Targeted therapy of human osteosarcoma with 17AAG or rapamycin: Characterization of induced apoptosis and inhibition of mTOR and Akt/MAPK/Wnt pathways

  • Authors:
    • Yair Gazitt
    • Venkatasubbarao Kolaparthi
    • Karla Moncada
    • Charles Thomas
    • James Freeman
  • View Affiliations

  • Published online on: February 1, 2009     https://doi.org/10.3892/ijo_00000181
  • Pages: 551-561
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Abstract

Osteosarcoma is highly resistant to current chemotherapy regimens. Novel therapeutic approaches, potentially involving targeting of specific survival pathways, are needed. We used 17-AAG to inhibit Hsp90 and rapamycin to inhibit mTOR, in the osteosarcoma cell lines, HOS and KHOS/NP. HOS and KHOS cells were treated for 24 and 48 h with 17-AAG or rapamycin and studied drug-induced apoptosis, cell cycle, mitochondrial membrane potential and levels of reduced glutathione (GSH), dephosphorylation of signal transduction proteins in the Akt/MAP kinase pathway and mTOR signaling. 17-AAG was a potent inducer of apoptosis, involving effective depletion of GSH and mitochondrial membrane (MM) depolarization, strong activation of caspase-8 and -9 and release of AIF from mitochondria to the cytosol. Furthermore, 17-AAG down-regulated pAkt, p44Erk, p-mTOR, p70S6, TSC1/2 and pGSK-3β. Treatment with 17-AAG also caused down-regulation of cyclin D1, GADD45a, GADD34 and pCdc2 and upregulation of cyclin B1 and mitotic block. A decrease in Hsp90 and increase in Hsp70 and Hsp70 C-terminal fragments were also observed. Rapamycin was a less potent inducer of apoptosis, involving a small decrease in GSH and MM potential with no activation of caspases or release of AIF. Rapamycin strongly inhibited cell growth with an increase in G1 and a decrease in S-phase of the cell cycle concomitant with down-regulation of cyclin D1. Rapamycin also down-regulated the activity of p70S6, pAkt and p-mTOR, but had no effect on pGSK-3β, p44Erk, pCdc2, TSC1/2 or Hsp70 or Hsp90. We conclude that Hsp90 inhibition merits further study in the therapy of osteosarcoma.

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February 2009
Volume 34 Issue 2

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

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APA
Gazitt, Y., Kolaparthi, V., Moncada, K., Thomas, C., & Freeman, J. (2009). Targeted therapy of human osteosarcoma with 17AAG or rapamycin: Characterization of induced apoptosis and inhibition of mTOR and Akt/MAPK/Wnt pathways. International Journal of Oncology, 34, 551-561. https://doi.org/10.3892/ijo_00000181
MLA
Gazitt, Y., Kolaparthi, V., Moncada, K., Thomas, C., Freeman, J."Targeted therapy of human osteosarcoma with 17AAG or rapamycin: Characterization of induced apoptosis and inhibition of mTOR and Akt/MAPK/Wnt pathways". International Journal of Oncology 34.2 (2009): 551-561.
Chicago
Gazitt, Y., Kolaparthi, V., Moncada, K., Thomas, C., Freeman, J."Targeted therapy of human osteosarcoma with 17AAG or rapamycin: Characterization of induced apoptosis and inhibition of mTOR and Akt/MAPK/Wnt pathways". International Journal of Oncology 34, no. 2 (2009): 551-561. https://doi.org/10.3892/ijo_00000181