Safety and efficacy of arsenic trioxide and all-trans retinoic acid therapy in acute promyelocytic leukemia patients with a high risk for early death

Maximizing arsenic trioxide's anticancer potential: Targeted nanocarriers for solid tumor therapy

Arsenic trioxide (ATO) has gained significant attention due to its promising therapeutic effects in treating different diseases, particularly acute promyelocytic leukemia (APL). Its potent anticancer mechanisms have been extensively studied. Despite the great efficacy ATO shows in fighting cancers, drawbacks in the clinical use are obvious, especially for solid tumors, which include rapid renal clearance and short half-life, severe adverse effects, and high toxicity to normal cells. Recently, the emergence of nanomedicine offers a potential solution to these limitations. The enhanced biocompatibility, excellent targeting capability, and desirable effectiveness have attracted much interest. Therefore, we summarized various nanocarriers for targeted delivery of ATO to solid tumors. We also provided detailed anticancer mechanisms of ATO in treating cancers, its clinical trials and shortcomings as well as the combination therapy of ATO and other chemotherapeutic agents for reduced drug resistance and synergistic effects. Finally, the future study direction and prospects were also presented.

Arsenic Trioxide Decreases Lymphangiogenesis by Inducing Apoptotic Pathways and Inhibition of Important Endothelial Cell Receptors

Tumor-induced lymphangiogenesis is strongly associated with the formation of tumor metastasis. Therefore, the regulation of lymphangiogenesis offers a promising target in cancer therapy. Arsenic trioxide (ATO) is highly effective in the treatment of patients with acute promyelocytic leukemia (APL). As ATO mediates anti-angiogenic effects on endothelial and tumor cells, we aimed to explore the impact of ATO on lymphangiogenesis in human lymphatic endothelial cells (LEC). The BrdU assay and flow cytometry analysis were used to evaluate the influence of ATO on the proliferation and cell cycle distribution of LECs. The lymphatic suppression effects of ATO were investigated in vitro using the lymphatic tube formation assay. The effects of ATO on apoptosis, mitochondrial membrane potential and endothelial cell receptors were investigated by Western blotting, ELISA, flow cytometry and qRT-PCR. The treatment of LECs with ATO attenuated cell proliferation, blocked tube formation and induced subG0/G1 arrest in LECs, thus suggesting enhanced apoptosis. Although subG0/G1 arrest was accompanied by the upregulation of p21 and p53, ATO treatment did not lead to visible cell cycle arrest in LECs. In addition, ATO caused apoptosis via the release of cytochrome c from mitochondria, activating caspases 3, 8 and 9; downregulating the anti-apoptotic proteins survivin, XIAP and cIAP-2; and upregulating the pro-apoptotic protein Fas. Furthermore, we observed that ATO inhibited the VEGF-induced proliferation of LECs, indicating that pro-survival VEGF/VEGFR signaling was affected by ATO treatment. Finally, we found that ATO inhibited the expression of the important endothelial cell receptors VEGFR-2, VEGFR-3, Tie-2 and Lyve-1. In conclusion, we demonstrate that ATO inhibits lymphangiogenesis by activating apoptotic pathways and inhibiting important endothelial cell receptors, which suggests that this drug should be further evaluated in the treatment of tumor-associated lymphangiogenesis.

A Metabolic Profiling Study of Realgar-Induced Acute Kidney Injury in Mice

Realgar has been used as a type of mineral drug that contains arsenic for thousands of years. Previous studies have shown that Realgar-induced acute kidney injury is associated with abnormal metabolism, but the underlying mechanism is poorly understood. The aim of this study is to investigate the metabolic changes in serum and kidney tissues of mice exposed to Realgar by using a metabolomic approach and explore the molecular mechanisms of acute kidney injury induced by Realgar. Forty mice were randomly divided into four groups: Control group, 0.5-, 1.0, and 2.0 g/kg Realgar group. After 1 week, the body weight and kidney weight of the mice were measured. The serum and kidney samples were used for LC-MS spectroscopic metabolic profiling. Principal component analysis (PCA), correlation analysis, and pathway analysis were used to detect the nephrotoxic effects of Realgar. Body weight decreased significantly in the 2.0 g/kg group, and the kidney weight index also showed a dose-dependent increase in Realgar. The PCA score plot showed the serum and kidney tissue metabolic profile of mice exposed to 2.0 g/kg Realgar separated from the control group, while the lower-doses of 0.5 g/kg and 1.0 g/kg Realgar shown a similar view to the Control group. Thirty-three metabolites and seventeen metabolites were screened and identified in the serum and kidney of mice in a dose-dependent manner. respectively. Correlation analysis showed a strong correlation among these metabolites. Amino acid metabolism, lipid metabolism, glutathione metabolism, and purine metabolism pathways were found to be mainly associated with Realgar nephrotoxicity. This work illustrated the metabolic alterations in Realgar-induced nephrotoxic mice through a metabolomic approach.

Monomethylated arsenic was the Major methylated arsenic in Red blood cells of acute promyelocytic leukemia patients treated with arsenic trioxide

BACKGROUND

Arsenic trioxide (ATO) has been successfully applied in the treatment of acute promyelocytic leukemia (APL). Arsenic metabolites including inorganic arsenic and methylated arsenic could lead to different toxicity and curative effect. This study aims to establish a method to determine arsenic species in red blood cells (RBCs), clarify the distribution characteristics of arsenic species in RBCs.

METHODS

Steady state blood samples were collected from 97 APL patients. H₂O₂ and HClO₄ were used to release the hemoglobin bounding arsenic and precipitate protein. Arsenite (iAs^III), arsenate (iAs^V), monomethylarsonic acid (MMA^V) and dimethylarsinic acid (DMA^V) in plasma and RBCs were detected by HPLC-HG-AFS. Free and bound arsenic species in RBCs were separated by 30 kDa molecular mass cutoff filters and determined to evaluate hemoglobin binding capacity of different arsenic species.

RESULTS

The method was validated with accuracy ranged from 84.75% to 104.13%. Arsenic species in RBCs followed the trend iAs > MMA > DMA (p < 0.01), while the concentration of DMA was significantly higher than iAs and MMA in plasma (p < 0.01). The correlation between iAs concentration in plasma and corresponding RBCs arsenic level was weak. And the concentrations of DMA and MMA in plasma were moderately positive correlated with those in RBCs. Hemoglobin-binding ratios of iAs, MMA and DMA were all over 70 %.

CONCLUSIONS

In this study, we provided a reliable method to determine arsenic species in RBCs of APL patients treated with ATO by HPLC-HG-AFS. It was confirmed that the concentration of DMA is the highest in plasma, while MMA is the most predominant methylated arsenic in RBCs. High affinity of MMA with human Hb was responsible for the accumulation of arsenic in RBCs of APL patients.

Tetraarsenic oxide affects non-coding RNA transcriptome through deregulating polycomb complexes in MCF7 cells

Non-coding RNAs (ncRNAs) play important and diverse roles in mammalian cell biology and pathology. Although the functions of an increasing number of ncRNAs have been identified, the mechanisms underlying ncRNA gene expression remain elusive and are incompletely understood. Here, we investigated ncRNA gene expression in Michigan cancer foundation 7 (MCF7), a malignant breast cancer cell line, on treatment of tetraarsenic oxide (TAO), a potential anti-cancer drug. Our genomic analyses found that TAO up- or down-regulated ncRNA genes genome-wide. A subset of identified ncRNAs with critical biological and clinical functions were validated by real-time quantitative polymerase chain reaction. Intriguingly, these TAO-regulated genes included CDKN2B-AS, HOXA11-AS, SHH, and DUSP5 that are known to interact with or be targeted by polycomb repressive complexes (PRCs). In addition, the PRC subunits were enriched in these TAO-regulated ncRNA genes and TAO treatment deregulated the expression of PRC subunits. Strikingly, TAO decreased the cellular and gene-specific levels of EZH2 expression and H3K27me3. In particular, TAO reduced EZH2 and H3K27me3 and increased transcription at MALAT1 gene. Inhibiting the catalytic activity of EZH2 using GSK343 increased representative TAO-inducible ncRNA genes. Together, our findings suggest that the expression of a subset of ncRNA genes is regulated by PRC2 and that TAO could be a potent epigenetic regulator through PRCs to modulate the ncRNA gene expression in MCF7 cells.