Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Original Article
  • Published:

Rapamycin induces feedback activation of Akt signaling through an IGF-1R-dependent mechanism

Oncogene volume 26, pages 1932–1940 (2007)Cite this article

Abstract

Rapamycin and several analogs, such as CCI-779 and RAD001, are currently undergoing clinical evaluation as anticancer agents. In this study, we show that inhibition of mammalian target of rapamycin (mTOR) signaling by rapamycin leads to an increase of Akt phosphorylation in Rh30 and RD human rhabdomyosarcoma cell lines and xenografts, and insulin-like growth factor (IGF)-II-treated C2C12 mouse myoblasts and IGF-II-overexpressing Chinese hamster ovary cells. RNA interference-mediated knockdown of S6K1 also results in an increase of Akt phosphorylation. These data suggest that mTOR/S6K1 inhibition either by rapamycin or small interfering RNA (siRNA) triggers a negative feedback loop, resulting in the activation of Akt signaling. We next sought to investigate the mechanism of this negative feedback regulation from mTOR to Akt. Suppression of insulin receptor substrate (IRS)-1 and tuberous sclerosis complex-1 by siRNAs failed to abrogate rapamycin-induced upregulation of Akt phosphorylation in both Rh30 and RD cells. However, pretreatment with h7C10 antibody directed against insulin-like growth factor-1 receptor (IGF-1R) led to a blockade of rapamycin-induced Akt activation. Combined mTOR and IGF-1R inhibition with rapamycin and h7C10 antibody, respectively, resulted in additive inhibition of cell growth and survival. These data suggest that rapamycin mediates Akt activation through an IGF-1R-dependent mechanism. Thus, combining an mTOR inhibitor and an IGF-1R antibody/inhibitor may be an appropriate strategy to enhance mTOR-targeted anticancer therapy.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Figure 1
Figure 2
Figure 3
Figure 4
Figure 5

Similar content being viewed by others

References

  • Abraham RT, Wiederrecht GJ . (1996). Immunopharmacology of rapamycin. Annu Rev Immunol 14: 483–510.

    Article  CAS  PubMed  Google Scholar 

  • Dagher R, Helman L . (1999). Rhabdomyosarcoma: an overview. Oncologist 4: 34–44.

    CAS  PubMed  Google Scholar 

  • Fingar DC, Blenis J . (2004). Target of rapamycin (TOR): an integrator of nutrient and growth factor signals and coordinator of cell growth and cell cycle progression. Oncogene 23: 3151–3171.

    Article  CAS  PubMed  Google Scholar 

  • Fingar DC, Salama S, Tsou C, Harlow E, Blenis J . (2002). Mammalian cell size is controlled by mTOR and its downstream targets S6K1 and 4EBP1/eIF4E. Genes Dev 16: 1472–1487.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  • Goetsch L, Gonzalez A, Leger O, Beck A, Pauwels PJ, Haeuw JF et al. (2005). A recombinant humanized anti-insulin-like growth factor receptor type I antibody (h7C10) enhances the antitumor activity of vinorelbine and anti-epidermal growth factor receptor therapy against human cancer xenografts. Int J Cancer 113: 316–328.

    Article  CAS  PubMed  Google Scholar 

  • Goncharova EA, Goncharov DA, Eszterhas A, Hunter DS, Glassberg MK, Yeung RS et al. (2002). Tuberin regulates p70 S6 kinase activation and ribosomal protein S6 phosphorylation. A role for the TSC2 tumor suppressor gene in pulmonary lymphangioleiomyomatosis (LAM). J Biol Chem 277: 30958–30967.

    Article  CAS  PubMed  Google Scholar 

  • Harrington LS, Findlay GM, Gray A, Tolkacheva T, Wigfield S, Rebholz H et al. (2004). The TSC1-2 tumor suppressor controls insulin-PI3K signaling via regulation of IRS proteins. J Cell Biol 166: 213–223.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  • Hay N . (2005). The Akt-mTOR tango and its relevance to cancer. Cancer Cell 8: 179–183.

    Article  CAS  PubMed  Google Scholar 

  • Hay N, Sonenberg N . (2004). Upstream and downstream of mTOR. Genes Dev 18: 1926–1945.

    Article  CAS  PubMed  Google Scholar 

  • Hidalgo M, Rowinsky EK . (2000). The rapamycin-sensitive signal transduction pathway as a target for cancer therapy. Oncogene 19: 6680–6686.

    Article  CAS  PubMed  Google Scholar 

  • Huang S, Houghton PJ . (2003). Targeting mTOR signaling for cancer therapy. Curr Opin Pharmacol 3: 371–377.

    Article  CAS  PubMed  Google Scholar 

  • Inoki K, Li Y, Zhu T, Wu J, Guan KL . (2002). TSC2 is phosphorylated and inhibited by Akt and suppresses mTOR signalling. Nat Cell Biol 4: 648–657.

    Article  CAS  PubMed  Google Scholar 

  • Kido Y, Burks DJ, Withers D, Bruning JC, Kahn CR, White MF et al. (2000). Tissue-specific insulin resistance in mice with mutations in the insulin receptor, IRS-1, and IRS-2. J Clin Invest 105: 199–205.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  • Lawlor MA, Alessi DR . (2001). PKB/Akt: a key mediator of cell proliferation, survival and insulin responses? J Cell Sci 114: 2903–2910.

    CAS  PubMed  Google Scholar 

  • LeRoith D, Baserga R, Helman L, Roberts Jr CT . (1995). The role of the insulin-like growth factor-I receptor in cancer. Ann NY Acad Sci 766: 402–408.

    Article  CAS  PubMed  Google Scholar 

  • LeRoith D, Helman L . (2004). The new kid on the block(ade) of the IGF-1 receptor. Cancer Cell 5: 201–202.

    Article  CAS  PubMed  Google Scholar 

  • Manning BD . (2004). Balancing Akt with S6K: implications for both metabolic diseases and tumorigenesis. J Cell Biol 167: 399–403.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  • Merlino G, Helman L . (1999). Rhabdomyosarcoma – working out the pathways. Oncogene 18: 5340–5348.

    Article  CAS  PubMed  Google Scholar 

  • Minniti CP, Luan D, O’Grady C, Rosenfeld RG, Oh Y, Helman LJ . (1995). Insulin-like growth factor II overexpression in myoblasts induces phenotypic changes typical of the malignant phenotype. Cell Growth Differ 6: 263–269.

    CAS  PubMed  Google Scholar 

  • O’Reilly KE, Rojo F, She QB, Solit D, Mills GB, Smith D et al. (2006). mTOR inhibition induces upstream receptor tyrosine kinase signaling and activates Akt. Cancer Res 66: 1500–1508.

    Article  PubMed  PubMed Central  Google Scholar 

  • Pappo AS, Shapiro DN, Crist WM, Maurer HM . (1995). Biology and therapy of pediatric rhabdomyosarcoma. J Clin Oncol 13: 2123–2139.

    Article  CAS  PubMed  Google Scholar 

  • Potter CJ, Pedraza LG, Xu T . (2002). Akt regulates growth by directly phosphorylating Tsc2. Nat Cell Biol 4: 658–665.

    Article  CAS  PubMed  Google Scholar 

  • Radimerski T, Montagne J, Hemmings-Mieszczak M, Thomas G . (2002). Lethality of Drosophila lacking TSC tumor suppressor function rescued by reducing dS6 K signaling. Genes Dev 16: 2627–2632.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  • Sarbassov DD, Ali SM, Kim DH, Guertin DA, Latek RR, Erdjument-Bromage H et al. (2004). Rictor, a novel binding partner of mTOR, defines a rapamycin-insensitive and raptor-independent pathway that regulates the cytoskeleton. Curr Biol 14: 1296–1302.

    Article  CAS  PubMed  Google Scholar 

  • Sarbassov DD, Guertin DA, Ali SM, Sabatini DM . (2005). Phosphorylation and regulation of Akt/PKB by the rictor-mTOR complex. Science 307: 1098–1101.

    Article  CAS  PubMed  Google Scholar 

  • Schmelzle T, Hall MN . (2000). TOR, a central controller of cell growth. Cell 103: 253–262.

    Article  CAS  PubMed  Google Scholar 

  • Shah OJ, Wang Z, Hunter T . (2004). Inappropriate activation of the TSC/Rheb/mTOR/S6 K cassette induces IRS1/2 depletion, insulin resistance and cell survival deficiencies. Curr Biol 14: 1650–1656.

    Article  CAS  PubMed  Google Scholar 

  • Stocker H, Radimerski T, Schindelholz B, Wittwer F, Belawat P, Daram P et al. (2004). Rheb is an essential regulator of S6 K in controlling cell growth in Drosophila. Nat Cell Biol 5: 559–565.

    Article  Google Scholar 

  • Sun SY, Rosenberg LM, Wang X, Zhou Z, Yue P, Fu H et al. (2005). Activation of Akt and eIF4E survival pathways by rapamycin-mediated mammalian target of rapamycin inhibition. Cancer Res 65: 7052–7058.

    Article  CAS  PubMed  Google Scholar 

  • Sun XJ, Rothenberg P, Kahn CR, Backer JM, Araki E, Wilden PA et al. (1991). Structure of the insulin receptor substrate IRS-1 defines a unique signal transduction protein. Nature 352: 73–77.

    Article  CAS  PubMed  Google Scholar 

  • Tremblay F, Marette A . (2001). Amino acid and insulin signaling via the mTOR/p70 S6 kinase pathway. A negative feedback mechanism leading to insulin resistance in skeletal muscle cells. J Biol Chem 276: 38052–38060.

    CAS  PubMed  Google Scholar 

  • Wan X, Helman LJ . (2002). Effect of insulin-like growth factor II on protecting myoblast cells against cisplatin-induced apoptosis through p70 S6 kinase pathway. Neoplasia 4: 400–408.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  • Wan X, Helman LJ . (2003). Levels of PTEN protein modulate Akt phosphorylation on serine 473, but not on threonine 308, in IGF-II-overexpressing rhabdomyosarcomas cells. Oncogene 22: 8205–8211.

    Article  CAS  PubMed  Google Scholar 

  • Wan X, Mendoza A, Khanna C, Helman LJ . (2005). Rapamycin inhibits ezrin-mediated metastatic behavior in a murine model of osteosarcoma. Cancer Res 65: 2406–2411.

    Article  CAS  PubMed  Google Scholar 

  • White MF . (1998). The IRS-signalling system: a network of docking proteins that mediate insulin action. Mol Cell Biochem 182: 3–11.

    Article  CAS  PubMed  Google Scholar 

  • Womer RB, Pressey JG . (2000). Rhabdomyosarcoma and soft tissue sarcoma in childhood. Curr Opin Oncol 12: 337–344.

    Article  CAS  PubMed  Google Scholar 

  • Zhang L, Kim M, Choi YH, Goemans B, Yeung C, Hu Z et al. (1999). Diminished G1 checkpoint after gamma-irradiation and altered cell cycle regulation by insulin-like growth factor II overexpression. J Biol Chem 274: 13118–13126.

    Article  CAS  PubMed  Google Scholar 

Download references

Acknowledgements

This research was supported by the Intramural Research Program of the NIH, National Cancer Institute, Center for Cancer Research. We thank Merck Inc. for providing us with the h7C10 antibody.

Author information

Authors and Affiliations

  1. Molecular Oncology Section, Pediatric Oncology Branch, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, MD, USA

    X Wan, B Harkavy, N Shen, P Grohar & L J Helman

Authors
  1. X Wan
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. B Harkavy
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. N Shen
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. P Grohar
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. L J Helman
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to X Wan.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Wan, X., Harkavy, B., Shen, N. et al. Rapamycin induces feedback activation of Akt signaling through an IGF-1R-dependent mechanism. Oncogene 26, 1932–1940 (2007). https://doi.org/10.1038/sj.onc.1209990

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/sj.onc.1209990

Keywords

This article is cited by

Search

Advanced search

Quick links