Faculty Bibliography

Despite increasing amounts of experimental evidence depicting the involvement of non-coding RNAs in cancer, the study of BRAFV600E-regulated genes has thus far focused mainly on protein-coding ones. Here, we identify and study the microRNAs that BRAFV600E regulates through the ERK pathway.By performing small RNA sequencing on A375 melanoma cells and a vemurafenib-resistant clone that was taken as negative control, we discover miR-204 and miR-211 as the miRNAs most induced by vemurafenib. We also demonstrate that, although belonging to the same family, these two miRNAs have distinctive features. miR-204 is under the control of STAT3 and its expression is induced in amelanotic melanoma cells, where it acts as an effector of vemurafenib's anti-motility activity by targeting AP1S2. Conversely, miR-211, a known transcriptional target of MITF, is induced in melanotic melanoma cells, where it targets EDEM1 and consequently impairs the degradation of TYROSINASE (TYR) through the ER-associated degradation (ERAD) pathway. In doing so, miR-211 serves as an effector of vemurafenib's pro-pigmentation activity. We also show that such an increase in pigmentation in turn represents an adaptive response that needs to be overcome using appropriate inhibitors in order to increase the efficacy of vemurafenib.In summary, we unveil the distinct and context-dependent activities exerted by miR-204 family members in melanoma cells. Our work challenges the widely accepted "same miRNA family = same function" rule and provides a rationale for a novel treatment strategy for melanotic melanomas that is based on the combination of ERK pathway inhibitors with pigmentation inhibitors.

Metastatic cancers produce exosomes that condition pre-metastatic niches in remote microenvironments to favor metastasis. In contrast, here we show that exosomes from poorly metastatic melanoma cells can potently inhibit metastasis to the lung. These "non-metastatic" exosomes stimulate an innate immune response through the expansion of Ly6Clow patrolling monocytes (PMo) in the bone marrow, which then cause cancer cell clearance at the pre-metastatic niche, via the recruitment of NK cells and TRAIL-dependent killing of melanoma cells by macrophages. These events require the induction of the Nr4a1 transcription factor and are dependent on pigment epithelium-derived factor (PEDF) on the outer surface of exosomes. Importantly, exosomes isolated from patients with non-metastatic primary melanomas have a similar ability to suppress lung metastasis. This study thus demonstrates that pre-metastatic tumors produce exosomes, which elicit a broad range of PMo-reliant innate immune responses via trigger(s) of immune surveillance, causing cancer cell clearance at the pre-metastatic niche.

Circular RNAs are a novel class of non-coding RNAs with functions that remain poorly characterized in normal and pathological conditions. CDR1as is a non-canonical circRNA observed to act as a sponge for miR-7 in brain tissues. Analysis of RNA-seq data of melanocytes and melanoma cell lines and short-term cultures revealed loss of CDR1as expression as a hallmark of melanoma cells. We confirmed silencing of CDR1as in melanoma cells and tissues by RT-qPCR using divergent primers. Clinically, we observed CDR1as loss associated with metastatic progression and poor patient outcomes in a cohort of fresh-frozen melanoma tissue samples. Depletion of CDR1as in melanoma cell lines enhanced invasion in vitro and lung metastasis in vivo, demonstrating functional significance of CDR1as silencing. Surprisingly, CDR1as depletion had no clear effect on miR-7 activity in melanoma cells, and miR-7 inhibition was insufficient to rescue CDR1as silencing-induced invasion. Moreover, GSEA analyses of proteomic profiling of melanoma cells depleted of CDR1as revealed reductions of proteins involved in oxidative phosphorylation (OXPHOS) and mitochondrial function, suggesting CDR1as loss may alter metabolism of melanoma cells. Mining of CLIP-Seq data sets and subsequent RIP-PCR revealed direct interactions of CDR1as with the IGF2BP family of proteins and TAR

BACKGROUND: Metastatic melanoma of unknown primary (MUP) is uncommon, biologically ill defined, and clinically understudied. MUP outcomes are seldom reported in clinical trials. In this study, we analyze responses of MUP patients treated with systemic therapy in an attempt to inform treatment guidelines for this unique population. METHODS: New York University (NYU)'s prospective melanoma database was searched for MUP patients treated with systemic therapy. PubMed and Google Scholar were searched for MUP patients treated with immunotherapy or targeted therapy reported in the literature, and their response and survival data were compared to the MUP patient data from NYU. Both groups' response data were compared to those reported for melanoma of known primary (MKP). RESULTS: The MUP patients treated at NYU had better outcomes on immunotherapy but worse on targeted therapy than the MUP patients in the literature. The NYU MUP patients and those in the literature had worse outcomes than the majority-MKP populations in 10 clinical trial reports. CONCLUSIONS: Our study suggests that MUP patients might have poorer outcomes on systemic therapy as compared to MKP patients. Our cohort was small and limited data were available, highlighting the need for increased reporting of MUP outcomes and multi-institutional efforts to understand the mechanism behind the observed differences.

Background: Unlike other solid tumors, the impact of primary HS on melanoma survival and response to systemic therapy is not well studied. Nodular melanoma (NM) has a worse prognosis than superficial spreading melanoma (SSM), which is usually attributed to thicker primary tumors. Herein, we examine the hypothesis that HS might have an impact on MSS independent of thickness and that NM and SSM exhibit different mutational landscapes that associate with response to checkpoint inhibitor immunotherapy (IT) and BRAF targeted therapy (TT) in the metastatic setting. Methods: Primary NM and SSM patients prospectively enrolled at NYU (2002 - 2016) were compared to the most recent SEER cohort (1973 - 2012) and analyzed with respect to MSS. Next-Generation Sequencing (NGS) was performed on a subset of matched tumor-germline pairs, allowing a comparison of the mutational landscape between NM and SSM. In the metastatic setting, survival analyses were used to compare outcomes and responses to treatment across HS. Results: The NYU cohort of 1,621 patients with either NM (n = 510) or SSM (n = 1,111) was representative of the analogous SEER cohort (21,339 NM, 97,169 SSM), with NM presenting as thicker, more ulcerated, and later stage (all p < 0.001). Among the NYU cohort, NM was found to have lower rates of TIL (p = 0.047), higher mitotic index (p < 0.001), and higher rates of NRAS mutation (p < 0.001). In multivariate Cox models, NM was a significant predictor of worse MSS, independent of thickness and stage (p = 0.01). NM had a significantly lower mutational burden across the exome (p < 0.001). Some of the most under-mutated genes noted in NM were NOTCH4, BCL2L12 and RPS6KA6 (all p < 0.01). Among patients treated with TT (n = 56), NM remained a significant predictor of worse MSS (p = 0.004). However, there was no difference in response to IT. Conclusions: NM and SSM show divergent mutational patterns which may contribute to their different clinical behaviors and responses to BRAF targeted therapy. More studies are needed to better understand the key molecular and cellular processes driving such differences. Integration of HS data into prospective clinical trial reporting is needed to better assess its impact on response to treatment

Background: Recently, tumor mutation burden (TMB) has been shown to increase the presentation of neoantigens that stimulate immune tumor recognition, resulting in improved immunotherapy (IT) outcomes in melanoma and other cancers. As melanoma is highly immunogenic, here we tested whether TMB associates with immune recognition during tumor progression, hence impacting melanoma overall survival (OS), independently of IT treatment. Methods: We have generated somatic mutation data from 314 IT-naive metastatic melanomas from The Cancer Genome Atlas (TCGA). In the TCGA cohort, TMB has been calculated for 210 genes (200GS) previously established from TMB studies of anti-CTLA4 and anti-PD1/PD-L1 IT. For validation, we have sequenced exonic regions of 20 genes (20GS) with the highest TMB among 200GS in 89 IT-naive metastatic melanomas ascertained at New York University Langone Medical Center. The TMB was defined using total number of somatic, non-synonymous mutations in either 200GS (TCGA discovery) or 20GS (validation), respectively. For discovery and validation cohorts, OS from primary diagnosis of samples with high TMB was compared against low TMB, using thresholds established in previous studies. Results: We found that total TMB predicts better OS (p = 0.03, HR = 2.64) in TCGA melanomas. Restricting the analysis only to the established 200GS, this association became more significant in all patients (p = 0.01, HR = 2.67) as well as in patients without IT (p = 0.01, HR = 2.67). In the validation stage of 89 melanomas without prior IT treatment, a high TMB in a subset of 20GS accurately determined favorable OS (p = 0.02, HR = 2.69) and confirmed TCGA observations from the 200GS. Conclusions: Here we show, for the first time, that in addition to IT, high TMB predicts more favorable OS in patients that never received IT, potentially serving as a novel marker of prognosis of melanoma and likely other immunogenic tumors at early stages. In addition, our study suggests that TMB test can be robust when applied to only a small subset of genes that trigger significantly higher immunogenicity. This may also eventually assist with accurate sub-selection of early stage patients likely to respond to IT regimens