Synergistic Effect of Ethaselen and Selenite Treatment against A549 Human Non-small Cell Lung Cancer Cells

  • Xu, Wei (State Key Laboratory of Natural and Biomimetic Drugs, Peking University) ;
  • Ma, Wei-Wei (State Key Laboratory of Natural and Biomimetic Drugs, Peking University) ;
  • Zeng, Hui-Hui (State Key Laboratory of Natural and Biomimetic Drugs, Peking University)
  • Published : 2014.09.15


Background: 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. Materials and Methods: 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. Results: 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 $IC_{50}$ 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. Conclusions: 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.


  1. An P. Selenium and endemic cancer in China. In 'Environmental Bioinorganic Chemistry of Selenium', Eds Whanger PM, Combs GF, Jr And Yeh JY, Chinese Academy of Science, Beijing, pp 91-149.
  2. Berggren M, Gallegos A, Gasdaska JR, et al (1996). Thioredoxin and thioredoxin reductase gene expression in human tumors and cell lines, and the effects of serum stimulation and hypoxia. Anticancer Res, 16, 3459-66.
  3. Combs GF Jr. Selenium. In 'Nutrition and Cancer Prevention', Eds Moon T and Micozzi M, Marcel Dekker, New York, pp 389-420.
  4. Combs GF Jr. Selenium and cancer. In 'Antioxidants and Disease Prevention', Eds Garewal H, CRC Press, New York, Ch.8, pp 97-113.
  5. Chou TC, Martin N (2005). PC software and user's guide (comboSyn, Paramus, NJ).
  6. Chou TC (2006). Theoretical basis, experimental design, and computerized simulation of synergism and antagonism in drug combination studies. Pharmacol Rev, 58, 622-81.
  7. Chou TC (2010). Drug combination studies and their synergy quantification using the Chou-Talalay Method. Cancer Res, 70, 440-6.
  8. Deniz A Hakan B, Seyda G, Deniz T, et al (2014). Survival results and prognostic factors in T4N0-3 non-small cell lung cancer patients according to the AJCC 7th edition staging system. Asian Pac J Cancer Prev, 15, 2465-72.
  9. EI-Bayoumy K. The role of selenium in cancer prevention. In 'Practice of Oncology, 4th edn', Eds DeVita VT , Hellman S.and Rosenberg SS, Lippincott, Philadelpia, pp 1-15.
  10. Fu JN, Li J, Tan Q, et al (2011). Thioredoxin reductase inhibitor ethaselen increases the drug sensitivity of the colon cancer cell line LoVo towards cisplatin via regulation of G1 phase and reversal of G2/M phase arrest. Investigational new drugs, 29, 627-36.
  11. Ganther HE. Chemistry and metabolism of selenium. In 'Selenium in Biology and Medicine, Part A', Eds Combs GF Jr, Spallholz JE, Levander OA and Oldfield JE, AVI, Westport, pp 53-65.
  12. Han H, Bears DJ, Browne LW, et al (2002). Identification of Differentially Expressed Genes in Pancreatic Cancer Cells Using cDNA Microarray. Cancer Res, 62, 2890-96.
  13. IP C, Medina D. Currrent concepts of selenium and mammary tumorigenesis. In 'Cellular and Molecular Biology of Breast Cancer', Eds Medina D, Kidwell W, Heppner Gand Anderson EP, Plenum Press, New York, pp 479-94.
  14. Irfan R, Aruna K, Saibal KB (2006). Assay for quantitative determination of glutathione and glutathione disulfide levels using enzymatic recycling method. Nat Protoc, 6, 3159-65.
  15. Li JY, Taylor PR, Li B, et al (1993). Nutrition intervention trials in Linxian, China. J Natl Cancer Inst, 85, 1492-8.
  16. Li J, Fang JC, Zeng HH (2008). Therapeutic effect of combination therapy with ethaselen and cicplatin of fluorouracil on gastric cancer cell BGC-823. Chinese J New Drugs Clinical Remedies, 27, 839-43.
  17. Liu YQ, Li Y, Qin J, et al (2014). Matrine reduces proliferation of human lung cancer cells by inducing apoptosis and changing miRNA expression profiles. Asian Pac J Cancer Prev, 15, 2169-77.
  18. Lincoln DT, Aliemadi EM, Tonissen KF (2003). The thioredoxinthioredoxin reductase system: Over-expression in human cancer. Anticancer Res, 23, 2425-33.
  19. Milner JA (1985). Effect of selenium on virally induced and transplantable tumor models. Fed Proc, 44, 2568-72.
  20. Medina D, Morrison DG (1988). Current ideas on selenium as a chemoprenventive agent. Pathol Immunopathol Res, 7, 187-99.
  21. Roy M, Kiremidjian-Schumacher L, Wishen HI, Cohen MW, Stotzky G (1994). Supplementation with selenium and human immune cell functions. I. Effect on lymphocyte proliferation and interleukin 2 receptor expression. Biol Trace Elem Res, 41, 103-14.
  22. Shamberger RJ, Frost DV (1969). Possible protective effect and selenium against human cancer. Can Med Assoc J, 100, 682.
  23. Shi C, Yu L, Yang F, Yan J, Zeng HH (2003). A novel organoselenium compound induces cell cycle arrest and apoptosis in prostate cancer cell lines. Biochem Biophys Res Commun, 309, 578-83.
  24. Tan Q, Li J, Yin HW, et al (2010). Augumented antitumor effects of combination therapy of cisplatin with ethaselen as a novel thioredoxin reductase inhibitor on human A549 cell in vivo. Investigational new drugs, 28, 205-15.
  25. Ueno H, Kajihara H, Nakamura H, Yodoi J, Nakamuro K (2007). Contribution of thioredoxin reductase to T-cell mitogenesis and NF-kappa B DNA-binding promotoed by selenite. Antioxid Redox Signal, 9, 115-21.
  26. Vichai V, Kirtikara K (2006). Sulforhodamine B colorimetric assay for cytotoxicity screening. Nat Protoc, 1, 1112-6.
  27. Whanger PD (1992). Selenium in the treatment of heavy metal poisoning and chemical carcinogenesis. J Trace Elem Electrolytes Health Dis, 6, 209-21.
  28. Wang LH, Zeng HH (2009). Investigation of the redox status in H22 hepatocellular carcinoma xenografts treated by a novel anticancer drug-ethaselen. J Pharmaceutical Sciences, 18, 245-51.
  29. Wang L, Fu JN, Wang JY, et al (2011). Selenium containing thioredoxin reductase inhibitor ethaselen sensitizes nonsmall cell lung cancer to radiotherapy. Anti-Cancer Drugs, 22, 732-40.
  30. Xiong K, Xu W, Zeng HH (2014). Reactive oxygen species mediate ethaselen-induced rapid apoptosis in A549 cells. J Pharmaceutical Sciences, 23, 54-59.
  31. Zeng HH (2002). Selenite and selenomethione promote HL-60 cell cycle progression. J Nutr, 132, 674-9.
  32. Zhao F, Yan J, Deng SJ, et al (2006). A thioredoxin reductase inhibitor induces growth inhibition and apoptosis in five cultured human carcinoma cell lines. Cancer Letters, 236, 46-53.