Nuclear factors of activated T cells (NFAT) are critical modulators of
cancer cell growth and survival. However, the mechanisms of their oncogenic dysregulation and strategies for targeting in
tumors remain elusive. Here, we report coupling of anti- apoptotic NFAT (NFAT2) activation to
cholesterol-enriched
lipid raft microdomains of
malignant melanoma cells and interruption of this pathway by the aminobisphosphonate
zoledronic acid (Zol). The pathway was indicated by capability of Zol to promote apoptosis and to retard in vivo outgrowth of tumorigenic
melanoma cell variants through inhibition of permanently active NFAT2. NFAT2 inhibition resulted from disintegration of
cholesterol-enriched rafts due to reduction of cellular
cholesterol by Zol. Mechanistically, raft disruption abolished raft-localized robust store-operated Ca(2+) (SOC) entry, blocking constitutive activation of
protein kinase B/Akt (PKB) and thereby reactivating the NFAT repressor
glycogen synthase kinase 3β (GSK3β). Pro-apoptotic inactivation of NFAT2 also followed reactivation of GSK3β by direct inhibition of PKB or SOC, whereas GSK3β blockade prevented Zol-induced NFAT2 inhibition and cell death. The rescuing effect of GSK3β blockade was reproduced by recovery of entire SOC/PKB/GSK3β cascade after reconstitution of rafts by
cholesterol replenishment of Zol-treated tumorigenic cells. Remarkably, these malignant cells displayed higher
cholesterol and
lipid raft content than non-tumorigenic cells, which expressed weak SOC, PKB and NFAT2 activities and resisted raft-ablating action of Zol. Together, the results underscore the functional relevance of amplified
melanoma rafts for
tumor-promoting NFAT2 signaling and reveal these distinctive microdomains as a target for in vitro and in vivo demise of tumorigenic cells through NFAT2 inhibition by the clinical agent Zol.