Population genomics reveals mechanisms and dynamics of de novo expressed open reading frame emergence in Drosophila melanogaster.

Novel genes are essential for evolutionary innovations and differ substantially even between closely related species. Recently, multiple studies across many taxa showed that some novel genes arise de novo, that is, from previously noncoding DNA. To characterize the underlying mutations that allowed de novo gene emergence and their order of occurrence, homologous regions must be detected within noncoding sequences in closely related sister genomes. So far, most studies do not detect noncoding homologs of de novo genes because of incomplete assemblies and annotations, and long evolutionary distances separating genomes. Here, we overcome these issues by searching for de novo expressed open reading frames (neORFs), the not-yet fixed precursors of de novo genes that emerged within a single species. We sequenced and assembled genomes with long-read technology and the corresponding transcriptomes from inbred lines of Drosophila melanogaster, derived from seven geographically diverse populations. We found line-specific neORFs in abundance but few neORFs shared by lines, suggesting a rapid turnover. Gain and loss of transcription is more frequent than the creation of ORFs, for example, by forming new start and stop codons. Consequently, the gain of ORFs becomes rate limiting and is frequently the initial step in neORFs emergence. Furthermore, transposable elements (TEs) are major drivers for intragenomic duplications of neORFs, yet TE insertions are less important for the emergence of neORFs. However, highly mutable genomic regions around TEs provide new features that enable gene birth. In conclusion, neORFs have a high birth-death rate, are rapidly purged, but surviving neORFs spread neutrally through populations and within genomes.

Knockdown of the stem cell marker Musashi-1 inhibits endometrial cancer growth and sensitizes cells to radiation.

BACKGROUND: Endometrial carcinoma is the most common gynecological cancer in Europe. Musashi-1 is known to be a key regulator of endometrial cancer stem cells and a negative prognostic marker. In the present study, we aimed to understand growth and gene expression patterns in endometrial carcinoma after Musashi-1 knockdown in vitro and in vivo. Changes in therapeutic resistance were also assessed. METHODS: First, we performed analyses to understand Musashi-1 expression patterns using The Cancer Genome Atlas database. We then proceeded to assess effects of small interfering RNA-based Musashi-1 targeting in two endometrial carcinoma cell lines, Ishikawa and KLE. After quantifying baseline changes in cell metabolism, we used MTT tests to assess chemotherapy effects and colony formation assays to understand changes in radioresistance. For mechanistic study, we used quantitative polymerase chain reaction (qPCR) and western blotting of key Musashi-1 target genes and compared results to primary tissue database studies. Finally, xenograft experiments in a mouse model helped understand in vivo effects of Musashi-1 knockdown. RESULTS: Musashi-1 is aberrantly expressed in primary tumor tissues. In vitro, silencing of Musashi-1 resulted in a strong decline in cell proliferation and radioresistance, while chemoresistance remained unchanged. Loss of Musashi-1 led to downregulation of telomerase, DNA-dependent protein kinase, the Notch pathway and overexpression of cyclin-dependent kinase inhibitor p21, the latter of which we identified as a key mediator of Msi-1 knockdown-related anti-proliferative signaling. In vivo, the anti-proliferative effect was confirmed, with Msi-1 knockdown tumors being about 40% reduced in size. CONCLUSIONS: Musashi-1 knockdown resulted in a strong decrease in endometrial cancer proliferation and a loss of radioresistance, suggesting therapeutic potential.

γ-Secretase inhibition affects viability, apoptosis, and the stem cell phenotype of endometriotic cells.

INTRODUCTION: Stem cells mediate cyclic regeneration of the endometrium. The upregulated expression of receptors and modulators of the notch signaling pathway in endometriosis suggests an involvement in the pathogenetic process. Here, we investigated the effects of notch pathway inhibition by a γ-secretase inhibitor (GSI) on stemness-associated properties of the epithelial endometriotic cell line 12Z and of primary endometriotic stroma cells. MATERIAL AND METHODS: 12Z cells and primary endometriotic stroma cells of 7 patients were treated with or without GSI, and analyzed for changes in gene expression by TaqMan low-density arrays, quantitative PCR, and flow cytometry. The functional impact of GSI treatment was studied by MTT assay, cell cycle analysis, colony formation assay, annexin V apoptosis assay, and aldehyde dehydrogenase activity assays. RESULTS: In 12Z cells, GSI treatment reduced aldehyde dehydrogenase activity and colony formation, and induced a shift to the G2/M phase of the cell cycle. Cell viability was decreased and apoptosis was increased in both cell models. GSI further induced transcriptional downregulation of the stemness-associated factors leukemia inhibitory factor receptor (LIFR), sex-determining region Y (SRY)- box 2, interferon-induced transmembrane protein 1, and hes-related family bHLH transcription factor with YRPW motif 1, in 12Z cells and in primary cell cultures. Downregulation of LIFR expression by GSI was confirmed at the protein level by flow cytometry. CONCLUSIONS: Our in vitro data suggest that application of GSI may be a worthwhile approach in the treatment of endometriosis that warrants further investigation.

MDA-MB-231 breast cancer cell viability, motility and matrix adhesion are regulated by a complex interplay of heparan sulfate, chondroitin-/dermatan sulfate and hyaluronan biosynthesis.

Proteoglycans and glycosaminoglycans modulate numerous cellular processes relevant to tumour progression, including cell proliferation, cell-matrix interactions, cell motility and invasive growth. Among the glycosaminoglycans with a well-documented role in tumour progression are heparan sulphate, chondroitin/dermatan sulphate and hyaluronic acid/hyaluronan. While the mode of biosynthesis differs for sulphated glycosaminoglycans, which are synthesised in the ER and Golgi compartments, and hyaluronan, which is synthesized at the plasma membrane, these polysaccharides partially compete for common substrates. In this study, we employed a siRNA knockdown approach for heparan sulphate (EXT1) and heparan/chondroitin/dermatan sulphate-biosynthetic enzymes (ß4GalT7) in the aggressive human breast cancer cell line MDA-MB-231 to study the impact on cell behaviour and hyaluronan biosynthesis. Knockdown of ß4GalT7 expression resulted in a decrease in cell viability, motility and adhesion to fibronectin, while these parameters were unchanged in EXT1-silenced cells. Importantly, these changes were associated with a decreased expression of syndecan-1, decreased signalling response to HGF and an increase in the synthesis of hyaluronan, due to an upregulation of the hyaluronan synthases HAS2 and HAS3. Interestingly, EXT1-depleted cells showed a downregulation of the UDP-sugar transporter SLC35D1, whereas SLC35D2 was downregulated in ß4GalT7-depleted cells, indicating an intricate regulatory network that connects all glycosaminoglycans synthesis. The results of our in vitro study suggest that a modulation of breast cancer cell behaviour via interference with heparan sulphate biosynthesis may result in a compensatory upregulation of hyaluronan biosynthesis. These findings have important implications for the development of glycosaminoglycan-targeted therapeutic approaches for malignant diseases.

microRNA miR-142-3p Inhibits Breast Cancer Cell Invasiveness by Synchronous Targeting of WASL, Integrin Alpha V, and Additional Cytoskeletal Elements.

MicroRNAs (miRNAs, micro ribonucleic acids) are pivotal post-transcriptional regulators of gene expression. These endogenous small non-coding RNAs play significant roles in tumorigenesis and tumor progression. miR-142-3p expression is dysregulated in several breast cancer subtypes. We aimed at investigating the role of miR-142-3p in breast cancer cell invasiveness. Supported by transcriptomic Affymetrix array analysis and confirmatory investigations at the mRNA and protein level, we demonstrate that overexpression of miR-142-3p in MDA-MB-231, MDA-MB-468 and MCF-7 breast cancer cells leads to downregulation of WASL (Wiskott-Aldrich syndrome-like, protein: N-WASP), Integrin-αV, RAC1, and CFL2, molecules implicated in cytoskeletal regulation and cell motility. ROCK2, IL6ST, KLF4, PGRMC2 and ADCY9 were identified as additional targets in a subset of cell lines. Decreased Matrigel invasiveness was associated with the miR-142-3p-induced expression changes. Confocal immunofluorescence microscopy, nanoscale atomic force microscopy and digital holographic microscopy revealed a change in cell morphology as well as a reduced cell volume and size. A more cortical actin distribution and a loss of membrane protrusions were observed in cells overexpressing miR-142-3p. Luciferase activation assays confirmed direct miR-142-3p-dependent regulation of the 3'-untranslated region of ITGAV and WASL. siRNA-mediated depletion of ITGAV and WASL resulted in a significant reduction of cellular invasiveness, highlighting the contribution of these factors to the miRNA-dependent invasion phenotype. While knockdown of WASL significantly reduced the number of membrane protrusions compared to controls, knockdown of ITGAV resulted in a decreased cell volume, indicating differential contributions of these factors to the miR-142-3p-induced phenotype. Our data identify WASL, ITGAV and several additional cytoskeleton-associated molecules as novel invasion-promoting targets of miR-142-3p in breast cancer.

MicroRNA miR-145 inhibits proliferation, invasiveness, and stem cell phenotype of an in vitro endometriosis model by targeting multiple cytoskeletal elements and pluripotency factors.

OBJECTIVE: To study the function of miR-145, known to be dysregulated in endometriosis, and to identify its target genes in an in vitro endometriosis model. DESIGN: Experimental laboratory study. SETTING: University medical centers. PATIENT(S): Primary endometrial stroma cells were derived from eutopic endometrium of three American Society for Reproductive Medicine stage III endometriosis patients and from ectopic lesions of four patients with deep infiltrating endometriosis. INTERVENTION(S): The human endometriotic cell line 12Z and primary eutopic and ectopic endometrial stroma cells were transiently transfected with miR-145 precursors or anti-miR-145 inhibitors and investigated for posttranscriptional regulation of predicted target genes and changes in cell behavior. MAIN OUTCOME MEASURE(S): Predicted target expression was measured by quantitative reverse transcription-polymerase chain reaction and Western blotting, and altered cell behavior was monitored by cell proliferation assays. The 12Z cells were additionally investigated by Matrigel invasion assays, cell cycle analysis, side population analysis, and aldehyde dehydrogenase activity assays. RESULT(S): In all cells investigated, miR-145 overexpression inhibited cell proliferation and induced down-regulation of FASCIN-1, SOX2, and MSI2. In 12Z cells miR-145 upregulation increased Matrigel invasiveness and reduced side population and aldehyde dehydrogenase-1 activity. Additional down-regulated targets in 12Z cells included OCT4, KLF4, PODXL, JAM-A, and SERPINE1/PAI-1. ACTG2 and TAGLN were up-regulated upon pre-miR-145 transfection. JAM-A, FASCIN-1, and PAI-I down-regulation in 12Z cells were confirmed by Western blotting. CONCLUSION(S): miR-145 inhibits endometriotic cell proliferation, invasiveness, and stemness by targeting multiple pluripotency factors, cytoskeletal elements, and protease inhibitors.