Project description:Oncogenic mutations in BRAF and NRAS occur in 70% of melanomas. Here we identify a microRNA, miR-146a, that is highly upregulated by oncogenic BRAF and NRAS. Expression of miR-146a increases the ability of human melanoma cells to proliferate in culture and form tumors in mice, whereas knockdown of miR-146a has the opposite effects. We show these oncogenic activities are due to miR-146a targeting the NUMB mRNA, a repressor of Notch signaling. Previous studies have shown that pre-miR-146a contains a single nucleotide polymorphism (C>G rs2910164). We find that the ability of pre-miR-146a/G to activate Notch signaling and promote oncogenesis is substantially higher than that of pre-miR-146a/C. Analysis of melanoma cell lines and matched patient samples indicates that during melanoma progression pre-miR-146a/G is enriched relative to pre-miR-146a/C, resulting from a C-to-G somatic mutation in pre-miR-146a/C. Collectively, our results reveal a central role for miR-146a in the initiation and progression of melanoma.
Project description:Oncogenic mutations in BRAF and NRAS occur in 70% of melanomas. Here we identify a microRNA, miR-146a, that is highly upregulated by oncogenic BRAF and NRAS. Expression of miR-146a increases the ability of human melanoma cells to proliferate in culture and form tumors in mice, whereas knockdown of miR-146a has the opposite effects. We show these oncogenic activities are due to miR-146a targeting the NUMB mRNA, a repressor of Notch signaling. Previous studies have shown that pre-miR-146a contains a single nucleotide polymorphism (C>G rs2910164). We find that the ability of pre-miR-146a/G to activate Notch signaling and promote oncogenesis is substantially higher than that of pre-miR-146a/C. Analysis of melanoma cell lines and matched patient samples indicates that during melanoma progression pre-miR-146a/G is enriched relative to pre-miR-146a/C, resulting from a C-to-G somatic mutation in pre-miR-146a/C. Collectively, our results reveal a central role for miR-146a in the initiation and progression of melanoma.
Project description:Oncogenic mutations in BRAF and NRAS occur in 70% of melanomas. Here we identify a microRNA, miR-146a, that is highly upregulated by oncogenic BRAF and NRAS. Expression of miR-146a increases the ability of human melanoma cells to proliferate in culture and form tumors in mice, whereas knockdown of miR-146a has the opposite effects. We show these oncogenic activities are due to miR-146a targeting the NUMB mRNA, a repressor of Notch signaling. Previous studies have shown that pre-miR-146a contains a single nucleotide polymorphism (C>G rs2910164). We find that the ability of pre-miR-146a/G to activate Notch signaling and promote oncogenesis is substantially higher than that of pre-miR-146a/C. Analysis of melanoma cell lines and matched patient samples indicates that during melanoma progression pre-miR-146a/G is enriched relative to pre-miR-146a/C, resulting from a C-to-G somatic mutation in pre-miR-146a/C. Collectively, our results reveal a central role for miR-146a in the initiation and progression of melanoma. SKMEL28 melanoma cell line stably expressing either an empty vector or pre-miR146a with either C or G SNP (SKMEL28-FG12, SKMEL28-miR-146a/C and SKMEL28-miR-146a/G) were used to prepare total RNA. Microarray analysis was performed by using biological replicates for each stable cell lines for a total of 6 samples.
Project description:To find out potiential target gene of miR-146a,we have employed whole genome microarray expression profiling as a discovery platform to identify genes with the potential to target miR-146a. Human keratinocytes was transfected with either miR-146a mimics (Pre-146a) or negative control (Pre-NC) for 48h, then RNA was extracted for whole genome microarray expression profiling.
Project description:Oncogenic mutations in BRAF and NRAS occur in 70% of melanomas. Here we identify a microRNA, miR-146a, that is highly upregulated by oncogenic BRAF and NRAS. Expression of miR-146a increases the ability of human melanoma cells to proliferate in culture and form tumors in mice, whereas knockdown of miR-146a has the opposite effects. We show these oncogenic activities are due to miR-146a targeting the NUMB mRNA, a repressor of Notch signaling. Previous studies have shown that pre-miR-146a contains a single nucleotide polymorphism (C>G rs2910164). We find that the ability of pre-miR-146a/G to activate Notch signaling and promote oncogenesis is substantially higher than that of pre-miR-146a/C. Analysis of melanoma cell lines and matched patient samples indicates that during melanoma progression pre-miR-146a/G is enriched relative to pre-miR-146a/C, resulting from a C-to-G somatic mutation in pre-miR-146a/C. Collectively, our results reveal a central role for miR-146a in the initiation and progression of melanoma. WI-38 cells were either infected with BRAFV600E or Empty retroviral vectors and small RNA were prepared from these cells. As an additional control, WI-38 cells were serum starved and used to generate quiscent cells, which were also used to prepase small RNA. The small RNA were then used to generate small RNA library and were used on Illumina genome analyzer.
Project description:Human vein umbilical endothelial cells (HUVEC) were transfected with pre-miR control and pre-miR 146 (Ambion) in order to identify targets (direct and indirect) downregulated by miR-146a in endothelial cells. 164 transcripts were downregulated with a fold change ≥ 1.2. Total RNA was obtained from cells transfected in HUVEC with pre-miR control and pre-miR 146a. Three independent transfections were performed for each condition. 2 replicates for control re-control and 3 for pre-miR 146a were analyzed.
Project description:A long-prevailing model has held that the “seed” region (nucleotides 2-8) of a microRNA is typically sufficient to mediate target recognition and repression. However, numerous recent studies, both within the context of defining miRNA/target pairs by direct physical association and by directly assessing this model in vivo in C. elegans have brought this model into question. To test the importance of miRNA 3' pairing in vivo, in a mammalian system, we engineered a mutant murine mir-146a allele in which the 5' half of the mature microRNA retains the sequence of the wild-type mir-146a but the 3ʹ half has been altered to be anti-complementary to the wild-type miR-146a sequence. Mice homozygous or hemizygous for this mutant allele are phenotypically indistinguishable from wild-type controls and do not recapitulate any of the immunopathology previously described for mir-146a-null mice. Our results strongly support the conclusion that 3ʹ pairing is dispensable in the context of the function of a key mammalian microRNA.
Project description:MiR-146a is an important regulator of innate inflammatory responses and is also implicated in cell death and survival. Here, we identified microglia as the main cellular source of miR-146a among mouse CNS resident cells. We further characterized the phenotype of miR-146a KO microglia cells during in vivo demyelination induced by cuprizone (CPZ) and found reduced number of CD11c+ microglia in the KO compared to WT mice. Microglia were also isolated from the brain, and the proteome was analyzed by liquid chromatography mass spectrometry.