Skip to main content

Advertisement

Log in

Metformin and rapamycin have distinct effects on the AKT pathway and proliferation in breast cancer cells

  • Brief Report
  • Published:
Breast Cancer Research and Treatment Aims and scope Submit manuscript

Abstract

Rapamycin and its analogues inhibit mTOR, which leads to decreased protein synthesis and decreased cancer cell proliferation in many experimental systems. Adenosine 5′- monophosphate-activated protein kinase (AMPK) activators such as metformin have similar actions, in keeping with the TSC2/1 pathway linking activation of AMPK to inhibition of mTOR. As mTOR inhibition by rapamycin is associated with attenuation of negative feedback to IRS-1, rapamycin is known to increase activation of AKT, which may reduce its anti-neoplastic activity. We observed that metformin exposure decreases AKT activation, an action opposite to that of rapamycin. We show that metformin (but not rapamycin) exposure leads to increased phosphorylation of IRS-1 at Ser789, a site previously reported to inhibit downstream signaling and to be an AMPK substrate phosphorylated under conditions of cellular energy depletion. siRNA methods confirmed that reduction of AMPK levels attenuates both the IRS-1 Ser789 phosphorylation and the inhibition of AKT activation associated with metformin exposure. Although both rapamycin and metformin inhibit mTOR (the former directly and the latter through AMPK signaling), our results demonstrate previously unrecognized differences between these agents. The data are consistent with the observation that maximal induction of apoptosis and inhibition of proliferation are greater for metformin than rapamycin.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7

Similar content being viewed by others

References

  1. Rini B, Kar S, Kirkpatrick P (2007) Temsirolimus. Nat Rev Drug Discov 6:599–600

    Article  CAS  Google Scholar 

  2. Sun SY, Rosenberg LM, Wang X, Zhou Z, Yue P, Fu H, Khuri FR (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 

  3. O’Reilly KE, Rojo F, She QB, Solit D, Mills GB, Smith D, Lane H, Hofmann F, Hicklin DJ, Ludwig DL, Baselga J, Rosen N (2006) mTOR inhibition induces upstream receptor tyrosine kinase signaling and activates Akt. Cancer Res 66:1500–1508

    Article  PubMed  Google Scholar 

  4. Bhaskar PT, Hay N (2007) The two TORCs and Akt. Dev Cell 12:487–502

    Article  CAS  PubMed  Google Scholar 

  5. Guertin DA, Sabatini DM (2007) Defining the role of mTOR in cancer. Cancer Cell 12:9–22

    Article  CAS  PubMed  Google Scholar 

  6. Wang X, Yue P, Kim YA, Fu H, Khuri FR, Sun SY (2008) Enhancing mammalian target of rapamycin (mTOR)-targeted cancer therapy by preventing mTOR/raptor inhibition-initiated, mTOR/rictor-independent Akt activation. Cancer Res 68:7409–7418

    Article  CAS  PubMed  Google Scholar 

  7. Easton JB, Kurmasheva RT, Houghton PJ (2006) IRS-1: auditing the effectiveness of mTOR inhibitors. Cancer Cell 9:153–155

    Article  CAS  PubMed  Google Scholar 

  8. Ozes ON, Akca H, Mayo LD, Gustin JA, Maehama T, Dixon JE, Donner DB (2001) A phosphatidylinositol 3-kinase/Akt/mTOR pathway mediates and PTEN antagonizes tumor necrosis factor inhibition of insulin signaling through insulin receptor substrate-1. Proc Natl Acad Sci USA 98:4640–4645

    Article  CAS  PubMed  Google Scholar 

  9. Tzatsos A, Kandror KV (2006) Nutrients suppress phosphatidylinositol 3-kinase/Akt signaling via raptor-dependent mTOR-mediated insulin receptor substrate 1 phosphorylation. Mol Cell Biol 26:63–76

    Article  CAS  PubMed  Google Scholar 

  10. Harrington LS, Findlay GM, Gray A, Tolkacheva T, Wigfield S, Rebholz H, Barnett J, Leslie NR, Cheng S, Shepherd PR, Gout I, Downes CP, Lamb RF (2004) The TSC1-2 tumor suppressor controls insulin-PI3K signaling via regulation of IRS proteins. J Cell Biol 166:213–223

    Article  CAS  PubMed  Google Scholar 

  11. Guertin DA, Sabatini DM (2009) The pharmacology of mTOR inhibition. Sci Signal 2:e24

    Google Scholar 

  12. Hardie DG (2008) AMPK and Raptor: matching cell growth to energy supply. Mol Cell 30:263–265

    Article  CAS  PubMed  Google Scholar 

  13. Gwinn DM, Shackelford DB, Egan DF, Mihaylova MM, Mery A, Vasquez DS, Turk BE, Shaw RJ (2008) AMPK phosphorylation of raptor mediates a metabolic checkpoint. Mol Cell 30:214–226

    Article  CAS  PubMed  Google Scholar 

  14. Shaw RJ (2009) LKB1 and AMP-activated protein kinase control of mTOR signalling and growth. Acta Physiol (Oxf) 196:65–80

    Article  CAS  Google Scholar 

  15. Zakikhani M, Dowling R, Fantus IG, Sonenberg N, Pollak M (2006) Metformin is an AMP kinase-dependent growth inhibitor for breast cancer cells. Cancer Res 66:10269–10273

    Article  CAS  PubMed  Google Scholar 

  16. Zakikhani M, Dowling RJ, Sonenberg N, Pollak MN (2008) The effects of adiponectin and metformin on prostate and colon neoplasia involve activation of AMP-activated protein kinase. Cancer Prev Res (Phila Pa) 1:369–375

    Google Scholar 

  17. Dowling RJ, Zakikhani M, Fantus IG, Pollak M, Sonenberg N (2007) Metformin inhibits mammalian target of rapamycin-dependent translation initiation in breast cancer cells. Cancer Res 67:10804–10812

    Article  CAS  PubMed  Google Scholar 

  18. Algire C, Zakikhani M, Blouin M-J, Shuai JH, Pollak M (2008) Metformin attenuates the stimulatory effect of a high energy diet on in vivo H59 carcinoma growth. Endocr Relat Cancer 15:833–839

    Article  CAS  PubMed  Google Scholar 

  19. Pollak M (2008) Insulin and insulin-like growth factor signalling in neoplasia. Nat Rev Cancer 8:915–928

    Article  CAS  PubMed  Google Scholar 

  20. Tzatsos A, Tsichlis PN (2007) Energy depletion inhibits phosphatidylinositol 3-kinase/Akt signaling and induces apoptosis via AMP-activated protein kinase-dependent phosphorylation of IRS-1 at Ser-794. J Biol Chem 282:18069–18082

    Article  CAS  PubMed  Google Scholar 

  21. Jakobsen SN, Hardie DG, Morrice N, Tornqvist HE (2001) 5′-AMP-activated protein kinase phosphorylates IRS-1 on Ser-789 in mouse C2C12 myotubes in response to 5-aminoimidazole-4-carboxamide riboside. J Biol Chem 276:46912–46916

    Article  CAS  PubMed  Google Scholar 

  22. Choo AY, Yoon SO, Kim SG, Roux PP, Blenis J (2008) Rapamycin differentially inhibits S6Ks and 4E-BP1 to mediate cell-type-specific repression of mRNA translation. Proc Natl Acad Sci USA 105:17414–17419

    Article  CAS  PubMed  Google Scholar 

  23. Boura-Halfon S, Zick Y (2009) Phosphorylation of IRS proteins, insulin action, and insulin resistance. Am J Physiol Endocrinol Metab 296:E581–E591

    Article  CAS  PubMed  Google Scholar 

  24. Gual P, Marchand-Brustel Y, Tanti JF (2005) Positive and negative regulation of insulin signaling through IRS-1 phosphorylation. Biochimie 87:99–109

    Article  CAS  PubMed  Google Scholar 

  25. Manning BD, Cantley LC (2007) AKT/PKB signaling: navigating downstream. Cell 129:1261–1274

    Article  CAS  PubMed  Google Scholar 

  26. Vivanco I, Sawyers CL (2002) The phosphatidylinositol 3-Kinase AKT pathway in human cancer. Nat Rev Cancer 2:489–501

    Article  CAS  PubMed  Google Scholar 

  27. Hartley D, Cooper GM (2002) Role of mTOR in the degradation of IRS-1: regulation of PP2A activity. J Cell Biochem 85:304–314

    Article  CAS  PubMed  Google Scholar 

  28. Virshup DM, Shenolikar S (2009) From promiscuity to precision: protein phosphatases get a makeover. Mol Cell 33:537–545

    Article  CAS  PubMed  Google Scholar 

  29. Padmanabhan S, Mukhopadhyay A, Narasimhan SD, Tesz G, Czech MP, Tissenbaum HA (2009) A PP2A regulatory subunit regulates C. elegans insulin/IGF-1 signaling by modulating AKT-1 phosphorylation. Cell 136:939–951

    Article  CAS  PubMed  Google Scholar 

  30. Shu Y, Sheardown SA, Brown C, Owen RP, Zhang S, Castro RA, Ianculescu AG, Yue L, Lo JC, Burchard EG, Brett CM, Giacomini KM (2007) Effect of genetic variation in the organic cation transporter 1 (OCT1) on metformin action. J Clin Invest 117:1422–1431

    Article  CAS  PubMed  Google Scholar 

  31. Zhuang Y, Miskimins WK (2008) Cell cycle arrest in Metformin treated breast cancer cells involves activation of AMPK, downregulation of cyclin D1, and requires p27Kip1 or p21Cip1. J Mol Signal 3:18

    Article  PubMed  Google Scholar 

  32. Liu B, Fan Z, Edgerton SM, Deng XS, Alimova IN, Lind SE, Thor AD (2009) Metformin induces unique biological and molecular responses in triple negative breast cancer cells. Cell Cycle 8:2031–2040

    Article  CAS  PubMed  Google Scholar 

  33. Huang J, Wu S, Wu CL, Manning BD (2009) Signaling events downstream of mammalian target of rapamycin complex 2 are attenuated in cells and tumors deficient for the tuberous sclerosis complex tumor suppressors. Cancer Res 69:6107–6114

    Article  CAS  PubMed  Google Scholar 

Download references

Acknowledgments

We thank Ms. L. Lui for valuable assistance in manuscript preparation. This study was supported by the Translational Acceleration grant #16512 from the Canadian Breast Cancer Research Alliance and the Translational Cancer Research Award ref: 2008-08 from the Terry Fox Research Institute.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Michael N. Pollak.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Zakikhani, M., Blouin, MJ., Piura, E. et al. Metformin and rapamycin have distinct effects on the AKT pathway and proliferation in breast cancer cells. Breast Cancer Res Treat 123, 271–279 (2010). https://doi.org/10.1007/s10549-010-0763-9

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s10549-010-0763-9

Keywords

Navigation