title: Down-Regulation of miR-129-5p and the let-7 Family in Neuroendocrine Tumors and Metastases Leads to Up-Regulation of Their Targets Egr1, G3bp1, Hmga2 and Bach1.
abstract: Expression of miRNAs in Neuroendocrine Neoplasms (NEN) is poorly characterized. We therefore wanted to examine the miRNA expression in Neuroendocrine Tumors (NETs), and identify their targets and importance in NET carcinogenesis. miRNA expression in six NEN primary tumors, six NEN metastases and four normal intestinal tissues was characterized using miRNA arrays, and validated by in-situ hybridization and qPCR. Among the down-regulated miRNAs miR-129-5p and the let-7f/let-7 family, were selected for further characterization. Transfection of miR-129-5p inhibited growth of a pulmonary and an intestinal carcinoid cell line. Analysis of mRNA expression changes identified EGR1 and G3BP1 as miR-129-5p targets. They were validated by luciferase assay and western blotting, and found robustly expressed in NETs by immunohistochemistry. Knockdown of EGR1 and G3BP1 mimicked the growth inhibition induced by miR-129-5p. let-7 overexpression inhibited growth of carcinoid cell lines, and let-7 inhibition increased protein content of the transcription factor BACH1 and its targets MMP1 and HMGA2, all known to promote bone metastases. Immunohistochemistry analysis revealed that let-7 targets are highly expressed in NETs and metastases. We found down-regulation of miR-129-5p and the let-7 family, and identified new neuroendocrine specific targets for these miRNAs, which contributes to the growth and metastatic potential of these tumors.
authors.affiliation: Center for Genomic Medicine, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark. kristina@doessing.dk.
authors.forename: Kristina B V
authors.initials: KB
authors.lastname: Døssing
authors.affiliation: Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark. ulrich.knigge@rh.regionh.dk.
authors.forename: Tina
authors.initials: T
authors.lastname: Binderup
authors.affiliation: The Bioinformatics Center, Department of Biology and Biotech and Research Innovation Centre, Ole Maaløes Vej 5, 2200 Copenhagen, Denmark. b.kaczkowski@gmail.com.
authors.forename: Bogumil
authors.initials: B
authors.lastname: Kaczkowski
authors.affiliation: The Bioinformatics Center, Department of Biology and Biotech and Research Innovation Centre, Ole Maaløes Vej 5, 2200 Copenhagen, Denmark. andersmbj@gmail.com.
authors.forename: Anders
authors.initials: A
authors.lastname: Jacobsen
authors.affiliation: Center for Genomic Medicine, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark. maria.rossing@rh.regionh.dk.
authors.forename: Maria
authors.initials: M
authors.lastname: Rossing
authors.affiliation: DTU Informatics, Technical University of Denmark, Anker Engelunds Vej 1, 2800 Kongens Lyngby, Denmark. ole.winther@gmail.com.
authors.forename: Ole
authors.initials: O
authors.lastname: Winther
authors.affiliation: Department of Pathology, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark. birgitte.federspiel@rh.regionh.dk.
authors.forename: Birgitte
authors.initials: B
authors.lastname: Federspiel
authors.affiliation: Cluster for Molecular Imaging, Faculty of Health Sciences, Blegdamsvej 3B, 2100 Copenhagen, Denmark. ulrich.knigge@rh.regionh.dk.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Knigge
authors.affiliation: Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark. ulrich.knigge@rh.regionh.dk.
authors.forename: Andreas
authors.initials: A
authors.lastname: Kjær
authors.affiliation: Center for Genomic Medicine, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark. lejf@regionsjaelland.dk.
authors.forename: Lennart
authors.initials: L
authors.lastname: Friis-Hansen