MiR-377 targets E2F3 and alters the NF-kB signaling pathway through MAP3K7 in malignant melanoma.

BACKGROUND: The incidence of cutaneous malignant melanoma continues to rise, and once the disease metastasizes it is almost inevitably fatal. We recently reported that a large miRNAs cluster on human chromosome 14q32, implicated in many types of cancers, is significantly down-regulated in melanoma. miR-377, one of the miRNAs located within this cluster, was studied here. METHODS: qRT-pCR was used to quantify miR-377 levels in melanoma cell lines and samples. Melanoma cell lines ectopically expressing miR-377 were generated by stable transfection, mRNA expression was assessed using mRNA arrays and protein expression was assessed by Western blot analysis. Potential targets of miR-377 were identified through luciferase reporter assays. Cellular proliferation, migration and soft-agar colony formation were monitored in control and miR-377-expressing cells using cell biology techniques. RESULTS: miR-377 is expressed in normal melanocytes but not in melanoma cell lines or samples. Its ectopic stable expression in melanoma cell lines decreased their proliferative and migratory capacity and their colony-forming capability. mRNA arrays of melanoma cells over-expressing miR-377 pointed to several down-regulated mRNAs that have putative binding sites for miR-377 in their 3'UTR, of which both E2F3 and MAP3K7 were found to be direct targets of miR-377. E2F3, a potent transcriptional inducer of cell-cycle progression, was found to be elevated in melanoma cell lines, but decreased following ectopic expression of miR-377. Ectopic miR-377 also led to a decrease in the activity of a reporter plasmid containing three E2F DNA-binding sites linked to a luciferase cDNA sequence, demonstrating that miR-377 down-regulates E2F3-induced transcription. MAP3K7 (known as TAK1), a serine/threonine kinase along the MAPK signaling pathway, was over-expressed in melanoma but decreased following ectopic expression of miR-377. MAP3K7 is involved in the activation of NF-κB. MiR-377 over-expression led to decreased activity of a reporter plasmid containing two NF-κB DNA-binding sites and to decreased output along the NF-kB signaling pathway. CONCLUSION: Our results suggest that miR-377 is an important negative regulator of E2F and MAP3K7/NF-kB signaling pathway in melanoma cells; it is tempting to speculate that its silencing in melanoma promotes the tumorigenic and metastatic potential of the cells through activation of these pathways.

Virtual Patient Simulation Offers an Objective Assessment of CME Activity by Improving Clinical Knowledge and the Levels of Competency of Healthcare Providers.

The main goal of continuing medical education (CME) is to help healthcare providers (HCP) improve their knowledge and levels of competency with an ultimate enhancement of their performance in practice. Despite the long and well-intentional history of CME, the proof of success (based on improved clinical outcomes) is difficult to obtain objectively. In the past several years, the traditional CME world has been disrupted by replacing multiple-choice questions with virtual simulation. We utilised an innovative, next-generation virtual patient simulation (VPS) platform to develop objective measures to assess the success of educational activities that can be applied to the CME. This VPS platform was used at five distinct educational events designed to assess learners' knowledge and competency in the guideline-driven management of Type 2 diabetes, hyperlipidaemia, and hypertension. A total of 432 learners (medical doctors, nurse practitioners, and clinical pharmacists) participated in these educational events of whom 149 went through two consecutive cases with a similar clinical picture and educational goals. Their ability to achieve glycaemic, lipid, and blood pressure control improved significantly as they moved from the first to the second case. The participants improved their test performance in all categories - between 5 and 38%, achieving statistically significant increases in the many goals examined. In conclusion, this study employed the pioneering application of technology to produce, collect and analyse the VPS data to evaluate objectively educational activities. This VPS platform allows not only an objective assessment of the effectiveness of the CME activity but also provides timely and helpful feedback to both learners and providers of a given educational event.

Silencing of a large microRNA cluster on human chromosome 14q32 in melanoma: biological effects of mir-376a and mir-376c on insulin growth factor 1 receptor.

BACKGROUND: Metastatic melanoma is a devastating disease with limited therapeutic options. MicroRNAs (miRNAs) are small non coding RNA molecules with important roles in post-transcriptional gene expression regulation, whose aberrant expression has been implicated in cancer. RESULTS: We show that the expression of miRNAs from a large cluster on human chromosome 14q32 is significantly down-regulated in melanoma cell lines, benign nevi and melanoma samples relative to normal melanocytes. This miRNA cluster resides within a parentally imprinted chromosomal region known to be important in development and differentiation. In some melanoma cell lines, a chromosomal deletion or loss-of-heterozygosity was observed in the cis-acting regulatory region of this cluster. In several cell lines we were able to re-express two maternally-induced genes and several miRNAs from the cluster with a combination of de-methylating agents and histone de-acetylase inhibitors, suggesting that epigenetic modifications take part in their silencing. Stable over-expression of mir-376a and mir-376c, two miRNAs from this cluster that could be re-expressed following epigenetic manipulation, led to modest growth retardation and to a significant decrease in migration in-vitro. Bioinformatic analysis predicted that both miRNAs could potentially target the 3'UTR of IGF1R. Indeed, stable expression of mir-376a and mir-376c in melanoma cells led to a decrease in IGF1R mRNA and protein, and a luciferase reporter assay indicated that the 3'UTR of IGF1R is a target of both mir-376a and mir-376c. CONCLUSIONS: Our work is the first to show that the large miRNA cluster on chromosome 14q32 is silenced in melanoma. Our results suggest that down-regulation of mir-376a and mir-376c may contribute to IGF1R over-expression and to aberrant negative regulation of this signaling pathway in melanoma, thus promoting tumorigenesis and metastasis.