Melanoma is notorious for its propensity to metastasize, which makes treatment extremely difficult.,Receptor tyrosine kinase c-Met is activated in human melanoma and is involved in melanoma progression and metastasis.,Hepatocyte growth factor (HGF)-mediated activation of c-Met signaling has been suggested as a therapeutic target for melanoma metastasis.,Quercetin is a dietary flavonoid that exerts anti-metastatic effect in various types of cancer including melanoma.,In a previous report, we demonstrated that quercetin inhibited melanoma cell migration and invasion in vitro, and prevented melanoma cell lung metastasis in vivo.,In this study, we sought to determine the involvement of HGF/c-Met signaling in the anti-metastatic action of quercetin in melanoma.,Transwell chamber assay was conducted to determine the cell migratory and invasive abilities.,Western blotting was performed to determine the expression levels and activities of c-Met and its downstream molecules.,And immunoblotting was performed in BS3 cross-linked cells to examine the homo-dimerization of c-Met.,Quantitative real-time PCR analysis was carried out to evaluate the mRNA expression level of HGF.,Transient transfection was used to overexpress PAK or FAK in cell models.,Student’s t-test was used in analyzing differences between two groups.,Quercetin dose-dependently suppressed HGF-stimulated melanoma cell migration and invasion.,Further study indicated that quercetin inhibited c-Met phosphorylation, reduced c-Met homo-dimerization and decreased c-Met protein expression.,The effect of quercetin on c-Met expression was associated with a reduced expression of fatty acid synthase.,In addition, quercetin suppressed the phosphorylation of c-Met downstream molecules including Gab1 (GRB2-associated-binding protein 1), FAK (Focal Adhesion Kinase) and PAK (p21-activated kinases).,More importantly, overexpression of FAK or PAK significantly reduced the inhibitory effect of quercetin on the migration of the melanoma cells.,Our findings suggest that suppression of the HGF/c-Met signaling pathway contributes to the anti-metastatic action of quercetin in melanoma.,The online version of this article (doi:10.1186/s12943-015-0367-4) contains supplementary material, which is available to authorized users.
Aberrations of protein-coding genes are a focus of cancer genomics; however, the impact of oncogenes on expression of the ∼50% of transcripts without protein-coding potential, including long noncoding RNAs (lncRNAs), has been largely uncharacterized.,Activating mutations in the BRAF oncogene are present in >70% of melanomas, 90% of which produce active mutant BRAFV600E protein.,To define the impacts of oncogenic BRAF on the melanocyte transcriptome, massively parallel cDNA sequencing (RNA-seq) was performed on genetically matched normal human melanocytes with and without BRAFV600E expression.,To enhance potential disease relevance by verifying expression of altered genes in BRAF-driven cancer tissue, parallel RNA-seq was also undertaken of two BRAFV600E-mutant human melanomas.,BRAFV600E regulated expression of 1027 protein-coding transcripts and 39 annotated lncRNAs, as well as 70 unannotated, potentially novel, intergenic transcripts.,These transcripts display both tissue-specific and multi-tissue expression profiles and harbor distinctive regulatory chromatin marks and transcription factor binding sites indicative of active transcription.,Coding potential analysis of the 70 unannotated transcripts suggested that most may represent newly identified lncRNAs.,BRAF-regulated lncRNA 1 (BANCR) was identified as a recurrently overexpressed, previously unannotated 693-bp transcript on chromosome 9 with a potential functional role in melanoma cell migration.,BANCR knockdown reduced melanoma cell migration, and this could be rescued by the chemokine CXCL11.,Combining RNA-seq of oncogene-expressing normal cells with RNA-seq of their corresponding human cancers may represent a useful approach to discover new oncogene-regulated RNA transcripts of potential clinical relevance in cancer.