Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.


Sci. Signal., 29 March 2011
Vol. 4, Issue 166, p. ra17
[DOI: 10.1126/scisignal.2001752]


Amplification of the Driving Oncogene, KRAS or BRAF, Underpins Acquired Resistance to MEK1/2 Inhibitors in Colorectal Cancer Cells

Annette S. Little1*, Kathryn Balmanno1, Matthew J. Sale1, Scott Newman2, Jonathan R. Dry3, Mark Hampson4, Paul A. W. Edwards2, Paul D. Smith3, and Simon J. Cook1*

1 Laboratory of Molecular Signalling, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK.
2 Hutchison-MRC Research Centre and Department of Pathology, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK.
3 iMed Oncology, AstraZeneca, Mereside, Alderley Park, Macclesfield, Cheshire SK10 4TG, UK.
4 R&D Genetics, AstraZeneca, Mereside, Alderley Park, Macclesfield, Cheshire SK10 4TG, UK.

Abstract: The acquisition of resistance to protein kinase inhibitors is a growing problem in cancer treatment. We modeled acquired resistance to the MEK1/2 (mitogen-activated or extracellular signal–regulated protein kinase kinases 1 and 2) inhibitor selumetinib (AZD6244) in colorectal cancer cell lines harboring mutations in BRAF (COLO205 and HT29 lines) or KRAS (HCT116 and LoVo lines). AZD6244-resistant derivatives were refractory to AZD6244-induced cell cycle arrest and death and exhibited a marked increase in ERK1/2 (extracellular signal–regulated kinases 1 and 2) pathway signaling and cyclin D1 abundance when assessed in the absence of inhibitor. Genomic sequencing revealed no acquired mutations in MEK1 or MEK2, the primary target of AZD6244. Rather, resistant lines showed a marked up-regulation of their respective driving oncogenes, BRAF600E or KRAS13D, due to intrachromosomal amplification. Inhibition of BRAF reversed resistance to AZD6244 in COLO205 cells, which suggested that combined inhibition of MEK1/2 and BRAF may reduce the likelihood of acquired resistance in tumors with BRAF600E. Knockdown of KRAS reversed AZD6244 resistance in HCT116 cells as well as reduced the activation of ERK1/2 and protein kinase B; however, the combined inhibition of ERK1/2 and phosphatidylinositol 3-kinase signaling had little effect on AZD6244 resistance, suggesting that additional KRAS effector pathways contribute to this process. Microarray analysis identified increased expression of an 18-gene signature previously identified as reflecting MEK1/2 pathway output in resistant cells. Thus, amplification of the driving oncogene (BRAF600E or KRAS13D) can drive acquired resistance to MEK1/2 inhibitors by increasing signaling through the ERK1/2 pathway. However, up-regulation of KRAS13D leads to activation of multiple KRAS effector pathways, underlining the therapeutic challenge posed by KRAS mutations. These results may have implications for the use of combination therapies.

* To whom correspondence should be addressed. E-mail: annette.little{at} (A.S.L.); simon.cook{at} (S.J.C.).

Citation: A. S. Little, K. Balmanno, M. J. Sale, S. Newman, J. R. Dry, M. Hampson, P. A. W. Edwards, P. D. Smith, S. J. Cook, Amplification of the Driving Oncogene, KRAS or BRAF, Underpins Acquired Resistance to MEK1/2 Inhibitors in Colorectal Cancer Cells. Sci. Signal. 4, ra17 (2011).

Read the Full Text

Splicing factor hnRNP A2 activates the Ras-MAPK-ERK pathway by controlling A-Raf splicing in hepatocellular carcinoma development.
A. Shilo, V. Ben Hur, P. Denichenko, I. Stein, E. Pikarsky, J. Rauch, W. Kolch, L. Zender, and R. Karni (2014)
RNA 20, 505-515
   Abstract »    Full Text »    PDF »
Adaptation to mTOR kinase inhibitors by amplification of eIF4E to maintain cap-dependent translation.
C. L. Cope, R. Gilley, K. Balmanno, M. J. Sale, K. D. Howarth, M. Hampson, P. D. Smith, S. M. Guichard, and S. J. Cook (2014)
J. Cell Sci. 127, 788-800
   Abstract »    Full Text »    PDF »
Development, Characterization, and Reversal of Acquired Resistance to the MEK1 Inhibitor Selumetinib (AZD6244) in an In Vivo Model of Childhood Astrocytoma.
H. K. Bid, A. Kibler, D. A. Phelps, S. Manap, L. Xiao, J. Lin, D. Capper, D. Oswald, B. Geier, M. DeWire, et al. (2013)
Clin. Cancer Res. 19, 6716-6729
   Abstract »    Full Text »    PDF »
Antitumor Activity of the Selective Pan-RAF Inhibitor TAK-632 in BRAF Inhibitor-Resistant Melanoma.
A. Nakamura, T. Arita, S. Tsuchiya, J. Donelan, J. Chouitar, E. Carideo, K. Galvin, M. Okaniwa, T. Ishikawa, and S. Yoshida (2013)
Cancer Res. 73, 7043-7055
   Abstract »    Full Text »    PDF »
Defective K-Ras oncoproteins overcome impaired effector activation to initiate leukemia in vivo.
A. Shieh, A. F. Ward, K. L. Donlan, E. R. Harding-Theobald, J. Xu, C. G. Mullighan, C. Zhang, S.-C. Chen, X. Su, J. R. Downing, et al. (2013)
Blood 121, 4884-4893
   Abstract »    Full Text »    PDF »
Kinase-Substrate Enrichment Analysis Provides Insights into the Heterogeneity of Signaling Pathway Activation in Leukemia Cells.
P. Casado, J.-C. Rodriguez-Prados, S. C. Cosulich, S. Guichard, B. Vanhaesebroeck, S. Joel, and P. R. Cutillas (2013)
Science Signaling 6, rs6
   Abstract »    Full Text »    PDF »
Resistance to BRAF Inhibition in BRAF-Mutant Colon Cancer Can Be Overcome with PI3K Inhibition or Demethylating Agents.
M. Mao, F. Tian, J. M. Mariadason, C. C. Tsao, R. Lemos Jr, F. Dayyani, Y. N. V. Gopal, Z.-Q. Jiang, I. I. Wistuba, X. M. Tang, et al. (2013)
Clin. Cancer Res. 19, 657-667
   Abstract »    Full Text »    PDF »
Selective requirement for Mediator MED23 in Ras-active lung cancer.
X. Yang, M. Zhao, M. Xia, Y. Liu, J. Yan, H. Ji, and G. Wang (2012)
PNAS 109, E2813-E2822
   Abstract »    Full Text »    PDF »
Identification of Unique MEK-Dependent Genes in GNAQ Mutant Uveal Melanoma Involved in Cell Growth, Tumor Cell Invasion, and MEK Resistance.
G. Ambrosini, C. A. Pratilas, L.-X. Qin, M. Tadi, O. Surriga, R. D. Carvajal, and G. K. Schwartz (2012)
Clin. Cancer Res. 18, 3552-3561
   Abstract »    Full Text »    PDF »
Distinct requirement for an intact dimer interface in wild-type, V600E and kinase-dead B-Raf signalling.
M. Roring, R. Herr, G. J. Fiala, K. Heilmann, S. Braun, A. E. Eisenhardt, S. Halbach, D. Capper, A. von Deimling, W. W. Schamel, et al. (2012)
EMBO J. 31, 2629-2647
   Abstract »    Full Text »    PDF »
A comprehensive survey of genomic alterations in gastric cancer reveals systematic patterns of molecular exclusivity and co-occurrence among distinct therapeutic targets.
N. Deng, L. K. Goh, H. Wang, K. Das, J. Tao, I. B. Tan, S. Zhang, M. Lee, J. Wu, K. H. Lim, et al. (2012)
Gut 61, 673-684
   Abstract »    Full Text »    PDF »
ERK Inhibition Overcomes Acquired Resistance to MEK Inhibitors.
G. Hatzivassiliou, B. Liu, C. O'Brien, J. M. Spoerke, K. P. Hoeflich, P. M. Haverty, R. Soriano, W. F. Forrest, S. Heldens, H. Chen, et al. (2012)
Mol. Cancer Ther. 11, 1143-1154
   Abstract »    Full Text »    PDF »
Circumventing Cancer Drug Resistance in the Era of Personalized Medicine.
L. A. Garraway and P. A. Janne (2012)
Cancer Discovery 2, 214-226
   Abstract »    Full Text »    PDF »
ERK1/2 Regulation of CD44 Modulates Oral Cancer Aggressiveness.
N. P. Judd, A. E. Winkler, O. Murillo-Sauca, J. J. Brotman, J. H. Law, J. S. Lewis Jr, G. P. Dunn, J. D. Bui, J. B. Sunwoo, and R. Uppaluri (2012)
Cancer Res. 72, 365-374
   Abstract »    Full Text »    PDF »
Resistance to MEK Inhibitors: Should We Co-Target Upstream?.
P. I. Poulikakos and D. B. Solit (2011)
Science Signaling 4, pe16
   Abstract »    Full Text »    PDF »

To Advertise     Find Products

Science Signaling. ISSN 1937-9145 (online), 1945-0877 (print). Pre-2008: Science's STKE. ISSN 1525-8882