Effect of rapamycin, an mTOR inhibitor, on radiation sensitivity of lung cancer cells having different p53 gene status

  • Authors:
    • Yoko Nagata
    • Akihisa Takahashi
    • Ken Ohnishi
    • Ichiro Ota
    • Takeo Ohnishi
    • Takashi Tojo
    • Shigeki Taniguchi
  • View Affiliations

  • Published online on: October 1, 2010     https://doi.org/10.3892/ijo_00000751
  • Pages: 1001-1010
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Abstract

Activation to a large extent of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway and mutations in the p53 gene are involved in lung cancer therapeutic resistance. The mammalian target of rapamycin (mTOR) acts as a downstream effector for Akt. Activation of the Akt/mTOR signal is a contributing factor to decreased radiation sensitivity. The purpose of this study was to examine whether the effect of rapamycin on radiation sensitivity is affected by cellular p53 gene status. Cellular radiation sensitivity was evaluated by using two human non-small cell lung cancer (NSCLC) cell lines with the same genetic background except for their p53 gene status (H1299/wtp53 and H1299/mp53). The cells were treated with rapamycin and/or radiation. Cell viability, cell proliferation, apoptosis, cell cycle and Akt/mTOR signaling activity were explored. Rapamycin synergistically enhanced the cytotoxicity of radiation, promoting the induction of apoptosis. Moreover, the combined treatment augmented the cytostatic effects of radiation regardless of cellular p53 gene status. Rapamycin in combination with radiation increased G1 arrest and suppressed progression to S phase in both cell lines. Furthermore, the combined treatment conduced to a prominent p53-independent down-regulation of the mTOR signal and pro-survival molecule, cyclin D1. Rapamycin can enhance the effect of radiation through the repression of pro-survival signals and the reduction in the apoptotic threshold. Taken together, inhibition of the mTOR signal may be a promising strategy for radiosensitization with no relevance to p53 gene status from the aspects of cell lethality and cell growth depression.

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October 2010
Volume 37 Issue 4

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

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Spandidos Publications style
Nagata Y, Takahashi A, Ohnishi K, Ota I, Ohnishi T, Tojo T and Taniguchi S: Effect of rapamycin, an mTOR inhibitor, on radiation sensitivity of lung cancer cells having different p53 gene status. Int J Oncol 37: 1001-1010, 2010
APA
Nagata, Y., Takahashi, A., Ohnishi, K., Ota, I., Ohnishi, T., Tojo, T., & Taniguchi, S. (2010). Effect of rapamycin, an mTOR inhibitor, on radiation sensitivity of lung cancer cells having different p53 gene status. International Journal of Oncology, 37, 1001-1010. https://doi.org/10.3892/ijo_00000751
MLA
Nagata, Y., Takahashi, A., Ohnishi, K., Ota, I., Ohnishi, T., Tojo, T., Taniguchi, S."Effect of rapamycin, an mTOR inhibitor, on radiation sensitivity of lung cancer cells having different p53 gene status". International Journal of Oncology 37.4 (2010): 1001-1010.
Chicago
Nagata, Y., Takahashi, A., Ohnishi, K., Ota, I., Ohnishi, T., Tojo, T., Taniguchi, S."Effect of rapamycin, an mTOR inhibitor, on radiation sensitivity of lung cancer cells having different p53 gene status". International Journal of Oncology 37, no. 4 (2010): 1001-1010. https://doi.org/10.3892/ijo_00000751