Sensitization of cancer cells to radiation by selenadiazole derivatives by regulation of ROS-mediated DNA damage and ERK and AKT pathways

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.

Selenadiazole-Induced Hela Cell Apoptosis through the Redox Oxygen Species-Mediated JAK2/STAT3 Signaling Pathway

Cervical cancer is a significant global health concern, and novel therapeutic strategies are continually being sought to combat this disease. In recent years, selenadiazole found latent therapeutic effects on tumors. Herein, investigating the mechanism of selenadiazole in Hela cells holds promise for advancing cervical cancer treatment. Hela cells, a widely utilized model for studying cervical cancer, were treated with selenadiazole, and cell viability was assessed by using the cell counting kit-8 (CCK-8) assay. Changes in mitochondrial membrane potential were evaluated using JC-1 staining, while apoptosis induction was examined using AnnexinV-PI double staining. Intracellular ROS levels were measured by using specific fluorescent probes and the ELIASA system. Additionally, Western blotting was performed to assess the activation of related proteins in response to selenadiazole. Data analysis was performed using GraphPad. Exposure to selenadiazole led to a substantial increase in intracellular redox oxygen species (ROS) levels in Hela cells. Importantly, the induction of ROS by selenadiazole was associated with a marked increase in mitochondrial apoptosis, as evidenced by elevated levels of AnnexinV-positive cells, the JC-1 monomer, caspase-9, and Bcl-2. Furthermore, activation of the JAK2/STAT3 pathway was observed following the selenadiazole treatment. Selenadiazole holds the potential to suppress tumor growth in cervical cancer cells by increasing reactive oxygen species (ROS) levels and inducing mitochondrial apoptosis via the JAK2/STAT3 pathway. This study offers valuable insights into potential cervical cancer therapies and underscores the need for further research into the specific mechanisms of selenadiazole.

Inhibition of the thioredoxin system for radiosensitization therapy of cancer

Radiotherapy (RT) stands as a cornerstone in the clinical armamentarium against various cancers due to its proven efficacy. However, the intrinsic radiation resistance exhibited by cancer cells, coupled with the adverse effects of RT on normal tissues, often compromises its therapeutic potential and leads to unwanted side effects. This comprehensive review aims to consolidate our understanding of how radiosensitizers inhibit the thioredoxin (Trx) system in cellular contexts. Notable radiosensitizers, including gold nanoparticles (GNPs), gold triethylphosphine cyanide ([Au(SCN) (PEt3)]), auranofin, ceria nanoparticles (CONPs), curcumin and its derivatives, piperlongamide, indolequinone derivatives, micheliolide, motexafin gadolinium, and ethane selenide selenidazole derivatives (SeDs), are meticulously elucidated in terms of their applications in radiotherapy. In this review, the sensitization mechanisms and the current research progress of these radiosensitizers are discussed in detail, with the overall aim of providing valuable insights for the judicious application of Trx system inhibitors in the field of cancer radiosensitization therapy.

Therapeutic application of manganese-based nanosystems in cancer radiotherapy

Radiotherapy is an important therapeutic modality in the treatment of cancers. Nevertheless, the characteristics of the tumor microenvironment (TME), such as hypoxia and high glutathione (GSH), limit the efficacy of radiotherapy. Manganese-based (Mn-based) nanomaterials offer a promising prospect for sensitizing radiotherapy due to their good responsiveness to the TME. In this review, we focus on the mechanisms of radiosensitization of Mn-based nanosystems, including alleviating tumor hypoxia, increasing reactive oxygen species production, increasing GSH conversion, and promoting antitumor immunity. We further illustrate the applications of these mechanisms in cancer radiotherapy, including the development and delivery of radiosensitizers, as well as their combination with other therapeutic modalities. Finally, we summarize the application of Mn-based nanosystems as contrast agents in realizing precision therapy. Hopefully, the present review will provide new insights into the biological mechanisms of Mn-based nanosystems, as well as their applications in radiotherapy, in order to address the difficulties and challenges that remain in their clinical application in the future.

Novel Vectors and Administrations for mRNA Delivery

mRNA therapy has shown great potential in infectious disease vaccines, cancer immunotherapy, protein replacement therapy, gene editing, and other fields due to its central role in all life processes. However, mRNA is challenging to pass through the cell membrane due to its significant negative charges and degradation from RNase, so the key to mRNA therapy is efficient packaging and delivery of it with appropriate vectors. Presently researchers have developed various vectors such as viruses and liposomes, but these conventional vectors are now difficult to meet the growing requirement like safety, efficiency, and targeting, so many novel delivery vectors with unique advantages have emerged recently. This review mainly introduces two categories of novel vectors: biomacromolecules and inorganic nanoparticles, as well as two novel methods of control and administration based on these novel vectors: controlled-release administration and non-invasive administration. These novel delivery strategies have the advantages of high safety, biocompatibility, versatility, intelligence, and targeting. This paper analyzes the challenges faced by the field of mRNA delivery in depth, and discusses how to use the characteristics of novel vectors and administrations to solve these problems.

5-Nitrobenzo[c][1, 2, 5]selenadiazole as therapeutic agents in the regulation of oxidative stress and inflammation induced by influenza A(H1N1)pdm09 in vitro and in vivo

Currently, various problems are being faced in the treatment of influenza, so the development of new safe and effective drugs is crucial. Selenadiazole, an important component of selenium heterocyclic compounds, has received wide attention for its biological activity. This study aimed to verify the antiviral activity of 5-nitrobenzo[c][1,2,5]selenadiazole (SeD-3) in vivo and in vitro. The cell counting kit-8 assay and observation of cytopathic effect verified that SeD-3 could improve the survival of influenza A(H1N1)pdm09-infected Madin-Darby canine kidney cells. Polymerase chain reaction quantification and neuraminidase assay showed that SeD-3 could inhibit the proliferation of H1N1 virus. The time of addition assay demonstrated that SeD-3 may have a direct effect on virus particles and block some stages of H1N1 life cycle after virus adsorption. Cell cycle, JC-1, Annexin V, and terminal deoxynucleotidyl transferase (TdT) dUTP nick-end labeling-4',6-diamidino-2-phenylindole (TUNEL-DAPI) assays showed that SeD-3 inhibited H1N1 infection-induced apoptosis. Cytokine detection demonstrated SeD-3 inhibited the production of proinflammatory factors after infection, including tumor necrosis factor-α (TNF-α), TNF-β, interferon-γ, interleukin 12 (IL-12), and IL-17F. In vivo experiments suggested that the pathological damage in the lungs was significantly alleviated after treatment with SeD-3 by hematoxylin and eosin staining. The TUNEL assay of lung tissues indicated that SeD-3 inhibited DNA damage during H1N1 infection. Immunohistochemical assays were performed to further explore the mechanism that SeD-3 inhibited H1N1-induced apoptosis via reactive oxygen species-mediated MAPK, AKT, and P53 signaling pathways. In conclusion, SeD-3 may become a new potential anti-H1N1 influenza virus drug due to its antiviral and anti-inflammatory activity.

Thioredoxin reductase: An emerging pharmacologic target for radiosensitization of cancer

Novel agents are required to increase the radiosensitivity of cancer and improve the outcome of radiotherapy. Thioredoxin (Trx) and thioredoxin reductase (TrxR) reduce the oxidized cysteine thiols in several proteins, which regulate cellular redox, survival, proliferation, DNA synthesis, transcription factor activity and apoptosis. TrxR is essential for maintaining a conducive redox state for tumor growth, survival and resistance to therapy. Therefore, it is an appealing pharmacological target for the radiosensitization of tumors. Ionizing radiation (IR) is known to cause cytotoxicity through ROS, oxidative stress and DNA damage. Inhibition of thioredoxin system augments IR induced oxidative stress and potentiates cytotoxic effects. However, TrxR also regulates several critical cellular processes in normal cells. Here, we highlight the pre-clinical research and pharmacological studies to surmise possible utility of different TrxR inhibitors for radiosensitization. This review provides a succinct perspective on the role of TrxR inhibitors during the radiotherapy of cancer.

Structure Dependent Differential Modulation of Aβ Fibrillization by Selenadiazole-Based Inhibitors

Misfolding and fibrillar aggregation of Aβ is a characteristic hallmark of Alzheimer's disease and primarily participates in neurodegenerative pathologies. There has been no breakthrough made in the therapeutic regime of Alzheimer's disease while the pharmacological interventions against Aβ are designed to sequester and clear Aβ burden from the neurological tissues. Based on the physiological relevance of Aβ, therapeutic approaches are required to inhibit and stabilize Aβ fibrillization, instead of cleaning it from the neurological system. In this context, we have designed a selenadiazole-based library of compounds against the fibrillization paradigm of Aβ. Compounds that completely inhibited the Aβ fibrillization appeared to stabilize Aβ at the monomeric stage as indicated by ThT assay, CD spectrophotometry, and TEM imaging. Partial inhibitors elongated the nucleation phase and allowed limited fibrillization of Aβ into smaller fragments with slightly higher β-sheets contents, while noninhibitors did not interfere in Aβ aggregation and resulted in mature fibrils with fibrillization kinetics similar to Aβ control. Molecular docking revealed the different binding positions of the compounds for three classes. Complete inhibitors alleviated Aβ toxicity to SH-SY5Y neuroblastoma cells and permeated across the blood-brain barrier in zebrafish larvae. The amino acid residues from Aβ peptide that interacted with the compounds from all three classes were overlapping and majorly lying in the amyloidogenic regions. However, compounds that stabilize Aβ monomers displayed higher association constants (K_a) and lower dissociation constants (K_d) in comparison to partial and noninhibitors, as corroborated by ITC. These results support further structure activity-based preclinical development of these selenadiazole compounds for potential anti-Alzheimer's therapy.

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.

HMGB1 knockdown increases the radiosensitivity of esophageal squamous cell carcinoma by regulating the expression of molecules involved in DNA repair

Radiotherapy is an effective therapeutic strategy in esophageal squamous cell carcinoma (ESCC). However, acquired radioresistance of cancer cells leads to radiotherapy failure. The present study aimed to investigate the mechanisms of the effect of high mobility group box 1 (HMGB1) on the radiation sensitivity of ESCC. Small interfering RNA (si) transfection was used to generate three groups of TE-1 cells (TE-1, negative control and TE-1+siHMGB1), and the protein expression levels of HMGB1 in TE-1 cells were detected by western blotting. These groups of TE-1 cells were irradiated with different doses (0, 2, 4, 6 and 8 Gy) of X-rays after transfection. Subsequently, the viability of TE-1 cells was detected using an MTT assay, and the survival fraction of TE-1 cells was observed using a colony formation assay. The apoptotic rate, reactive oxygen species (ROS) content and levels of phosphorylated (p)-histone H2AX at S139 (p-γH2AX) of the cells were detected by flow cytometry. The alterations in mRNA expression levels of nicotinamide adenine nucleotide phosphate oxidase (NOX)1 and NOX5 were detected by reverse transcription-quantitative PCR, while the changes in protein levels of caspase-3, poly(ADP-ribose) polymerase, p-p38, p-ERK1/2 and p-JNK were detected by western blotting. The results revealed that HMGB1 knockdown significantly decreased cell viability, and the apoptosis rate of TE-1 cells transfected with siHMGB1 combined with radiation treatment was increased compared with that in cells with either siHMGB1 transfection or radiation treatment alone. HMGB1 knockdown increased nicotinamide adenine nucleotide phosphate oxidase-mediated ROS production and induced DNA damage via the MAPK signaling pathway, which may promote apoptosis and radiosensitivity after radiation in TE-1 cells. In conclusion, targeting HMGB1 may represent a promising strategy to increase the efficacy of radiation therapy for ESCC.

PBA2, a novel compound, enhances radiosensitivity in various carcinoma cells by activating the p53 pathway in vitro and in vivo

Radiotherapy is the main method used to treat human carcinoma; however, certain types of carcinomas are radiation-insensitive. The present study aimed to explore whether a novel compound, PBA2, could enhance the radiosensitivity of various carcinoma cells in vitro and in vivo, and investigate its underlying mechanism. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to assess the cytotoxicity of PBA2. Colony formation assays were used to observe the radiosensitivity effect of PBA2 in vitro. Cell cycle distributions and cell apoptosis were estimated using flow cytometry. Comet assays and Immunofluorescence assays were used to analyze DNA damage. The intracellular RNA was extracted and analyzed by sequencing. Western blotting was used to determine protein levels. A stable cell line with TP53 (encoding p53) knockdown was constructed by cell transfection. A mouse xenograft model was used to assess the radiosensitivity effect of PBA2 in vivo. We found that PBA2 at a low concentration (0.1 μM) enhanced radiosensitivity in various carcinoma cells, including CNE1, MG63, KB, HEP2, GLC82, and SMMC7221, in vitro. Combined with PBA2, radiation induced significant cell apoptosis in CNE1 and MG63 cells, accompanied by increased DNA damage, but did not affect cell cycle arrest. Mechanistically, PBA2 promoted p53 expression significantly; however, when p53 was mutated, functionally impaired, or knocked down, PBA2 could not enhance the radiosensitivity of these cells. Additionally, the combination of PBA2 and radiation reduced the tumor volume and tumor weight in CNE1 xenograft models significantly, without obvious toxicities. Our results demonstrated that PBA2 enhanced the radiosensitivity of various carcinoma cells in vitro and in vivo. The underlying mechanism might involve increasing DNA damage and cell apoptosis via activating the p53 pathway.

In Vitro Anti-Prostate Cancer Activity of Two Ebselen Analogues

Scientific research has been underway for decades in order to develop an effective anticancer drug, and it has become crucial to find a novel and effective chemotherapeutics in the case of prostate cancer treatment. Ebselen derivatives have been shown to possess a variety of biological activities, including cytostatic and cytotoxic action against tumor cells. In this study, the cytotoxic effect and anticancer mechanism of action of two organoselenium compounds— (N-allyl-1,2-benzisoselenazol-3(2H)-one (N-allyl-BS) and N-(3-methylbutyl)-1,2-benzisoselenazol-3(2H)-one) (N-(3-mb)-BS)—were investigated on two phenotypically different prostate cancer cell lines DU 145 and PC-3. The influence of analyzed compounds on the viability parameter was also assessed on normal prostate cell line PNT1A. The results showed that both organoselenium compounds (OSCs) efficiently inhibited cancer cell proliferation, whereas normal PNT1A cells were less sensitive to the analazyed ebselen analouges. Both OSCs induced G2/M cell cycle arrest and prompted cell death through apoptosis. The detection of cleaved Poly (ADP-ribose) Polymerase (PARP) confirmed this. In addition, N-allyl-BS and N-(3-m)-b-BS increased the level of reactive oxygen species (ROS) formation, however only N-allyl-BS induced DNA damage. Based on our data, we assume that OSCs’ anticancer action can be associated with oxidative stress induction and inactivation of the Akt- dependent signalling pathway. In conclusion, our data demonstrate that ebselen derivatives showed strong cytotoxic efficiency towards prostate cancer cells and may be elucidated as a novel, potent anticancer agent.

Rational design and action mechanisms of chemically innovative organoselenium in cancer therapy

Organo-seleno compounds (org-Se) have been widely used in antitumor, antiviral, and antiinflammatory therapy; antioxidation and other biological fields. As such, they have made an important contribution to overcoming various kinds of diseases, and researchers are increasingly attracted to org-Se's synthesis and functional design. This review is mainly focused on the design and synthesis of various kinds of org-Se, followed by their anticancer mechanisms such as the mitochondria mediated pathway induced by ROS, death receptor mediated pathways involving p53 phosphorylation, and the activation of the AMPK pathway to promote apoptosis. Org-Se also serves as a sensitizer in chemotherapy and radiotherapy, and an antagonist against the cytotoxic effects induced by chemotherapeutic agents. Finally, we will summarize the development of cancer-targeted org-Se containing complexes, and nanotechnology-based org-Se for anticancer application. This review could provide information for the future design of chemically innovative org-Se with anticancer potential, and shed light on the discovery of nanomaterial-based pharmaceuticals to improve drug development and formation.

Development and Therapeutic Potential of Selenazo Compounds

Incorporation of selenium (Se) atom into small molecules can substantially enhance their antioxidant, anti-inflammatory, antimutagenic, antitumoral or chemopreventive, antiviral, antibacterial, antifungal, antiparasitic, and neuroprotective effects. Specifically, selenazo compounds have received great attention owing to their chemical properties, pharmaceutical applications, and low toxicity. In this Perspective, we compile extensive literature evidence with the description and discussion of the most recent advances in different selenazo and selenadiazo motifs as potential pharmacological candidates. We also provide some perspectives on the challenges and future directions in the advancement of these selenazo compounds, each of which could generate drug candidates for various diseases.

Emerging Perspective: Role of Increased ROS and Redox Imbalance in Skin Carcinogenesis

Strategies to battle malignant tumors have always been a dynamic research endeavour. Although various vehicles (e.g., chemotherapeutic therapy, radiotherapy, surgical resection, etc.) are used for skin cancer management, they mostly remain unsatisfactory due to the complex mechanism of carcinogenesis. Increasing evidence indicates that redox imbalance and aberrant reactive oxygen species (ROS) are closely implicated in the oncogenesis of skin cancer. When ROS production goes beyond their clearance, excessive or accumulated ROS could disrupt redox balance, induce oxidative stress, and activate the altered ROS signals. These would damage cellular DNA, proteins, and lipids, further leading to gene mutation, cell hyperproliferation, and fatal lesions in cells that contribute to carcinogenesis in the skin. It has been known that ROS-mediated skin carcinogenesis involves multiple ways, including modulating related signaling pathways, changing cell metabolism, and causing the instability of the genome and epigenome. Nevertheless, the exact role of ROS in skin cancer has not been thoroughly elucidated. In spite of ROS inducing skin carcinogenesis, toxic-dose ROS could trigger cell death/apoptosis and, therefore, may be an efficient therapeutic tool to battle skin cancer. Considering the dual role of ROS in the carcinogenesis and treatment of skin cancer, it would be essential to clarify the relationship between ROS and skin cancer. Thus, in this review, we get the related data together to seek the connection between ROS and skin carcinogenesis. Besides, strategies basing on ROS to fight skin cancer are discussed.

Iron (II) Polypyridyl Complexes as Antiglioblastoma Agents to Overcome the Blood-Brain Barrier and Inhibit Cell Proliferation by Regulating p53 and 4E-BP1 Pathways

Background and Purpose: It is urgently required to develop promising candidates to permeate across blood-brain barrier (BBB) efficiently with simultaneous disrupting vasculogenic mimicry capability of gliomas. Previously, a series of iron (II) complexes were synthesized through a modified method. Hence, the aim of this study was to evaluate anticancer activity of Fe(PIP)₃SO₄ against glioma cancer cells. Methods: Cytotoxic effects were determined via MTT assay, and IC₅₀ values were utilized to evaluate the cytotoxicity. Cellular uptake of Fe(PIP)₃SO₄ between U87 and HEB cells was conducted by subtracting content of the complex remaining in the cell culture supernatants. Propidium Iodide (PI)-flow cytometric analysis was used to analyze cell cycle proportion of U87 cells treated with Fe(PIP)₃SO₄. The reactive oxygen species levels induced by Fe(PIP)₃SO₄ were measured by 2'-deoxycoformycin (DCF) probe; ABTS assay was utilized to examine the radical scavenge capacity of Fe(PIP)₃SO₄. To study the bind efficiency to thioredoxin reductase (TrxR), Fe(PIP)₃SO₄ was introduced into solution containing TrxR. To verify if Fe(PIP)₃SO₄ could penetrate BBB, HBMEC/U87 coculture as BBB model was established, and penetrating capability of Fe(PIP)₃SO₄ was tested. In vitro U87 tumor spheroids were formed to test the permeating ability of Fe(PIP)₃SO₄. Acute toxicity and biodistribution of Fe(PIP)₃SO₄ were tested on mice for 72 h. Protein profiles associated with U87 cells treated with Fe(PIP)₃SO₄ were determined by Western blotting analysis. Results: Results showed that Fe(PIP)₃SO₄ could suppress cell proliferation by inducing G2/M phase cycle retardation and apoptotic pathways, which was related with expression of p53 and initiation factor 4E binding protein 1. In addition, Fe complex could suppress cell proliferation by downregulating reactive oxygen species levels via scavenging free radicals and interaction with TrxR. Furthermore, Fe(PIP)₃SO₄ could permeate across BBB and simultaneously inhibited the vasculogenic mimicry-channel of U87 cells, suggesting favorable antiglioblastoma efficacy. Acute toxicity manifested lower degree of the complex compared with cisplatin and temozolomide. Conclusion: Fe(PIP)₃SO₄ exhibited favorable anticancer activity against glioma cells associated with p53 and 4E binding protein 1, accompanied with negligible toxic effects on normal tissues. Herein, Fe(PIP)₃SO₄ could be developed as a promising metal-based chemotherapeutic agent to overcome BBB and antagonize glioblastomas.

A novel role for NFIA in restoring radiosensitivity in radioresistant NSCLC cells by downregulating the AKT and ERK pathways

Radioresistance remains the most challenging issue leading to radiotherapy failure in the treatment of non-small cell lung cancer (NSCLC). The nuclear factor IA (NFIA) is associated with tumor response to treatments in many cancers, but its role in NSCLC radioresistance remains unclear. Here, we established two radioresistant NSCLC cell lines, H226R and H460R, by dose-gradient irradiation to investigate the function of NFIA in NSCLC radioresistance. The results showed a dramatically reduced expression of NFIA in radioresistant cells accompanied with elevated phosphorylation of AKT and ERK, when compared with their parental cells. Overexpression of NFIA restored the sensitivity of radioresistant cells to radiation through increased ionizing radiation (IR)-induced apoptosis and DNA damage by downregulating p-AKT and p-ERK, whereas knockdown of NFIA promoted radioresistance of the parental cells. Our findings suggested that NFIA enhanced cell radiosensitivity by downregulating p-AKT and p-ERK in NSCLC. Our study fills a gap in the field of NFIA and radioresistance, and establishes a mechanistic foundation to improve radiotherapy efficiency in NSCLC patients.

Autocrine secretions enhance radioresistance in an exosome‑independent manner in NSCLC cells

Radiotherapy resistance in patient with non‑small cell lung cancer (NSCLC) reduces patient survival and remains a significant challenge for the treatment of NSCLC. Radiation resistance has been demonstrated to be affected by secreted factors, yet it remains unclear how autocrine secretions affect the radioresistance of NSCLC cells. In the present study, the NSCLC cell line, NCI‑H460, was irradiated with γ‑rays (4 Gy) and then cultured in medium from H460 cells or normal medium to examine the potential influence of cell secretions on the radiation resistance of H460 cells. Cell viability, accumulation of reactive oxygen species and DNA repair capacity were all markedly improved in the irradiated H460 cells that were cultured in conditioned medium (CM), compared with those cells cultured in normal medium. In addition, G2/M cell cycle arrest and upregulation of homologous recombination repair proteins were observed in the CM‑treated cells, while exosomes secreted by H460 cells had no influence on the radiation resistance of H460 cells. Taken together, these results indicate that autocrine secretions enhance the radiation resistance of γ‑irradiated H460 cells and that these secretions mainly affect the DNA repair process.

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.

Inhibition of ERK1/2 or AKT Activity Equally Enhances Radiation Sensitization in B16F10 Cells

Background

The aim of the study was to evaluate the radiation sensitizing ability of ERK1/2, PI3K-AKT and JNK inhibitors in highly radiation resistant and metastatic B16F10 cells which carry wild-type Ras and Braf.

Methods

Mouse melanoma cell line B16F10 was exposed to 1.0, 2.0 and 3.0 Gy of electron beam radiation. Phosphorylated ERK1/2, AKT and JNK levels were estimated by ELISA. Cells were exposed to 2.0 and 3.0 Gy of radiation with or without prior pharmacological inhibition of ERK1/2, AKT as well as JNK pathways. Cell death induced by radiation as well as upon inhibition of these pathways was measured by TUNEL assay using flow cytometry.

Results

Exposure of B16F10 cells to 1.0, 2.0 and 3.0 Gy of electron beam irradiation triggered an increase in all the three phosphorylated proteins compared to sham-treated and control groups. B16F10 cells pre-treated with either ERK1/2 or AKT inhibitors equally enhanced radiation-induced cell death at 2.0 as well as 3.0 Gy (P < 0.001), while inhibition of JNK pathway increased radiation-induced cell death to a lesser extent. Interestingly combined inhibition of ERK1/2 or AKT pathways did not show additional cell death compared to individual ERK1/2 or AKT inhibition. This indicates that ERK1/2 or AKT mediates radiation resistance through common downstream molecules in B16F10 cells.

Conclusions

Even without activating mutations in Ras or Braf genes, ERK1/2 and AKT play a critical role in B16F10 cell survival upon radiation exposure and possibly act through common downstream effector/s.

Selenadiazole derivatives antagonize hyperglycemia-induced drug resistance in breast cancer cells by activation of AMPK pathways

Hyperglycemia is an important factor for chemoresistance of breast cancer patients with diabetes. In the present study, a novel selenadiazole derivative has been evaluated and found to be able to antagonize the doxorubicin (DOX) resistance of MCF-7 cells under simulated diabetes conditions. Hyperglycemia promotes the proliferation, invasion and migration of MCF-7 cells through activation of ERK and AKT pathways, which could be inhibited by the synthetic selenadiazole derivative. The antitumor effects of the selenadiazole derivative were attributed to its ability to activate AMPK pathways. Furthermore, the high lipophilicity (log P = 1.9) of the synthetic selenadiazole derivative facilitated its uptake by cancer cells and subsequently potentiated the cellular uptake of DOX, leading to a strong enhancment of the antiproliferative activity of DOX on MCF-7 cells by induction of apoptosis. The apoptosis was initiated by the ROS overproduction induced by the cooperation of the selenadiazole derivative and DOX. The excessive ROS then caused damage to DNA, which upregulated the expression of proapoptosis Bcl-2 family proteins and led to fragmentation of mitochondria, which finally caused apoptosis of the cancer cells. Taken together, this study provides a rational strategy for using selenadiazole derivatives to overcome hyperglycemia-induced drug resistance in breast cancer by activation of AMPK-mediated pathways.

Cancer stem cells and signaling pathways in radioresistance

Radiation therapy (RT) is one of the most important strategies in cancer treatment. Radioresistance (the failure to RT) results in locoregional recurrence and metastasis. Therefore, it is critically important to investigate the mechanisms leading to cancer radioresistance to overcome this problem and increase patients' survival. Currently, the majority of the radioresistance-associated researches have focused on preclinical studies. Although the exact mechanisms of cancer radioresistance have not been fully uncovered, accumulating evidence supports that cancer stem cells (CSCs) and different signaling pathways play important roles in regulating radiation response and radioresistance. Therefore, targeting CSCs or signaling pathway proteins may hold promise for developing novel combination modalities and overcoming radioresistance. The present review focuses on the key evidence of CSC markers and several important signaling pathways in cancer radioresistance and explores innovative approaches for future radiation treatment.

The effects of combined selenium nanoparticles and radiation therapy on breast cancer cells in vitro

Radiosensitizers that increase cancer cell radio-sensitivity can enhance the effectiveness of irradiation and minimize collateral damage. Nanomaterial has been employed in conjunction with radiotherapy as radiosensitizers, due to its unique physicochemical properties. In this article, we evaluated selenium nanoparticles (Nano-Se) as a new radiosensitizer. Nano-Se was used in conjunction with irradiation on MCF-7 breast cancer cells, and efficacy and mechanisms of this combined treatment approach were evaluated. Nano-Se reinforced the toxic effects of irradiation, leading to a higher mortality rate than either treatment used alone, inducing cell cycle arrest at the G2/M phase and the activation of autophagy, and increasing both endogenous and irradiation-induced reactive oxygen species formation. These results suggest that Nano-Se can be used as an adjuvant drug to improve cancer cell sensitivity to the toxic effects of irradiation and thereby reduce damage to normal tissue nearby.

Nucleolin-targeted selenium nanocomposites with enhanced theranostic efficacy to antagonize glioblastoma

Glioblastoma is considered as the most lethal cancer, due to the inability of chemotherapeutic agents to reach the glioma core as well as the infiltration zone of the invasive glioma cells. Nanotechnology based delivery systems bring new hope to cancer targeted therapy and diagnosis owing to their enhancement of selective cellular uptake and cytotoxicity to cancer cells through various smart designs. We prepared a novel selenium-based composite nanosystem (QDs/Se@Ru(A)) surface functionalized with the AS1411 aptamer and loaded with quantum dots to realize selectivity against glioblastoma and enhance theranostic effects. This cancer targeted nanosystem significantly enhanced the cellular uptake in glioma cells through nucleolin mediated endocytosis, and increased selectivity between cancer and normal cells. The QDs/Se@Ru(A) nanosystem can also be used for spontaneous fluorescence of biological probes to explore their localization in cancer cells, because of the green fluorescent quantum dots loaded into the selenium nanoparticles. QDs/Se@Ru(A) promotes excess reactive oxygen species (ROS) production in glioma cells to induce DNA damage, thus activating diverse downstream signaling pathways, and inhibiting proliferation of U87 cells through the G2/M phase cycle. Thus, this study provides an effective strategy to design a theranostic agent to simultaneously realize cell imaging and therapy for glioblastoma treatment.

Ruthenium complexes with phenylterpyridine derivatives target cell membrane and trigger death receptors-mediated apoptosis in cancer cells

Elucidation of the communication between metal complexes and cell membrane may provide useful information for rational design of metal-based anticancer drugs. Herein we synthesized a novel class of ruthenium (Ru) complexes containing phtpy derivatives (phtpy = phenylterpyridine), analyzed their structure-activity relationship and revealed their action mechanisms. The result showed that, the increase in the planarity of hydrophobic Ru complexes significantly enhanced their lipophilicity and cellular uptake. Meanwhile, the introduction of nitro group effectively improved their anticancer efficacy. Further mechanism studies revealed that, complex (2c), firstly accumulated on cell membrane and interacted with death receptors to activate extrinsic apoptosis signaling pathway. The complex was then transported into cell cytoplasm through transferrin receptor-mediated endocytosis. Most of the intracellular 2c accumulated in cell plasma, decreasing the level of cellular ROS, inducing the activation of caspase-9 and thus intensifying the apoptosis. At the same time, the residual 2c can translocate into cell nucleus to interact with DNA, induce DNA damage, activate p53 pathway and enhance apoptosis. Comparing with cisplatin, 2c possesses prolonged circulation time in blood, comparable antitumor ability and importantly, much lower toxicity in vivo. Taken together, this study uncovers the role of membrane receptors in the anticancer actions of Ru complexes, and provides fundamental information for rational design of membrane receptor targeting anticancer drugs.

Selenadiazole derivatives antagonize glucocorticoid-induced osteoblasts cells apoptosis by blocking ROS-mediated signaling, a new anti-osteoporosis strategy

Herein we demonstrate that synthetic selenadiazole derivatives could protect osteoblasts cells against Dex-induced cell apoptosisviaattenuating oxidative stress and downstream signalling pathways.

Enhancement of cell uptake and antitumor activity of selenadiazole derivatives through interaction and delivery by serum albumin

A series of selenadiazole derivatives has been synthesized and exhibit potent anticancer efficacy through interaction and delivery by serum albumin.

Allyl isothiocyanate induces replication-associated DNA damage response in NSCLC cells and sensitizes to ionizing radiation

Allyl isothiocyanate (AITC), a constituent of many cruciferous vegetables exhibits significant anticancer activities in many cancer models. Our studies provide novel insights into AITC-induced anticancer mechanisms in human A549 and H1299 non-small cell lung cancer (NSCLC) cells. AITC exposure induced replication stress in NSCLC cells as evidenced by γH2AX and FANCD2 foci, ATM/ATR-mediated checkpoint responses and S and G2/M cell cycle arrest. Furthermore, AITC-induced FANCD2 foci displayed co-localization with BrdU foci, indicating stalled or collapsed replication forks in these cells. Although PITC (phenyl isothiocyanate) exhibited concentration-dependent cytotoxic effects, treatment was less effective compared to AITC. Previously, agents that induce cell cycle arrest in S and G2/M phases were shown to sensitize tumor cells to radiation. Similar to these observations, combination therapy involving AITC followed by radiation treatment exhibited increased DDR and cell killing in NSCLC cells compared to single agent treatment. Combination index (CI) analysis revealed synergistic effects at multiple doses of AITC and radiation, resulting in CI values of less than 0.7 at Fa of 0.5 (50% reduction in survival). Collectively, these studies identify an important anticancer mechanism displayed by AITC, and suggest that the combination of AITC and radiation could be an effective therapy for NSCLC.

Highly stable selenadiazole derivatives induce bladder cancer cell apoptosis and inhibit cell migration and invasion through the activation of ROS-mediated signaling pathways

Herein highly stable selenadiazole derivatives were synthesized and found to be able to induce bladder cancer cell apoptosis and inhibit cell migration and invasion through the activation of ROS-mediated pathways.

Chabamide induces cell cycle arrest and apoptosis by the Akt/MAPK pathway and inhibition of P-glycoprotein in K562/ADR cells

One of the major mechanisms of multidrug resistance in cancer therapy is the overexpression of P-glycoprotein (P-gp). Chabamide, a dimeric alkaloid isolated from Piper chaba Hunter, shows antimalarial, antituberculosis, and cytotoxic activities. However, its mechanism of action has not been elucidated. In this study, the molecular mechanism underlying the cytotoxicity and downregulation of P-gp expression by chabamide in adriamycin-resistant human leukemia cells (K562/ADR) was clarified. Results show that chabamide inhibited the growth of K562/ADR cells in a dose-dependent and time-dependent manner, and significantly inhibited cell proliferation by cell cycle arrest in the G0/G1 phase, which was associated with an obvious increase in p21 and decrease in cyclin D1 and CDK2/4/6 protein expression. Moreover, chabamide could regulate the changes in the mitochondrial membrane potential, increase the expression of apoptosis-related proteins, such as Bax and cytochrome c, and decrease the protein expression levels of Bcl-2, caspase-9, caspase-3, PARP-1, and p-Akt. In addition, we found that JNK, ERK1/2, and p38 were regulated by chabamide in K562/ADR cells. Further studies indicated that the decrease in the reactive oxygen species level inhibited intrinsic P-gp expression. Therefore, chabamide-induced apoptosis in K562/ADR cells was associated with Akt/MAPK and the inhibition of P-gp. These results provide a biochemical basis for possible clinical applications of chabamide in the treatment of leukemia.

Enhancement of radiotherapy by ceria nanoparticles modified with neogambogic acid in breast cancer cells

Radiotherapy is one of the main strategies for cancer treatment but has significant challenges, such as cancer cell resistance and radiation damage to normal tissue. Radiosensitizers that selectively increase the susceptibility of cancer cells to radiation can enhance the effectiveness of radiotherapy. We report here the development of a novel radiosensitizer consisting of monodispersed ceria nanoparticles (CNPs) covered with the anticancer drug neogambogic acid (NGA-CNPs). These were used in conjunction with radiation in MCF-7 breast cancer cells, and the efficacy and mechanisms of action of this combined treatment approach were evaluated. NGA-CNPs potentiated the toxic effects of radiation, leading to a higher rate of cell death than either treatment used alone and inducing the activation of autophagy and cell cycle arrest at the G2/M phase, while pretreatment with NGA or CNPs did not improve the rate of radiation-induced cancer cells death. However, NGA-CNPs decreased both endogenous and radiation-induced reactive oxygen species formation, unlike other nanomaterials. These results suggest that the adjunctive use of NGA-CNPs can increase the effectiveness of radiotherapy in breast cancer treatment by lowering the radiation doses required to kill cancer cells and thereby minimizing collateral damage to healthy adjacent tissue.

Peroxiredoxin 1 suppresses apoptosis via regulation of the apoptosis signal-regulating kinase 1 signaling pathway in human oral leukoplakia

Peroxiredoxin 1 (Prx1) has a significant role in several malignant types of tumor. However, the role of Prx1 in oral leukoplakia (OLK) has remained to be elucidated. OLK is a common precancerous lesion of the oral mucosa that has a very high malignant transformation rate. The aim of the present study was to investigate the roles of Prx1, and its association with apoptosis signal-regulating kinase 1 (ASK1) and p38 in OLK. A total of 20 OLK samples and 10 normal oral mucosa samples were obtained from patients at the Beijing Stomatological Hospital (Beijing, China). The messenger RNA (mRNA) and protein expression levels of Prx1, ASK1 and p38 were determined by polymerase chain reaction and western blot analysis, respectively. Flow cytometry was used to detect cell apoptosis. The interaction between Prx1 and ASK1 was examined in H₂O₂-treated DOK cells by glutathione-S-transferase pull-down assays and by co-immunoprecipitation in vitro. Compared with those of the normal oral mucosa, the mRNA levels of Prx1, ASK1 and p38 were elevated in OLK tissues (P<0.05). The protein expression levels of Prx1, phosphorylated-ASK1 (p-ASK1) and p-p38 were also significantly enhanced in OLK tissues compared with those of the normal mucosa (P<0.05). In Prx1-knockdown DOK cells, ASK1 and p38 were activated, leading to enhanced levels of apoptosis in response to H₂O₂. No clear interaction between Prx1 and ASK1 was detected in H₂O₂-treated DOK cells. Prx1 was suggested to be involved in OLK pathogenesis by providing resistance against extracellular damages from oxidative stress via inhibition of the ASK1-induced apoptotic signaling pathway. Targeting Prx1 may provide a novel therapeutic strategy for the treatment of patients with OLK.

An integrin-targeting nanosystem as a carrier of the selenadiazole derivative to induce ROS-mediated apoptosis in bladder cancer cells, from rational design to action mechanisms

Herein an integrin-targeting nanosystem is rationally designed and used as a carrier of a selenadiazole derivative to induce ROS-mediated apoptosis in bladder cancer cells.

Selenadiazole derivatives as theranostic agents for simultaneous cancer chemo-/radiotherapy by targeting thioredoxin reductase

Herein we have identified selenadiazole derivatives as effective and safe theranostic agents for simultaneous cancer chemo-/radiotherapy.

A selenium-containing ruthenium complex as a cancer radiosensitizer, rational design and the important role of ROS-mediated signalling

We have described the rational design of selenium-containing ruthenium complexes and their use as cancer radiosensitizers through regulating ROS-mediated pathways.