The Heart Valve Society

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Targeting nuclear Export To Attenuate Aortic Valve Calcification
Punashi Dutta, Joy Lincoln.
Nationwide Children's Hospital, Columbus, OH, USA.

OBJECTIVE: Calcific aortic valve disease (CAVD) is a common disorder characterized by progressive buildup of calcium-rich nodules on valve surface leading to stenosis. Surgical intervention is standard treatment with no guarantee of long-term success. Therefore, there is a critical need to develop effective therapeutic alternatives. The molecular mechanisms of CAVD are complex but previous studies have shown an association with increased Wnt signaling. Therefore our goal is to identify novel therapeutic alternatives that target this key signaling pathway and treat CAVD.
METHODS:
KPT-330 is a CRM1-dependent nuclear export inhibitor drug in Phase III clinical trials for cancer treatment. Its therapeutic potential for CAVD has not been examined and therefore KPT-330 was administered during early stages of aortic annular calcification in an established mouse model (Klotho-/-). In parallel, KPT-330 was added to human and porcine aortic valve interstitial cells cultured under osteogenic stimulus. To determine KPT-330's mechanism of action, Mass Spectrometry was performed on nuclear lysates isolated from treated VICs compared to vehicle controls. Target proteins were identified based on those that lleave the nucleus during calcification, are retained in the nucleus by KPT-330, and harbor a CRM-1 dependent nuclear export signaling.
RESULTS:
Our preliminary findings show that early treatment of Klotho-/- with KPT-330 prevents CAVD in vivo (n=4); while treatment of cultured cells at later stages is sufficient to attenuate and mitigate calcific nodule formation. Mass Spectrometry has identified NFAT5 as a novel modulator of KPT-330 action in the treatment of CAVD and we show that this is associated with antagonism of Wnt signaling.
CONCLUSIONS:
Together, these studies for the first time have identified KPT as a novel therapeutic drug in the treatment of CAVD and our studies suggest a mechanism of action via NFAT5-Wnt signaling.


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