Journal of Neuro-Oncology

, Volume 71, Issue 3, pp 215–222

PKB/Akt mediates radiosensitization by the signaling inhibitor LY294002 in human malignant gliomas

  • Jean L. Nakamura
  • Amelia Karlsson
  • Nils D. Arvold
  • Alexander R. Gottschalk
  • Russell O. Pieper
  • David Stokoe
  • Daphne A. Haas-Kogan
Laboratory Investigation

Abstract

The phosphoinositide 3-kinase (PI3-kinase) signaling pathway is frequently aberrantly activated in glioblastoma multiforme (GM) by mutation or loss of the 3′ phospholipid phosphatase PTEN. PTEN abnormalities result in inappropriate signaling to downstream molecules including protein kinase B (PKB/Akt), and mammalian target of rapamycin (mTOR). PI3-kinase activation increases resistance to radiation-induced cell death; conversely, PI3-kinase inhibition enhances the sensitivity of tumors to radiation. The effects of LY294002, a biochemical inhibitor of PI3-kinase, on the response to radiation were examined in the PTEN mutant glioma cell line U251 MG. Low doses of LY294002 sensitized U251 MG to clinically relevant doses of radiation. In contrast to LY294002, rapamycin, an inhibitor of mTOR, did not result in radiosensitization. We demonstrate that among multiple known targets of LY294002, PI3-kinase is the most likely molecule responsible for LY294002-induced radiosensitization. Furthermore, using a myristoylated PKB/Akt construct, we identified PKB/Akt as the downstream molecule that mediates the synergistic cytotoxicity between LY294002 and radiation. Thus PI3-kinase dysregulation may contribute to the notable radioresistance of GM tumors and inhibition of PKB/Akt offers an excellent target to enhance radiosensitivity.

Keywords

glioma LY294002 phosphatidylinositol 3-kinase radiation signal transduction 

Abbreviations

GM

glioblastoma multiforme

PI3-kinase

phosphatidylinositol 3-kinase

PKB

protein kinase B

PTEN

phosphatase and tensin homologue deleted on chromosome ten

SEM

standard error of the mean

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Gupta, AK, Cerniglia, GJ, Mick, R, Ahmed, MS, Bakanauskas, VJ, Muschel, RJ, McKenna, WG 2003Radiation sensitization of human cancer cells in vivo by inhibiting the activity of PI3K using LY294002.Int J Radiat Oncol Biol Phys56846853Google Scholar
  2. Rosenzweig KE, Youmell, MB, Palayoor, ST, Price 1997Radiosensitization of human tumor cells by the phosphatidylinositol3-kinase inhibitors wortmannin and LY294002 correlates with inhibition of DNA-dependent protein kinase and prolonged G2-M delayClin Cancer Res311491156Google Scholar
  3. Shi, YQ, Blattmann, H, Crompton, NE 2001Wortmannin selectively enhances radiation-induced apoptosis in proliferative but not quiescent cellsInt J Radiat Oncol Biol Phys49421425Google Scholar
  4. Gupta, AK, Bakanauskas, VJ, Cerniglia, GJ, Cheng, Y, Bernhard, EJ, Muschel, RJ, McKenna, WG 2001The Ras radiation resistance pathwayCancer Res6142784282Google Scholar
  5. Mayo, LD, Dixon, JE, Durden, DL, Tonks, NK, Donner, DB 2002PTEN protects p53 from Mdm2 and sensitizes cancer cells to chemotherapyJ Biol Chem27754845489Google Scholar
  6. Sarkar, A, Dolan, ME, Gonzalez, GG, Marton, LJ, Pegg, AE, Deen, DF 1993The effects of O6-benzylguanine and hypoxia on the cytotoxicity of 1,3-bis(2-chloroethyl)-1-nitrosourea in nitrosourea-resistant SF-763 cellsCancer Chemother Pharmacol32477481Google Scholar
  7. Albright, N 1987Computer programs for the analysis of cellular survival dataRadiat Res112331340Google Scholar
  8. Fertil, B, Malaise, EP 1985Intrinsic radiosensitivity of human cell lines is correlated with radioresponsiveness of human tumors: analysis of 101 published survival curvesInt J Radiat Oncol Biol Phys1116991707Google Scholar
  9. Haas-Kogan, D, Shalev, N, Wong, M, Mills, G, Yount, G, Stokoe, D 1998Protein kinase B (PKB/Akt) activity is elevated in glioblastoma cells due to mutation of the tumor suppressor PTEN/MMACCurr Biol811951198Google Scholar
  10. Adachi, J, Ohbayashi, K, Suzuki, T, Sasaki, T 1999Cell cycle arrest and astrocytic differentiation resulting from PTEN expression in glioma cellsJ Neurosurg91822830Google Scholar
  11. Gottschalk, AR, Basila, D, Wong, M, Dean, NM, Brandts, CH, Stokoe, D, Haas-Kogan, DA 2001p27Kip1 is required for PTEN-induced G1 growth arrestCancer Res6121052111Google Scholar
  12. Ishii, N, Maier, D, Merlo, A, Tada, M, Sawamura, Y, Diserens, AC, Van Meir, EG 1999Frequent co-alterations of TP53, p16/CDKN2A, p14ARF, PTEN tumor suppressor genes in human glioma cell linesBrain Pathol9469479Google Scholar
  13. Podsypanina, K, Lee, RT, Politis, C, Hennessy, I, Crane, A, Puc, J, Neshat, M, Wang, H, Yang, L, Gibbons, J, Frost, P, Dreisbach, V, Blenis, J, Gaciong, Z, Fisher, P, Sawyers, C, Hedrick-Ellenson, L, Parsons, R 2001An inhibitor of mTOR reduces neoplasia and normalizes p70/S6 kinase activity in Pten+/-miceProc Natl Acad Sci USA981032010325Google Scholar
  14. Neshat, MS, Mellinghoff, IK, Tran, C, Stiles, B, Thomas, G, Petersen, R, Frost, P, Gibbons, JJ, Wu, H, Sawyers, CL 2001Enhanced sensitivity of PTEN-deficient tumors to inhibition of FRAP/mTORProc Natl Acad Sci USA981031410319Google Scholar
  15. Kohn, AD, Barthel, A, Kovacina, KS, Boge, A, Wallach, B, Summers, SA, Birnbaum, MJ, Scott, PH, Lawrence, JC,Jr 1998Roth RA Construction and characterization of a conditionally active version of the serine/threonine kinase Akt.J Biol Chem2731193711943Google Scholar
  16. Andjelkovic, M, Alessi, DR, Meier, R, Fernandez, A, Lamb, NJ, Frech, M, Cron, P, Cohen, P, Lucocq, JM, Hemmings, BA 1997Role of translocation in the activation and function of protein kinase BJÆBiol Chem2723151531524Google Scholar
  17. Wick, W, Furnari, FB, Naumann, U, Cavenee, WK, Weller, M 1999PTEN gene transfer in human malignant glioma: sensitization to irradiation and CD95L-induced apoptosisOncogene1839363943Google Scholar
  18. Liu, AX, Testa, JR, Hamilton, TC, Jove, R, Nicosia, SV, Cheng, JQ 1998AKT2, a member of the protein kinase B family, is activated by growth factors, v-Ha-ras, and v-src through phosphatidylinositol 3-kinase in human ovarian epithelial cancer cellsCancer Res5829732977Google Scholar
  19. Leibiger, B, Leibiger, IB, Moede, T, Kemper, S, Kulkarni, RN, Kahn, CR, de Vargas, LM, Berggren, PO 2001Selective insulin signaling through A and B insulin receptors regulates transcription of insulin and glucokinase genes in pancreatic beta cellsMol Cell7559570Google Scholar
  20. Radu, A, Neubauer, V, Akagi, T, Hanafusa, H, Georgescu, MM 2003PTEN induces cell cycle arrest by decreasing the level and nuclear localization of cyclin D1Mol Cell Biol2361396149Google Scholar
  21. Liang, J, Slingerland, JM 2003Multiple Roles of the PI3K/PKB (Akt) Pathway in Cell Cycle ProgressionCell Cycle2339345Google Scholar
  22. Nicholson, KM, Anderson, NG 2002The protein kinase B/Akt signalling pathway in human malignancyCell Signal14381395Google Scholar
  23. Contessa, JN, Hampton, J, Lammering, G, Mikkelsen, RB, Dent, P, Valerie, K, Schmidt-Ullrich, RK 2002Ionizing radiation activates Erb-B receptor dependent Akt and p70 S6 kinase signaling in carcinoma cellsOncogene2140324041Google Scholar
  24. Eshleman, JS, Carlson, BL, Mladek, AC, Kastner, BD, Shide, KL, Sarkaria, JN 2002Inhibition of the mammalian target of rapamycin sensitizes U87 xenografts to fractionated radiation therapyCancer Res6272917297Google Scholar
  25. Moscatello, DK, Holgado-Madruga, M, Emlet, DR, Montgomery, RB, Wong, AJ 1998Constitutive activation of phosphatidylinositol 3-kinase by a naturally occurring mutant epidermal growth factor receptorJ Biol Chem273200206Google Scholar
  26. Lammering, G, Valerie, K, Lin, PS, Mikkelsen, RB, Contessa, JN, Feden, JP, Farnsworth, J, Dent, P, Schmidt-Ullrich, RK 2001Radiosensitization of malignant glioma cells through overexpression of dominant-negative epidermal growth factor receptorClin Cancer Res7682690Google Scholar

Copyright information

© Springer 2005

Authors and Affiliations

  • Jean L. Nakamura
    • 1
  • Amelia Karlsson
    • 1
  • Nils D. Arvold
    • 1
  • Alexander R. Gottschalk
    • 1
  • Russell O. Pieper
    • 2
  • David Stokoe
    • 2
    • 3
  • Daphne A. Haas-Kogan
    • 1
    • 2
    • 4
  1. 1.Departments of Radiation OncologyThe University of CaliforniaUSA
  2. 2.Brain Tumor Research Center and NeurosurgeryThe University of CaliforniaUSA
  3. 3.Cancer Research CenterThe University of CaliforniaSan FranciscoUSA
  4. 4.Department of Radiation Oncology and Comprehensive Cancer CenterUCSFSan FranciscoUSA

Personalised recommendations