Arsenic trioxide-mediated growth inhibition of myeloma cells is associated with an extrinsic or intrinsic signaling pathway through activation of TRAIL or TRAIL receptor 2

Arsenic exposure and pulmonary function decline: Potential mediating role of TRAIL in chronic obstructive pulmonary disease patients

BACKGROUND

Environmental arsenic (As) exposure is strongly related to the progression of chronic obstructive pulmonary disease (COPD). Pulmonary epithelial cells apoptosis is implicated in the pathophysiological mechanisms of COPD. However, the role of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), one biomarker of apoptosis, remains unclear in As-mediated pulmonary function alternations in COPD patients.

METHODS

This study included 239 COPD patients. The serum level of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) was measured by enzyme-linked immunosorbent assay (ELISA). The blood As level was determined through inductively coupled plasma mass spectrometry (ICP-MS).

RESULTS

Blood As levels exhibited a negative and dose-dependent correlation with pulmonary function. Per unit elevation of blood arsenic concentrations was related to reductions of 0.339 L in FEV1, 0.311 L in FVC, 1.171% in FEV1/FVC%, and 7.999% in FEV1% in COPD subjects. Additionally, a positive dose-response correlation of blood As with serum TRAIL was found in COPD subjects. Additionally, the level of serum TRAIL was negatively linked to lung function. Elevated TRAIL significantly mediated As-induced decreases of 11.05%, 13.35%, and 31.78% in FVC, FEV1, and FEV1%, respectively among the COPD patients.

CONCLUSION

Blood As level is positively correlated with pulmonary function decline and serum TRAIL increase in individuals with COPD. Our findings suggest that elevated TRAIL levels may serve as a mediating mechanism through which As contributes to declining lung function in COPD patients.

Inheritance of paternal lifestyles and exposures through sperm DNA methylation

Many different lifestyle factors and chemicals present in the environment are a threat to the reproductive tracts of humans. The potential for parental preconception exposure to alter gametes and for these alterations to be passed on to offspring and negatively affect embryo growth and development is of concern. The connection between maternal exposures and offspring health is a frequent focus in epidemiological studies, but paternal preconception exposures are much less frequently considered and are also very important determinants of offspring health. Several environmental and lifestyle factors in men have been found to alter sperm epigenetics, which can regulate gene expression during early embryonic development. Epigenetic information is thought to be a mechanism that evolved for organisms to pass on information about their lived experiences to offspring. DNA methylation is a well-studied epigenetic regulator that is sensitive to environmental exposures in somatic cells and sperm. The continuous production of sperm from spermatogonial stem cells throughout a man's adult life and the presence of spermatogonial stem cells outside of the blood-testis barrier makes them susceptible to environmental insults. Furthermore, altered sperm DNA methylation patterns can be maintained throughout development and ultimately result in impairments, which could predispose offspring to disease. Innovations in human stem cell-based spermatogenic models can be used to elucidate the paternal origins of health and disease.

Realgar nanoparticles versus ATO arsenic compounds induce in vitro and in vivo activity against multiple myeloma

Multiple myeloma (MM), a B cell malignancy characterized by clonal proliferation of plasma cells in the bone marrow, remains incurable despite the use of novel and conventional therapies. In this study, we demonstrated MM cell cytotoxicity triggered by realgar (REA; As₄ S₄ ) nanoparticles (NREA) versus Arsenic trioxide (ATO) against MM cell lines and patient cells. Both NREA and ATO showed in vivo anti-MM activity, resulting in significantly decreased tumour burden. The anti-MM activity of NREA and ATO is associated with apoptosis, evidenced by DNA fragmentation, depletion of mitochondrial membrane potential, cleavage of caspases and anti-apoptotic proteins. NREA induced G₂ /M cell cycle arrest and modulation of cyclin B1, p53 (TP53), p21 (CDKN1A), Puma (BBC3) and Wee-1 (WEE1). Moreover, NREA induced modulation of key regulatory molecules in MM pathogenesis including JNK activation, c-Myc (MYC), BRD4, and histones. Importantly, NREA, but not ATO, significantly depleted the proportion and clonogenicity of the MM stem-like side population, even in the context of the bone marrow stromal cells. Finally, our study showed that both NREA and ATO triggered synergistic anti-MM activity when combined with lenalidomide or melphalan. Taken together, the anti-MM activity of NREA was more potent compared to ATO, providing the preclinical framework for clinical trials to improve patient outcome in MM.

Arsenic Trioxide Induces Apoptosis via Specific Signaling Pathways in HT-29 Colon Cancer Cells

BACKGROUND

Arsenic trioxide (ATO) is highly effective in the treatment of patients with acute promyelocytic leukemia (APL). It is a chemotherapeutic agent that has been shown to induce apoptosis in several tumor cell lines. However, research into its effects on colon carcinoma cells is still very limited. We previously reported that ATO is cytotoxic and causes DNA damage in HT-29 human colorectal adenocarcinoma cells. In the present study, we further evaluated its effect on oxidative stress (OS), and examined its apoptotic mechanisms of action on HT-29 cells.

METHODS

OS was assessed by spectrophotometric measurements of MDA levels while cell cycle analysis was evaluated by flow cytometry to determine whether ATO induces cell cycle arrest. Its effect on early apoptosis was also evaluated by flow cytometry using Annexin V-FITC/PI staining. Fluorescence microscopy was used to detect the morphological changes, and Western blotting was carried out to determine the expression of apoptosis-related proteins.

RESULTS

The lipid peroxidation assay revealed a dose-dependent increase in MDA production. DAPI staining showed morphological changes in the cell's nucleus due to apoptosis. Cell cycle analysis and Annexin V-FITC assay also demonstrated a dose-dependent effect of ATO in the accumulation of cells at the sub G1 phase, and the percentages of Annexin V-positive cells, respectively. Western blot data showed that ATO upregulated the expression of caspase 3, Bax, and cytochrome C, and down-regulated the expression of Bcl-2.

CONCLUSION

Taken together, our findings indicate that ATO induces OS and cytotoxicity in HT-29 cells through the mitochondria mediated intrinsic pathway of apoptosis.

Targeting hedgehog signalling by arsenic trioxide reduces cell growth and induces apoptosis in rhabdomyosarcoma

Rhabdomyosarcomas (RMS) are soft tissue tumours treated with a combination of surgery and chemotherapy. However, mortality rates remain high in case of recurrences and metastatic disease due to drug resistance and failure to undergo apoptosis. Therefore, innovative approaches targeting specific signalling pathways are urgently needed. We analysed the impact of different hedgehog (Hh) pathway inhibitors on growth and survival of six RMS cell lines using MTS assay, colony formation assay, 3D spheroid cultures, flow cytometry and western blotting. Especially the glioma-associated oncogene family (GLI) inhibitor arsenic trioxide (ATO) effectively reduced viability as well as clonal growth and induced cell death in RMS cell lines of embryonal, alveolar and sclerosing, spindle cell subtype, whereas normal skeletal muscle cells were hardly compromised by ATO. Combination of ATO with itraconazole potentiated the reduction of colony formation and spheroid size. These results show that ATO is a promising substance for treatment of relapsed and refractory RMS by directly targeting GLI transcription factors. The combination with itraconazole or other chemotherapeutic drugs has the opportunity to enforce the treatment efficiency of resistant and recurrent RMS.

Arsenic trioxide reduces chemo-resistance to 5-fluorouracil and cisplatin in HBx-HepG2 cells via complex mechanisms

Background

Multidrug resistance is one of the major reasons chemotherapy-based treatments failed in hepatitis B virus (HBV) related hepatocellular carcinoma (HCC). Hypoxia is generally associated with tumor chemo-resistance. The aim of the study was to investigate the effect of Arsenic trioxide (As₂O₃) on the hypoxia-induced chemo-resistance to 5-FU or cisplatin and explored its underlying mechanism in the HBx-HepG2 cells.

Methods

MTT assay was used to examine the cell viability. Mitochondrial membrane potential (MMP) and cell cycle was examined by flow cytometry. qRT-PCR was employed to observe the mRNA expression level; and western blot assay was used to determine the protein expression level.

Results

Our results showed that transfection of HBx plasmid established the HBx-HepG2 cells expressing HBx, and the expression of HBx was confirmed by qRT-PCR and western blot. Exposure of HBx-HepG2 cells to hypoxia (5 % O₂, 3 % O₂, 1 % O₂) for 48 h increased the chemo-resistance to 5-fluorouracil (5-FU) (50–1600 µM) and cisplatin (25–800 µM), reduced MMP, and caused the cell cycle arrest at G₀/G₁ phase in a concentration-dependent manner. Hypoxia also concentration-dependently (5 % O₂, 3 % O₂, 1 % O₂) reduced mRNA expression level of P-glycoprotein (P-gp), multidrug resistance protein (MRP1), lung resistance protein (LRP), and decreased the protein expression level of hypoxia-inducible factor-1α (HIF-1α), P-gp MRP1, and LRP. Following pretreatment with As₂O₃ at a non-cytotoxic concentration re-sensitized the hypoxia (1 % O₂)-induced chemo-resistance to 5-FU and cisplatin in HBx-HepG2 cells. As₂O₃ pretreatment also prevented MMP reduction and G₀/G₁ arrest induced by hypoxia. Meanwhile, As₂O₃ antagonized increase of HIF-1α protein induced by hypoxia, and it also suppresses the increase in expression levels of P-gp, MRP1, and LRP mRNA and proteins. In addition, As₂O₃ in combination with 5-FU treatment caused up-regulation of DR5, caspase 3, caspase 8, and caspase 9, and down-regulation of BCL-2, but had no effect of DR4.

Conclusions

Our results may suggest that As₂O₃ re-sensitizes hypoxia-induced chemo-resistance in HBx-HepG2 via complex pathways, and As₂O₃ may be a potential agent that given in combination with other anti-drugs for the treatment of HBV related HCC, which is resistant to chemotherapy.

The clinical activity of arsenic trioxide, ascorbic acid, ifosfamide and prednisone combination therapy in patients with relapsed and refractory multiple myeloma

This study aimed to investigate the activity of arsenic trioxide (As2O3) combined with ascorbic acid, ifosfamide, and prednisone chemotherapy in patients with repeatedly relapsed and refractory multiple myeloma (MM). Here, we retrospectively analyzed medical data of 30 MM patients showing progressive disease after receiving at least two previous lines of treatment including an immunomodulatory agent (thalidomide or lenalidomide) and a proteasome inhibitor. There were 19 men and eleven women, aged 54-73 (median 65) years, in this study. The distribution of different isotypes included immunoglobulin G(IgG) (12 patients), IgA (six patients), IgD (three), and light chain (nine patients). All the patients were Durie-Salmon stage III and had relapsed at least three times; the median cycles of prior therapies was 15 (range 10-18). The patients were treated with As2O3, ascorbic acid, and CP (ifosfamide 1 g on day 1, day 3, day 5, and day 7; prednisone 30 mg taken orally for 2 weeks). As2O3 was administered as an intravenous infusion at a dose of 10 mg/d and ascorbic acid at a dose of 2 g/d for 14 days of each 4-week cycle. The results showed that after 2 cycles of therapy, there were five patients that attained partial response, 15 had minimal response, five had no change, and five had progressive disease. The overall response rate was 66.7% (20/30 cases), 50% (10/20 cases), and 40% (2/5 cases), respectively, after 2, 4, and 6 cycles of the therapy. But there were no patients that attained complete remission. The median time of overall survival and progression-free survival were 48 (29-120) and 6 (2-8) months, respectively. The most common treatment-related adverse events included neutropenia, fatigue, anemia, thrombocytopenia, and infection that could be tolerated. The results showed that As2O3 combined with ascorbic acid, ifosfamide, and prednisone chemotherapy may be a choice treatment for repeatedly relapsed and refractory MM patients.

Bruton tyrosine kinase is a therapeutic target in stem-like cells from multiple myeloma

Ibrutinib (Imbruvica), a small-drug inhibitor of Bruton tyrosine kinase (BTK), is currently undergoing clinical testing in patients with multiple myeloma, yet important questions on the role of BTK in myeloma biology and treatment are outstanding. Using flow-sorted side population cells from human myeloma cell lines and multiple myeloma primary samples as surrogate for the elusive multiple myeloma stem cell, we found that elevated expression of BTK in myeloma cells leads to AKT/WNT/β-catenin-dependent upregulation of key stemness genes (OCT4, SOX2, NANOG, and MYC) and enhanced self-renewal. Enforced transgenic expression of BTK in myeloma cells increased features of cancer stemness, including clonogenicity and resistance to widely used myeloma drugs, whereas inducible knockdown of BTK abolished them. Furthermore, overexpression of BTK in myeloma cells promoted tumor growth in laboratory mice and rendered side population-derived tumors that contained high levels of BTK more sensitive to the selective, second-generation BTK inhibitor, CGI1746, than side population-derived tumors that harbored low levels of BTK. Taken together, these findings implicate BTK as a positive regulator of myeloma stemness and provide additional support for the clinical testing of BTK-targeted therapies in patients with myeloma.

Arsenic trioxide inhibits cell proliferation and human papillomavirus oncogene expression in cervical cancer cells

Arsenic trioxide (As2O3) has shown therapeutic effects in some leukemias and solid cancers. However, the molecular mechanisms of its anticancer efficacy have not been clearly elucidated, particularly in solid cancers. Our previous data showed that As2O3 induced apoptosis of human papillomavirus (HPV) 16 DNA-immortalized human cervical epithelial cells and cervical cancer cells and inhibited the expression of HPV oncogenes in these cells. In the present study, we systemically examined the effects of As2O3 on five human cervical cancer cell lines and explored the possible molecular mechanisms. MTT assay showed that HPV-negative C33A cells were more sensitive to growth inhibition induced by As2O3 than HPV-positive cervical cancer cells, and HPV 18-positive HeLa and C4-I cells were more sensitive to As2O3 than HPV 16-positive CaSki and SiHa cells. After As2O3 treatment, both mRNA and protein levels of HPV E6 and E7 obviously decreased in all HPV positive cell lines. In contrast, p53 and Rb protein levels increased in all tested cell lines. Transcription factor AP-1 protein expression decreased significantly in HeLa, CaSki and C33A cells with ELISA method. These results suggest that As2O3 is a potential anticancer drug for cervical cancer.

Imprinted genes and the environment: links to the toxic metals arsenic, cadmium, lead and mercury

Imprinted genes defy rules of Mendelian genetics with their expression tied to the parent from whom each allele was inherited. They are known to play a role in various diseases/disorders including fetal growth disruption, lower birth weight, obesity, and cancer. There is increasing interest in understanding their influence on environmentally-induced disease. The environment can be thought of broadly as including chemicals present in air, water and soil, as well as food. According to the Agency for Toxic Substances and Disease Registry (ATSDR), some of the highest ranking environmental chemicals of concern include metals/metalloids such as arsenic, cadmium, lead and mercury. The complex relationships between toxic metal exposure, imprinted gene regulation/expression and health outcomes are understudied. Herein we examine trends in imprinted gene biology, including an assessment of the imprinted genes and their known functional roles in the cell, particularly as they relate to toxic metals exposure and disease. The data highlight that many of the imprinted genes have known associations to developmental diseases and are enriched for their role in the TP53 and AhR pathways. Assessment of the promoter regions of the imprinted genes resulted in the identification of an enrichment of binding sites for two transcription factor families, namely the zinc finger family II and PLAG transcription factors. Taken together these data contribute insight into the complex relationships between toxic metals in the environment and imprinted gene biology.

Heme oxygenase-1 silencing increases the sensitivity of human osteosarcoma MG63 cells to arsenic trioxide

Arsenic trioxide (ATO) has been successfully used to treat leukemia and some solid malignant tumors. Our previous study regarding the effects of ATO on mesenchymal-derived human osteosarcoma MG63 cells showed that heme oxygenase-1 (HO-1) was strongly induced upon treatment with ATO. The present study sought to investigate the effect of silencing HO-1 on the sensitivity of osteosarcoma cells to ATO to determine the potential for therapeutic applications. Small hairpin RNA (shRNA)-mediated interference was used to silence HO-1 in MG63 cells. Viability, apoptosis, and intracellular reactive oxygen species (ROS) of the cells were assessed to evaluate the sensitivity of the cells to ATO as well as the potential mechanisms responsible. shRNA-mediated interference prevented the induction of HO-1, increased cell death, and increased intracellular ROS levels in MG63 cells upon treatment with ATO. Silencing HO-1 increased the susceptibility of MG63 cells to the chemotherapeutic drug ATO by enhancing intracellular accumulation of ROS. Our results suggest that the inhibition of HO-1 could improve the outcome of osteosarcoma treated with ATO.

Arsenic trioxide inhibits the proliferation of myeloma cell line through notch signaling pathway

Arsenic Trioxide (ATO) has shown remarkable efficacy for the treatment of multiple myeloma (MM). However, the mechanism by which ATO exerts its inhibitory effect on the proliferation of myeloma cells remains to be clarified. We study the inhibitory effect of ATO at various concentrations on the proliferation of the myeloma cell line RPMI 8226 and discussed the molecular mechanism of ATO on myeloma cell line. Our results proved that ATO had a significant dose-dependent and time-dependent inhibitory effect on the expressions of the Notch receptor (Notch1) and Notch ligand (Jag2). Data from the real-time PCR assay showed that the mRNA expression levels of the Jag2 gene and its downstream gene Hes1 were both significantly down-regulated after the myeloma cells were treated with ATO while the expression of the tumor suppressor gene PTEN was up-regulated. These results elucidated the molecular mechanism underlying the ATO mediated inhibition of myeloma cell proliferation. This is the first report on the anti-myeloma activity in myeloma cells through inhibition of the Notch signaling pathway.

A Phase I study of arsenic trioxide (Trisenox), ascorbic acid, and bortezomib (Velcade) combination therapy in patients with relapsed/refractory multiple myeloma

PURPOSE

This Phase I study assessed the feasibility of concomitant arsenic trioxide (ATO), ascorbic acid (AA), and bortezomib (Velcade™) (AAV) for patients with relapsed/refractory multiple myeloma.

EXPERIMENTAL DESIGN

ATO (0.25 mg/kg) and AA (1 g) were given with an escalating dose of bortezomib (1 mg/m(2) or 1.3 mg/m(2) IV bolus on days 1 and 8 of a 21-day cycle).

RESULTS

Ten patients (median age 62 years), with a median of 3 prior regimens, were enrolled. Four (40%) patients achieved clinical benefit, with one patient achieving a durable partial response. No formal DLTs were encountered.

CONCLUSION

AAV combination was feasible and demonstrated some benefits in this heavily pretreated population.

SNP-based mapping arrays reveal high genomic complexity in monoclonal gammopathies, from MGUS to myeloma status

Genetic events mediating transformation from premalignant monoclonal gammopathies (MG) to multiple myeloma (MM) are unknown. To obtain a comprehensive genomic profile of MG from the early to late stages, we performed high-resolution analysis of purified plasma cells from 20 MGUS, 20 smoldering MM (SMM) and 34 MM by high-density 6.0 SNP array. A progressive increase in the incidence of copy number abnormalities (CNA) from MGUS to SMM and to MM (median 5, 7.5 and 12 per case, respectively) was observed (P=0.006). Gains on 1q, 3p, 6p, 9p, 11q, 19p, 19q and 21q along with 1p, 16q and 22q deletions were significantly less frequent in MGUS than in MM. Although 11q and 21q gains together with 16q and 22q deletions were apparently exclusive of MM status, we observed that these abnormalities were also present in minor subclones in MGUS. Overall, a total of 65 copy number-neutral LOH (CNN-LOH) were detected. Their frequency was higher in active MM than in the asymptomatic entities (P=0.047). A strong association between genetic lesions and fragile sites was also detected. In summary, our study shows an increasing genomic complexity from MGUS to MM and identifies new chromosomal regions involved in CNA and CNN-LOH.

Mutant p53 protein is targeted by arsenic for degradation and plays a role in arsenic-mediated growth suppression

p53 is frequently mutated in tumor cells, and mutant p53 is often highly expressed due to its increased half-life. Thus, targeting mutant p53 for degradation might be explored as a therapeutic strategy to manage tumors that are addicted to mutant p53 for survival. Arsenic trioxide, a drug for patients with acute promyelocytic leukemia, is found to target and degrade a class of proteins with high levels of cysteine residues and vicinal thiol groups, such as promyelocytic leukemia protein (PML) and PML-retinoic acid receptor α fusion protein. Interestingly, wild type p53 is accumulated in cells treated with arsenic compounds, presumably due to arsenic-induced oxidative stresses. In this study, we found that wild type p53 is induced by arsenic trioxide in tumor cells, consistent with published studies. In contrast, we found that arsenic compounds degrade both endogenous and ectopically expressed mutant p53 in time- and dose-dependent manners. We also found that arsenic trioxide decreases the stability of mutant p53 protein through a proteasomal pathway, and blockage of mutant p53 nuclear export can alleviate the arsenic-induced mutant p53 degradation. Furthermore, we found that knockdown of endogenous mutant p53 sensitizes, whereas ectopic expression of mutant p53 desensitizes, tumor cells to arsenic treatment. Taken together, we found that mutant p53 is a target of arsenic compounds, which provides an insight into exploring arsenic compound-based therapy for tumors harboring a mutant p53.

Arsenic trioxide induces apoptosis of p53 null osteosarcoma MG63 cells through the inhibition of catalase

This study is aimed at investigating the effect of arsenic trioxide (ATO) on p53 null human osteosarcoma MG63 cells and the mechanisms underlying the effect. Apoptotic cells were detected by flow cytometry with Annexin-V-FITC/PI dual staining. Intracellular ROS was measured by flow cytometry using a cell-based ROS assay kit. Catalase activity and mRNAs were analyzed by ELISA and real-time qRT-PCR, respectively. Apoptosis and intracellular ROS of MG63 cells increased in a dose-dependent manner following arsenic treatments. Both were prevented by the presence of the anti-oxidative reagent N-acetyl-L: -cysteine (NAC) or catalase (CAT). Furthermore, the activity and mRNA of catalase were decreased strikingly following arsenic exposure. The present study indicates that p53 null osteosarcoma MG63 cells are susceptible to the ATO; the inhibition of catalase and the resulted intracellular ROS accumulation are an important molecular mechanism under which ATO induces apoptosis of p53-deficient osteosarcoma cells.