Arsenic Trioxide Inhibits the Metastasis of Small Cell Lung Cancer by Blocking Calcineurin-Nuclear Factor of Activated T Cells (NFAT) Signaling

Abstract

Background The inhibitory effect of arsenic trioxide (As 2 O 3 ) on lung cancer has been reported in some preclinical studies. However, its effect on small cell lung cancer (SCLC) has been poorly explored. Calcineurin and its substrate, nuclear factor of activated T cells (NFAT), mediate the downstream signaling of VEGF, and is critical in the process endothelium activation and tumor metastasis. In this study, we aimed to evaluate whether As 2 O 3 had inhibitory effects on endothelial cells activation and the metastasis of SCLC, and to explore the possible mechanisms. Material/Methods In vitro , human umbilical vein endothelial cells (HUVECs) were used. Cell Counting Kit-8 assay and cell migration assay were performed to determine the effect of As 2 O 3 on HUVECs proliferation and migration. The level of calcineurin, NFAT, downstream factors for Down syndrome candidate region 1 (DSCR1), and the endogenous inhibitor of calcineurin, were evaluated by quantitative PCR and western blotting. In vivo , SCLC metastasis models were established by injecting NCI-H446 cells into tail veins of nude mice. Tumor-bearing mice were treated with As 2 O 3 or calcineurin inhibitor for 10 days, after which tumor metastasis in target organs was evaluated. Results As 2 O 3 significantly inhibited the proliferation and migration of endothelial cells. Also, As 2 O 3 inhibited the expression levels of calcineurin, NFAT, and the downstream target genes CXCR7 and RND1, while it upregulated the level of DSCR1. Both As 2 O 3 and calcineurin inhibitor exhibited notable inhibitory effect on the metastasis of SCLC, without obvious side effects. Conclusions These findings suggested that As 2 O 3 had remarkable inhibitory effects on the endothelial cell activation and SCLC metastasis, and the mechanism might be related to the blocking of calcineurin-NFAT signaling by upregulating DSCR1.

Combination therapy: Future directions of immunotherapy in small cell lung cancer

“…And SCLC cells were more sensitive than NSCLC cells to As 2 O 3 , with lower IC 50 values (1 to 2 Amol/L vs. 2 to 5 Amol/L) [ 58 ]. In a word, As 2 O 3 can significantly inhibit SCLC through various mechanisms as follow: 1) induces cytotoxicity via altered redox homeostasis and mitochondrial integrity [ 59 ]; 2) inhibits tumor growth through antiangiogenesis through the blockade of Notch signaling [ 60 ]; 3) inhibits the metastasis by blocking calcineurin-nuclear factor of activated T cells signaling [ 61 ]. However, the results from a phase II clinical trial of As 2 O 3 for the treatment of patients with relapsed SCLC are frustrating.…”

RCAN1-mediated calcineurin inhibition as a target for cancer therapy

“…In small cell lung cancer (SCLC), RCAN1 inhibited proliferation, colony formation, migration, invasion, and bone adherence, but not cell apoptosis, in vitro (Ma et al 2017 ). The inhibitory effect of arsenic trioxide (As2O3) on SCLC metastasis may be related to the blocking of CN-NFAT signaling by upregulating RCAN1 (Zheng et al 2019 ). In non-small cell lung cancer (NSCLC), RCAN1.4 was found to be a target of exosome miR-619-5p.…”

Advances in the study of cancer metastasis and calcium signaling as potential therapeutic targets

“…Numerous Ca 2+ -dependent proteins containing Ca 2+ -binding sites, such as calmodulin (CaM) [ 123 , 124 ], Ca 2+ /CaM-dependent kinase (CaMK) [ 125 ], calreticulin [ 126 ], Ca 2+ sensor [ 127 ], Ca 2+ -sensing receptor (CaSR) [ 128 ], calpain [ 129 ], calcineurin [ 130 ], myosin light-chain kinase (MLCK) [ 131 ] and phospholipase S100 family proteins [ 132 ], have been widely proven to be vital to cancer metastasis. CaM, with four EF-hands, is one of the most important Ca 2+ signal-decoding proteins.…”