br Materials and Methods br Results br Discussion In sum

Materials and Methods
Results
Discussion In sum, we found that a ‘melanoma-related’ panel of miRNAs was expressed in metastatic melanoma in a stage-specific manner and, together with the tissue pathology and nodal status, was prognostic for recurrence and OS. These markers may therefore also be useful to support histopathologic diagnosis of metastatic deposits suspected of being melanoma. We further observed that Prostaglandin E2 of the various miRNAs from the MELmiR-17 panel in stage IV tissues was often lower than in stage III tissue, which is in keeping with previous studies. For example, miR-211 expression is commonly lost in subsets of melanoma cell lines (Stark et al., 2015; Boyle et al., 2011), and miR-506, a member of the miR-506–514 cluster, has been shown to be lost during metastatic colonisation despite being up-regulated in early melanoma progression (Streicher et al., 2012; Mueller et al., 2009). We have also recently reported that inhibition of miR-514a leads to increased cell proliferation (Stark et al., 2015). These data indicate that expression of this cluster reduces during melanoma progression. Currently there is an unmet need for a minimally invasive, highly specific, and predictive serum biomarker of melanoma burden. For many years the use of the seroprotein markers S100B and LDH has been disputed, due to reported inconsistencies in sensitivity and specificity (Brochez and Naeyaert, 2000; Finck et al., 1983; Karakousis et al., 1996; Sirott et al., 1993; Weide et al., 2012; Guo et al., 1995; Smit et al., 2005; Kruijff et al., 2009). Despite this lack of consensus, a recent study did find that elevated levels of S100B were prognostic of survival times in patients with unresectable melanoma (Weide et al., 2013). Here, we present data that shows that our ‘MELmiR-7’ panel has the potential to be used as a primary screening tool for clinically undetected metastatic melanoma due to its high sensitivity (93%) and specificity (≥82%). However, detection of early melanoma lesions (in situ and stages I/II melanoma) is currently being adequately achieved (as evident by high survival rates) via clinical strategies. The ‘MELmiR-7’ panel could be utilised during routine follow-up (i.e., post-primary excision of melanoma and later in advanced disease) of melanoma patients. In comparison with serum LDH and S100B, expression levels of the ‘MELmiR-7’ panel performed better than both markers in predicting overall survival. We have shown that the ‘MELmiR-7’ panel was measurable at time of progression in 100% of stage IV melanoma patients. These data suggest that this panel would therefore be suited to monitor tumour burden. According to the AJCC Staging committee, stage III melanoma patients have a 50% chance of survival beyond 5years (Balch et al., 2009); these patients also remain the most difficult for whom to provide effective treatments/surveillance regimens and accurate survival estimates. Following treatment, stage III patients are subjected to a series of physical examinations, scans and serology at regular intervals. The frequency of these tests is deemed necessary for early detection of recurrence; however this causes a burden to both the patient and the healthcare system. It is important to note that these guidelines are not universally accepted and differ from centre to centre (Leiter et al., 2014). We foresee that the ‘MELmiR-7’ panel could be offered to patients to complement physical examination. If the diagnostic score for melanoma positivity has changed from earlier measurements, then this may indicate the presence of disease recurrence and as such, these patients may qualify earlier for adjuvant, systemic, or targeted therapies that would otherwise be only offered to stage IV patients. As previously discussed, due to the panel\'s high sensitivity and specificity, the use of this miRNA panel in this manner has the potential to increase the chances of survival, by earlier and more precise detection of the presence of metastases.