Generation of an inducible mouse model to reversibly silence Stat3

Abstract

Signal transducer and activator of transcription 3 (Stat3) is a transcription factor that has many essential roles during inflammation, development and cancer. Stat3 is therefore an attractive therapeutic target in many diseases. While current Stat3 knockout mouse models led to a better understanding of the role of Stat3, the irreversible nature of Stat3 ablation does not model the effects of transient Stat3 therapeutic inhibition, and does not inform on potential dosage effects of Stat3. Using RNAi technology, we have generated a new mouse model allowing the inducible and reversible silencing of Stat3 in vivo, which mirrors the effects of specific Stat3 therapeutic interference. We showed that upon Doxycycline-mediated activation of the Stat3 short-hairpin RNA, Stat3 expression was efficiently reduced by about 80% in multiple organs and cell types. Moreover, Stat3 reduction was sufficient to reduce tumor burden in a clinically-validated mouse model of gastric cancer. Finally, we demonstrated that Stat3 silencing during embryonic development led to reduced birth rate without leading to complete embryonic lethality, in contrast to full Stat3 ablation. In conclusion, this new mouse model will be invaluable to understand the effects of Stat3 therapeutic interference and Stat3 dosage effects.

Repurposing the selective estrogen receptor modulator bazedoxifene to suppress gastrointestinal cancer growth

“…In this model, gastric adenomas spontaneously and reproducibly develop with 100% penetrance in 4-week-old mice with an absolute genetic dependence on bi-allelic expression of the il11ra and Stat3 genes, but completely independent of IL6 signaling (Jenkins et al, 2005;Ernst et al, 2008). Importantly, we had previously shown that therapeutic treatment of tumor-bearing, 10-to 13-weekold gp130 Y757F mice with either the antagonistic IL11-Mutein peptide (Putoczki et al, 2013), JAK1/2 kinase inhibitors , STAT3 antisense oligonucleotides (Ernst et al, 2008), or inducible short hairpin STAT3-RNA (Alorro et al, 2017), reduces tumor burden associated with reduced cell proliferation and increased apoptosis. Thus, we treated 13-week-old gp130 Y757F mice with A Crystal structure of the extracellular domains of the IL6 hexameric signaling complex (PDB ID: 1P9M; Boulanger et al, 2003), depicted in cartoon format.…”

STAT3 Signalling via the IL-6ST/gp130 Cytokine Receptor Promotes Epithelial Integrity and Intestinal Barrier Function during DSS-Induced Colitis

“…The second CAGs-rtTA;shStat3 mouse model, referred to as shStat3 hereafter, was generated to carry a GFP-linked, doxycycline (dox)-inducible Stat3 short hairpin RNA for the reversible silencing of Stat3 and has been characterised previously [ 19 ]. Two different controls were used to complement the dox-treated shStat3 cohort.…”

“…In addition, we also employed dox-treated CAGs-rtTA;shLuc (referred to as shLuc) transgenic mice, which harbour a GFP-linked irrelevant hairpin to account for any non-specific effects from the short hairpin RNA. Dox treatment resulted in Stat3 knockdown by 80% in multiple organs and cell types including the gastrointestinal tract, while Stat1 expression remained unaltered [ 19 ]. Immunohistochemistry confirmed a reduction in the expression of pSTAT3 in shStat3 mice after doxycycline treatment, but not in shStat3 chow and dox-treated shLuc controls ( Supplementary Figure S1D ).…”

“…Immunohistochemistry confirmed a reduction in the expression of pSTAT3 in shStat3 mice after doxycycline treatment, but not in shStat3 chow and dox-treated shLuc controls ( Supplementary Figure S1D ). Short hairpin expression or Stat3 silencing did not have an effect on their overall phenotype [ 19 ] or intestinal morphology under normal tissue homeostasis ( Supplementary Figure S2C,D ).…”

“…GP130 ∆STAT/+ , CAG-rtTA3;TRE-Stat3 (shStat3), and CAG-rtTA3;TRE-Luc (shLuc) mice were derived as previously described [ 18 , 19 ]. GP130 ∆STAT/+ mice were maintained on a mixed C57BL/6 × 129SV background, whereas CAG-rtTA3;TRE-Stat3, CAG-rtTA3;TRE-Luc, and RosaCre ERT2 ;Stat3 fl/fl mice were maintained on a C57BL/6 background and under specific pathogen-free conditions.…”