Arsenic trioxide induces depolymerization of microtubules in an acute promyelocytic leukemia cell line

Arsenic trioxide and Erlotinib loaded in RGD-modified nanoliposomes for targeted combination delivery to PC3 and PANC-1 cell lines

During the past few years, advances in drag delivery have provided many opportunities in the treatment of various diseases and cancer. Arsenic trioxide (ATO) and Erlotinib (Erlo) are two drugs, approved by the United States Food and Drug Administration to treat cancer, but their use is limited in terms of the toxicity of ATO and the low solubility of Erlo. This study aimed to prepare arginine-glycine-aspartic acid (RGD)-decorated nanoliposomes (NLPs) containing Erlo and ATO (NLPs-ATO-Erlo-RGD) to increase the solubility and reduce the toxicity of Erlo and ATO for cancer treatment. The results of transmission electron microscopy and dynamic light scattering showed that NLPs were synthesized uniformly, with spherical shape morphology and particle sizes between 140 and 160 nm. High-performance liquid chromatography and ICP-MS results showed that about 90% of the drug was loaded in the NLPs. In comparison with NLPs-ATO-Erlo, NLPs-ATO-Erlo-RGD demonstrated considerable toxicity against the αvβ3 overexpressing PC3 cell line in the MTT experiment. It had no effect on the PANC-1 cell line. In addition, apoptosis assays using Annexin V/PI demonstrated that NLPs-ATO-Erlo-RGD generated the highest apoptotic rates in PC3 cells when compared with NLPs-ATO-Erlo and the combination of free ATO and Erlo. Furthermore, treatment with NLPs-ATO-Erlo-RGD in (p < 0.05) PC3 cell line significantly reduced EGFR level. It is concluded NLPs-ATO-Erlo-RGD as a novel drug delivery system may be a promising platform for the treatment of cancer.

Effects of sodium arsenite and dimethyl arsenic acid on Liaoning cashmere goat skin fibroblasts

The morphology and oxidation state of arsenic in its compounds affects the skin cell toxicity. Accordingly, the present study was conducted to explore the effects of two different arsenic compounds on the proliferation and survival of Liaoning cashmere goat skin fibroblasts. Based on MTT assay results, at 24 h, the proliferation concentration, critical concentration, and half inhibitory concentration (IC50) of sodium arsenite were 0.50, 5.00, and 45.66 μmol/L, respectively. The corresponding values for dimethyl arsenic acid were 0.85, 1.00, and 38.68 mmol/L. Immunofluorescence, transmission electron microscopy, and mitochondria membrane potential (MMP) assays showed that sodium arsenite promotes microtubule polymerization and increases MMP, while cells treated with dimethyl arsenic acid exhibited cytoskeletal collapse and decreased MMP. In the IC50 groups for both arsenic agents, the cytoskeletons collapsed, microtubules were gathered into bundles, and MMP was significantly decreased. Dimethyl arsenic acid had a stronger effect on MMP than sodium arsenite. Flow cytometry revealed a slightly lower occurrence of apoptosis in the sodium arsenite proliferation group, while it was slightly increased in the dimethyl arsenic acid proliferation group. Apoptosis was increased more significantly in the sodium arsenite IC50 group than in the dimethyl arsenic acid IC50 group. These results indicate that the differences in cell proliferation and cytotoxicity induced by inorganic and organic arsenic are related to their effects on cellular structures.

Mechanistic effects of arsenic trioxide on acute promyelocytic leukemia and other types of leukemias

Acute promyelocytic leukemia (APL), a subtype of acute myeloid leukemia characterized with a translocation between promyelocytic leukemia gene (PML) on chromosome 15 and retinoic acid receptor alpha gene (RARα) on chromosome 17. Transcription of this fusion gene results in PML/RARα fusion protein blocking expression of critical genes involved in differentiation of myeloid cells through interaction with RAR element. PML/RARα fusion protein prevents normal function of PML and RARα as well as inhibiting apoptosis. Arsenic trioxide (ATO) is an important agent for the treatment of relapsed and newly diagnosed APL. ATO induces apoptosis, autophagy, and partial cellular differentiation as well as inhibiting cell growth and angiogenesis. Recognition of signaling pathways and molecular mechanisms induced by ATO can be effective for discovering novel treatment strategies to target leukemia cells. Also, it can be developed for the treatment of a variety of cancer cells. This review provides a perspective on anticancerous effects of ATO on APL and leukemia cells.

Characterization of the cellular effects and mechanism of arsenic trioxide-induced hepatotoxicity in broiler chickens

To characterize the cellular effects and mechanism of arsenic trioxide (ATO)-induced hepatotoxicity in broiler chickens, increasing concentrations of ATO (0, 0.6, 1.2, 2.4, and 4.8 μM) were added to chicken hepatocyte cultures in vitro. The changes in hepatocyte morphology, oxidative stress and apoptosis were evaluated using fluorescence microscopy and flow cytometry. The effects of ATO on mRNA or protein expression of antioxidant enzymes, especially methionine sulfoxide reductase (Msr), were analyzed using qRT-PCR and western blotting assays. Increased apoptosis were concomitant with increased reactive oxygen species (ROS) accumulation and upregulation of antioxidant enzymes such as catalase (CAT) and superoxide dismutase (SOD) with increasing ATO concentrations. Moreover, G₁ phase arrest and dysregulation of the balance between antiapoptotic versus proapoptotic factors were noted. Furthermore, upregulation of HO-1, SOD-1, and TRX in the ATO groups were consistent with ATO-induced oxidative damage. High Msr, SOD-1, TRX, Bak1, Bax, and p53 protein levels in the ATO groups indicate that these proteins may have accumulated to counter ATO-induced oxidative stress. ROS scavenger N-acetyl-l-cysteine (NAC) could reverse ATO-induced oxidative damage and restore hepatocyte viability, even with compromised Msr function. Our findings suggest that Msr can protect broiler hepatocytes against ATO-induced oxidative stress. Furthermore, NAC-mediated reversal of oxidative damage may represent a strategy to mitigate potential economic losses associated with arsenic poisoning in the poultry industry.

Arsenic trioxide induces cell cycle arrest and alters DNA methylation patterns of cell cycle regulatory genes in colorectal cancer cells

AIMS

Cell cycle dysregulation is important in tumorigenesis. Transcriptional silencing of cell cycle regulatory genes, due to DNA methylation, is a common epigenetic event in malignancies. As₂O₃ has been shown to induce cell cycle arrest and also to be a potential hypomethylating agent. Our study aimed to investigate DNA methylation patterns of cell cycle regulatory genes promoters, the effects of Arsenic trioxide (As₂O₃) on the methylated genes and cell cycle distribution in colorectal cancer (CRC) cell lines.

MAIN METHODS

The methylation-specific PCR (MSP) and/or restriction enzyme-based methods were used to study the promoter methylation patterns of 24 cell cycle regulatory genes in CRC cell lines. Gene expression level and cell cycle distribution were determined by Real-time PCR and flow cytometric analyses, respectively.

KEY FINDINGS

Our methylation analysis indicated that only promoters of RBL1 (p107), CHFR and p16 genes were aberrantly methylated in three cell lines. As₂O₃ significantly decreased DNA methylation in promoter regions of these genes and restored their expression. We found that As₂O₃ significantly reduced the expression of DNA methyltransferase 1 (DNMT1) and increased arsenic methyltransferase (AS3MT). Furthermore, As₂O₃ altered transcriptional activity of several unmethylated cell cycle regulatory genes including cyclin B1, E1, D1, GADD45A and p21. Cell cycle flow cytometry analysis showed As₂O₃ induced G2/M arrest in all three cell lines.

SIGNIFICANCE

These data suggest that demethylation and alteration in the expression level of the cell cycle-related genes may be possible mechanisms in As₂O₃-induced cell cycle arrest in colorectal cancer cells.

E2F1 downregulation by arsenic trioxide in lung adenocarcinoma

Lung cancer is one of the most common cancers worldwide. Arsenic trioxide (ATO) has been approved by the US Food and Drug Administration for the treatment of acute promyelocytic leukemia. Nonetheless preliminary data have suggested potential activity of ATO in solid tumors including lung cancer. This study aimed to examine the underlying mechanisms of ATO in the treatment of lung adenocarcinoma. Using a panel of 7 lung adenocarcinoma cell lines, the effects of ATO treatment on cell viability, expression of E2F1 and its downstream targets, phosphatidylserine externalization, mitochondrial membrane depolarization and alteration of apoptotic/anti-apoptotic factors were studied. Tumor growth inhibition in vivo was investigated using a nude mouse xenograft model. ATO decreased cell viability with clinically achievable concentrations (8 µM) in all cell lines investigated. This was accompanied by reduced expression of E2F1, cyclin A2, skp2, c-myc, thymidine kinase and ribonucleotide reductase M1, while p-c-Jun was upregulated. Cell viability was significantly decreased with E2F1 knockdown. Treatment with ATO resulted in phosphatidylserine externalization in H23 cells and mitochondrial membrane depolarization in all cell lines, associated with truncation of Bid, downregulation of Bcl-2, upregulation of Bax and Bak, caspase-9 and -3 activation and PARP cleavage. Using the H358 xenograft model, the tumor growth was suppressed in the ATO treatment group during 8 days of treatment, associated with downregulation of E2F1 and upregulation of truncated Bid and cleaved caspase-3. In conclusion, ATO has potent in vitro and in vivo activity in lung adenocarcinoma, partially mediated through E2F1 downregulation and apoptosis.