Reinstatement represents a phenomenon that may be used to model the effects of retraumatization observed in patients with posttraumatic stress disorder (PTSD). In this study, we found intraperitoneal injection of the -adrenergic receptor antagonist propranolol (10 mg/kg) 1 h before reinstatement training attenuated reinstatement of fear memory in rats. Conversely, reinstatement was facilitated by intra-amygdalar administration of -adrenergic receptor agonist isoproterenol (Iso; 2 g per side) 30 min before reinstatement training. The frequency and amplitude of the miniature IPSC (mIPSC) and the surface expression of the 3 and ␥2 subunits of the GABA A receptor (GABA A R) were significantly lower in reinstated than in extinction rats, whereas the AMPA/NMDA ratio and the surface expression of GluR1 and GluR2 in the amygdala did not differ between groups. In amygdala slices, Iso-induced decrease in the surface 3 subunit of GABA A receptor was blocked by a Tat-conjugated dynamin function-blocking peptide (Tat-P4) pretreatment (10 M for 30 min). By contrast, Tat-scramble peptide had no effect. Intravenous injection (3 mol/kg) or intra-amygdalar infusion (30 pmol per side) of Tat-P4 interfered with reinstatement. Reinstatement increased the association between protein phosphatase 2A (PP2A) and the 3 subunit of the GABA A R, which was abolished by PP1/PP2A inhibitors okadaic acid and calyculin A. These results suggest the involvement of -adrenergic receptor activation and GABA A receptor endocytosis in the amygdala for the reinstatement in fear memory.
No approved therapy exists for cancer-associated cachexia. The colon-26 mouse model of cancer cachexia mimics recent late-stage clinical failures of anabolic anti-cachexia therapy and was unresponsive to anabolic doses of diverse androgens, including the selective androgen receptor modulator (SARM) GTx-024. The histone deacetylase inhibitor (HDACi) AR-42 exhibited anticachectic activity in this model. We explored combined SARM/AR-42 therapy as an improved anti-cachectic treatment paradigm. A reduced dose of AR-42 provided limited anti-cachectic benefits, but, in combination with GTx-024, significantly improved body weight, hindlimb muscle mass, and grip strength versus controls. AR-42 suppressed the IL-6/GP130/STAT3 signaling axis in muscle without impacting circulating cytokines. GTx-024-mediated bcatenin target gene regulation was apparent in cachectic mice only when combined with AR-42. Our data suggest cachectic signaling in this model involves catabolic signaling insensitive to anabolic GTx-024 therapy and a blockade of GTx-024-mediated anabolic signaling. AR-42 mitigates catabolic gene activation and restores anabolic responsiveness to GTx-024. Combining GTx-024, a clinically established anabolic therapy, with AR-42, a clinically evaluated HDACi, represents a promising approach to improve anabolic response in cachectic patients.
Substantial evidence has clearly demonstrated the role of the IL-6-NF-κB signaling loop in promoting aggressive phenotypes in breast cancer. However, the exact mechanism by which this inflammatory loop is regulated remains to be defined. Here, we report that integrin-linked kinase (ILK) acts as a molecular switch for this feedback loop. Specifically, we show that IL-6 induces ILK expression via E2F1 upregulation, which, in turn, activates NF-κB signaling to facilitate IL-6 production. shRNA-mediated knockdown or pharmacological inhibition of ILK disrupted this IL-6-NF-κB signaling loop, and blocked IL-6-induced cancer stem cells in vitro and estrogen-independent tumor growth in vivo Together, these findings establish ILK as an intermediary effector of the IL-6-NF-κB feedback loop and a promising therapeutic target for breast cancer.
BackgroundCancer cachexia impacts the majority of advanced cancer patients but no approved anticachexia therapeutic exits. Recent late stage clinical failures of anabolic anti-cachexia therapy revealed heterogeneous responses to anabolic therapies and a limited ability to translate improved body composition into functional benefit. It is currently unclear what governs anabolic responsiveness in cachectic patient populations. Methods We evaluated anabolic androgen therapy combined with the novel anti-cachectic histone deacetylase inhibitor (HDACi) AR-42 in a series of studies using the C-26 mouse model of experimental cachexia. The ability of treatment to suppress tumor-mediated catabolic signaling and promote anabolic effects were characterized. Results Anabolic anti-cachexia monotherapy with the selective androgen receptor modulator (SARM) GTx-024 or enobosarm had no impact on cachectic outcomes in the C-26 model. A minimally effective dose of AR-42 provided mixed anti-cachectic benefits when administered alone but when combined with GTx-024 significantly improved bodyweight (p <0.0001), hind limb muscle mass (p <0.05), and voluntary grip strength (p <0.0001) versus tumor bearing controls. Similar efficacy resulted from the combination of AR-42 with multiple androgens. Anti-cachectic efficacy was associated with the ability to reverse pSTAT3 and atrogene induction in gastrocnemius muscle of tumor-bearing animals in the absence of treatment-mediated changes in serum IL-6 or LIF. Conclusions Anabolic GTx-024 monotherapy is incapable of overcoming catabolic signaling in the C-26 model of experimental cachexia. Anti-cachectic androgen therapy is greatly improved by successful blockade of STAT3 mediated atrophy with AR-42. Combined androgen and HDAC inhibitor administration represents promising approach to improve anabolic response in cachectic patient populations.
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