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Signal transducer and activator of transcription-3 induces microRNA-155 expression in chronic lymphocytic leukemia.

Li P, Grgurevic S, Liu Z, Harris D, Rozovski U, Calin GA, Keating MJ, Estrov Z - PLoS ONE (2013)

Bottom Line: Of the two putative binding sites, STAT3-siRNA reduced the luciferase activity of the construct containing the 700-709 bp STAT3 binding site, suggesting that this site is involved in STAT3-induced transcription.Finally, STAT3-small hairpin RNA downregulated miR-155 gene expression, suggesting that constitutively activated STAT3 binds to the miR-155 gene promoter.Together, these results suggest that STAT3 activates miR-155 in CLL cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Leukemia, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.

ABSTRACT
MicroRNA (miR) abnormalities play a key role in the pathogenesis of chronic lymphocytic leukemia (CLL). High levels of miR-155 have been detected in human neoplasms, and overexpression of miR-155 has been found to induce lymphoma in mice. High levels of miR-155 were detected in CLL cells and STAT3, which is known to induce miR-21 and miR-181b-1 expression, is constitutively activated in CLL. Given these findings, we hypothesized that STAT3 induces miR-155. Sequence analysis revealed that the miR-155 promoter harbors two putative STAT3 binding sites. Therefore, truncated miR-155 promoter constructs and STAT3 small interfering RNA (siRNA) were co-transfected into MM1 cells. Of the two putative binding sites, STAT3-siRNA reduced the luciferase activity of the construct containing the 700-709 bp STAT3 binding site, suggesting that this site is involved in STAT3-induced transcription. Electrophoretic mobility shift assay confirmed that STAT3 bound to the miR-155 promoter in CLL cells, and chromatin immunoprecipitation and luciferase assay confirmed that STAT3 bound to the 700-709 bp but not the 615-624 bp putative STAT3 binding site in CLL cells. Finally, STAT3-small hairpin RNA downregulated miR-155 gene expression, suggesting that constitutively activated STAT3 binds to the miR-155 gene promoter. Together, these results suggest that STAT3 activates miR-155 in CLL cells.

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Related in: MedlinePlus

Sequence of the miR-155 gene promoter.Sequence analysis of the miR-155 promoter detected two putative STAT3 binding sites (red).
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pone-0064678-g001: Sequence of the miR-155 gene promoter.Sequence analysis of the miR-155 promoter detected two putative STAT3 binding sites (red).

Mentions: We first sought to determine whether miR-155 has any STAT3 binding sites. Typically, phosphorylated STAT3 binds to the γ-interferon activation sequence (GAS)-like element, also referred to as the sis-inducible element, in the promoters of various genes [23]. Because STAT3 is constitutively activated in CLL and activates several STAT3 target genes [15] and miR-155 is overexpressed in CLL [19], we sought to determine whether miR-155 has any STAT3 binding sites. Sequence analysis identified two GAS-like elements in the miR-155 promoter (Fig. 1), suggesting that STAT3 binds to the miR-155 promoter in CLL cells.


Signal transducer and activator of transcription-3 induces microRNA-155 expression in chronic lymphocytic leukemia.

Li P, Grgurevic S, Liu Z, Harris D, Rozovski U, Calin GA, Keating MJ, Estrov Z - PLoS ONE (2013)

Sequence of the miR-155 gene promoter.Sequence analysis of the miR-155 promoter detected two putative STAT3 binding sites (red).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3672147&req=5

pone-0064678-g001: Sequence of the miR-155 gene promoter.Sequence analysis of the miR-155 promoter detected two putative STAT3 binding sites (red).
Mentions: We first sought to determine whether miR-155 has any STAT3 binding sites. Typically, phosphorylated STAT3 binds to the γ-interferon activation sequence (GAS)-like element, also referred to as the sis-inducible element, in the promoters of various genes [23]. Because STAT3 is constitutively activated in CLL and activates several STAT3 target genes [15] and miR-155 is overexpressed in CLL [19], we sought to determine whether miR-155 has any STAT3 binding sites. Sequence analysis identified two GAS-like elements in the miR-155 promoter (Fig. 1), suggesting that STAT3 binds to the miR-155 promoter in CLL cells.

Bottom Line: Of the two putative binding sites, STAT3-siRNA reduced the luciferase activity of the construct containing the 700-709 bp STAT3 binding site, suggesting that this site is involved in STAT3-induced transcription.Finally, STAT3-small hairpin RNA downregulated miR-155 gene expression, suggesting that constitutively activated STAT3 binds to the miR-155 gene promoter.Together, these results suggest that STAT3 activates miR-155 in CLL cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Leukemia, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.

ABSTRACT
MicroRNA (miR) abnormalities play a key role in the pathogenesis of chronic lymphocytic leukemia (CLL). High levels of miR-155 have been detected in human neoplasms, and overexpression of miR-155 has been found to induce lymphoma in mice. High levels of miR-155 were detected in CLL cells and STAT3, which is known to induce miR-21 and miR-181b-1 expression, is constitutively activated in CLL. Given these findings, we hypothesized that STAT3 induces miR-155. Sequence analysis revealed that the miR-155 promoter harbors two putative STAT3 binding sites. Therefore, truncated miR-155 promoter constructs and STAT3 small interfering RNA (siRNA) were co-transfected into MM1 cells. Of the two putative binding sites, STAT3-siRNA reduced the luciferase activity of the construct containing the 700-709 bp STAT3 binding site, suggesting that this site is involved in STAT3-induced transcription. Electrophoretic mobility shift assay confirmed that STAT3 bound to the miR-155 promoter in CLL cells, and chromatin immunoprecipitation and luciferase assay confirmed that STAT3 bound to the 700-709 bp but not the 615-624 bp putative STAT3 binding site in CLL cells. Finally, STAT3-small hairpin RNA downregulated miR-155 gene expression, suggesting that constitutively activated STAT3 binds to the miR-155 gene promoter. Together, these results suggest that STAT3 activates miR-155 in CLL cells.

Show MeSH
Related in: MedlinePlus