Targeting the Grb7 SH2 domain with cell-permeable cyclic peptides — ASN Events
  1. Schedule
  2. Session Ten - Poster Session C including Refreshments
  3. Targeting the Grb7 SH2 domain with cell-permeable cyclic peptides

Targeting the Grb7 SH2 domain with cell-permeable cyclic peptides (#333)

Gabrielle Watson 1 , Menachem Gunzburg 1 , Ketav Kulkarni 1 2 , Katie Cergol 3 , Richard Payne 3 , Patrick Perlmutter 2 , Matthew Wilce 1 , Jackie Wilce 1
  1. Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, Australia
  2. Department of Chemistry, Monash University, Clayton, VIC
  3. Department of Chemistry, University of Sydney, Sydney, NSW

Uncontrollable proliferation and migration is characteristic of cancerous cells, and targeting deregulated signaling pathways is a common strategy when developing anti-cancer therapeutics. Human growth factor receptor bound protein 7 (Grb7) is an intracellular adaptor protein with an established role in cancer cell proliferation and migration. Grb7 is overexpressed in a multitude of cancers, particularly pancreatic and breast cancer, and is a prime therapeutic target1,2. 

A non-phosphorylated cyclic peptide, G7-18NATE, binds to the Grb7 SH2 domain, blocking interactions with upstream binding partners. Cell permeable G7-18NATE has been shown to inhibit pancreatic cell migration, and reduce cellular growth and migration in breast cancer cell lines2,3. The peptide binds to Grb7 with moderate affinity4; therefore, to improve on this, functionalized and constrained derivatives have been developed. Tested by SPR, a functionalized G7-18NATE derivative with a carboxymethylphenylalanine substitution has 3-fold increased affinity for the Grb7 SH2 domain compared with G7-18NATE. Structural analysis reveals additional protein- peptide interactions occurring in the Grb7 phosphotyrosine binding pocket, a natural binding surface for Grb7- substrate interactions. Constrained derivatives with varying additional linkages also improve affinity up to 0.7 μM with an unexpected mode of binding encountered at an alternate interface to the phosphotyrosine-binding pocket.

Combining both these strategies, and hence covering a broad Grb7 interface, is predicted to generate a potent and specific inhibitor of Grb7 and mark considerable progress in Grb7 based anti-cancer drug development. Furthermore, developing G7-18NATE derivatives will establish fundamental methods that can be readily applied to other intracellular therapeutic targets.

  1. Stein, D., Wu, J., Fuqua, S.A., Roonprapunt, C., Yajnik, V., D’Eustachio, P., Moskow, J., Buchberg, A.M., Osborne, C.K. and Margolis, B. (1994) The SH2 domain protein GRB-7 is co-amplified, overexpressed and in a tight complex with HER2 in breast cancer. EMBO J. 13, 1331
  2. Tanaka, S., Pero, S.C., Taguchi, K., Shimada, M., Mori, M., Krag, D.N., and Arii, S. (2006) Specific peptide ligand for Grb7 signal transduction protein and pancreatic cancer metastasis. J. Natl. Cancer Inst. 98, 491
  3. Pero, S.C., Shukla, G.S., Cookson, M. M., Flemer, S., and Krag, D.N. (2007) Combination treatment with Grb7 peptide and Doxorubicin or Trastuzumab (Herceptin) results in cooperative cell growth inhibition in breast cancer cells. Br. J. Cancer 96, 1520
  4. Gunzburg, M.J., Ambaye, N.D., Del Borgo, M.P., Pero, S.C., Krag, D.N., Wilce, M.C., Wilce, J.A. (2012) Interaction of the non-phosphorylated peptide G7-18NATE with Grb7-SH2 domain requires phosphate for enhanced affinity and specificity. J. Mol. Recognit. 25, 57