The highly aggressive character of melanoma makes it an excellent model for probing the mechanisms underlying metastasis, which remains one of the most difficult challenges in treating cancer. We find that miR-182, member of a miRNA cluster in a chromosomal locus (7q31-34) frequently amplified in melanoma, is commonly upregulated in human melanoma cell lines and tissue samples; this up-regulation correlates with gene copy number in a subset of melanoma cell lines. Moreover, miR-182 ectopic expression stimulates migration of melanoma cells in vitro and their metastatic potential in vivo, whereas miR-182 down-regulation impedes invasion and triggers apoptosis. We further show that miR-182 over-expression promotes migration and survival by directly repressing microphthalmiaassociated transcription factor-M and FOXO3, whereas enhanced expression of either microphthalmia-associated transcription factor-M or FOXO3 blocks miR-182's proinvasive effects. In human tissues, expression of miR-182 increases with progression from primary to metastatic melanoma and inversely correlates with FOXO3 and microphthalmia-associated transcription factor levels. Our data provide a mechanism for invasion and survival in melanoma that could prove applicable to metastasis of other cancers and suggest that miRNA silencing may be a worthwhile therapeutic strategy.microRNA ͉ cancer ͉ invasion M etastasis is a central problem in cancer, yet the mechanisms underlying a cell's ability to extravasate from the primary tumor, circulate, and invade new tissue remain poorly understood. We reasoned that melanoma, one of the most notoriously invasive neoplasia, would provide an excellent model for investigating the alterations that contribute to metastasis. Melanomas are characterized by certain well-defined genetic alterations (reviewed in ref. 1) as well as frequent chromosomal aberrations associated with tumor progression (2). Recent work has also shown that melanomas display genomic alterations involving numerous microRNA genes (3). MicroRNAs (miRNAs) are endogenous noncoding small RNAs that interfere with the translation of coding messenger RNAs (mRNAs) in a sequence-specific manner (4), often to regulate processes involved in development or tissue homeostasis (5-7). Intriguingly, dysregulation of miRNAs has been found to contribute to neoplasia (8). We decided to investigate the possible contributions of miRNA dysregulation to melanoma extravasation, migration, and invasion.We compared the expression of miRNAs in a large cohort of melanoma cell lines with that of normal melanocytes. We found that miR-182, flanked by the c-MET and BRAF oncogenes in the 7q31-34 region that is frequently amplified in melanoma (9, 10), is highly expressed in metastatic melanoma cell lines and tumors, often in association with increased copy number. Moreover, we demonstrate that antisense-mediated repression of miR-182 inhibited invasion and induced melanoma cell death, whereas ectopic miR-182 up-regulation enhanced the oncogenic activity of melanoma cells in vitro ...

Purpose To identify a melanoma miRNA expression signature that is predictive of outcome and then evaluate its potential to improve risk stratification when added to the standard of care staging criteria. Experimental design Total RNA was extracted from 59 formalin-fixed paraffin embedded (FFPE) melanoma metastases and hybridized to miRNA arrays containing 911 probes. We then correlated miRNA expression with post-recurrence survival and other clinicopathological criteria. Results We identified a signature of 18 miRNAs whose overexpression was significantly correlated with longer survival, defined as more than 18 months post-recurrence survival. Subsequent cross-validation showed that a small subset of these miRNAs can predict post-recurrence survival in metastatic melanoma with an estimated accuracy of 80.2% [95% CI: 79.8%, 80.6%]. In contrast to standard of care staging criteria, this six-miRNA signature significantly stratified stage III patients into “better” and “worse” prognostic categories, and a multivariate Cox regression analysis revealed the signature to be an independent predictor of survival. Furthermore, we demonstrated that most miRNAs from the signature also showed differential expression between patients with “better” and “worse prognosis” in the corresponding paired primary melanoma. Conclusion MiRNA signatures have potential as clinically relevant biomarkers of prognosis in metastatic melanoma. Our data suggest that molecularly-based models of risk assessment can improve the standard staging criteria and support the incorporation of miRNAs into such models.

BACKGROUND: Melanoma patients who develop brain metastases (B-Met) have limited survival and are excluded from most clinical trials. In the current study, the authors attempted to identify primary tumor characteristics and clinical features predictive of B-Met development and post-B-Met survival. METHODS: A prospectively accrued cohort of 900 melanoma patients was studied to identify clinicopathologic features of primary melanoma (eg, thickness, ulceration, mitotic index, and lymphovascular invasion) that are predictive of B-Met development and survival after a diagnosis of B-Met. Associations between clinical variables present at the time of B-Met diagnosis (eg, extracranial metastases, B-Met location, and the presence of neurological symptoms) and post-B-Met survival were also assessed. Univariate associations were analyzed using Kaplan-Meier survival analysis, and the effect of independent predictors was assessed using multivariate Cox proportional hazards regression analysis. RESULTS: Of the 900 melanoma patients studied, 89 (10%) developed B-Met. Ulceration and site of the primary tumor on the head and neck were found to be independent predictors of B-Met development on multivariate analysis (P ¼ .001 and P ¼ .003, respectively). Clinical variables found to be predictive of post-B-Met survival on multivariate analysis included the presence of neurological symptoms (P ¼ .008) and extracranial metastases (P ¼ .04). Ulceration was the only primary tumor characteristic that remained a significant predictor of post-B-Met survival on multivariate analysis (P ¼ .04). CONCLUSIONS: Primary tumor ulceration was found to be the strongest predictor of B-Met development and remained an independent predictor of decreased post-B-Met survival in a multivariate analysis inclusive of primary tumor characteristics and clinical variables. The results of the current study suggest that patients with ulcerated primary tumors should be prospectively studied to determine whether heightened surveillance for B-Met can improve clinical outcome.

Background Despite the lack of an established survival benefit of sentinel lymph node (SLN) biopsy, this technique has been increasingly applied in the staging of thin (≤1 mm) melanoma patients, without clear evidence to support this recommendation. We performed a meta-analysis to estimate the risk, potential predictors, and outcome of SLN positivity in this group of patients. Methods MEDLINE, EMBASE, and Cochrane databases were searched for rates of SLN positivity in patients with thin melanoma. The methodological quality of included studies was assessed using the MINORS criteria. Heterogeneity was assessed using Cochran’s Q-statistic, and publication bias was examined through funnel plot and Begg and Mazumdar’s method. Overall SLN positivity in thin melanoma patients was estimated using DerSimonial-Laird random effect method. Results 34 studies comprising 3,651 patients met inclusion criteria. The pooled SLN positivity rate was 5.6%. Significant heterogeneity among studies was detected (p=0.005). There was no statistical evidence of publication bias (p=0.21). 18 studies reported select clinical and histopathologic data limited to SLN positive patients (n=113). Among the tumors from these patients, 6.1% were ulcerated, 31.5% showed regression, and 47.5% were Clark’s level IV/V. Only 4 melanoma-related deaths were reported. Conclusion Relatively few patients with thin melanoma have a positive SLN. There are no clinical or histopathologic criteria which can reliably identify thin melanoma patients who might benefit from this intervention. Given the increasing diagnosis of thin melanoma, in addition to the cost and potential morbidity of this procedure, alternative strategies to identify patients at risk for nodal disease are needed.