Faculty Bibliography

Background: Genetic risk factors of human cancer emerge as promising markers of clinical outcome. The recent melanoma genome-wide scans (GWAS) have identified loci associated with the disease risk, nevi or UV/pigmentation, but the prognostic potential of these variants is yet to be determined. In this study, we performed the first-to-date systematic evaluation of the association between established melanoma risk loci and melanoma progression. Methods: 891 melanoma patients prospectively accrued and followed up at NYU Medical Center were studied. We examined the association of 108 melanoma susceptibility single nucleotide polymorphisms (SNPs), selected or imputed from recent GWASs on melanoma, nevi or pigmentation, with recurrence-free survival (RFS) and overall survival (OS). The genotyping was performed using Sequenom I-plex. Cox PH model was used to test the association between each SNP and RFS and OS adjusted by age at diagnosis, gender, tumor stage and histological subtype. ROC curves were used to measure predictive utility of SNPs in predicting 3-year recurrence. Results: The strong association was observed for rs7538876 (RCC2) with RFS (HR=2.445, 95% CI 1.57 - 3.8, p=0.0006) and rs9960018 (DLGAP1) with both RFS and OS (HR=4.7, 95% CI=2.11-10.43, p=0.0061, HR=1.55, 95% CI=1.11-2.17, p=0.0094, respectively) using adjusted multivariate analysis. In addition, we identified the classifier with rs7538876 and rs9960018, stage and histological type at primary tumor diagnosis, achieving a higher area under the ROC curve (AUC=84%) compared to the baseline (AUC=78%) in predicting 3-year recurrence. Univariate survival analyses have identified associations of several SNPs with ulceration and/or tumor thickness. Conclusions: Our data revealed an association between specific melanoma susceptibility variants and worse clinicopathological variables at the time of diagnosis as well as worse disease outcome. The strength of associations observed for rs7538876 and rs9960018 suggest biological implication of!

ABSTRACT: Angiogenesis is essential for promoting growth and metastasis of solid tumors by ensuring blood supply to the tumor mass. Targeting angiogenesis is therefore an attractive approach to therapeutic intervention of cancer. Tumor angiogenesis is a process that is controlled by a complex network of molecular components including sensors, signaling transducers, and effectors, leading to cellular responses under hypoxic conditions. Positioned at the center of this network are the hypoxia-inducible factors (HIFs). HIF-1 is a major transcription factor that consists of two subunits, HIF-1alpha and HIF-1beta. It mediates transcription of a spectrum of gene targets whose products are essential for mounting hypoxic responses. HIF-1alpha protein level is very low in the normoxic condition but is rapidly elevated under hypoxia. This dramatic change in the cellular HIF-1alpha level is primarily regulated through the proteosome-mediated degradation process. In the past few years, scientific progress has clearly demonstrated that HIF-1alpha phosphorylation is mediated by several families of protein kinases including GSK3beta and ERKs both of which play crucial roles in the regulation of HIF-1alpha stability. Recent research progress has identified that Polo-like kinase 3 (Plk3) phosphorylates HIF-1alpha at two previously unidentified serine residues and that the Plk3-mediated phosphorylation of these residues results in destabilization of HIF-1alpha. Plk3 has also recently been found to phosphorylate and stabilize PTEN phosphatase, a known regulator of HIF-1alpha and tumor angiogenesis. Given the success of targeting protein kinases and tumor angiogenesis in anti-cancer therapies, Plk3 could be a potential molecular target for the development of novel and effective therapeutic agents for cancer treatment.

The incidence of melanoma is increasing faster than that of any other cancer, and predicted to double every 10-20 years. Surgery can be curative in Stage I, II, or III disease, but 75% of patients with deep primary lesions develop extensive recurrence or distant metastases and have dismal prognosis. In fact, there is no curative treatment for stage IV melanoma. Although novel targeted therapies, such as BRAF inhibitors and anti-CTLA4 antibodies are showing promising results in melanoma clinical trials, resistance to these agents and patient relapse rapidly ensue. Therapeutic resistance has been commonly attributed to functional redundancy between intimately hardwired cellular pathways responsible for tumor cell maintenance and survival. In order to avoid redundancy, we propose to directly inhibit the transcription of multiple genes required for the establishment or maintenance of tumors. First, we analyzed the expression of Bromodomain (BrD)-containing proteins, a family of epigenetic readers that bind acetylated lysine. BrDs are present in histone acetyl transferases (i.e. CBP/p300, PCAF, GCN5) and transcriptional regulators (i.e. BET family members: BRD2, 3, and 4). mRNA expression arrays showed several BrD-containing genes as upregulated in primary and metastatic melanoma cell lines compared to normal melanocytes. Analysis of available expression profiles also revealed higher levels of BRD2 and BRD4 in melanoma tissues relative to nevi or normal skin (P<0.001). Furthermore, immunohistochemistry staining of a melanoma tissue microarray confirmed overexpression of BRD4 protein in primary (P<0.001) and metastatic tumors (P<0.001) compared to nevi. BRD4 knockdown using siRNA or shRNA suppressed the proliferation and colony formation capacity of several metastatic melanoma cell lines. Moreover, melanoma cells stably infected with shBRD4 carrying lentivirus displayed reduced tumor growth in vivo compared with their counterpart infected with a non-silencing control. To identify cellular pathways mo!

The classification of melanoma subtypes into prognostically relevant and therapeutically insightful categories has been a challenge since the first description of melanoma in the 1800s. One limitation has been the assumption that the two most common histological subtypes of melanoma, superficial spreading and nodular, evolve according to a linear model of progression, as malignant melanocytes spread radially and then invade vertically. However, recent clinical, pathological, and molecular data indicate that these two histological subtypes might evolve as distinct entities. Here, we review the published data that support distinct molecular characterization of superficial spreading and nodular melanoma, the clinical significance of this distinction including prognostic relevance and the therapeutic implications

The rationale for using small molecule inhibitors of oncogenic proteins as cancer therapies depends, at least in part, on the assumption that metastatic tumors are primarily clonal with respect to mutant oncogene. With the emergence of BRAF(V600E) as a therapeutic target, we investigated intra- and inter-tumor heterogeneity in melanoma using detection of the BRAF(V600E) mutation as a marker of clonality. BRAF mutant-specific PCR (MS-PCR) and conventional sequencing were performed on 112 tumors from 73 patients, including patients with matched primary and metastatic specimens (n = 18). Nineteen patients had tissues available from multiple metastatic sites. Mutations were detected in 36/112 (32%) melanomas using conventional sequencing, and 85/112 (76%) using MS-PCR. The better sensitivity of the MS-PCR to detect the mutant BRAF(V600E) allele was not due to the presence of contaminating normal tissue, suggesting that the tumor was comprised of subclones of differing BRAF genotypes. To determine if tumor subclones were present in individual primary melanomas, we performed laser microdissection and mutation detection via sequencing and BRAF(V600E)-specific SNaPshot analysis in 9 cases. Six of these cases demonstrated differing proportions of BRAF(V600E)and BRAF(wild-type) cells in distinct microdissected regions within individual tumors. Additional analyses of multiple metastatic samples from individual patients using the highly sensitive MS-PCR without microdissection revealed that 5/19 (26%) patients had metastases that were discordant for the BRAF(V600E) mutation. In conclusion, we used highly sensitive BRAF mutation detection methods and observed substantial evidence for heterogeneity of the BRAF(V600E) mutation within individual melanoma tumor specimens, and among multiple specimens from individual patients. Given the varied clinical responses of patients to BRAF inhibitor therapy, these data suggest that additional studies to determine possible associations between clinical outcomes and intra- and inter-tumor heterogeneity could prove fruitful