The noncoding MIR100HG RNA enhances the autocrine function of transforming growth factor \u03b2 signaling

Panagiotis Papoutsoglou,Carl-Henrik Heldin,Anita Morén,Andrew Bergman,Aristidis Moustakas,Laia Caja,Cédric Coulouarn,Fredrik Pontén,Dorival Mendes Rodrigues-Junior

doi:10.1038/s41388-021-01803-8

Panagiotis Papoutsoglou, Carl-Henrik Heldin + Show 7 more

Open Access

https://doi.org/10.1038/s41388-021-01803-8

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Abstract

Activation of the transforming growth factor β (TGFβ) pathway modulates the expression of genes involved in cell growth arrest, motility, and embryogenesis. An expression screen for long noncoding RNAs indicated that TGFβ induced mir-100-let-7a-2-mir-125b-1 cluster host gene (MIR100HG) expression in diverse cancer types, thus confirming an earlier demonstration of TGFβ-mediated transcriptional induction of MIR100HG in pancreatic adenocarcinoma. MIR100HG depletion attenuated TGFβ signaling, expression of TGFβ-target genes, and TGFβ-mediated cell cycle arrest. Moreover, MIR100HG silencing inhibited both normal and cancer cell motility and enhanced the cytotoxicity of cytostatic drugs. MIR100HG overexpression had an inverse impact on TGFβ signaling responses. Screening for downstream effectors of MIR100HG identified the ligand TGFβ1. MIR100HG and TGFB1 mRNA formed ribonucleoprotein complexes with the RNA-binding protein HuR, promoting TGFβ1 cytokine secretion. In addition, TGFβ regulated let-7a-2–3p, miR-125b-5p, and miR-125b-1–3p expression, all encoded by MIR100HG intron-3. Certain intron-3 miRNAs may be involved in TGFβ/SMAD-mediated responses (let-7a-2–3p) and others (miR-100, miR-125b) in resistance to cytotoxic drugs mediated by MIR100HG. In support of a model whereby TGFβ induces MIR100HG, which then enhances TGFβ1 secretion, analysis of human carcinomas showed that MIR100HG expression correlated with expression of TGFB1 and its downstream extracellular target TGFBI. Thus, MIR100HG controls the magnitude of TGFβ signaling via TGFβ1 autoinduction and secretion in carcinomas.

Highlights

Parts of the human genome are transcribed into noncoding RNAs that regulate gene expression, and have little or no protein-coding potential, such as microRNAs
(c, f), TGFB1 mRNA (d, g) expression by real-time RT-qPCR, and corresponding secreted mature TGFβ1 ligand detected by ELISA in the conditioned medium (e, h) of A549 (c–e) and PC3U (f–h) cells transiently transfected with negative control or MIR100HG-specific antisense oligonucleotide (ASO) in the absence of transforming growth factor β (TGFβ) stimulation
We here establish that TGFβ upregulates spliced MIR100HG, which positively regulates TGFβ responses in several normal and cancer cell types (Figs. 1–4)

Summary

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Parts of the human genome are transcribed into noncoding RNAs (ncRNAs) that regulate gene expression, and have little or no protein-coding potential, such as microRNAs. MiR-125b targets CDK6 and other cell cycle regulators, acting as an antiproliferative miRNA [8]. MiRNAs may exert context-dependent actions in cancer, when viewed as units of signaling pathways. One such pathway is transforming growth factor β (TGFβ) that signals via membrane receptors, which activate effector transcription factors (SMADs) and mitogen-. Activated protein kinases (MAPKs), to regulate target genes that control the cell cycle, migration, extracellular matrix remodeling, and epithelial–mesenchymal transition (EMT) [9]. Such target genes of TGFβ can be proteincoding or noncoding [10]. We established a role of MIR100HG in TGFβ autoinduction, a central feature in TGFβ biology, especially in the context of cancer

Results

Discussion

Materials and methods

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