Faculty Bibliography

OBJECTIVES: The impact of ethnicity and the socioeconomic status (SES) among Caucasians is not well studied. Here, we examine the impact of income on melanoma presentation and prognosis within a Caucasian cohort, accounting for ethnicity, as some reports suggest increased melanoma incidence in Ashkenazi Jewish (AJ) BRCA mutation carriers. METHODS: We studied prospectively enrolled primary melanoma patients at New York University. SES data were estimated using United States' Census Bureau data and patient zip codes. We evaluated associations between ethnicity, SES, and baseline characteristics using the x03C7;2 test and multivariate logistic regression. We compared survival distributions using Kaplan-Meier curves, log-rank tests, and Cox proportional hazard ratios. RESULTS: Of the 1,339 enrolled patients, AJ represented 32% (n = 423). Apart from AJ being older at presentation (p < 0.001), no significant differences were observed in baseline characteristics between ethnic groups. Patients with a median household income (MHI) lower than the median of the cohort were significantly more likely to present with advanced stages (p < 0.001) compared to patients with a higher MHI. Shorter overall (p = 0.016) and post-recurrence survival (p = 0.042) was also observed in patients from lower-income households. CONCLUSION: Data suggest that disparities in melanoma presentation in Caucasians stratify according to income independent of ethnic background.

PURPOSE: Brain metastasis is the major cause of mortality among melanoma patients. A molecular prognostic test that can reliably stratify patients at initial melanoma diagnosis by risk of developing brain metastasis may inform the clinical management of these patients. EXPERIMENTAL DESIGN: We performed a retrospective, cohort-based study analyzing genome-wide and targeted microRNA expression profiling of primary melanoma tumors of three patient cohorts (n= 92, n= 119, n= 45) with extensive clinical follow up. We used Cox regression analysis to establish a microRNA-based signature that improves the ability of the current clinicopathologic staging system to predict the development of brain metastasis. RESULTS: Our analyses identified a 4-microRNA (miR-150-5p, miR-15b-5p, miR-16-5p, and miR-374b-3p) prognostic signature that, in combination with stage, distinguished primary melanomas that metastasized to the brain from non-recurrent and non-brain-metastatic primary tumors (training cohort: C-index=81.4%, validation cohort: C-index=67.4%, independent cohort: C-index=76.9%). Corresponding Kaplan-Meier curves of high- vs. low-risk patients displayed a clear separation in brain-metastasis-free and overall survival (training: p<0.001, p<0.001, validation: p=0.033, p=0.007, independent: p=0.021, p=0.022, respectively). Finally, of the microRNA in the prognostic model, we found that the expression of a key lymphocyte miRNA, miR-150-5p, which is less abundant in primary melanomas metastatic to brain, correlated with presence of CD45+ tumor infiltrating lymphocytes. CONCLUSIONS: A prognostic assay based on the described miRNA expression signature combined with the currently used staging criteria may improve accuracy of primary melanoma patient prognoses and aid clinical management of patients, including selection for adjuvant treatment or clinical trials of adjuvant therapies.

BACKGROUND: Cardiac manifestations of neonatal lupus (cardiac NL) include congenital heart block and cardiomyopathy. Several candidate biomarkers were evaluated in cases at risk for cardiac NL on the basis of potential roles in inflammation, fibrosis, and cardiac dysfunction: C-reactive protein (CRP); NT-pro-B-type natriuretic peptide (NT-proBNP); troponin I; matrix metalloproteinase (MMP)-2; urokinase plasminogen activator (uPA); urokinase plasminogen activator receptor (uPAR); plasminogen; and vitamin D. OBJECTIVES: Identification of maternal and fetal biomarkers associated with development and morbidity of cardiac NL should provide clues to pathogenesis with translational implications for management. METHODS: Cord (139) and maternal (135) blood samples collected during pregnancies at risk for cardiac NL were available for study. Levels of cord and maternal CRP, cord NT-proBNP, and cord troponin I were evaluated using multiplex assays. Cord and maternal vitamin D were assessed by liquid chromatography-mass spectrometry. MMP-2, uPA, uPAR, and plasminogen were evaluated using ELISA. RESULTS: Cord CRP, NT-proBNP, MMP-2, uPA, uPAR, and plasminogen levels were higher in cardiac NL-affected fetuses than in unaffected cases, independent of maternal rheumatic disease, season at highest risk of cardiac NL development, and medications taken during pregnancy. These biomarkers were positively associated with a disease severity score derived from known risk factors for mortality in cardiac NL. Maternal CRP and cord troponin I levels did not differ between the groups. Cord and maternal vitamin D levels were not significantly associated with cardiac NL, but average maternal vitamin D level during pregnancy was positively associated with longer time to postnatal pacemaker placement. CONCLUSIONS: These data support the association of fetal reactive inflammatory and fibrotic components with development and morbidity of cardiac NL. Following CRP and NT-proBNP levels after birth can potentially monitor severity and progression of cardiac NL. MMP-2 and the uPA/uPAR/plasminogen cascade provide therapeutic targets to decrease fibrosis. Although decreased vitamin D did not confer increased risk, given the positive influence on postnatal outcomes, maternal levels should be optimized.

Amino acid deprivation promotes the inhibition of the kinase complex mTORC1 (mammalian target of rapamycin complex 1) and activation of the kinase GCN2 (general control nonrepressed 2). Signaling pathways downstream of both kinases have been thought to independently induce autophagy. We showed that these two amino acid-sensing systems are linked. We showed that pharmacological inhibition of mTORC1 led to activation of GCN2 and phosphorylation of the eukaryotic initiation factor 2alpha (eIF2alpha) in a mechanism dependent on the catalytic subunit of protein phosphatase 6 (PP6C). Autophagy induced by pharmacological inhibition of mTORC1 required PP6C, GCN2, and eIF2alpha phosphorylation. Although some of the PP6C mutants found in melanoma did not form a strong complex with PP6 regulatory subunits and were rapidly degraded, these mutants paradoxically stabilized PP6C encoded by the wild-type allele and increased eIF2alpha phosphorylation. Furthermore, these PP6C mutations were associated with increased autophagy in vitro and in human melanoma samples. Thus, these data showed that GCN2 activation and phosphorylation of eIF2alpha in response to mTORC1 inhibition are necessary for autophagy. Additionally, we described a role for PP6C in this process and provided a mechanism for PP6C mutations associated with melanoma.

BACKGROUND: Surgical management of primary melanoma is curative for most patients with clinically localized disease at diagnosis; however, a substantial number of patients recur and progress to advanced disease. Understanding molecular alterations that influence differential tumor progression of histopathologically similar lesions may lead to improved prognosis and therapies to slow or prevent metastasis. METHODS: We examined microRNA dysregulation by expression profiling of primary melanoma tumors from 92 patients. We screened candidate microRNAs selected by differential expression between recurrent and nonrecurrent tumors or associated with primary tumor thickness (Student's t test, Benjamini-Hochberg False Discovery Rate [FDR] < 0.05), in in vitro invasion assays. We performed in vivo metastasis assays, matrix remodeling experiments, and molecular studies to identify metastasis-regulating microRNAs and their cellular and molecular mechanisms. All statistical tests were two-sided. RESULTS: We identified two microRNAs (hsa-miR-382, hsa-miR-516b) whose expression was lower in aggressive vs nonaggressive primary tumors, which suppressed invasion in vitro and metastasis in vivo (mean metastatic foci: control: 37.9, 95% confidence interval [CI] = 25.6 to 50.2; miR-382: 19.5, 95% CI = 12.2 to 26.9, P = .009; miR-516b: 12.5, 95% CI = 7.7 to 17.4, P < .001, Student's t test). Mechanistically, miR-382 overexpression inhibits extracellular matrix degradation by melanoma cells. Moreover, we identified actin regulators CTTN, RAC1, and ARPC2 as direct targets of miR-382. Depletion of CTTN partially recapitulates miR-382 effects on matrix remodeling, invasion, and metastasis. Inhibition of miR-382 in a weakly tumorigenic melanoma cell line increased tumor progression and metastasis in vivo. CONCLUSIONS: Aberrant expression of specific microRNAs that can functionally impact progression of primary melanoma occurs as an early event of melanomagenesis.

Heat-shock factor 1 (HSF1) orchestrates the heat-shock response in eukaryotes. Although this pathway has evolved to help cells adapt in the presence of challenging conditions, it is co-opted in cancer to support malignancy. However, the mechanisms that regulate HSF1 and thus cellular stress response are poorly understood. Here we show that the ubiquitin ligase FBXW7alpha interacts with HSF1 through a conserved motif phosphorylated by GSK3beta and ERK1. FBXW7alpha ubiquitylates HSF1 and loss of FBXW7alpha results in impaired degradation of nuclear HSF1 and defective heat-shock response attenuation. FBXW7alpha is either mutated or transcriptionally downregulated in melanoma and HSF1 nuclear stabilization correlates with increased metastatic potential and disease progression. FBXW7alpha deficiency and subsequent HSF1 accumulation activates an invasion-supportive transcriptional program and enhances the metastatic potential of human melanoma cells. These findings identify a post-translational mechanism of regulation of the HSF1 transcriptional program both in the presence of exogenous stress and in cancer.