic role in STEMI patients with or without diabetes?

Background and aimsHyperglycemia at hospital admission is a common finding in patients with STEMI. However, whether elevated acute glycemia in these patients may have a direct impact on worsening prognosis or is just a marker of a greater neurohormonal activation in response to the infarction is still unsettled.We sought to investigate the prognostic impact of hyperglycemia at hospital admission in patients undergoing primary PCI (pPCI) for STEMI, and the influence of the presence of diabetes mellitus (DM) on its prognostic impact.Methodsand Results, We enrolled 2958 consecutive STEMI patients treated by pPCI. Hyperglycemia was defined as plasma glucose >198 mg/dL (or >11 mmol/L). Patients with hyperglycemia showed a greater risk-profile; they also experienced a higher mortality both at univariable (17.6% vs 5.2%, p < 0.001) and multivariable (HR 1.9, 95%IC 1.5–2.9, p = 0.001) analysis. However, after stratification for DM presence, hyperglycemia resulted as an independent predictor of mortality only in patients without DM (HR 2, 95%IC 1.2–3.4, p = 0.01).ConclusionHyperglycemia in the setting of myocardial infarction treated with primary PCI in an independent predictor of all-cause mortality in patients without diabetes; in patients with diabetes, its prognostic impact seems attenuated.     

Fundus autofluorescence in patients with age-related macular degeneration and high risk of visual loss

PURPOSE: To describe fundus autofluorescence (AF) patterns and their change over time in patients with age-related macular degeneration (AMD) and high risk of visual loss participating in the drusen laser study (DLS). DESIGN: Randomized clinical trial. METHODS: The study population consisted of 29 patients (35 eyes) participating in the DLS, which is a prospective, randomized, controlled clinical trial of prophylactic laser therapy in patients with AMD and high risk of neovascular complications. The intervention consisted of 16 eyes having prophylactic laser and 19 receiving no treatment. The main outcome measures were changes in the distribution of drusen and AF. Patients were reviewed for a median follow-up or 24 months (range 12-36 months). RESULTS: At baseline, four patterns of fundus AF were recognized: focal increased AF (n = 18), reticular AF (n = 3), combined focal and reticular AF (n = 2), and homogeneous AF (n = 12). At last follow-up, fundus AF remained unchanged in 15 untreated (78%) and in seven treated (43%) eyes. In only one untreated eye, focal areas of increased AF returned to background levels and were no longer detectable at last follow-up, compared with six treated eyes. This difference was statistically significant (P =.03). Only large foveal soft drusen (drusenoid pigment epithelium detachments) consistently corresponded with focal changes in AF, whereas no obvious correspondence was found between small soft drusen located elsewhere and changes in AF. CONCLUSION: The lack of obvious correspondence between the distribution of drusen and of AF found in this study appears to indicate that drusen and AF represent independent measures of aging in the posterior pole.     

Left ventricular mass in dippers and nondippers with newly diagnosed hypertension

Hypertensive subjects can be subdivided into 2 groups, dippers and nondippers, according to the presence or the lack of a nocturnal fall of blood pressure of more than 10%. Several studies have investigated cardiac organ damage in the 2 groups with discordant results, but they included subjects with different onset, severity, and treatment of hypertension. The authors selected 23 dippers and 17 nondippers affected by newly (< 1 year) diagnosed grades 1 and 2 hypertension, never treated, who underwent 24-hour ambulatory blood pressure monitoring and M-mode echocardiography. They did not find significant differences between the 2 groups as regards the echocardiographic left ventricular and atrial dimensions or regarding the left ventricular mass, left ventricular mass index, or relative wall thickness. Also no significant differences were found in the rate of either left ventricular remodeling or left ventricular hypertrophy. These data suggest that nondipping status is not associated with a higher level of cardiac involvement in the early phases of hypertension compared to dipping status.     

Epidermal growth factor receptor activation: how exon 19 and 21 mutations changed our understanding of the pathway.

The discovery of epidermal growth factor receptor (EGFR) mutations in never-smokers has been the most relevant finding ever in non-small cell lung cancer. When patients whose tumors bear the sensitizing mutations are treated with the tyrosine kinase inhibitors gefitinib or erlotinib, we witness response rates and durations never before reported, including complete responses. At the same time, the presence of EGFR mutations has raised numerous new questions, tantalizing data, and new challenges for treatment. This is particularly true as we try to generalize the findings in lung cancer to other malignancies. The indiscriminate use of gefitinib or erlotinib in the general lung cancer population results in meager survival benefit for patients. Similarly, the tyrosine kinase inhibitors have limited activity in a variety of tumor types with EGFR overexpression. This has led to the question of whether EGFR remains a viable target in patients other than those whose tumors contain mutations, and whether the modest activity of cetuximab in colorectal cancer and head and neck cancer represents all that we can expect from inhibition of this pathway in the absence of mutation. Mechanisms of pathway activation other than mutation have been discovered in recent years, and include overexpression mediated by gene amplification or by amplification of a dinucleotide repeat in the EGFR promoter, mutation of an extracellular region on EGFR generating a mutant protein termed EGFRvIII, and enhanced signaling due to heterodimerization with other members of the EGFR family, particularly overexpression of HER2/HER3. The extent to which these paths to EGFR activation will confer sensitivity to the tyrosine kinase inhibitors or to EGFR monoclonal antibodies is being explored. Thus far, published clinical data suggest that there is little room for the administration of gefitinib or erlotinib in the absence of EGFR mutations. The five articles in this edition of CCR Focus will address the various mechanisms of EGFR pathway activation and provide insight into the potential for translation into clinical relevance.     

Tumor angiogenesis is associated with plasma levels of stromal-derived factor-1alpha in patients with multiple myeloma.

PURPOSE: Multiple myeloma is an incurable hematologic malignancy characterized by increased bone marrow angiogenesis and extensive lytic bone disease. We have previously shown that elevated levels of stromal-derived factor-1alpha (SDF-1alpha) in peripheral blood plasma are associated with osteolysis in multiple myeloma patients. We have now examined whether SDF-1alpha levels also correlate with angiogenesis. EXPERIMENTAL DESIGN: We examined the contribution of multiple myeloma plasma cell-derived SDF-1alpha in the stimulation of in vitro angiogenesis using a tube formation assay. We also collected trephine and peripheral blood plasma samples from patients with multiple myeloma to analyze microvessel density and SDF-1alpha levels, respectively. RESULTS: We show that multiple myeloma plasma cell line-derived conditioned medium containing SDF-1alpha stimulates in vitro angiogenesis. In addition, in a large cohort of patients with multiple myeloma and its precursor condition monoclonal gammopathy of undetermined significance, we confirm previous findings that plasma cell burden correlates with both angiogenesis and plasma levels of SDF-1alpha. We now extend these observations and show the novel finding that peripheral blood plasma levels of SDF-1alpha positively correlate with the degree of bone marrow angiogenesis in multiple myeloma and monoclonal gammopathy of undetermined significance patients. CONCLUSIONS: High levels of SDF-1alpha produced by multiple myeloma plasma cells promote osteolysis and bone marrow angiogenesis. Therefore, we propose that inhibition of SDF-1alpha may be an effective mechanism by which angiogenesis and osteolysis can be reduced in multiple myeloma patients.