TY  - GEN
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/13147/
ID  - heidok13147
KW  - microRNA 
KW  -  melanoma 
KW  -  aggressiveness 
KW  -  invasion 
KW  -  miR-101 
KW  -  miR-137
N2  - Malignant melanoma is the most severe form of skin cancer being refractory to current therapies at advanced stages (stage III and IV). The survival of individual patients can vary from months to years, but the molecular mechanism behind this broad survival time range is unknown so far. Many signaling pathways have been found to be important in melanoma and recently microRNAs (miRNAs) have emerged to be essential regulators in these pathways. This study aimed at the identification of miRNAs accounting for the aggressiveness of melanoma. Using bead-based microarray analyses, we performed miRNA expression profiling on a panel of melanoma cell lines derived from metastatic melanoma patients with either long or short survival times. Upon comparison of these two patient groups a number of differentially expressed miRNAs could be identified. However, subsequent real-time quantitative PCR (qPCR) revealed that only one candidate miRNA (miR-101) was confirmed to be down-regulated in cell lines from short term survivors, compared to long term survivors. We found that miR-101 could directly target microphthalmia-associated transcription factor (MITF) in melanoma cells, leading to a decrease in intracellular MITF protein expression. One of the predicted target sites for miR-101 in the 3? UTR of MITF was confirmed by luciferase reporter assay. Furthermore, we show that the expression of ?enhancer of zeste homolog 2? (EZH2), previously reported as miR-101 target in other types of cancer, was down-regulated by miR-101 also in melanoma. Overexpression of miR-101 inhibited proliferation, invasion and migration of melanoma cells, which could be phenocopied by siRNA-mediated knockdown of MITF or EZH2 using specific siRNA. miR-137 was reported to act as a tumor suppressor in different cancer entities including melanoma. In this study, we showed that low miR-137 expression correlated with poor survival of stage IV melanoma patients. We identified three novel targets (proto-oncogene c-Met, Y box binding protein 1 [YB1] and the ATP-binding cassette, sub-family B, member 5 [ABCB5]) and confirmed two previously reported targets (MITF and EZH2) for miR-137. Overexpression of miR-137 suppressed invasion of melanoma cells, which could be phenocopied by siRNA-mediated knockdown of the miR-137 targets c-Met, YB1, MITF and EZH2. Furthermore, miR-137 inhibited melanoma cell migration and proliferation likely through the down-regulation of certain proteins (e.g. YB1 and EZH2) whose individual impact on these processes varied among the two cell lines tested. Finally, miR-137 induced apoptosis in melanoma cell lines and decreased B-cell lymphoma 2 (BCL2) protein expression levels. In conclusion, our study suggests that miR-101 and miR-137 can function as tumor suppressors in melanoma. We show that overexpression of these miRNAs could lower the aggressiveness of melanoma cells by regulation of multiple signaling pathways, offering new options for targeted therapy against melanoma.
A1  - Luo, Chonglin
AV  - public
TI  - MicroRNAs involved in the aggressiveness of malignant melanoma
Y1  - 2012///
ER  -