Open Access

Chemosensitizing effect of podophyllotoxin acetate on topoisomerase inhibitors leads to synergistic enhancement of lung cancer cell apoptosis

  • Authors:
    • Wan Gi Hong
    • Jeong Hyun Cho
    • Sang-Gu Hwang
    • Eunah Lee
    • Jaeseok Lee
    • Jong-Il Kim
    • Hong-Duck Um
    • Jong Kuk Park
  • View Affiliations

  • Published online on: April 1, 2016     https://doi.org/10.3892/ijo.2016.3471
  • Pages: 2265-2276
  • Copyright: © Hong et al. This is an open access article distributed under the terms of Creative Commons Attribution License.

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Abstract

Podophyllotoxin acetate (PA) acts as a radiosensitizer against non-small cell lung cancer (NSCLC) in vitro and in vivo. In this study, we examined its potential role as a chemosensitizer in conjunction with the topoisomerase inhibitors etoposide (Eto) and camptothecin (Cpt). The effects of combinations of PA and Eto/Cpt were examined with CompuSyn software in two NSCLC cell lines, A549 and NCI-H1299. Combination index (CI) values indicated synergistic effects of PA and the topoisomerase inhibitors. The intracellular mechanism underlying synergism was further determined using propidium iodide uptake, immunoblotting and electrophoretic mobility shift assay (EMSA). Combination of PA with Eto/Cpt promoted disruption of the dynamics of actin filaments, leading to subsequent enhancement of apoptotic cell death via induction of caspase-3, -8, and -9, accompanied by increased phosphorylation of p38. Conversely, suppression of p38 phosphorylation blocked the apoptotic effect of the drug combinations. Notably, CREB-1, a transcription factor, was constitutively activated in both cell types, and synergistically inhibited upon combination treatment. Our results collectively indicate that PA functions as a chemosensitizer by enhancing apoptosis through activation of the p38/caspase axis and suppression of CREB-1.
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June-2016
Volume 48 Issue 6

Print ISSN: 1019-6439
Online ISSN:1791-2423

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Spandidos Publications style
Hong WG, Cho JH, Hwang S, Lee E, Lee J, Kim J, Um H and Park JK: Chemosensitizing effect of podophyllotoxin acetate on topoisomerase inhibitors leads to synergistic enhancement of lung cancer cell apoptosis. Int J Oncol 48: 2265-2276, 2016
APA
Hong, W.G., Cho, J.H., Hwang, S., Lee, E., Lee, J., Kim, J. ... Park, J.K. (2016). Chemosensitizing effect of podophyllotoxin acetate on topoisomerase inhibitors leads to synergistic enhancement of lung cancer cell apoptosis. International Journal of Oncology, 48, 2265-2276. https://doi.org/10.3892/ijo.2016.3471
MLA
Hong, W. G., Cho, J. H., Hwang, S., Lee, E., Lee, J., Kim, J., Um, H., Park, J. K."Chemosensitizing effect of podophyllotoxin acetate on topoisomerase inhibitors leads to synergistic enhancement of lung cancer cell apoptosis". International Journal of Oncology 48.6 (2016): 2265-2276.
Chicago
Hong, W. G., Cho, J. H., Hwang, S., Lee, E., Lee, J., Kim, J., Um, H., Park, J. K."Chemosensitizing effect of podophyllotoxin acetate on topoisomerase inhibitors leads to synergistic enhancement of lung cancer cell apoptosis". International Journal of Oncology 48, no. 6 (2016): 2265-2276. https://doi.org/10.3892/ijo.2016.3471