(1-2-bis(1-2-benzisoselenazolone-3(2h)-ketone))ethane and Lung-Neoplasms

Treating cancer metastasis is of vital importance to prolong patients' survival. Thioredoxin reductase (TrxR) is overexpressed in many cancer types and has been recognized as an anti-cancer target. The organoselenium compound ethaselen (BBSKE) has been proved to be a TrxR inhibitor and inhibit various types of tumor growth. However, whether BBSKE could inhibit tumor metastasis remains unclear. In this study, we aim to explore the antimetastatic effect of BBSKE and underlying mechanisms. BBSKE was found to dose-dependently suppress migration and invasion of MCF-7 and LoVo cells in vitro. The underlying mechanisms may include inhibition of TrxR activity, elevation of reactive oxygen species (ROS), decrease of EGFR activation and HER2 expression. Besides, the epithelial to mesenchymal transition process and expression of CD44, MMP-9, VEGFR2 and PD-L1 were also abrogated. Decreased migration and invasion, lower expression levels of EGFR, HER2, N-cadherin, CD44, MMP-9, VEGFR2 and PD-L1 were also observed in TrxR1-knockdown MCF-7 and LoVo cells. In the mouse breast cancer 4T1 model, BBSKE not only inhibited progression of primary tumor, but also suppressed formation of metastatic lung nodules and liver micro-metastases, indicating that BBSKE could effectively abolish tumor metastasis. In conclusion, our findings show that BBSKE is able to inhibit migration and invasion of cancer cells in vitro and in vivo, and may be used to prevent and treat metastasis.

Topics: Animals; Antineoplastic Agents; B7-H1 Antigen; Breast Neoplasms; Bridged Bicyclo Compounds, Heterocyclic; Cadherins; Cell Line, Tumor; Cell Movement; Cell Proliferation; ErbB Receptors; Female; Gene Expression Regulation, Neoplastic; Humans; Hyaluronan Receptors; Liver Neoplasms; Lung Neoplasms; Matrix Metalloproteinase 9; MCF-7 Cells; Mice; Mice, Inbred BALB C; Neoplasm Transplantation; Organoselenium Compounds; Oxidative Stress; Reactive Oxygen Species; Receptor, ErbB-2; Signal Transduction; Thioredoxin Reductase 1; Tumor Burden

New effective treatment for human non-small cell lung cancer (NSCLC) is needed. The thioredoxin (Trx) system composes of thioredoxin reductase (TrxR), Trx and NADPH. In this study, we combined an organic selenium compound--TrxR inhibitor ethaselen (BBSKE) with low dosage sodium selenite to inhibit proliferation and induce death of NSCLC cells, and identified underlying mechanisms. Synergistic anti-proliferation effect of BBSKE and selenite was found in human NSCLC cell lines, A549, NCI-H1299 and NCI-1266. A significant increase of apoptosis, necrosis and autophagy were observed in the group of BBSKE plus selenite in A549 cells. The autophagy induced by BBSKE and selenite inhibited apoptosis and necrosis. In addition, BBSKE plus selenite induced G2/M arrest, which was verified by the alteration of gene and protein expression of cell cycle regulatory complexes. The intracellular enzyme activity of TrxR was remarkably decreased by cotreatment of BBSKE and selenite. Besides, the mRNA and protein level of TrxR1 and Trx1 were significantly inhibited by cotreatment of BBSKE and selenite. HEK 293 cells overexpressing TrxR1 were more sensitive to BBSKE plus selenite. The nuclear translocation of Trx1 and Ref-1, as well as expression of Ref-1 and AP-1 were inhibited by combination treatment. In short, BBSKE synergizes selenite in inhibiting proliferation and inducing death of NSCLC cells; BBSKE combined with selenite may be a treatment strategy for NSCLC.

Topics: A549 Cells; Antineoplastic Agents; Apoptosis; Autophagy; Bridged Bicyclo Compounds, Heterocyclic; Carcinoma, Non-Small-Cell Lung; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; Cell Survival; Drug Synergism; HEK293 Cells; Humans; Lung Neoplasms; Microtubule-Associated Proteins; Organoselenium Compounds; RNA-Binding Proteins; Sodium Selenite; Thioredoxin-Disulfide Reductase; Thioredoxins; Transcription Factor AP-1

In this study, we aimed to evaluate the growth inhibitory effect of the combination of ethaselen (BBSKE) and low fixed dose of selenite against A549 human non-small cell lung cancer cells in vitro.. Growth inhibitory effects against A549 cells were determined by SRB assay. Combination index (CI) values were calculated based on Chou-Talalay median-effect analyses. Dose reduction index (DRI) values were applied to calculate dose reduction of selenite. Contents of free thiols and GSH were determined by DTNB assay and intracellular ROS levels by DCFH-DA fluorescence labeling.. Compared with BBSKE or selenite single treatment, the combined application of ethaselen and a low fixed dose of selenite shortened the onset time of sodium selenite, reduced IC50 values, and increased the maximum inhibition rates, suggesting a possible molecular mechanism of the synergism. Obvious synergistic effects were observed after different times of combination treatment, especially after 24 h. Compared with selenite single treatment, dosage of selenite could be remarkably reduced in combination therapy to gain the same inhibitory effect on cell proliferation. Compared with BBSKE single treatment, the content of free thiols and GSH were significantly reduced and ROS levels greatly elevated in the combination group. For the combination treatment, cell viability increased as greater concentrations of GSH were added.. All these results indicate that the combination treatment of BBSKE and selenite showed synergism to inhibit A549 cell proliferation in vitro, and also reduced the selenite dosage to mitigate its toxicity which is very meaningful for combination chemotherapy of lung cancer. The synergism was probably caused by the accelerated exhaustion of intracellular reductive substances, such as free thiols and GSH, which ultimately leads to enhanced oxidative stress and apoptosis.

Topics: Antineoplastic Agents; Apoptosis; Bridged Bicyclo Compounds, Heterocyclic; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Cell Proliferation; Cell Survival; Drug Screening Assays, Antitumor; Drug Synergism; Humans; In Vitro Techniques; Lung Neoplasms; Organoselenium Compounds; Reactive Oxygen Species; Selenious Acid

It has been proposed that thioredoxin reductase (TR) is a mediator that allows non-small cell lung cancer (NSCLC) to develop resistance to irradiation; however, little is known regarding the detailed mechanisms of action. Thus, ethaselen {1, 2-[bis (1,2-benzisoselenazolone-3 (2H)-ketone)] ethane, BBSKE}, a novel organoselenium TR inhibitor, is currently being investigated in a phase I clinical trial in China. However, its radiosensitizing effect remains unexplored. In this study, we found that the activity of TR increased dramatically in both A549 and H1299 cells after radiation, and moreover, could be inhibited by pretreatment with BBSKE (5 μmol/l). As a TR inhibitor, BBSKE enhanced the efficacy of radiation therapy both in vivo and in vitro without observable toxicity. BBSKE was found to suppress irradiation-induced NF-κB activation dramatically when using A549 cells stably transfected with NF-κB luciferase reporter. These results show the critical role of TR in the radioresistance of NSCLC and suggest that BBSKE is a potentially promising agent for the treatment of patients with NSCLC clinically.

Topics: Animals; Bridged Bicyclo Compounds, Heterocyclic; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Genes, Reporter; Humans; Luciferases; Lung Neoplasms; Male; Mice; Mice, Inbred C57BL; NF-kappa B; Organoselenium Compounds; Radiation Tolerance; Radiation-Sensitizing Agents; Thioredoxin-Disulfide Reductase; Transfection