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MiR-146a Exerts Differential Effects on Melanoma Growth and Metastatization.

ABSTRACT: Malignant melanoma is the most aggressive form of skin cancer therefore it is crucial to disclose its underlying molecular mechanisms. MicroRNAs are small endogenous non-coding RNAs able to post-transcriptionally down-regulate the expression of direct target genes. Using a melanoma progression model, we identified miR-146a as a key double-acting player in melanoma malignancy. In fact, miR-146a is able to enhance tumor growth while it suppresses dissemination. We evidenced that melanoma cell growth is coordinated by its direct target lunatic fringe (LFNG) which operates on the NOTCH/PTEN/Akt pathway. Instead, metastasis formation inhibition is linked to decreased expression of ITGAV and ROCK1. Relevantly, miR-146a expression correlates with melanoma recurrence and it is enriched both in patients-derived melanoma and cutaneous metastasis samples, while its direct targets are depleted. However, miR-146a levels drop in Circulating Tumor Cells, suggesting the necessity for miR-146a expression to fluctuate during tumor progression in order to favor tumor growth and allow dissemination. This study reconciles the contradictory biological functions of miR-146a in melanoma progression and unravels distinct molecular mechanisms that need to be considered for therapeutic interventions.

ORGANISM(S): Homo sapiens

PROVIDER: GSE77090 | GEO | 2016/03/18

SECONDARY ACCESSION(S): PRJNA309420

REPOSITORIES: GEO

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miR-146a promotes the initiation and progression of melanoma by activating Notch signaling

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.

2014-02-18 | E-GEOD-39294 | biostudies-arrayexpress

miR-146a promotes the initiation and progression of melanoma by activating Notch signaling

2014-02-18 | GSE39983 | GEO

miR-146a promotes the initiation and progression of melanoma by activating Notch signaling

2014-02-18 | GSE39294 | GEO

miR-146a promotes the initiation and progression of melanoma by activating Notch signaling

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.

2014-02-18 | E-GEOD-39983 | biostudies-arrayexpress

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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.

2019-02-09 | PXD011413 | Pride

Inhibition of extracellular vesicle-derived miR-146a-5p decreases the progression of melanoma brain metastasis in vitro and in vivo

Project description:Development of melanoma brain metastasis is caused by an interaction between tumor cells and normal cells in the brain microenvironment. miRNAs delivered by exosomes derived from the tumor cells seem to prime the brain microenvironment, prior to extravasation of tumor cells into the brain. We investigated miRNA in exosomes extracted from normal (astrocytes, melanocytes) and metastatic melanoma cells (brain, skin and lymph node metastasis). We have discovered that miR-146a-5p is an important player in brain metastatic development: this miRNA was highly upregulated in exosomes from melanoma brain metastasis cells, compared to normal cells.

2023-09-29 | E-MTAB-11798 | biostudies-arrayexpress

Homo sapiens

Project description:miR-146a Exerts Differential Effects on Melanoma Growth and Metastatization.

| PRJNA309420 | ENA

Over-expression of miR-146a in basal-like breast cancer cells confers enhanced tumorigenic potential in association with altered p53 status

Project description:The tumor suppressor p53 is the most frequently mutated gene in human cancers, mutated in 25-30% of breast cancers. However, mutation rates differ according to breast cancer subtype, being more prevalent in aggressive estrogen receptor (ER) negative tumors, basal-like and HER2 amplified subtypes. This heterogeneity suggests that p53 may function differently across breast cancer subtypes. We used RNAi-mediated p53 knockdown (KD) and antagomir-mediated KD of microRNAs to study how gene expression and cellular response to p53 loss differ in luminal vs. basal-like breast cancer. As expected, p53 loss caused down regulation of established p53 targets (e.g. p21 and miR-34 family) and increased proliferation in both luminal and basal-like cell lines. However, some p53-dependent changes were subtype-specific, including expression of miR-134, miR-146a, and miR-181b. To study the cellular response to miR-146a upregulation in p53-impaired basal-like lines, antagomir knockdown of miR-146a was performed. KD of miR-146a caused decreased proliferation and increased apoptosis, effectively ablating the effects of p53 loss. Furthermore, we found that miR-146a upregulation decreased NF-kB expression and downregulated the NF-kB-dependent extrinsic apoptotic pathway (including TNF, FADD, and TRADD) and antagomir-mediated miR-146a KD restored expression of these components, suggesting a plausible mechanism for miR-146a-dependent cellular responses. These findings are relevant to human basal-like tumor progression in vivo, since miR-146a is highly expressed in p53-mutant basal-like breast cancers. These findings suggest that targeting miR-146a expression may have value for altering the aggressiveness of p53 mutant basal-like tumors. reference x sample

2014-06-30 | E-GEOD-52783 | biostudies-arrayexpress

MicroRNA-146a modulates B-cell oncogenesis by regulating EGR1

Project description:miR-146a is a NF-κB induced microRNA that serves as a feedback regulator of this critical pathway. In mice, deficiency of miR-146a results in hematolymphoid cancer at advanced ages as a consequence of constitutive NF-κB activity. In this study, we queried whether the deficiency of miR-146a contributes to B-cell oncogenesis. Combining miR-146a deficiency with transgenic expression of c-Myc led to the development of highly aggressive B-cell malignancies. Mice transgenic for c-Myc and deficient for miR-146a were characterized by significantly shortened survival, increased lymph node involvement, differential involvement of the spleen and a mature B-cell phenotype. High-throughput sequencing of the tumors revealed significant dysregulation of approximately 250 genes. Amongst these, the transcription factor Egr1 was consistently upregulated in mice deficient for miR-146a. Interestingly, transcriptional targets of Egr1 were enriched in both the high-throughput dataset and in a larger set of miR-146a-deficient tumors. miR-146a overexpression led to downregulation of Egr1 and downstream targets with concomitant decrease in cell growth. Direct targeting of the human EGR1 by miR-146a was seen by luciferase assay. Together our findings illuminate a bona fide role for miR-146a in the modulation of B-cell oncogenesis and reveal the importance of understanding microRNA function in a cell- and disease-specific context.

2016-03-20 | GSE67113 | GEO

Role of miR-146a in colon cancer cells

Project description:miRNAs exert various biological functions by targeting different cellular targets. Studying miR-146a functions in colon cancer cells helps to understand colorectal cancer (CRC) malignancy and progression. HT29 miR-146a-expressing cells and empty control cells were established for mining the gene expression profiles upon miR-146a expression.

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