Project description:Since the early 1980s remarkable progress has been made in understanding the role of the HER2 locus in carcinogenesis, but many details of its regulatory network are still elusive. We recently reported the finding of 367 new human microRNA (miRNA) genes of which one, mir-4728, is encoded in an intron of the HER2 gene. Here, we confirm that the HER2 oncogene is a bi-functional locus encoding the membrane receptor and a functional miRNA gene. We further show that miR-4728-3p has alternative functionalities depending on the region used for interaction with its target; the canonical seed between nucleotides 2-8 or a novel, more internal seed shifted to nucleotides 6-12. Analysis of public data shows that this internal seed region, although rare compared to the far more abundant canonical 2-8 seed interaction, can also direct targeted down-regulation by other miRNAs. Through the internal seed, miR-4728-3p regulates expression of estrogen receptor alpha, an interaction that would have remained undetected if classic rules for miRNA-target interaction had been applied. In summary, we present here an alternative mode of miRNA regulation and demonstrate this dual function of the HER2 locus, linking the two major biomarkers in breast cancer. 6 samples treated with hsa-miR-4728-3p mimic and 6 samples treated with non-targeting control 4 samples treated with hsa-miR-1-3p mimic and 4 samples treated with non-targeting control
Project description:Since the early 1980s remarkable progress has been made in understanding the role of the HER2 locus in carcinogenesis, but many details of its regulatory network are still elusive. We recently reported the finding of 367 new human microRNA (miRNA) genes of which one, mir-4728, is encoded in an intron of the HER2 gene. Here, we confirm that the HER2 oncogene is a bi-functional locus encoding the membrane receptor and a functional miRNA gene. We further show that miR-4728-3p has alternative functionalities depending on the region used for interaction with its target; the canonical seed between nucleotides 2-8 or a novel, more internal seed shifted to nucleotides 6-12. Analysis of public data shows that this internal seed region, although rare compared to the far more abundant canonical 2-8 seed interaction, can also direct targeted down-regulation by other miRNAs. Through the internal seed, miR-4728-3p regulates expression of estrogen receptor alpha, an interaction that would have remained undetected if classic rules for miRNA-target interaction had been applied. In summary, we present here an alternative mode of miRNA regulation and demonstrate this dual function of the HER2 locus, linking the two major biomarkers in breast cancer.
Project description:Oxaliplatin (oxPt) resistance in colorectal cancers (CRC) is a major unsolved problem. Consequently, predictive markers and a better understanding of resistance mechanisms are urgently needed. To investigate if the recently identified predictive miR-625-3p is functionally involved in oxPt resistance, stable and inducible models of miR-625-3p dysregulation were analyzed. Ectopic expression of miR-625-3p in CRC cells led to increased resistance towards oxPt. The mitogen-activated protein kinase (MAPK) kinase 6 (MAP2K6/MKK6) – an activator of p38 MAPK - was identified as a functional target of miR-625-3p, and, in agreement, was down-regulated in patients not responding to oxPt therapy. The miR-625-3p resistance phenotype could be reversed by anti-miR-625-3p treatment and by ectopic expression of a miR-625-3p insensitive MAP2K6 variant. Transcriptome, proteome and phosphoproteome profiles revealed inactivation of MAP2K6-p38 signaling as a possible driving force behind oxPt resistance. We conclude that miR-625-3p induces oxPt resistance by abrogating MAP2K6-p38 regulated apoptosis and cell cycle control networks.
Project description:HER2-positive (HER2+) breast cancer patients that do not respond to targeted treatment have a poor prognosis. The effects of targeted treatment on endogenous microRNA (miRNA) expression levels are unclear. We report that responsive HER2+ breast cancer cell lines had a higher number of miRNAs with altered expression after treatment with trastuzumab and lapatinib compared to poorly responsive cell lines. To evaluate whether miRNAs can sensitize HER2+ cells to treatment, we performed a high-throughput screen of 1626 miRNA mimics and inhibitors in combination with trastuzumab and lapatinib in HER2+ breast cancer cells. We identified eight miRNA mimics sensitizing cells to targeted treatment, miR-101-5p, mir-518a-5p, miR-19b-2-5p, miR-1237-3p, miR-29a-3p, miR-29c-3p, miR-106a-5p, and miR-744-3p. A higher expression of miR-101-5p predicted better prognosis in patients with HER2+ breast cancer (OS: p=0.0392; BCSS: p=0.0125), supporting the tumor-suppressing role of this miRNA. In conclusion, we have identified miRNAs that sensitize HER2+ breast cancer cells to targeted therapy. This indicates the potential of combining targeted drugs with miRNAs to improve current treatments for HER2+ breast cancers.
Project description:miRNAs are small noncoding RNA molecules that play an important role in post-transcriptional regulation of gene expression. Length and/or sequence variants of the same miRNA are termed isomiRs. While most isomiRs are functionally redundant compared to their canonical counterparts, so-called 5âisomiRs exhibit a shifted 5â end and therefore a shifted seed sequence resulting in a different target spectrum. However, not much is known about the functional relevance of these isoforms. Analysis of miRNA-seq data from breast cancer cell lines identified six pairs of highly expressed miRNAs and associated 5âisomiRs. Among them, hsa-miR-140-3p was of particular interest because its 5âisomiR showed higher expression compared to the canonical miRNA annotated in miRbase. This miRNA has previously been shown to control stemness of breast cancer cells. MiRNAseq data of breast cancer patients (TCGA dataset) showed that both the canonical hsa-miR-140-3p and its 5âisomiR-140-3p were highly expressed in patients compared to normal breast tissue. In the current work, we present the functional characterization of 5âisomiR-140-3p and the cellular phenotypes associated with its overexpression in MCF10A and MDA-MB-231 cell lines in comparison to the canonical hsa-miR-140-3p. Contrary to the effect of the canonical hsa miR 140-3p, overexpression of the 5âisomiR-140-3p led to a decrease in cell viability. The latter observation was supported by cell cycle analysis, where the 5âisomiR-140-3p but not the hsa-miR-140-3p caused cell cycle arrest in G0/G1-phase. Additionally, 5âismoiR-140-3p overexpression was found to cause a decrease in cell migration in MCF10A cells. We identified three novel direct target genes of the 5â isomiR-140-3p; COL4A1, ITGA6 and MARCKSL1. Finally, we have shown that knocking down these genes partially phenocopied the effects of the 5âisomiR-140-4p overexpression, where COL4A1 and ITGA6 knockdown led to reduced cell viability and cell cycle arrest, while MARCKSL1 knockdown resulted in a decrease in the migratory potential of cells. In summary, this work presents evidence that there is a functional synergy between the canonical hsa-miR-140-3p and the newly identified 5âisomiR-140-3p in suppressing growth and progression of breast cancer by simultaneously targeting genes related to differentiation, proliferation, and migration. With this array, we aimed to address the question which genes are regulated by either of the two forms of the miRNA. Samples were measured in one biological replicate of cells transfected with mimic-ctrl1 and mimic-ctrl2 (Dharmacon) as control samples and two biological replicates of cells transfected with hsa-miR-140-3p and 5'isomiR-140-3p (Exiqon) in 30nM concentration using Lipofectamin 2000 as transfection reagent.
Project description:MiR-140 is selectively expressed in cartilage. Deletion of the entire miR-140 locus in mice results in a growth retardation phenotype and an early-onset osteoarthritis-like pathology, however the relative contribution of miR-140-5p or miR-140-3p to the phenotype remains to be determined. An unbiased small RNA sequencing approach identified that miR-140-3p was in vast abundance (>10-fold) to miR-140-5p in human cartilage. Analysis of these data identified multiple miR-140-3p isomiRs differing from the miRBase [1] annotation at both the 5´ and 3´ end, with >99% of miR-140-3p isomiRs having one of two ‘seed’ sequences (5´ bases 2-8). The most abundant isomiR with each seed were selected for further analysis; miR-140-3p.2 which has an identical seed to the miRBase miR-140-3p (ACCACAG) and miR-140-3p.1 which has an altered seed (CCACAGG), and thus different potential targets. Each isomiR was overexpressed in chondrocytes and whole-genome transcriptomics used to identify targets. miR-140-3p.1 and miR-140-3p.2 significantly down-regulated 694 and 238 genes respectively (adj.P.Val<0.05), of which only 162 genes were commonly down-regulated by both isomiRs. Targets of both isomiRs were validated using 3´UTR luciferase assays. A significant enrichment of miR-140-3p.1 targets was identified within genes whose expression increase in the rib chondrocytes of Mir140-null mice and within genes whose expression decreased during human chondrogenesis. Finally, through imputing the expression of miR-140 from the expression of the host gene WWP2 in 124 previously published datasets an inverse correlation with miR-140-3p.1 predicted targets was identified. Together these data suggest the novel seed containing isomiR miR-140-3p.1 is more functional than the original consensus miR-140-3p or the isomiR with the same seed, miR-140-3p.2.
Project description:Background: Hypertrophic cardiomyopathy (HCM) is an autosomal dominant genetic disorder, characterized by cardiomyocyte hypertrophy, cardiomyocyte disarray and fibrosis, which has a prevalence of ~1:200-500 and predisposes individuals to sudden death and heart failure. The mechanisms through which diverse HCM-causing mutations cause cardiac dysfunction remain mostly unknown and their identification may reveal new therapeutic avenues. MicroRNAs have emerged as critical regulators of gene expression and disease phenotype in various pathologies. We explored whether miRNAs could play a role in HCM pathogenesis and offer potential therapeutic targets. Methods and Results: Using high-throughput miRNA expression profiling and qPCR analysis in two distinct mouse models of HCM, we found that miR-199a-3p expression levels are upregulated in mutant mice compared to age- and treatment-matched wild-type mice. We also found that miR-199a-3p expression is enriched in cardiac non-myocytes compared to cardiomyocytes. When we expressed miR-199a-3p mimic in cultured primary cardiac non-myocytes and analyzed the conditioned media by proteomics, we found that several ECM proteins (e.g., TSP2, FBLN3, COL11A1, LYOX) were differentially expressed. We confirmed our proteomics findings by qPCR analysis of selected mRNAs and demonstrated that miR-199a-3p mimic expression in cardiac non-myocytes drives upregulation of ECM genes including Tsp2, Fbln3, Pcoc1, Col1a1 and Col3a1. To examine the role of miR-199a-3p in vivo, we inhibited its function using lock-nucleic acid (LNA)-based inhibitors (antimiR-199a-3p) in an HCM mouse model. Our results revealed that progression of cardiac fibrosis is attenuated when miR-199a-3p function is inhibited in mild-to-moderate HCM. Finally, guided by computational target prediction algorithms, we identified mRNAs Cd151 and Itga3 as direct targets of miR-199a-3p and have shown that miR-199a-3p mimic expression negatively regulates AKT activation in cardiac non-myocytes. Conclusions: Altogether, our results suggest that miR-199a-3p may contribute to cardiac fibrosis in HCM through its actions in cardiac non-myocytes. Thus, inhibition of miR-199a-3p in mild-to-moderate HCM may offer therapeutic benefit in combination with complementary approaches that target the primary defect in cardiac myocytes.
Project description:The canonical mechanism behind tamoxifen (Tam)’s therapeutic effect on estrogen receptor /ESR1+ breast cancers is inhibition of ESR1-dependent estrogen signaling. Although ESR1+ tumors expressing wild-type p53 were reported to be more responsive to Tam therapy, p53 has not been factored into choice of this therapy and the mechanism underlying the role of p53 in Tam response remain unclear. In a window of opportunity trial on patients with newly diagnosed stage I-III ESR1+/HER2/ wild-type p53 –breast cancer who were randomized to arms with or without Tam prior to surgery, we reveal that the ESR1-p53 interaction in tumors was inhibited by Tam. This resulted in functional reactivation of p53 leading to transcriptional reprogramming that favors tumor suppressive signaling, as well as downregulation of oncogenic pathways. These findings illustrating the convergence of ESR1 and p53 signaling during Tam therapy contribute to mechanistic understanding of the impact of p53 on the response to Tam therapy.
Project description:To analyze the effect of miR-223-3p expression on the mRNA level we employed whole genome microarray expression profiling to identify genes with a potential seed region targeted by miR-223-3p. A549 cells were transfected for 48h with either a mirVana miRNA mimic Control or miR-223-3p.
Project description:Oxysterols, oxidized derivatives of cholesterol, act in breast cancer (BC) as selective estrogen receptor modulators and affect cholesterol homeostasis, drug transport, nuclear and cell receptors, and other signaling proteins. Using overlapping data from patients with early-stage estrogen receptor-positive BC—high-coverage targeted DNA sequencing (99 patients, 113 genes), mRNA sequencing (67 patients), and full miRNome by microarrays (123 patients)—we describe complex mRNA-miRNA and miRNA-miRNA interaction (correlation) networks, with validation in two carefully curated public datasets (n=538 in total) and 11 databases. The ESR1-CH25H-INSIG1-ABCA9 axis was the most prominent, being interconnected through hsa-miR-125b-5p, but also hsa-miR-99a-5p, hsa-miR-100-5p, hsa miR 143 3p, hsa-199b-5p, hsa-miR-376a-3p, and hsa-miR-376c-3p. Mutations in SC5D, CYP46A1, and its functionally linked gene set were associated with multiple differentially expressed genes. STARD5 was upregulated in patients with positive lymph node status. High expression of miR-19b-3p was weakly associated with poor survival in multiple datasets. This is the first detailed dedicated study of interactions between DNA variation and mRNA expression of oxysterol-related genes, the miRNA transcriptome, and clinical factors in BC.