Faculty Bibliography

PURPOSE: High mobility group AT-hook 1 (HMGA1) is a non-histone nuclear binding protein that is developmentally regulated. HMGA1 is significantly overexpressed in and associated with high grade and advance stage of prostate cancer (PC). The oncogenic role of HMGA1 is at least mediated through chromosomal instability and structural aberrations. However, regulation of HMGA1 expression is not well understood. Identification of microRNA mediated HMGA1 regulation will provide a promising therapeutic target in treating PC. Experimental Designs: In this study, we examined the functional relation between miR-296 and HMGA1 expression in several prostate cancer cell lines and a large prostate cancer cohort. We further examined the oncogenic property of HMGA1 regulated by miR-296. RESULTS: Here we report that miR-296, a microRNA predicted to target HMGA1, specifically represses HMGA1 expression by promoting degradation and inhibiting HMGA1translation . Repression of HMGA1 by miR-296 is direct and sequence-specific. Importantly, ectopic miR-296 expression significantly reduced prostate cancer cell proliferation and invasion, in part through the down-regulation of HMGA1. Examining prostate cancer patient samples, we found an inverse correlation between HMGA1 and miR-296 expression: high levels of HMGA1 were associated with low miR-296 expression and strongly linked to more advanced tumor grade and stage. CONCLUSIONS: Our results indicate miR-296 regulates HMGA1 expression and is associated with PC growth and invasion

A case of metastatic balloon cell malignant melanoma (BCMM) is presented. The balloon melanoma cells (BMC) were absent in the shave biopsy of the primary lesion and present as a minor component in the wide and deep excision. A subsequent right neck lymph node metastasis showed complete replacement of the lymph node by large, foamy cells. Though the tumor was amelanocytic and Fontana-Masson stain failed to reveal melanin, it stained positively for S-100, HMB-45, and Melan-A. Ultrastructurally, the foamy cells were characterized by cytoplasmic vacuolization and a lack of melanosomes. The differential diagnosis of metastatic balloon cell malignant melanoma is broad, and clinicopathologic correlation may play a critical role in achieving the correct diagnosis

In this study, we investigated the mechanism(s) of altered expression of protooncogene SKP2 in metastatic melanoma and its clinical relevance in patients with metastatic melanoma. The genomic status of SKP2 was assessed in cell lines by sequencing, single nucleotide polymorphism array, and genomic PCR. Copy number status was then evaluated for concordance with SKP2 mRNA and protein expression. SKP2 protein was further evaluated by immunohistochemistry in 93 human metastatic tissues. No mutations were identified in SKP2. Increased copy number at the SKP2 locus was observed in 6/14 (43%) metastatic cell lines and in 9/22 (41%) human metastatic tissues which was associated with overexpression of SKP2 protein. Overexpression of SKP2 protein in human tissues was associated with worse survival in a multivariate model controlling for the site of metastasis. Copy number gain is a major contributing mechanism of SKP2 overexpression in metastatic melanoma. Results may have implications for the development of therapeutics that target SKP2

MicroRNAs are endogenous non-coding RNAs, proven to regulate biological functions, including tumor progression, by regulating specific target genes post-trancriptionally. Cancer is often a fatal disease in its metastatic stage, hence it is essential to unravel the molecular mechanisms that govern metastasis dissemination. Using a melanoma progression model, represented by a poorly aggressive parental cell line (A375P) and its highly metastatic variants, we identified a novel pathway controlled by miR-214 that coordinates metastatic capability. The genes comprised in the pathway are over 70 and include TFAP2C, homologue of a well-established melanoma tumor suppressor, the adhesion receptor ITGA3 and multiple surface molecules, such as ALCAM, CD9, ADAM9. Modulations of miR-214 significantly alter tumor cell migration, invasion and survival to anoikis, as well as extravasation from blood vessels and metastasis formation in mice. Considering that miR-214 is highly expressed in human melanomas, our data suggest a critical role for this small RNA in the establishment of distant metastases. We are now carrying on a detailed analysis of the molecular mechanisms used by miR-214 to control metastatic dissemination and results will be presented

Objective: Previous melanoma studies evaluating prognostic factors of survival at recurrence have focused on primary tumor characteristics and clinical variables at first recurrence. We examined the prognostic relevance of recurrent tumor proliferation. Methods: 114 melanoma patients with available recurrent tissues who were prospectively enrolled at New York University Medical Center were studied. Standard of care prognostic variables (e.g. stage at initial diagnosis and lactate dehydrogenase level) and recurrent tissue expression of proliferative marker Ki-67 were evaluated for their association with overall survival. Results: High Ki-67 expression was observed in 57 (50%) of the 114 recurrent melanomas. On univariate analysis, the median overall survival of patients whose recurrent tumors overexpressed Ki-67 was significantly shorter than that of patients whose recurrent tumors had low Ki-67 expression (3.6 vs. 9.5 years, p = 0.03). On multivariate analysis, a high proliferative index of the recurrent melanoma remained an independent predictor of worse overall survival, controlling for stage at initial diagnosis, disease-free survival, and stage at first recurrence [HR = 2.09 (95% CI 1.24-3.54), p = 0.006]. Conclusions: Our results demonstrate the prognostic relevance of tumor proliferation in recurrent melanoma patients. Data also support restratification of risk assessment upon recurrence that considers tumor biology in addition to clinical variables evaluated as part of the standard of care

Background: Although the current median survival time of stage-IV melanoma patients is less than 12 months, there is a subset of patients who experience long-term survival. Due to poor response rates to standard cytotoxic agents in metastatic melanoma, patients are encouraged to participate in clinical trials, the overall impact of which has not been studied, however. The aim of our study was to identify the factors associated with long-term survival and to determine the impact of clinical trial enrollment on patient outcome. Methods: We studied stage-IV melanoma patients prospectively enrolled at New York University Medical Center from 2002-2008. Associations between clinicopathologic variables and overall post-stage-IV survival were examined. Kaplan-Meier survival analysis was used to identify univariate predictors of post-stage-IV survival and the independent effect of these variables was assessed in a multivariate Cox proportional hazards regression model. The associations between clinicopathologic variables and long-term survival status (>/=2 vs. <2 years) were examined by chi(2) analysis and the independent effect of these variables on the latter was assessed in a multivariate logistic regression model. Results: Site of metastasis, treatment (systemic vs. localized) and pretreatment lactate dehydrogenase (LDH) level independently correlated with post-stage-IV survival. Participation in clinical trials and normal LDH levels were associated with a long-term survival of >/=2 years. Conclusion: Our data suggest that enrollment in clinical trials independently correlates with prolonged survival after a diagnosis of stage IV melanoma.

[This corrects the article on p. e25264 in vol. 6.]

Several reports have demonstrated a role for aberrant NOTCH signaling in melanoma genesis and progression, prompting us to explore if targeting this pathway is a valid therapeutic approach against melanoma. We targeted NOTCH signaling using RO4929097, a novel inhibitor of gamma secretase, which is a key component of the enzymatic complex that cleaves and activates NOTCH. The effects of RO4929097 on the oncogenic and stem cell properties of a panel of melanoma cell lines were tested both in vitro and in vivo, using xenograft models. In human primary melanoma cell lines, RO4929097 decreased the levels of NOTCH transcriptional target HES1. This was accompanied by reduced proliferation and impaired ability to form colonies in soft agar and to organize in tridimensional spheres. Moreover, RO4929097 affected the growth of human primary melanoma xenograft in NOD/SCID/IL2gammaR-/- mice and inhibited subsequent tumor formation in a serial xenotransplantation model, suggesting that inhibition of NOTCH signaling suppresses the tumor initiating potential of melanoma cells. In addition, RO4929097 decreased tumor volume and blocked the invasive growth pattern of metastatic melanoma cell lines in vivo. Finally, increased gene expression of NOTCH signaling components correlated with shorter post recurrence survival in metastatic melanoma cases. Our data support NOTCH inhibition as a promising therapeutic strategy against melanoma