A novel organoselenium compound induces cell cycle arrest and apoptosis in prostate cancer cell lines

Exploring nickel-catalyzed organochalcogen synthesis via cross-coupling of benzonitrile and alkyl chalcogenols with computational tools

The preparation of organochalcogens has increased in recent times due to their promising biological activity properties. This work studies the reaction mechanism of a nickel(0)-catalyzed cross-coupling between benzonitrile and propanethiol to produce new C-S bonds by computational means. The proposed mechanism follows the classical oxidative addition/transmetalation/reductive elimination cross-coupling sequence, involving an unusual oxidative addition of a Ph-CN bond onto the active species. The computed catalytic cycle for thioether synthesis has been examined to determine whether the same protocol could be employed to build the analogous C-Se and C-Te bonds. The proposed mechanism for C-S coupling is validated by microkinetic modeling and shows a very good agreement with available experimental data. The extension of the proposed mechanism to C-Se and C-Te couplings indicates that these new reactions should be operative, although their reaction rates appear to be significantly slower.

Selenium in cancer management: exploring the therapeutic potential

Selenium (Se) is important and plays significant roles in many biological processes or physiological activities. Prolonged selenium deficiency has been conclusively linked to an elevated risk of various diseases, including but not limited to cancer, cardiovascular disease, inflammatory bowel disease, Keshan disease, and acquired immunodeficiency syndrome. The intricate relationship between selenium status and health outcomes is believed to be characterized by a non-linear U-shaped dose-response curve. This review delves into the significance of maintaining optimal selenium levels and the detrimental effects that can arise from selenium deficiency. Of particular interest is the important role that selenium plays in both prevention and treatment of cancer. Finally, this review also explores the diverse classes of selenium entities, encompassing selenoproteins, selenium compounds and selenium nanoparticles, while examining the mechanisms and molecular targets of their anticancer efficacy.

Polyfunctionalized organoselenides: New synthetic approach from selenium-containing cyanohydrins and anti-melanoma activity

A series of seleno-containing polyfunctionalized compounds was synthesized exploring cyanohydrin chemistry, including α-hydroxy esters, α-hydroxy acids, 1,2-diols, and 1,2-diacetates, with yields ranging from 26 up to 99 %. The cytotoxicity of all synthesized compounds was then evaluated using a non-tumor cell line (BALB/3T3 murine fibroblasts), and those deemed non-cytotoxic had their anti-melanoma activity evaluated using B16-F10 murine melanoma cells. These assays identified two compounds with selective cytotoxic activity against the tested melanoma cell line, showing a potential anti-melanoma application.

Straightforward synthesis of steroidal selenocyanates through oxidative umpolung selenocyanation of steroids and their antitumor activity

Straightforward access to steroidal selenocyanates in a single assembly step from steroids remains a significant challenge. However, the development of novel method for the synthesis of steroidal selenocyanates and further investigation of their bioactivities have largely lagged behind. In this work, selenocyano groups were directly introduced into the 17- or 21-position of pregnenolone, the 2-position of estradiol, and the 16-position of estrone. A total of 16 estrogen selenocyanate derivatives with diverse structures were synthesized, and the tumor cell lines closely related to the expression level of estrogen were used to investigate the inhibitory activity of the target products on tumor cell proliferation in vitro. The results revealed that the 17-selenocyano-substituted pregnenolone selenocyanate derivatives 1b-3b exhibit obvious inhibitory activity against the tested tumor cell lines. Additionally, the 2-selenocyano-substituted estradiol derivatives and 16-selenocyano-substituted estrone derivatives exhibit selective inhibitory on HeLa cell lines. Among them, 2-selenocyano-3-methoxyestradiol-17-benzoate (7e) displayed an IC₅₀ value of 4.1 µM against HeLa cells and induced programmed apoptosis in HeLa cancer cells. Furthermore, compound 7e could significantly inhibit the growth of human cervical cancer xenografts in zebrafish in vivo. This approach provides new insights for future steroid antitumor drug design.

Down regulation of fatty acid synthase via inhibition of PI3K/AKT/mTOR in ovarian cancer cell line by novel organoselenium pseudopeptide

Ovarian cancer (OC) is the 7th most common cancer in women world-wide and the 3rd most common female cancer. For the treatment of OC, there is no successful therapeutic. The medications that are currently available have significant side effects and a low therapeutic index. This work aimed to evaluate the anticancer activity of organoselenium pseudopeptide compound against OC cell lines. After treatment with 50 ​μM of compound 4 (CPD 4), the viability was determined. The anticancer activity was further investigated by different methods including cell cycle and apoptosis analysis, colony formation assay, zymography, comet assay and Western blot. In comparison to a positive control, compound 4 showed cytotoxicity toward A2780CP cells rather than A2780 and SKOV-3 ​cells. Compound 4 was more selective to OC cells rather than HSF cells. Moreover, Compound 4 was able to inhibit cell migration and proliferation. The anticancer effect of compound 4 was found to be partially via cell cycle arrest, overexpression of p27 ​cell cycle inhibitor and induction of apoptosis through DNA fragmentation and activated production of ROS. Compound 4 had a differential effect on the modulation of PI3K/AKT/mTOR signaling pathway in the OC treated cell lines, also inhibited lipogenesis process via downregulation of FASN expression. Conclusion: This work highlights the unique role of Compound 4 against OC via modulation of oxidative stress, inhibition of survival PI3K/AKT/mTOR pathway. Compound 4 was found to be a promising alternative therapy for the treatment of OC in this investigation.

Research progress of matrine's anticancer activity and its molecular mechanism

BACKGROUND

and ethnopharmacological relevance: Matrine (MT), a type of alkaloid extracted from the Sophora family of traditional Chinese medicine, has been documented to exert a variety of pharmacological effects, including anti-inflammatory, anti-allergic, anti-viral, anti-fibrosis, and cardiovascular protection. Sophora flavescens Aiton is a traditional Chinese medicine that is bitter and cold. Additionally, it also exhibits the effects of clearing heat, eliminating dampness, expelling insects, and promoting urination. Malignant tumors are the most important medical issue and are also the second leading cause of death worldwide. Numerous natural substances have recently been revealed to have potent anticancer properties, and several have been used in clinical trials.

AIMS OF THE STUDY

To summarize the antitumor effects and associated mechanisms of MT, we compiled this review by combining a huge body of relevant literature and our previous research.

MATERIALS AND METHODS

As demonstrated, we grouped the pharmacological effects of MT via a PubMed search. Further, we described the mechanism and current pharmacological research on MT's antitumor activity.

RESULTS

Additionally, extensive research has demonstrated that MT possesses superior antitumor properties, including accelerating cell apoptosis, inhibiting tumor cell growth and proliferation, inducing cell cycle arrest, inhibiting cancer metastasis and invasion, inhibiting angiogenesis, inducing autophagy, reversing multidrug resistance and inhibiting cell differentiation, thus indicating its significant potential for cancer treatment and prognosis.

CONCLUSION

This article summarizes current advances in research on the anticancer properties of MT and its molecular mechanism, to provide references for future research.

Small molecule selenium-containing compounds: Recent development and therapeutic applications

Selenium (Se) is an essential micronutrient of organism and has important function. It participates in the functions of selenoprotein in several manners. In recent years, Se has attracted much attention because of its therapeutic potential against several diseases. Many natural and synthetic organic Se-containing compounds were studied and explored for the treatment of cancer and other diseases. Studies have showed that incorporation of Se atom into small molecules significantly enhanced their bioactivities. In this paper, according to different applications and structural characteristics, the research progress and therapeutic application of Se-containing compounds are reviewed, and more than 110 Se-containing compounds were selected as representatives which showed potent activities such as anticancer, antioxidant, antifibrolytic, antiparasitic, antibacterial, antiviral, antifungal and central nervous system related effects. This review is expected to provide a basis for further study of new promising Se-containing compounds.

Cisatracurium inhibits the growth and induces apoptosis of ovarian cancer cells by promoting lincRNA-p21

As a common muscle relaxant, cisatracurium has shown good antitumor effect on some tumors. Recent studies reported that cisatracurium could inhibit the progression of colon cancer by upregulating tumor suppressor gene p53. However, its role in ovarian cancer and its regulatory effect on p53 and p53 downstream targeting gene long intergenic noncoding RNA p21 (lincRNA-p21) is still unknown. Quantitative Real-time Polymerase Chain Reaction (qRT-PCR) was used to assess the expression of p53, lincRNA-p21 and miR-181b. Cell viability and proliferation were detected by CCK-8 assay and Edu staining, respectively. Wound-healing and Transwell assays were performed to determine the abilities of cell migration and invasion. Apoptosis was evaluated by TUNEL staining. Luciferase reporter assay was conducted to detect the relationship between lincRNA-p21 and miR-181b. As a result, cisatracurium could increase the expressions of p53 and lincRNA-p21 of ovarian cancer cell line (OVCAR-3) in a dose-dependent manner. In addition, cisatracurium significantly inhibited the proliferation, migration and invasion of OVACR-3 cells, and induced apoptosis. However, these above changes in biological function can be attenuated by lincRNA-p21 knockdown. Next, lincRNA-p21 could directly target miR-181b and negatively regulate its expression by luciferase reporter assay. In conclusion, cisatracurium inhibited the progression of OVCAR-3 cells through upregulation of lincRNA-p21 expression activated by p53 inhibiting miR-181b expression. The experimental results provide a new research idea for the application of cisatracurium in ovarian cancer.

The double-edged roles of ROS in cancer prevention and therapy

Reactive oxygen species (ROS) serve as cell signaling molecules generated in oxidative metabolism and are associated with a number of human diseases. The reprogramming of redox metabolism induces abnormal accumulation of ROS in cancer cells. It has been widely accepted that ROS play opposite roles in tumor growth, metastasis and apoptosis according to their different distributions, concentrations and durations in specific subcellular structures. These double-edged roles in cancer progression include the ROS-dependent malignant transformation and the oxidative stress-induced cell death. In this review, we summarize the notable literatures on ROS generation and scavenging, and discuss the related signal transduction networks and corresponding anticancer therapies. There is no doubt that an improved understanding of the sophisticated mechanism of redox biology is imperative to conquer cancer.

A Systematic Review of the Pharmacology, Toxicology and Pharmacokinetics of Matrine

Matrine (MT) is a naturally occurring alkaloid and an bioactive component of Chinese herbs, such as Sophora flavescens and Radix Sophorae tonkinensis. Emerging evidence suggests that MT possesses anti-cancer, anti-inflammatory, anti-oxidant, antiviral, antimicrobial, anti-fibrotic, anti-allergic, antinociceptive, hepatoprotective, cardioprotective, and neuroprotective properties. These pharmacological properties form the foundation for its application in the treatment of various diseases, such as multiple types of cancers, hepatitis, skin diseases, allergic asthma, diabetic cardiomyopathy, pain, Alzheimer's disease (AD), Parkinson's disease (PD), and central nervous system (CNS) inflammation. However, an increasing number of published studies indicate that MT has serious adverse effects, the most obvious being liver toxicity and neurotoxicity, which are major factors limiting its clinical use. Pharmacokinetic studies have shown that MT has low oral bioavailability and short half-life in vivo. This review summarizes the latest advances in research on the pharmacology, toxicology, and pharmacokinetics of MT, with a focus on its biological properties and mechanism of action. The review provides insight into the future of research on traditional Chinese medicine.

The Thioredoxin System: A Promising Target for Cancer Drug Development

The thioredoxin system is highly conserved system found in all living cells and comprises NADPH, thioredoxin, and thioredoxin reductase. This system plays a critical role in preserving a reduced intracellular environment, and its involvement in regulating a wide range of cellular functions makes it especially vital to cellular homeostasis. Its critical role is not limited to healthy cells, it is also involved in cancer development, and is overexpressed in many cancers. This makes the thioredoxin system a promising target for cancer drug development. As such, over the last decade, many inhibitors have been developed that target the thioredoxin system, most of which are small molecules targeting the thioredoxin reductase C-terminal redox center. A few inhibitors of thioredoxin have also been developed. We believe that more efforts should be invested in developing protein/peptide-based inhibitors against both thioredoxin reductase and/or thioredoxin.

Selenium and selenoproteins: it's role in regulation of inflammation

Abstract

Selenium is an essential immunonutrient which holds the human’s metabolic activity with its chemical bonds. The organic forms of selenium naturally present in human body are selenocysteine and selenoproteins. These forms have a unique way of synthesis and translational coding. Selenoproteins act as antioxidant warriors for thyroid regulation, male-fertility enhancement, and anti-inflammatory actions. They also participate indirectly in the mechanism of wound healing as oxidative stress reducers. Glutathione peroxidase (GPX) is the major selenoprotein present in the human body, which assists in the control of excessive production of free radical at the site of inflammation. Other than GPX, other selenoproteins include selenoprotein-S that regulates the inflammatory cytokines and selenoprotein-P that serves as an inducer of homeostasis. Previously, reports were mainly focused on the cellular and molecular mechanism of wound healing with reference to various animal models and cell lines. In this review, the role of selenium and its possible routes in translational decoding of selenocysteine, synthesis of selenoproteins, systemic action of selenoproteins and their indirect assimilation in the process of wound healing are explained in detail. Some of the selenium containing compounds which can acts as cancer preventive and therapeutics are also discussed. These compounds directly or indirectly exhibit antioxidant properties which can sustain the intracellular redox status and these activities protect the healthy cells from reactive oxygen species induced oxidative damage. Although the review covers the importance of selenium/selenoproteins in wound healing process, still some unresolved mystery persists which may be resolved in near future.

Graphic abstract

Synthesis and antiproliferative evaluation of novel steroid-benzisoselenazolone hybrids

The two different types of steroidal benzisoselenazolone hybrids were synthesized by incorporating benzisoselenazolone scaffold into dehydroepiandrosterone and B-norcholesterol. The antiproliferative activity of the synthesized compounds against some carcinoma cell lines were investigated. The results showed that some of these compounds have better inhibitory activity than abiraterone on the proliferation of tumor cells associated with human growth hormone, and have less cytotoxicity on normal human cells. In particular, the IC₅₀ values of the compound 8a and 8f are 5.4 and 6.5 µmol/L against human ovarian carcinoma (SKOV3) cell line, and possess SI values of 13.9 and 10.5, respectively. The information obtained from the studies may be useful for the design of novel chemotherapeutic drugs.

Targeting the Thioredoxin System as a Strategy for Cancer Therapy

Thioredoxin reductase (TrxR) participates in the regulation of redox reactions in organisms. It works mainly via its substrate molecule, thioredoxin, to maintain the redox balance and regulate signal transduction, which controls cell proliferation, differentiation, death, and other important physiological processes. In recent years, increasing evidence has shown that the overactivation of TrxR is related to the development of tumors. The exploration of TrxR-targeted antitumor drugs has attracted wide attention and is expected to provide new therapies for cancer treatment. In this perspective, we highlight the specific relationship between TrxR and apoptotic signaling pathways. The cytoplasm and mitochondria both contain TrxR, resulting in the activation of apoptosis. TrxR activity influences reactive oxygen species (ROS) and further regulates the inflammatory signaling pathway. In addition, we discuss representative TrxR inhibitors with anticancer activity and analyze the challenges in developing TrxR inhibitors as anticancer drugs.

Selenium Species: Current Status and Potentials in Cancer Prevention and Therapy

Selenium (Se) acts as an essential trace element in the human body due to its unique biological functions, particularly in the oxidation-reduction system. Although several clinical trials indicated no significant benefit of Se in preventing cancer, researchers reported that some Se species exhibit superior anticancer properties. Therefore, a reassessment of the status of Se and Se compounds is necessary in order to provide clearer insights into the potentiality of Se in cancer prevention and therapy. In this review, we organize relevant forms of Se species based on the three main categories of Se-inorganic, organic, and Se-containing nanoparticles (SeNPs)-and overview their potential functions and applications in oncology. Here, we specifically focus on the SeNPs as they have tremendous potential in oncology and other fields. In general, to make better use of Se compounds in cancer prevention and therapy, extensive further study is still required to understand the underlying mechanisms of the Se compounds.

Synthesis and antiproliferative activity of 17-[1',2',3']-selenadiazolylpregnenolone compounds

Using pregnenolone as a starting material, some 3-substituted 17-[1',2',3']-selenadiazolylpregnenolone derivatives were synthesized, and their structures were characterized by IR, NMR and HRMS. The in vitro antitumor activity of the compounds was assayed against PC-3、SKOV3、T47D、MCF-7 and HEK293T cell lines. The results show that some compounds display selective antiproliferative activity against PC-3 and SKOV3 cells lines and are almost inactive to normal kidney epithelial cells (HEK293T). The IC₅₀ value are much better than that of abiraterone (positive control).

Organic selenium compounds as potential chemotherapeutic agents for improved cancer treatment

Selenium(Se)-containing compounds have attracted a growing interest as anticancer agents over recent decades, with mounting reports demonstrating their high efficacy and selectivity against cancer cells. Typically, Se compounds exert their cytotoxic effects by acting as pro-oxidants that alter cellular redox homeostasis. However, the precise intracellular targets, signalling pathways affected and mechanisms of cell death engaged following treatment vary with the chemical properties of the selenocompound and its metabolites, as well as the cancer model that is used. Naturally occurring organic Se compounds, besides encompassing a significant antitumor activity with an apparent ability to prevent metastasis, also seem to have fewer side effects and less systemic effects as reported for many inorganic Se compounds. On this basis, many novel organoselenium compounds have also been synthesized and examined as potential chemotherapeutic agents. This review aims to summarize the most well studied natural and synthetic organoselenium compounds and provide the most recent developments in our understanding of the molecular mechanisms that underlie their potential anticancer effects.

Significance of the mitochondrial thioredoxin reductase in cancer cells: An update on role, targets and inhibitors

Thioredoxin reductase 2 (TrxR2) is a key component of the mitochondrial thioredoxin system able to transfer electrons to peroxiredoxin 3 (Prx3) in a reaction mediated by thioredoxin 2 (Trx2). In this way, both the level of hydrogen peroxide and thiol redox state are modulated. TrxR2 is often overexpressed in cancer cells conferring apoptosis resistance. Due to their exposed flexible arm containing selenocysteine, both cytosolic and mitochondrial TrxRs are inhibited by a large number of molecules. The various classes of inhibitors are listed and the molecules acting specifically on TrxR2 are extensively described. Particular emphasis is given to gold(I/III) complexes with phosphine, carbene or other ligands and to tamoxifen-like metallocifens. Also chemically unrelated organic molecules, including natural compounds and their derivatives, are taken into account. An important feature of many TrxR2 inhibitors is provided by their nature of delocalized lipophilic cations that allows their accumulation in mitochondria exploiting the organelle membrane potential. The consequences of TrxR2 inhibition are presented focusing especially on the impact on mitochondrial pathophysiology. Inhibition of TrxR2, by hindering the activity of Trx2 and Prx3, increases the mitochondrial concentration of reactive oxygen species and shifts the thiol redox state toward a more oxidized condition. This is reflected by alterations of specific targets involved in the release of pro-apoptotic factors such as cyclophilin D which acts as a regulator of the mitochondrial permeability transition pore. Therefore, the selective inhibition of TrxR2 could be utilized to induce cancer cell apoptosis.

Novel selenadiazole derivatives as selective antitumor and radical scavenging agents

Twenty-seven novel benzo[c][1,2,5]selenadiazole-5-carboxylic acid (BSCA) derivatives were designed and synthesized. Anti-proliferative activity of these structures was tested in vitro against a panel of five human cancer cell lines, including prostate (PC-3), colon (HT-29), leukemia (CCRF-CEM), lung (HTB-54) and breast (MCF-7). Four compounds (5, 6, 7 and 19) showed potent inhibitory activity with GI₅₀ values below 10 μM in at least one of the cancer cell lines. The selectivity of these compounds was further examined in two non-malignant cell lines derived from breast (184B5) and lung (BEAS-2B). Compound 7 exhibited promising anti-proliferative activity (GI₅₀ = 3.7 μM) in MCF-7 cells, together with high selectivity index (SI > 27.1). The induction of cell death by compound 7 was independent of the apoptotic process and it did not affect cell cycle progression either. Likewise, radical scavenging properties of the new selenadiazole derivatives were confirmed by testing their ability to scavenge DPPH radicals. Four compounds (1, 2, 8 and 9) showed potent radical scavenging activity, compound 9 being the most effective. Overall, while compound 7 was identified as the most cell growth inhibitory agent and selectively toxic to cancer cells, compound 9 proved to be the most potent antioxidant among the selenadiazole derivatives synthesized. This series of compounds can serve as an excellent scaffold to achieve new and potent antioxidant compounds useful for several diseases, i.e. cancer, neurodegenerative, heart diseases and leishmaniasis, considering the high radical scavenging activity and low toxicity showed by most of the compounds.

Ethaselen: a novel organoselenium anticancer agent targeting thioredoxin reductase 1 reverses cisplatin resistance in drug-resistant K562 cells by inducing apoptosis

It has been reported that Ethaselen shows inhibitory effects on thioredoxin reductase (TrxR) activity and human tumor cell growth. In order to find an efficient way to reverse cisplatin resistance, we investigated the reversal effects of Ethaselen on cisplatin resistance in K562/cisplatin (CDDP) cells that were established by pulse-inducing human erythrocyte leukemic cell line K562, which are fivefold more resistant to cisplatin compared to K562 cells. The morphology and growth showed that the adhesion of K562/CDDP further decreased while the cell volume increased. The proliferation of K562/CDDP is strengthened. The antitumor activities in vitro were assessed by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and combination index (CI), showing the significant synergic effects of cisplatin and Ethaselen. Focusing on apoptosis, a series of comparisons was made between K562 and K562/CDDP. Cisplatin induced higher reactive oxygen species (ROS) generation in K562 and subsequently induced the formation of mitochondrial permeability transition pores (PTPs). In addition, cisplatin increased the ratio of Bax to Bcl-2 in K562, which can influence the mitochondrial membrane permeability. PTP formation and mitochondrial membrane permeabilization eventually resulted in the release of cytochrome c and activation of the Caspase pathway. However, these effects were not clearly seen in K562/CDDP, which may be the reason for the acquired CDDP resistance. However, Ethaselen can induce a high level of ROS in K562/CDDP by TrxR activity inhibition and increased ratio of Bax to Bcl-2 in K562/CDDP by nuclear factor κB (NF-κB) suppression, which subsequently induces the release of cytochrome c in K562/CDDP. This response is partly responsible for the reversal of the cisplatin resistance in K562/CDDP cells.

Targeting the Thioredoxin System for Cancer Therapy

Thioredoxin (Trx) and thioredoxin reductase (TrxR) are essential components of the Trx system which plays pivotal roles in regulating multiple cellular redox signaling pathways. In recent years TrxR/Trx have been increasingly recognized as an important modulator of tumor development, and hence targeting TrxR/Trx is a promising strategy for cancer treatment. In this review we first discuss the structural details of TrxR, the functions of the Trx system, and the rational of targeting TrxR/Trx for cancer treatment. We also highlight small-molecule TrxR/Trx inhibitors that have potential anticancer activity and review their mechanisms of action. Finally, we examine the challenges of developing TrxR/Trx inhibitors as anticancer agents and perspectives for selectively targeting TrxR/Trx.

Dose-biomarker-response modeling of the anticancer effect of ethaselen in a human non-small cell lung cancer xenograft mouse model

Thioredoxin reductase (TrxR) is a component of several redox-sensitive signaling cascades that mediate important biological processes such as cell survival, maturation, growth, migration and inhibition of apoptosis. The expression levels of TrxR1 in some human carcinoma cell lines are nearly 10 times higher than those in normal cells. Ethaselen is a novel antitumor candidate that exerts potent inhibition on non-small cell lung cancer (NSCLC) by targeting TrxR. In this study we explored the relationship between the ethaselen dose and TrxR activity level and the relationship between TrxR degradation and tumor apoptosis in a human lung carcinoma A549 xenograft model. BALB/c nude mice implanted with human NSCLC cell line A54 were administered ethaselen (36, 72, 108 mg·kg^-1·d^-1, ig) or vehicle for 10 d. The tumor size and TrxR activity levels in tumor tissues were daily recorded and detected. Based on the experimental data, NONMEM 7.2 was used to develop an integrated dose-biomarker-response model for describing the quantitative relationship between ethaselen dose and tumor eradication effects. The time course of TrxR activity levels was modeled using an indirect response model (IDR model), in which the influence of the tumor growth rates on K_in with the linear correction factor γ1 (0.021 d/mm). The drug binding-inhibition effects on K_out was described using a sigmoidal E_max model with S_max (5.95), SC₅₀ (136 mg/kg) and Hill's coefficient γ2 (2.29). The influence of TrxR activity inhibition on tumor eradication was characterized by an E_max model with an E_max (130 mm³/d) and EC₅₀ (0.0676). This model was further validated using a visual predictive check (VPC) and was used to predict the efficacy of different doses. In conclusion, the properties and characteristics of ethaselen acting on TrxR degradation and subsequently resulting in tumor apoptosis are characterized by the IDR model and integrated dose-biomarker-response model with high goodness-of-fit and great predicative ability. This approach shed new light on the detailed processes and mechanism of ethaselen action and may offer a valuable reference for an appropriate dosing regimen for use in further clinical applications.

MicroRNA-340 inhibits prostate cancer cell proliferation and metastasis by targeting the MDM2-p53 pathway

An increasing number of studies have demonstrated the important role of microRNAs (miRNAs) in modulating cancer progression and metastasis, but the mechanisms by which miRNAs regulate prostate cancer (PCa) tumorigenesis remain poorly understood. In the present study, we found that miR-340 may act as a tumor suppressor based on our finding that it was significantly downregulated in PCa tumor tissues and cell lines. Moreover, the expression of miR-340 was found to be correlated with the inhibition of cell proliferation, migration and invasion in vitro, and had a suppressive effect on tumor growth in a xenograft mouse model as well. The suppressive effect of miR-340 overexpression was observed in cell lines DU145 and BPH-1 which express wild-type (WT) p53. However, in the p53-null PC-3 cell line, the suppressive effect was not found, indicating that miR-340 may play a critical role in the p53 pathway. Further investigation revealed that mouse double minute 2 (MDM2), an important regulator of p53, was targeted by miR-340 through the direct binding to the 3'UTR of MDM2, which inhibited MDM2 translation. In addition, miR-340 expression stabilized p53 protein levels which caused an increase in p21 expression but a decrease in the anti‑apoptotic protein, BCL-2, in the p53 WT cell lines. Moreover, the miR-340-mediated inhibition of cell progression was mitigated by re-expressing MDM2 in the stable miR‑340-overexpressing PCa cell line, which harbors WT p53. Our findings suggest that miR-340 may function as a novel tumor suppressor in PCa through the MDM2-p53 pathway by directly targeting MDM2, which may be a promising miRNA-targeted therapy for PCa.

Thioredoxin reductase and its inhibitors

Thioredoxin plays a crucial role in a wide number of physiological processes, which span from reduction of nucleotides to deoxyriboucleotides to the detoxification from xenobiotics, oxidants and radicals. The redox function of Thioredoxin is critically dependent on the enzyme Thioredoxin NADPH Reductase (TrxR). In view of its indirect involvement in the above mentioned physio/pathological processes, inhibition of TrxR is an important clinical goal. As a general rule, the affinities and mechanisms of binding of TrxR inhibitors to the target enzyme are known with scarce precision and conflicting results abound in the literature. A relevant analysis of published results as well as the experimental procedures is therefore needed, also in view of the critical interest of TrxR inhibitors. We review the inhibitors of TrxR and related flavoreductases and the classical treatment of reversible, competitive, non competitive and uncompetitive inhibition with respect to TrxR, and in some cases we are able to reconcile contradictory results generated by oversimplified data analysis.

Human adipose derived stem cells induced cell apoptosis and s phase arrest in bladder tumor

The aim of this study was to determine the effect of human adipose derived stem cells (ADSCs) on the viability and apoptosis of human bladder cancer cells. EJ and T24 cells were cocultured with ADSCs or cultured with conditioned medium of ADSCs (ADSC-CM), respectively. The cell counting and colony formation assay showed ADSCs inhibited the proliferation of EJ and T24 cells. Cell viability assessment revealed that the secretions of ADSCs, in the form of conditioned medium, were able to decrease cancer cell viability. Wound-healing assay suggested ADSC-CM suppressed migration of T24 and EJ cells. Moreover, the results of the flow cytometry indicated that ADSC-CM was capable of inducing apoptosis of T24 cells and inducing S phase cell cycle arrest. Western blot revealed ADSC-CM increased the expression of cleaved caspase-3 and cleaved PARP, indicating that ADSC-CM induced apoptosis in a caspase-dependent way. PTEN/PI3K/Akt pathway and Bcl-2 family proteins were involved in the mechanism of this reaction. Our study indicated that ADSCs may provide a promising and practicable manner for bladder tumor therapy.

Selenium compounds as therapeutic agents in cancer

BACKGROUND

With cancer cells encompassing consistently higher production of reactive oxygen species (ROS) and with an induced antioxidant defense to counteract the increased basal ROS production, tumors have a limited reserve capacity resulting in an increased vulnerability of some cancer cells to ROS. Based on this, oxidative stress has been recognized as a tumor-specific target for the rational design of new anticancer agents. Among redox modulating compounds, selenium compounds have gained substantial attention due to their promising chemotherapeutic potential.

SCOPE OF REVIEW

This review aims in summarizing and providing the recent developments of our understanding of the molecular mechanisms that underlie the potential anticancer effects of selenium compounds.

MAJOR CONCLUSIONS

It is well established that selenium at higher doses readily can turn into a prooxidant and thereby exert its potential anticancer properties. However, the biological activity of selenium compounds and the mechanism behind these effects are highly dependent on its speciation and the specific metabolic pathways of cells and tissues. Conversely, the chemical properties and the main molecular mechanisms of the most relevant inorganic and organic selenium compounds as well as selenium-based nanoparticles must be taken into account and are discussed herein.

GENERAL SIGNIFICANCE

Elucidating and deepening our mechanistic knowledge of selenium compounds will help in designing and optimizing compounds with more specific antitumor properties for possible future application of selenium compounds in the treatment of cancer. This article is part of a Special Issue entitled Redox regulation of differentiation and de-differentiation.

Anti-tumor activities of matrine and oxymatrine: literature review

Matrine (MT) and oxymatrine (OMT), two kinds of alkaloid components found in the roots of Sophora species, have various pharmacological activities and are demonstrated to have anti-inflammatory, anti-allergic, anti-virus, anti-fibrotic, and cardiovascular protective effects. They are recently proved to have anti-cancer potentials, such as inhibiting cancer cell proliferation, inducing cell cycle arrest, accelerating apoptosis, restraining angiogenesis, inducing cell differentiation, inhibiting cancer metastasis and invasion, reversing multidrug resistance, and preventing or reducing chemotherapy- or radiotherapy-induced toxicity when combined with other chemotherapeutic drugs. In this review, we summarize the recent investigations regarding the anti-cancer activities and possible molecular targets of MT and OMT for cancer prevention and treatment in order to provide clues and references for further study.

Flavins and flavoproteins: applications in medicine

The potential of flavoproteins as targets of pharmacological treatments is immense. In this review we present an overview of the current research progress on medical interventions based on flavoproteins with a special emphasis on cancer, infectious diseases, and neurological disorders.

Suppression of urinary bladder urothelial carcinoma cell by the ethanol extract of pomegranate fruit through cell cycle arrest and apoptosis

Background

Pomegranate possesses many medicinal properties such as antioxidant, anti-inflammation and antitumor. It has been extensively used as a folk medicine by many cultures. Pomegranate fruit has been shown to have the inhibitory efficacy against prostate cancer and lung cancer in vitro and in vivo. It can be exploited in chemoprevention and chemotherapy of prostate cancer. In this study we examined the anti-cancer efficacy of pomegranate fruit grown in Taiwan against urinary bladder urothelial carcinoma (UBUC) and its mechanism of action.

Methods

Edible portion of Taiwanese pomegranate was extracted using ethanol and the anti-cancer effectiveness of ethanol extract was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Flow cytometry and western immunoblotting were exploited to uncover the molecular pathways underlying anti-UBUC activity of Taiwanese pomegranate ethanol extract.

Results

This study demonstrated that Taiwanese pomegranate fruit ethanol extract (PEE) could effectively restrict the proliferation of UBUC T24 and J82 cells. Cell cycle analyses indicated that the S phase arrest induced by PEE treatment might be caused by an increase in cyclin A protein level and a decrease in the expression of cyclin-dependent kinase 1. The results of western immunoblotting demonstrated that PEE treatment could not only evoke the activation of pro-caspase-3, -8,-9 but also increase Bax/Bcl-2 ratio in T24 cells. The above observations implicated that PEE administration might trigger the apoptosis in T24 cells through death receptor signaling and mitochondrial damage pathway. Besides we found that PEE exposure to T24 cells could provoke intensive activation of procaspase-12 and enhance the expressions of CHOP and Bip, endoplasmic reticulum (ER) stress marker, suggesting that ER stress might be the cardinal apoptotic mechanism of PEE-induced inhibition of bladder cancer cell.

Conclusions

The analytical results of this study help to provide insight into the molecular mechanism of induced bladder cancer cell apoptosis by pomegranate and to develop novel mechanism-based chemopreventive strategy for bladder cancer.

MicroRNA-302b suppresses cell proliferation by targeting EGFR in human hepatocellular carcinoma SMMC-7721 cells

BACKGROUND

MicroRNAs are regulators that can play an essential role in tumorigenesis. Although miR-302 families have been suggested to be tumor repressors in human cancer, the mechanism by which they suppress tumor development remains to be defined. In this study, we discover that miR302b suppresses tumor proliferation may due to directly targeting EGFR in human hepatocellular carcinoma (HCC).

METHODS

QRT-PCR was used to assess miR-302b and EGFR expression in 27 pairs of clinical hepatocellular carcinoma tissues and their corresponding adjacent nontumorous liver tissues. MTT, colony formation, immunofluorescence staining, and cell cycle assays were used to examine the tumor suppressor role of miR302b in cell proliferation. Luciferase assays were performed to assess the EGFR was a novel target of miR-302b. Western blot assay was used to validate the protein expression level.

RESULTS

We demonstrated that miR-302b was frequently down-regulated, whereas EGFR was up-regulated in 27 pairs of clinical HCC and non-tumorous counterparts. The dual-luciferase reporter assays revealed that EGFR was a novel target of miR-302b. Re-expression of miR-302b resulted in the inhibition of proliferation in hepatocellular carcinoma SMMC-7721 cells. The silencing of EGFR by miR-302b or siEGFR led to down-regulation of proliferation-related proteins, such as AKT2, CCND1, and CDK2.

CONCLUSION

miR-302b suppresses HCC growth may due to targeting the EGFR/AKT2/CCND1 pathway.

Selenium Biomarkers in Prostate Cancer Cell Lines and Influence of Selenium on Invasive Potential of PC3 Cells

Dietary selenium intake has been linked to reduced cancer risk, however the underlying mechanisms are yet unknown. We question the commonly used practice of applying selenium concentrations found in human blood to in vitro studies and evaluated the utility of biomarkers, e.g., glutathione peroxidase 1 (GPx1) and thioredoxin reductase 1 (TrxR1), to determine appropriate selenium levels for in vitro work. Furthermore, we investigated the effects of Se-methylselenocysteine (SeMSC) on prostate cancer cell migration and invasion. After excluding cytotoxicity, we demonstrated that prostate cancer cell lines respond differently to selenium treatment as observed through biomarker assessment. We found that the maximum levels of GPx1 activity and TrxR1 expression were reached at lower selenium concentrations in LNCaP compared to PC3 cells, and PC3 compared to DU145 cells. Therefore the use of selenium concentrations extrapolated from human studies for in vitro work may be applicable when further informed using a readout of selenium repletion including use of selenium responsive biomarkers. No effect on PC3 migration or invasion was observed after long term SeMSC treatment; however a slight increase was found when treatment was solely administered during the assay. The opposite could be observed when cells were cultured under low serum conditions, with a significant increase in migration upon long term but not upon acute SeMSC treatment. To conclude, these findings indicate that it is imperative to study the selenium sensitivity of an in vitro model preferably using biomarkers before investigating any effects on biological processes, or before comparing models.

Ethaselen: a potent mammalian thioredoxin reductase 1 inhibitor and novel organoselenium anticancer agent

Mammalian thioredoxin reductase 1 (TrxR1) is considered to be an important anticancer drug target and to be involved in both carcinogenesis and cancer progression. Here, we report that ethaselen, a novel organoselenium compound with anticancer activity, specifically binds to the unique selenocysteine-cysteine redox pair in the C-terminal active site of mammalian TrxR1. Ethaselen was found to be a potent inhibitor rather than an efficient substrate of mammalian TrxR1. It effectively inhibits wild-type mammalian TrxR1 at submicromolar concentrations with an initial mixed-type inhibition pattern. By using recombinant human TrxR1 variants and human glutathione reductase, we prove that ethaselen specifically targets the C-terminal but not the N-terminal active site of mammalian TrxR1. In A549 human lung cancer cells, ethaselen significantly suppresses cell viability in parallel with direct inhibition of TrxR1 activity. It does not, however, alter either the disulfide-reduction capability of thioredoxin or the activity of glutathione reductase. As a downstream effect of TrxR1 inactivation, ethaselen causes a dose-dependent thioredoxin oxidation and enhances the levels of cellular reactive oxygen species in A549 cells. Thus, we propose ethaselen as the first selenium-containing inhibitor of mammalian TrxR1 and provide evidence that selenium compounds can act as anticancer agents based on mammalian TrxR1 inhibition.

Small molecule inhibitors of mammalian thioredoxin reductase

Mammalian thioredoxin reductases (TrxRs) are a family of NADPH-dependent flavoproteins with a penultimate selenocysteine residue at the carboxy-terminus. Besides their native substrate thioredoxins (Trx), the enzymes show a broad substrate specificity, at least partially, because of the C-terminal redox-active site that is easily accessible in the reduced form. TrxRs are ubiquitous in all kinds of cells and have a critical role in regulating intracellular redox signaling. In recent years, a wealth of evidence has revealed that overactivation/dysfunction of TrxRs is closely related to various diseases, especially in tumor development, and thus the past decades have witnessed an expanding interest in finding TrxRs inhibitors, which might be promising agents for cancer chemotherapy. Herein we reviewed the small molecule inhibitors of mammalian TrxRs, with an emphasis on those that have potential anticancer activity. This review includes the nonpatent references up to 2010 that deal with mammalian TrxR inhibitors.

Effects of matrine on proliferation and apoptosis in gallbladder carcinoma cells (GBC-SD)

Although matrine, a primary active component of dried Sophora flavescens root (ku shen), is known to induce apoptosis in a variety of tumor cells in vitro, the molecular mechanism of such apoptosis remains elusive. This analysis of the cell cycle and apoptosis in matrine-treated human gallbladder carcinoma cells (GBC-SD) showed that matrine can indeed inhibit cell proliferation and induce G1 cell cycle arrest and apoptosis in a dose- and time-dependent manner. An additional western blot analysis of matrine-treated cells also showed caspase-3 and Bcl-2 activation, as well as cyclinE down-regulation. Overall, the results indicate that matrine perturbs gallbladder cancer cell progression during the G1 phase by down-regulating cyclinE and induces apoptosis by decreasing the expression of the antiapoptotic protein Bcl-2 and increasing expression of the proapoptotic protein Bax.

Preparation of tri-block copolymer micelles loading novel organoselenium anticancer drug BBSKE and study of tissue distribution of copolymer micelles by imaging in vivo method

BBSKE (1,2-[bis(1,2-benzisoselenazolone-3(2H)-ketone)] ethane, PCT: CN02/00412) is a novel organoselenium anticancer drug that plays a role in anticancer through inhibiting TrxR (thioredoxin reductase). In this study, we prepared a tri-block copolymer micelles loading BBSKE utilizing the amphiphilic tri-block copolymers (PEG6000-PLA6000) which we synthesized. And then the characters of the copolymer micelles were investigated. When packaged in polymeric micelles, the water solubility of BBSKE was improved to 0.21 mg/ml. The IC(50) were 7.14 microM, 5.05 microM and 4.23 microM when MCF-7 breast cancer cells were treated with BBSKE after 24h, 48h and 72h. The inhibition effect of polymeric micelles to MCF-7 tumor cells was bettered when folate, whose receptor was highly expressed in various tumors, was coated on the surface of these nanoparticles. Finally, by adopting a new way of imaging in vivo, we studied the distribution of micelles in nude mice with and without MCF-7 tumor. The results demonstrated that this copolymer micelles loading BBSKE can accumulate into tumor efficiently.

Self-assembled polymeric micellar nanoparticles as nanocarriers for poorly soluble anticancer drug ethaselen

A series of monomethoxy poly(ethylene glycol)-poly(lactide) (mPEG-PLA) diblock copolymers were synthesized, and mPEG-PLA micelle was fabricated and used as a nanocarrier for solubilization and delivery of a promising anticancer drug ethaselen. Ethaselen was efficiently encapsulated into the micelles by the dialysis method, and the solubility of ethaselen in water was remarkably increased up to 82 μg/mL before freeze-drying. The mean diameter of ethaselen-loaded micelles ranged from 51 to 98 nm with a narrow size distribution and depended on the length of PLA block. In vitro hemolysis study indicated that mPEG-PLA copolymers and ethaselen-loaded polymeric micelles had no hemolytic effect on the erythrocyte. The enhanced antitumor efficacy and reduced toxic effect of ethaselen-loaded polymeric micelle when compared with ethaselen-HP-β-CD inclusion were observed at the same dose in H22human liver cancer cell bearing mouse models. These suggested that mPEG-PLA polymeric micelle nanoparticles had great potential as nanocarriers for effective solubilization of poorly soluble ethaselen and further reducing side effects and toxicities of the drug.

Augmented antitumor effects of combination therapy of cisplatin with ethaselen as a novel thioredoxin reductase inhibitor on human A549 cell in vivo

Ethaselen (1, 2-[bis (1, 2-Benzisoselenazolone-3 (2H) -ketone)] ethane, BBSKE), as a novel organoselenium compound targeting thioredoxin reductase (TrxR), has been reported to inhibit tumor growth and TrxR activity in several human tumor cell lines. It has now entered Phase I clinical trails. Here we report the effects of ethaselen and cisplatin (cis-diamminedichloroplatinum II, DDP) combination therapy (ethaselen 36 mg/kg, i.g., o.d. x 10 d and cisplatin 1 mg/kg, i.p., single at day 0) on human A549-grafted nude mouse model (female, BALB/c nude mouse, n = 5, treatment after tumor volume reached 100 mm(3)). Compared to single drug administration (either ethaselen: 36 mg/kg, i.g., o.d. x 10 d or cisplatin: 1.0 mg/kg, i.p., single at day 0), the combination therapy showed significantly reduced tumor size (presumably due to a synergistic effect) and no obvious toxic damage (both in terms of body weight maintenance and liver/kidney damage). These results will be significant in the development of novel anti-tumoral therapeutic strategies directed to non-small cell lung cancer (NSCLC).

The thioredoxin system: a key target in tumour and endothelial cells

Thioredoxin is a redox-sensitive molecule that has pleiotropic cellular effects, such as the control of proliferation, redox states and apoptosis, and is often upregulated in malignancy. The system controls the activation of a number of transcription factors through sulphydryl transfer and, through its activity on hypoxia inducible factor 1alpha, it is able to regulate vascular endothelial growth factor levels and hence angiogenesis. The thioredoxin protein has been shown to be upregulated in hypoxic regions of certain tumours, suggesting that inhibitors could potentially exhibit enhanced hypoxic toxicity and/or indirect anti-angiogenic effects. Evidence of this is becoming apparent in the literature. The current report reviews the thioredoxin system as an anticancer drug target and focuses upon two recent compounds, PMX464 and PX12, which reportedly inhibit this important pathway.