Combination of arsenic trioxide and chemotherapy in small cell lung cancer

Can arsenic do anything good? Arsenic nanodrugs in the fight against cancer - last decade review

Arsenic has been an element of great interest among scientists for many years as it is a widespread metalloid in our ecosystem. Arsenic is mostly recognized with negative connotations due to its toxicity. Surely, most of us know that a long time ago, arsenic trioxide was used in medicine to treat, mainly, skin diseases. However, not everyone knows about its very wide and promising use in the treatment of cancer. Initially, in the seventies, it was used to treat leukemia, but new technological possibilities and the development of nanotechnology have made it possible to use arsenic trioxide for the treatment of solid tumours. The most toxic arsenic compound - arsenic trioxide - as the basis of anticancer drugs in which they function as a component of nanoparticles is used in the fight against various types of cancer. This review aims to present the current solutions in various cancer treatment using arsenic compounds with different binding motifs and methods of preparation to create targeted nanoparticles, nanodiamonds, nanohybrids, nanodrugs, or nanovehicles.

Arsenic trioxide: applications, mechanisms of action, toxicity and rescue strategies to date

Arsenical medicine has obtained its status in traditional Chinese medicine for more than 2,000 years. In the 1970s, arsenic trioxide was identified to have high efficacy and potency for the treatment of acute promyelocytic leukemia, which promoted many studies on the therapeutic effects of arsenic trioxide. Currently, arsenic trioxide is widely used to treat acute promyelocytic leukemia and various solid tumors through various mechanisms of action in clinical practice; however, it is accompanied by a series of adverse reactions, especially cardiac toxicity. This review presents a comprehensive overview of arsenic trioxide from preclinical and clinical efficacy, potential mechanisms of action, toxicities, and rescue strategies for toxicities to provide guidance or assistance for the clinical application of arsenic trioxide.

Mechanistic update of Trisenox in blood cancer

Acute promyelocytic leukemia (APL)/blood cancer is M3 type of acute myeloid leukemia (AML) formed inside bone marrow through chromosomal translocation mutation usually between chromosome 15 & 17. It accounts around 10% cases of AML worldwide. Trisenox (TX/ATO) is used in chemotherapy for treatment of all age group of APL patients with highest efficacy and survival rate for longer period. High concentration of TX inhibits growth of APL cells by diverse mechanism however, it cures only PML-RARα fusion gene/oncogene containing APL patients. TX resistant APL patients (different oncogenic make up) have been reported from worldwide. This review summarizes updated mechanism of TX action via PML nuclear bodies formation, proteasomal degradation, autophagy, p53 activation, telomerase activity, heteromerization of pRb & E2F, and regulation of signaling mechanism in APL cells. We have also provided important information of combination therapy of TX with other molecules mechanism of action in acute leukemia cells. It provides updated information of TX action for researcher which may help finding new target for further research in APL pathophysiology or new TX resistant APL patients drug designing.

The application of arsenic trioxide in cancer: An umbrella review of meta-analyses based on randomized controlled trials

ETHNOPHARMACOLOGICAL RELEVANCE

Processed from natural minerals, arsenic trioxide (ATO) as an ancient Chinese medicine has been used to treat diseases for over 2000 years. And it was applied to treat acute promyelocytic leukemia (APL) since the 1970s in China. Summarizing the clinical evidence of ATO in cancer is conducive to further understanding, development, and promotion of its pharmacological research.

AIM OF THE STUDY

It is the first time to comprehensively assess and summarize the evidence of ATO in cancer treatment via umbrella review.

MATERIALS AND METHODS

8 databases in English or Chinese from their inception to February 21, 2023 were searched by two reviewers separately and suitable meta-analyses (MAs) were included in this umbrella review. Their methodological quality and risk of bias were evaluated and data of outcomes was extracted and pooled again. The evidence certainty of pooled results was classified.

RESULTS

17 MAs with 27 outcomes and seven comparisons in three cancers were included in this umbrella review. However, their methodological quality was unsatisfactory with 6 MAs as low quality and 12 MAs as critically low quality. Their shortcomings were mainly focused on protocol, literature selecting, bias risk, small sample study bias, and conflicts of interest or funding. And they were all assessed as high risk in bias. It was suggested that ATO had an advantage in enhancing complete remission rate, event-free survival, and recurrence free survival and decreasing recurrence rate, cutaneous toxicity, hyper leukocyte syndrome, tretinoin syndrome, edema and hepatotoxicity in different comparisons of APL with low or moderate certainty. Besides, compared with transcatheter arterial chemoembolization (TACE) alone, ATO plus TACE also could improve objective response rate, disease control rate, survival rate (0.5, 1, 2, and 3-year) and life quality and reduce the level of alpha fetoprotein in primarily hepatocellular carcinoma with low or moderate certainty. However, no significant results were found in MM. Finally, key findings were as followed. ATO has potential broad-spectrum anticancer effects but the clinical transformation is rarely achieved. Route of administration may affect the antitumor effects of ATO. ATO can act synergistically in combination with a variety of antitumor therapies. The safety and drug resistance of ATO should be paid more attention to.

CONCLUSIONS

ATO may be a promising drug in anticancer treatment although earlier RCTs have dragged down the level of evidence. However, high-quality clinical trials are expected to explore its broad-spectrum anticancer effects, wide application, appropriate route of administration, and compound dosage form.

Brain-neuron targeted nanoparticles for peptide synergy therapy at dual-target of Alzheimer's disease

Since the complex interactions of multiple mechanisms involved in Alzheimer's disease (AD) preclude the monotherapeutic approaches from clinical application, combination therapy has become an attractive strategy for AD treatment. However, to be emphasized, the realization of the edges of combination therapy greatly depends on the reasonable choice of targets and the rational design of combination scheme. Acknowledgedly, amyloid plaques and hyperphosphorylated tau (p-tau) are two main hallmarks in AD with close pathological correlations, implying the hopeful prospect of combined intervention in them for AD treatment. Herein, we developed the nano-combination system, neuron-targeting PEG-PLA nanoparticles (CT-NP) loading two peptide drugs H102, a β-sheet breaker acting on Aβ, and NAP, a microtubule stabilizer acting on p-tau. Compared with free peptide combination, nano-combination system partly aligned the in vivo behaviors of combined peptides and enhanced peptide accumulation in lesion neurons by the guidance of targeting peptide CGN and Tet1, facilitating the therapeutic performance of peptide combination. Further, to maximize the therapeutic potential of nano-combination system, the combination ratio and mode were screened by the quantitative evaluation with combination index and U test, respectively, in vitro and in vivo. The results showed that the separated-loading CT-NP at the combination molar ratio of 2:1 (H102:NAP), CT-NP/H102 + CT-NP/NAP(2:1), generated the strongest synergistic therapeutic effects on Aβ, p-tau and their linkage, and effectually prevented neuroinflammation, reversed the neuronal damage and restored cognitive performance in 3 × Tg-AD transgenic mice. Our studies provide critical data on the effectiveness of nano-combination therapy simultaneously intervening in Aβ and p-tau, confirming the promising application of nano-combination strategy in AD treatment.

p53 as a unique target of action of cisplatin in acute leukaemia cells

Acute promyelocytic leukaemia (APL) occurs in approximately 10% of acute myeloid leukaemia patients. Arsenic trioxide (ATO) has been for APL chemotherapy, but recently several ATO‐resistant cases have been reported worldwide. Cisplatin (CDDP) enhances the toxicity of ATO in ovarian, lung cancer, chronic myelogenous leukaemia, and HL‐60 cells. Hence, the goal of this study was to investigate a novel target of CDDP action in APL cells, as an alternate option for the treatment of ATO‐resistant APL patients. We applied biochemical, molecular, confocal microscopy and advanced gene editing (CRISPR‐Cas9) techniques to elucidate the novel target of CDDP action and its functional mechanism in APL cells. Our main findings revealed that CDDP activated p53 in APL cells through stress signals catalysed by ATM and ATR protein kinases, CHK1 and CHK2 phosphorylation at Ser 345 and Thr68 residues, and downregulation and dissociation of MDM2‐DAXX‐HAUSP complex. Our functional studies confirmed that CDDP‐induced repression of MDM2‐DAXX‐HAUSP complex was significantly reversed in both nutilin‐3‐treated KG1a and p53‐knockdown NB4 cells. Our findings also showed that CDDP stimulated an increased number of promyelocytes with dense granules, activated p53 expression, and downregulated MDM2 in liver and bone marrow of APL mice. Principal conclusion of our study highlights a novel mode of action of CDDP targeting p53 expression which may provide a basis for designing new anti‐leukaemic compounds for treatment of APL patients.

Paradoxical effects of arsenic in the lungs

High levels (> 100 ug/L) of arsenic are known to cause lung cancer; however, whether low (≤ 10 ug/L) and medium (10 to 100 ug/L) doses of arsenic will cause lung cancer or other lung diseases, and whether arsenic has dose-dependent or threshold effects, remains unknown. Summarizing the results of previous studies, we infer that low- and medium-concentration arsenic cause lung diseases in a dose-dependent manner. Arsenic trioxide (ATO) is recognized as a chemotherapeutic drug for acute promyelocytic leukemia (APL), also having a significant effect on lung cancer. The anti-lung cancer mechanisms of ATO include inhibition of proliferation, promotion of apoptosis, anti-angiogenesis, and inhibition of tumor metastasis. In this review, we summarized the role of arsenic in lung disease from both pathogenic and therapeutic perspectives. Understanding the paradoxical effects of arsenic in the lungs may provide some ideas for further research on the occurrence and treatment of lung diseases.

Investigation of the ameliorative effects of baicalin against arsenic trioxide-induced cardiac toxicity in mice

Baicalin (BA), a kind of flavonoids compound, comes from Scutellaria baicalensis Georgi (a kind of perennial herb) and has beneficial effects on the cardiovascular system through anti-oxidant, anti-inflammation, and anti-apoptosis actions. However, the therapeutic effects and latent mechanisms of BA on arsenic trioxide (ATO)-induced cardiac toxicity has not been reported. The present research was performed to explore the effects and mechanisms of BA on ATO-induced heart toxicity. Male Kunming mice were treated with ATO (7.5 mg/kg) to induce cardiac toxicity. After the mice received ATO, BA (50 and 100 mg/kg) was administered for estimating its cardioprotective effects. Statistical data demonstrated that BA treatment alleviated electrocardiogram abnormalities and pathological injury caused by ATO. BA could also lead to recovery of CK and LDH activities to normal range and cause a decrease in MDA levels and ROS generation, augmentation of SOD, CAT, and GSH activities. We also found that BA caused a reduction in the expression of proinflammatory cytokines, such as TNF-α and IL-6. Moreover, BA attenuated ATO-induced apoptosis by promoting the expression of Bcl-2 and suppressing the expression of Bax and caspase-3. TUNEL test result demonstrated BA caused impediment of ATO-induced apoptosis. Furthermore, BA treatment suppressed the high expression of TLR4, NF-κB and P-NF-κB caused by ATO. In conclusion, these results indicate that BA may alleviate ATO-induced cardiac toxicity by restraining oxidative stress, apoptosis, and inflammation, and its mechanism would be associated with the inhibition of the TLR4/NF-κB signaling pathway.

The platination mechanism of RNase A by arsenoplatin: insight from the theoretical study

A detailed metalation process of the bovine pancreatic ribonuclease (RNase A) by a novel multitarget anti-cancer agent arsenoplatin-1, ([Pt(μ-NHC(CH₃)O)₂ClAs(OH)₂]), performed at DFT level and using different models size is provided.

Arsenic trioxide inhibits the growth of cancer stem cells derived from small cell lung cancer by downregulating stem cell-maintenance factors and inducing apoptosis via the Hedgehog signaling blockade

Background

Small cell lung cancer (SCLC) is the most deadly and aggressive type of primary lung cancer, with the 5-year survival rate lower than 5%. The FDA has approved arsenic trioxide (As₂O₃) for acute promyelocytic leukemia (APL) treatment. However, its role in SCLC-derived cancer stem cells (CSCs) remains largely unknown.

Methods

CSCs were enriched from SCLC cell lines by culturing them as spheres in conditioned serum-free medium. Then, qPCR, western blot, serial passage, limiting dilution, Transwell, and tumorigenesis assay were performed to verify the cells' stem phenotypic characteristics. Anticancer efficiency of As₂O₃ was assessed in these cells using CCK8, colony formation, sphere formation, flow cytometry, qPCR, western blot analysis in vitro, and tumor growth curve, immunofluorescence, and TUNEL staining analyses in vivo.

Results

The fifth-passage SCLC spheres showed a potent self-renewal capacity, higher clonal formation efficiency (CFE), SOX2, c-Myc, NANOG, and OCT4 levels, and invasion ability, and stronger tumorigenesis capacity than the parental SCLC cells, indicating that the SCLC sphere cells displayed CSC features. As₂O₃ inhibited the proliferation, clonality and sphere forming ability of SCLC-derived CSCs and suppressed the tumor growth of CSCs-derived xenograft tumors. As₂O₃ induced apoptosis and downregulation of SOX2 and c-Myc in vitro and in xenografts. Besides, SOX2 knockdown suppressed SCLC-derived CSCs to self-renew and induced apoptosis. Mechanistically, expression of GLI1 (a key transcription factor of Hedgehog pathway) and its downstream genes increased in SCLC-derived CSCs, compared to the parental cells. As₂O₃ dramatically downregulated GLI1 and its downstream genes in vitro and in vivo. The GLI inhibitor (GANT-61) recapitulated and enhanced the effects of As₂O₃ on SCLC-derived CSCs, including growth suppression, apoptosis induction, and GLI1, SOX2 and c-Myc downregulation.

Conclusions

Altogether, As₂O₃ effectively suppressed SCLC-derived CSCs growth by downregulating stem cell-maintenance factors and inducing apoptosis. These effects are mediated at least partly via the Hedgehog signaling blockade.

Beyond Cisplatin: Combination Therapy with Arsenic Trioxide

Platinum drugs (cisplatin, oxaliplatin, and carboplatin) and arsenic trioxide are the only commercial inorganic non-radioactive anticancer drugs approved by the US Food and Drug Administration. Numerous efforts are underway to take advantage of the synergy between the anticancer activity of cisplatin and arsenic trioxide - two drugs with strikingly different mechanisms of action. These include co-encapsulation of the two drugs in novel nanoscale delivery systems as well as the development of small molecule agents that combine the activity of these two inorganic materials. Several of these new molecular entities containing Pt-As bonds have broad anticancer activity, are robust in physiological buffer solutions, and form stable complexes with biopolymers. This review summarizes results from a number of preclinical studies involving the combination of cisplatin and As2O3, co-encapsulation and nanoformulation efforts, and the chemistry and cytotoxicity of the first member of platinum anticancer agents with an arsenous acid moiety bound to the platinum(II) center: arsenoplatins.

Arsenoplatin-1 Is a Dual Pharmacophore Anticancer Agent

Arsenoplatins are adducts of two chemically important anticancer drugs, cisplatin and arsenic trioxide, that have a Pt(II) bond to an As(III) hydroxide center. Screens of the NCI-60 human tumor cell lines reveal that arsenoplatin-1 (AP-1), [Pt(μ-NHC(CH3)O)2ClAs(OH)2], the first representative of this novel class of anticancer agents, displays a superior activity profile relative to the parent drugs As2O3 or cisplatin in a majority of cancer cell lines tested. These activity profiles are important because the success of arsenic trioxide in blood cancers (such as APL) has not been seen in solid tumors due to the rapid clearance of arsenous acid from the body. To understand the biological chemistry of these compounds, we evaluated interactions of AP-1 with the two important classes of biomolecules-proteins and DNA. The first structural studies of AP-1 bound to model proteins reveal that platinum(II) binds the Nε of His in a manner that preserves the Pt-As bond. We find that AP-1 readily enters cells and binds to DNA with an intact Pt-As bond (Pt:As ratio of 1). At longer incubation times, however, the Pt:As ratio in DNA samples increases, suggesting that the Pt-As bond breaks and releases the As(OH)2 moiety. We conclude that arsenoplatin-1 has the potential to deliver both Pt and As species to a variety of hematological and solid cancers.

A candidate for lung cancer treatment: arsenic trioxide

Arsenic trioxide (ATO), a highly effective drug in treating acute promyelocytic leukemia with low toxicity, demonstrates a significant effect on lung cancer. The anti-cancer mechanisms of ATO include inhibition of cancer stem-like cells, induction of apoptosis, anti-angiogenesis, sensitization of chemotherapy and radiotherapy, anti-cancer effects of hypoxia, and immunoregulation properties. In addition, some studies have reported that different lung cancers respond differently to ATO. It was concluded on numerous studies that the rational combination of administration and encapsulation of ATO have promising potentials in increasing drug efficacy and decreasing adverse drug effects. We reviewed the efficacy of ATO in the treatment of lung cancer in recent years to provide some views for further study.

Trisenox induces cytotoxicity through phosphorylation of mitogen-activated protein kinase molecules in acute leukemia cells

Trisenox (TX) has been used successfully for the treatment of acute promyelocytic leukemia (APL) patients. TX-induced cytotoxicity in APL cells remains poorly understood. In this study, we investigated the molecular mechanism of TX cytotoxicity using APL cell lines. We assessed TX toxicity by quantitatively measuring lactate dehydrogenase levels. Inhibition of cell cycle progression was assessed by confocal microscopy of Ki-67 expression. Apoptosis was evaluated by Western blot analysis of apoptotic proteins expression, immunocytochemistry, and confocal imaging of annexin V and propidium iodide. Mitogen-activated protein kinase (MAPK) signaling cascade was analyzed by Western blot analysis and inhibitor-based experiments with APL cells. We found that TX-induced cytotoxicity inhibited APL cell cycle progression. TX also induced significant (P < 0.05) changes in the expression levels of apoptotic molecules and activated the phosphorylation of MAPK signaling pathways in APL cells. Understanding the mechanism of TX cytotoxicity would be helpful in the design of new APL drugs.

Arsenic trioxide and sorafenib combination therapy for human hepatocellular carcinoma functions via up-regulation of TNF-related apoptosis-inducing ligand

The survival benefits of sorafenib treatment for patients with hepatocellular carcinoma (HCC) are limited due to drug resistance and side effects. Therefore, combinations of sorafenib with other low toxicity drugs, including arsenic trioxide (As₂O₃) require investigation. The present study aimed to evaluate the potency of apoptosis-induction by As₂O₃/sorafenib treatment in HCC cell lines, Huh7, 97H and freshly-isolated HCC cells, and also to elucidate the underlying mechanism. A total of 10 patients with HCC were enrolled in the present study. Freshly-isolated HCC cells were purified from HCC tissues collected at surgery. HCC-cell apoptosis was measured by flow cytometry using proprium iodide/Annexin-V staining. The impacts of As₂O₃ and/or sorafenib on Huh7, 97H and fresh-isolated HCC-cell proliferation were evaluated by Cell Counting Kit-8 assay. The expression of TNF-related apoptosis-inducing ligand (TRAIL) was determined by reverse transcription-quantitative polymerase chain reaction and western blotting. The downregulation of TRAIL protein expression was achieved using small interfering RNA. The combination of As₂O₃ and sorafenib had anti-proliferative and pro-apoptotic effects in the liver cancer cell line, Huh7, via increased expression of TRAIL, but not in 97H cells. TRAIL-knockdown increased the drug-resistance of Huh7 cells. Freshly-isolated HCC cells were more sensitive to the As₂O₃ and sorafenib combination than the single drug treatments. Overall, the combination of As₂O₃ and sorafenib demonstrated potent anti-tumor activity in Huh7 and freshly-isolated HCC cells via a TRAIL-dependent pathway. This may be a potential therapeutic approach for advanced HCC treatment.

Environmental arsenic exposure: From genetic susceptibility to pathogenesis

More than 200 million people in 70 countries are exposed to arsenic through drinking water. Chronic exposure to this metalloid has been associated with the onset of many diseases, including cancer. Epidemiological evidence supports its carcinogenic potential, however, detailed molecular mechanisms remain to be elucidated. Despite the global magnitude of this problem, not all individuals face the same risk. Susceptibility to the toxic effects of arsenic is influenced by alterations in genes involved in arsenic metabolism, as well as biological factors, such as age, gender and nutrition. Moreover, chronic arsenic exposure results in several genotoxic and epigenetic alterations tightly associated with the arsenic biotransformation process, resulting in an increased cancer risk. In this review, we: 1) review the roles of inter-individual DNA-level variations influencing the susceptibility to arsenic-induced carcinogenesis; 2) discuss the contribution of arsenic biotransformation to cancer initiation; 3) provide insights into emerging research areas and the challenges in the field; and 4) compile a resource of publicly available arsenic-related DNA-level variations, transcriptome and methylation data. Understanding the molecular mechanisms of arsenic exposure and its subsequent health effects will support efforts to reduce the worldwide health burden and encourage the development of strategies for managing arsenic-related diseases in the era of personalized medicine.

Radiation-enhanced therapeutic targeting of galectin-1 enriched malignant stroma in triple negative breast cancer

Currently there are no FDA approved targeted therapies for Triple Negative Breast Cancer (TNBC). Ongoing clinical trials for TNBC have focused primarily on targeting the epithelial cancer cells. However, targeted delivery of cytotoxic payloads to the non-transformed tumor associated-endothelium can prove to be an alternate approach that is currently unexplored. The present study is supported by recent findings on elevated expression of stromal galectin-1 in clinical samples of TNBC and our ongoing findings on stromal targeting of radiation induced galectin-1 by the anginex-conjugated arsenic-cisplatin loaded liposomes using a novel murine tumor model. We demonstrate inhibition of tumor growth and metastasis in response to the multimodal nanotherapeutic strategy using a TNBC model with orthotopic tumors originating from 3D tumor tissue analogs (TTA) comprised of tumor cells, endothelial cells and fibroblasts. The ‘rigorous’ combined treatment regimen of radiation and targeted liposomes is also shown to be well tolerated. More importantly, the results presented provide a means to exploit clinically relevant radiation dose for concurrent receptor mediated enhanced delivery of chemotherapy while limiting overall toxicity. The proposed study is significant as it falls in line with developing combinatorial therapeutic approaches for stroma-directed tumor targeting using tumor models that have an appropriate representation of the TNBC microenvironment.

Regulation of ABCG2 by nuclear factor kappa B affects the sensitivity of human lung adenocarcinoma A549 cells to arsenic trioxide

Arsenic trioxide (As₂O₃) is successfully used as an anticancer agent against acute promyelocytic leukemia and some solid tumors. However, the application of As₂O₃ is largely limited by its drug resistance in the treatment of non-small cell lung carcinoma (NSCLC). Therefore, it is an urgent task to enhance the sensitivity of lung cancer cells to As₂O₃. In this study, using human lung adenocarcinoma A549 cells as a cell culture model, we demonstrated that an adenosine triphosphate binding cassette (ABC) transporter, ABCG2, was significantly increased by As₂O₃ treatment, while other ABC transporters, ABCB1 and ABCC1 showed no remarkable change in the response to As₂O₃. After inhibition of ABCG2 by its specific inhibitor, the drug sensitivity of As₂O₃ to A549 cells was significantly enhanced, manifested by decreased cell viability and colony formation as well as the increased ROS production and cell apoptosis. To further understand the molecular mechanism underlying the elevation of ABCG2 expression in As₂O₃-treated cells, we detected the activation state of nuclear factor kappa B (NF-κB) pathway and its relationship with ABCG2 expression. Our results revealed that the increased expression of ABCG2 was regulated by NF-κB, and thus affecting the cell death of As₂O₃-treated A549 cells. These findings indicate that inhibition of NF-κB/ABCG2 pathway by specific inhibitors may be a new strategy for the improvement of As₂O₃ sensitivity in NSCLC treatment.

Elevation of sensitivity to anticancer agents of human lung adenocarcinoma A549 cells by knockdown of claudin-2 expression in monolayer and spheroid culture models

Claudins, tight junctional proteins, regulate the paracellular permeability of ions and small molecules. Claudin-2 is highly expressed in human lung adenocarcinoma cells and is involved in the up-regulation of cell proliferation. However, the effect of claudin-2 on cellular sensitivity to anticancer agents has not been clarified. The cytotoxicity of anticancer agents such as cisplatin, gefitinib and doxorubicin (DXR) was increased by claudin-2 knockdown in A549 cells. Claudin-2 knockdown also significantly decreased the expression level of multidrug resistance-associated protein/ABCC2. The expression levels of other drug efflux transporters were unchanged. The intracellular accumulation of 5-chloromethylfluorescein diacetate (CMFDA) and DXR, substrates of ABCC2, was increased by claudin-2 knockdown, whereas the efflux was decreased. MK-571, an inhibitor of ABCC2, enhanced the cytotoxicity of anticancer agents. Claudin-2 knockdown decreased the levels of p-c-Jun and nuclear Sp1. SP600125, an inhibitor of c-Jun, and mithramycin, an inhibitor of Sp1, decreased the level of ABCC2. The promoter activity of ABCC2 was decreased by claudin-2 knockdown, SP600125 and mithramycin treatments, suggesting that claudin-2 is involved in the up-regulation of ABCC2 expression at the transcriptional level. Claudin-2 knockdown increased the paracellular permeability of DXR in a 2D monolayer culture model. In addition, the accumulation of DXR into spheroids was enhanced by claudin-2 knockdown, resulting in a reduction in cell viability. We suggest that claudin-2 may be a novel therapeutic target in lung adenocarcinoma, because claudin-2 knockdown increased the accumulation of anticancer agents in cancer cells and spheroids.

Anti-angiogenic effect of arsenic trioxide in lung cancer via inhibition of endothelial cell migration, proliferation and tube formation

Arsenic trioxide (As₂O₃) exhibits a remarkable effect on leukemia treatment; however, its effect on solid tumors remains poorly explored. The present study demonstrated the inhibitory effect of As₂O₃ on lung cancer and explored its possible mechanism. It was observed that As₂O₃ significantly inhibited the growth of lung cancer xenografts and tumor angiogenesis in vivo. The inhibitory effect of As₂O₃ on cell proliferation in vitro was more remarkable in vascular endothelial cells than in lung cancer cells. It was also observed that As₂O₃ inhibited the migration of vascular endothelial cells and disrupted vascular tube formation on Matrigel assays. In addition, a series of key signaling factors involved in multiple stages of angiogenesis, including matrix metalloproteinase (MMP)-2, MMP-9, platelet-derived growth factor (PDGF)-BB/PDGF receptor-β, vascular endothelial growth factor (VEGF)-A/VEGF receptor-2, basic fibroblast growth factor (FGF)/FGF receptor-1 and delta like canonical Notch ligand 4/Notch-1, were regulated by As₂O₃. These findings suggested that anti-angiogenesis may be an underlying mechanism of As₂O₃ anticancer activity in lung cancer.

Arsenic trioxide inhibits EBV reactivation and promotes cell death in EBV-positive lymphoma cells

Background

Epstein-Barr Virus (EBV) is associated with hematopoietic malignancies, such as Burkitt’s lymphoma, post-transplantation lymphoproliferative disorder, and diffuse large B-cell lymphoma. The current approach for EBV-associated lymphoma involves chemotherapy to eradicate cancer cells, however, normal cells may be injured and organ dysfunction may occur with currently employed regimens. This research is focused on employing arsenic trioxide (ATO) as EBV-specific cancer therapy takes advantage of the fact the EBV resides within the malignant cells.

Methods and results

Our research reveals that low ATO inhibits EBV gene expression and genome replication. EBV spontaneous reactivation starts as early as 6 h after re-suspending EBV-positive Mutu cells in RPMI media in the absence of ATO, however this does not occur in Mutu cells cultured with ATO. ATO’s inhibition of EBV spontaneous reactivation is dose dependent. The expression of the EBV immediate early gene Zta and early gene BMRF1 is blocked with low concentrations of ATO (0.5 nM – 2 nM) in EBV latency type I cells and EBV-infected PBMC cells. The combination of ATO and ganciclovir further diminishes EBV gene expression. ATO-mediated reduction of EBV gene expression can be rescued by co-treatment with the proteasome inhibitor MG132, indicating that ATO promotes ubiquitin conjugation and proteasomal degradation of EBV genes. Co-immunoprecipitation assays with antibodies against Zta pulls down more ubiquitin in ATO treated cell lysates. Furthermore, MG132 reverses the inhibitory effect of ATO on anti-IgM-, PMA- and TGF-β-mediated EBV reactivation. Thus, mechanistically ATO’s inhibition of EBV gene expression occurs via the ubiquitin pathway. Moreover, ATO treatment results in increased cell death in EBV-positive cells compared to EBV-negative cells, as demonstrated by both MTT and trypan blue assays. ATO-induced cell death in EBV-positive cells is dose dependent. ATO and ganciclovir in combination further enhances cell death specifically in EBV-positive cells.

Conclusion

ATO-mediated inhibition of EBV lytic gene expression results in cell death selectively in EBV-positive lymphocytes, suggesting that ATO may potentially serve as a drug to treat EBV-related lymphomas in the clinical setting.

Combination effects of arsenic trioxide and fibroblast growth factor receptor inhibitor in squamous cell lung carcinoma

OBJECTIVES

Lung cancer remains the top cancer killer worldwide, with squamous cell carcinoma (SCC) as the second commonest histologic subtype. Arsenic trioxide (ATO) was previously shown to suppress growth of lung cancer. Fibroblast growth factor receptor (FGFR) amplification was recently demonstrated in lung SCC, with specific FGFR inhibitor (e.g. PD173074) developed as a potential targeted therapy. Therefore the combination effects of ATO and PD173074 in SCC was studied.

MATERIALS AND METHODS

The combination of ATO/PD173074 was studied in a proof-of-principle model using a lung SCC cell line with FGFR1 overexpression: SK-MES-1. The effects of ATO and/or PD173074 on cell viability and protein expression were studied by MTT assay and Western blot respectively. Cell cycle analysis, phosphatidylserine externalization and mitochondrial membrane depolarization were monitored by flow cytometry. FGFR1 knockdown was performed with siRNAs. Proteasome inhibitor (MG-132) was used to study the degradation mechanism. In vivo effect of ATO and/or PD173074 was investigated using a nude mice xenograft model.

RESULTS

Combined ATO/PD173074 reduced cell viability along with increased sub-G1 population, phosphatidylserine externalization and mitochondrial membrane depolarization more significantly than single treatments. Downregulation of FGFR1, p-Akt, Akt, p-Src, Src, p-c-Raf, c-Raf, Erk and survivin as well as upregulation of p-Erk and cleaved PARP were observed upon ATO and/or PD treatment. MG-132 partially reversed the degradation of Akt, Src, c-Raf and Erk induced by ATO/PD, suggestive of ubiquitin-independent proteasome-dependent degradation. However, the mechanism of FGFR1 downregulation remained unknown. Downregulation of FGFR1, Akt, Src, c-Raf and Erk as well as cleaved PARP elevation induced by ATO and/or PD were confirmed in vivo.

CONCLUSION

Massive protein degradation (FGFR1, Akt, Src, c-Raf and Erk) was induced by ATO and/or PD173074 treatment mainly mediated by activation of proteasomal degradation in SCC cell line SK-MES-1 in vitro and in vivo.

Molecular mechanisms of cisplatin cytotoxicity in acute promyelocytic leukemia cells

Cis-diamminedichloroplatinum (II) (cisplatin) is a widely used anti-tumor drug for the treatment of a broad range of human malignancies with successful therapeutic outcomes for head and neck, ovarian, and testicular cancers. It has been found to inhibit cell cycle progression and to induce oxidative stress and apoptosis in acute promyelocytic leukemia (APL) cells. However, its molecular mechanisms of cytotoxic action are poorly understood. We hypothesized that cisplatin induces cytotoxicity through DNA adduct formation, oxidative stress, transcriptional factors (p53 and AP-1), cell cycle regulation, stress signaling and apoptosis in APL cells. We used the APL cell line as a model, and applied a variety of molecular tools to elucidate the cytotoxic mode of action of cisplatin. We found that cisplatin inhibited cell proliferation by a cytotoxicity, characterized by DNA damage and modulation of oxidative stress. Cisplatin also activated p53 and phosphorylated activator protein (AP-1) component, c-Jun at serine (63, 73) residue simultaneously leading to cell cycle arrest through stimulation of p21 and down regulation of cyclins and cyclin dependent kinases in APL cell lines. It strongly activated the intrinsic pathway of apoptosis through alteration of the mitochondrial membrane potential, release of cytochrome C, and up-regulation of caspase 3 activity. It also down regulated the p38MAPK pathway. Overall, this study highlights the molecular mechanisms that underline cisplatin toxicity to APL cells, and provides insights into selection of novel targets and/or design of therapeutic agents to treat APL.

Patient-derived xenografts faithfully replicated clinical outcome in a phase II co-clinical trial of arsenic trioxide in relapsed small cell lung cancer

Background

SCLC has limited treatment options and inadequate preclinical models. Promising activity of arsenic trioxide (ASO) recorded in conventional preclinical models of SCLC supported the clinical evaluation of ASO in patients. We assessed the efficacy of ASO in relapsed SCLC patients and in corresponding patient-derived xenografts (PDX).

Methods

Single arm, Simon 2-stage, phase II trial to enroll patients with relapsed SCLC who have failed at least one line of therapy. ASO was administered as an intravenous infusion over 1–2 h daily for 4 days in week 1 and for 2 days in weeks 2–6 of an 8-week cycle. Treatment continued until disease progression. Pretreatment tumor biopsy was employed for PDX generation through direct implantation into subcutaneous pockets of SCID mice without in vitro manipulation and serially propagated for five generations. Ex vivo efficacy of cisplatin (3 mg/kg i.p. weekly) and ASO (3.75 mg/kg i.p. every other day) was tested in PDX representative of platinum sensitive and platinum refractory SCLC.

Results

The best response in 17 evaluable patients was stable disease in 2 (12 %), progressive disease in 15 (88 %) patients and median time-to-progression of seven (range 1–7) weeks. PDX was successfully grown in 5 of 9 (56 %) transplanted biopsy samples. Serially-propagated PDXs preserved characteristic small cell histology and genomic stability confirmed by immunohistochemistry, short tandem repeat (STR) profiling and targeted sequencing. ASO showed in vitro cytotoxicity but lacked in vivo efficacy against SCLC PDX tumor growth.

Conclusions

Cisplatin inhibited growth of PDX derived from platinum-sensitive SCLC but was ineffective against PDX from platinum-refractory SCLC. Strong concordance between clinical and ex vivo effects of ASO and cisplatin in SCLC supports the use of PDX models to prescreen promising anticancer agents prior to clinical testing in SCLC patients.

Trial Registration The study was registered at http://www.clinicaltrials.gov (NCT01470248)

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0861-5) contains supplementary material, which is available to authorized users.

Utilization of arsenic trioxide as a treatment of cisplatin-resistant non-small cell lung cancer PC-9/CDDP and PC-14/CDDP cells

Cisplatin is a commonly used drug in combination chemotherapy. However, various malignant tumors frequently acquire resistance to cisplatin. Arsenic trioxide (ATO) has been approved as a chemotherapeutic drug for the treatment of acute promyelocytic leukemia, and the combination of ATO and cisplatin has been revealed to demonstrate synergistic effects in ovarian and small cell lung cancer cells. Thus, it was hypothesized that ATO may also be active against cisplatin-resistant non-small cell lung cancer (NSCLC) PC-9/CDDP and PC-14/CDDP cells. The present study also evaluated the effects of ATO on the cisplatin-sensitive NSCLC PC-9 and PC-14 cell lines. Notably, ATO demonstrated a markedly decreased IC₅₀ in the cisplatin-resistant PC-9/CDDP and PC-14/CDDP cells compared with the IC₅₀ in the cisplatin-sensitive parental PC-9 and PC-14 cells. Additionally, it was found that arsenite accumulation in the PC-9 cell line was affected through the downregulation of GS-X pump systems. Although it is likely that cisplatin resistance in PC-9 cells does not depend on the GS-X pump systems, ATO was effective against cisplatin-resistant NSCLC PC-9/CDDP and PC-14/CDDP cells in combination chemotherapy.

Arsenic trioxide-induced cytotoxicity in small cell lung cancer via altered redox homeostasis and mitochondrial integrity

Arsenic trioxide (ATO) has demonstrated anticancer activity in different malignancies, especially acute promyelocytic leukemia, with a wide array of putative mechanisms. In this study, we aimed to elucidate the activity and mechanisms of ATO in small cell lung cancer (SCLC). A panel of SCLC cell lines (H841, DMS79, H526, H69 and H187) was employed to demonstrate the activity of ATO. Cell viability, apoptosis and mitochondrial membrane depolarization were assessed. Western blotting was performed to determine the alteration of pro-apoptotic and anti-apoptotic mediators. Reactive oxygen species (ROS) (hydrogen peroxide and superoxide) and intracellular glutathione (GSH) were measured. Antioxidants, N-acetyl-L-cysteine (NAC) and butylated hydroxyanisole (BHA), were applied to restore GSH content and reduce production of ROS. All SCLC cell lines were relatively sensitive to ATO with IC50 values below 10 µM. ATO induced cell death mainly through apoptosis in H841 cells in a dose-dependent manner. Hydrogen peroxide was the major ROS in SCLC cells induced by ATO. Along with GSH depletion and Bcl-2 downregulation, mitochondrial membrane permeabilization was enhanced, followed by release of AIF and SMAC from mitochondria to initiate different cell death pathways. NAC reversed cell death and molecular changes induced by ATO via restoring GSH and reducing ROS content. BHA inhibited hydrogen peroxide production completely and partially restored GSH content accounting for partial reversal of cell inhibition and mitochondrial dysfunction. Nonetheless, ATO reduced both reduced and oxidized form of thioredoxin 1 (Trx1) with no effect on Trx1 redox potential. ATO led to cell death in SCLC mainly through mitochondrial dysfunction, resulting from altered cellular redox homeostasis, namely, hydrogen peroxide generation, GSH depletion and Trx1 downregulation.

Biological activities of novel pyrazolyl hydroxamic acid derivatives against human lung cancer cell line A549

We synthesized a series of novel pyrazolyl hydroxamic acid derivatives (4a-4l) and investigated their biological activities against human lung cancer cell line A549 in vitro to determine their mechanism of action. The results showed that the majority of derivatives had inhibitory effects on the growth of A549 cancer cells in dose and time-dependent manners, in which the compounds 4b, 4f, 4h and 4j (10 μM) exerted more effective anti-proliferation activity. However, it should be noted that 4j may result in necrosis at 10 μM. Furthermore, the three compounds 4b, 4f and 4h induced cell cycle arrest at G1 phase and triggered autophagy, but could not obviously induce apoptosis and necrosis under the stimulatory condition. Therefore, the pyrazolyl hydroxamic acid derivatives 4b, 4f and 4h can be used to investigate the regulatory mechanism of autophagy and offer new approaches to the prevention of lung cancer.