Unknown,Transcriptomics,Genomics,Proteomics

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Metabolic reprogramming of triple-negative breast cancer and melanoma cell lines by the Let-7a microRNA

ABSTRACT: Let-7 microRNAs (miRNAs) are a family of highly conserved well-established promoters of terminal differentiation that are expressed in all healthy adult tissues and frequently repressed in cancer cells. The tumour suppressive role of let-7 in a variety of cancers in vitro and in vivo has been widely documented and prompted these miRNAs to be candidate genes for miRNA replacement therapy. Reprogrammed metabolism, recently identified as a new hallmark of cancer, contributes to cancer cell growth, proliferation, invasiveness and drug resistance. In this study we identified a new metabolic role of let-7a in triple-negative breast cancer and metastatic melanoma cell lines. We show that let-7a down-regulates key anabolic enzymes, promotes oxidative phosphorylation and mitochondrial ROS formation accompanied by the up-regulation of the oxidative stress responsive genes. To assess if we could exploit these increased ROS levels for therapeutic purposes, we combined let-7a transfection with the antitumor drug doxorubicin. In both cancer types we observed a stronger response to the doxorubicin treatment in let-7a transfected cells. Pre-treatment with an antioxidant N-acetyl cysteine totally abolished this difference, indicating that the increased doxorubicin sensitivity of let-7a cells depends on the redox pathway. We demonstrated that let-7a plays a prominent role in regulating energy metabolism in cancer cells. We propose that a benefit from let-7 miRNA replacement therapy could come not only from the repression of oncogenic pathways targeted directly by let-7, but also by increased sensitivity to chemotherapeutic agents through indirect metabolic changes caused by let-7. Investigation of let-7a metabolic role in breast cancer and melanoma cells.

ORGANISM(S): Homo sapiens

SUBMITTER: Leonardo Meza-Zepeda

PROVIDER: E-GEOD-60326 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Epigenetic modifications, particularly DNA methylation have been increasingly implicated in cancer. Although some genes display aberrant methylation in pancreatic cancer, a comprehensive global analysis is yet to be performed. To define the genome-wide pattern of DNA methylation in pancreatic ductal adenocarcinomas (PDAC), the methylation profile of 156 PDAC and 23 non-malignant pancreas was captured using high-density arrays. More than 90,000 CpG sites were significantly differentially methylated (DM) in PDAC relative to non-malignant pancreas, with pronounced alterations in a sub-set of 13,517 CpG sites. This sub-set of differentially methylated CpG sites segregated PDAC from non-malignant pancreas, regardless of tumour cellularity. As expected, PDAC hyper-methylation was most prevalent in the 5’ region of genes (including the proximal promoter, 5’UTR and CpG islands). From 3981 genes aberrantly methylated, approximately 36% showed significant correlation between methylation and mRNA expression levels. Pathway analysis revealed an enrichment of aberrant methylation in genes involved in key molecular mechanisms important to PDAC: TGF-β, WNT, Integrin signaling, Cell adhesion, Stellate cell activation and Axon guidance. Bisulfite amplicon deep sequencing and qRT-PCR expression analyses of axon guidance pathway genes SLIT2, SLIT3, ROBO1, ROBO3, SRGAP1, and MET suggested epigenetic suppression of SLIT-ROBO signaling and up-regulation of MET expression. Hypo-methylation of MET and ITGA2 correlated with high gene expression, which correlated with poor survival of PDAC patients. These data suggest that aberrant methylation plays an important role in pancreatic carcinogenesis affecting known core signaling pathways with important implications for disease pathophysiology and therapy. This dataset includes gene expression data from 103 primary tumour samples. 86 samples from this dataset have already been deposited into GEO (GSE36924), and has been duplicated here since the data has been processed differently. This data is also available through the International Cancer Genome Consortium (ICGC) Data Portal (http://dcc/icgc.org), under the project code: Pancreatic Cancer (QCMG, AU). Access to the restricted clinical data must be made through the ICGC Data Access Compliance Office (http://www.icgc.org/daco). This dataset contains gene expression array data from 103 primary pancreatic ductal adenocarcinoma samples. All samples have 1 biological replicate. These data have corresponding methylation 450K array data (GSE49149).

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Metabolic reprogramming of triple-negative breast cancer and melanoma cell lines by the Let-7a microRNA

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