title: MicroRNA-520/373 family functions as a tumor suppressor in estrogen receptor negative breast cancer by targeting NF-κB and TGF-β signaling pathways.
abstract: MicroRNAs (miRNAs) as modulators of gene expression have been described to display both tumor-promoting and tumor-suppressive functions. Although their role has been studied in different tumor types, little is known about how they regulate nuclear factor κB (NF-κB) signaling in breast cancer. Here, we performed an unbiased whole genome miRNA (miRome) screen to identify novel modulators of NF-κB pathway in breast cancer. The screen identified 13 miRNA families whose members induced consistent effects on NF-κB activity. Among those, the miR-520/373 family inhibited NF-κB signaling through direct targeting of RELA and thus strongly reduced expression and secretion of the pro-inflammatory cytokines interleukin (IL)-6 and IL-8. With a combination of in vitro and in vivo approaches, we propose a metastasis-suppressive role of miR-520/373 family. miR-520c and miR-373 abrogated both in vitro cell invasion and in vivo intravasation of highly invasive MDA-MB-231 cells. However, knockdown of RELA did not affect their metastatic ability. mRNA profiling of MDA-MB-231 cells on overexpression of miR-520/373 members revealed a strong downregulation of transforming growth factor-β (TGF-β) signaling. Mechanistically, the metastasis-suppressive role of miR-520/373 can be attributed to direct suppression of TGFBR2, as the silencing of TGFBR2 phenocopied the effects of miR-520/373 overexpression on suppression of Smad-dependent expression of the metastasis-promoting genes parathyroid hormone-related protein, plasminogen activator inhibitor-1 and angiopoietin-like 4 as well as tumor cell invasion, in vitro and in vivo. A negative correlation between miR-520c and TGFBR2 expression was observed in estrogen receptor negative (ER(-)) breast cancer patients but not in the ER positive (ER(+)) subtype. Remarkably, decreased expression of miR-520c correlated with lymph node metastasis specifically in ER(-) tumors. Taken together, our findings reveal that miR-520/373 family has a tumor-suppressive role in ER(-) breast cancer by acting as a link between the NF-κB and TGF-β pathways and may thus contribute to the interplay of tumor progression, metastasis and inflammation.
authors.affiliation: Division of Molecular Genome Analysis, German Cancer Research Center (DKFZ), Heidelberg, Germany. i.keklikoglou@dkfz-heidelberg.de
authors.forename: I
authors.initials: I
authors.lastname: Keklikoglou
authors.forename: C
authors.initials: C
authors.lastname: Koerner
authors.forename: C
authors.initials: C
authors.lastname: Schmidt
authors.forename: J D
authors.initials: JD
authors.lastname: Zhang
authors.forename: D
authors.initials: D
authors.lastname: Heckmann
authors.forename: A
authors.initials: A
authors.lastname: Shavinskaya
authors.forename: H
authors.initials: H
authors.lastname: Allgayer
authors.forename: B
authors.initials: B
authors.lastname: Gückel
authors.forename: T
authors.initials: T
authors.lastname: Fehm
authors.forename: A
authors.initials: A
authors.lastname: Schneeweiss
authors.forename: O
authors.initials: O
authors.lastname: Sahin
authors.forename: S
authors.initials: S
authors.lastname: Wiemann
authors.forename: U
authors.initials: U
authors.lastname: Tschulena
mesh_terms: D000075803:Angiopoietin-Like Protein 4; D042682:Angiopoietins / Q000096:biosynthesis; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D015850:Interleukin-6 / Q000096:biosynthesis; D016209:Interleukin-8 / Q000096:biosynthesis; D035683:MicroRNAs / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D009362:Neoplasm Metastasis / Q000235:genetics; D044162:Parathyroid Hormone-Related Protein / Q000096:biosynthesis / Q000378:metabolism; D017395:Plasminogen Activator Inhibitor 1 / Q000096:biosynthesis; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D000077294:Receptor, Transforming Growth Factor-beta Type II; D011960:Receptors, Estrogen / Q000172:deficiency / Q000378:metabolism; D018125:Receptors, Transforming Growth Factor beta / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D051996:Transcription Factor RelA / Q000235:genetics / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: C474772:ANGPTL4 protein, human; D000075803:Angiopoietin-Like Protein 4; D042682:Angiopoietins; D015850:Interleukin-6; D016209:Interleukin-8; C527114:MIRN373 microRNA, human; C575048:MIRN520 microRNA, human; D035683:MicroRNAs; D016328:NF-kappa B; D044162:Parathyroid Hormone-Related Protein; D017395:Plasminogen Activator Inhibitor 1; C498143:RELA protein, human; D011960:Receptors, Estrogen; D018125:Receptors, Transforming Growth Factor beta; C051321:SERPINE1 protein, human; D051996:Transcription Factor RelA; D016212:Transforming Growth Factor beta; D017346:Protein Serine-Threonine Kinases; D000077294:Receptor, Transforming Growth Factor-beta Type II