Global quantitative phosphoproteome analysis of human tumor xenografts treated with a CD44 antagonist.
The cell surface glycoprotein CD44 plays an important role in the development and progression of various tumor types. RG7356 is a humanized antibody targeting the constant region of CD44 that shows antitumor efficacy in mice implanted with CD44-expressing tumors such as MDA-MB-231 breast cancer cells. CD44 receptor seems to function as the main receptor for hyaluronic acid and osteopontin, serving as coreceptor for growth factor pathways like cMet, EGFR, HER-2, and VEGFR and by cytoskeletal modulation via ERM and Rho kinase signaling. To assess the direct impact of RG7356 binding to the CD44 receptor, a global mass spectrometry-based phosphoproteomics approach was applied to freshly isolated MDA-MB-231 tumor xenografts. Results from a global phosphoproteomics screen were further corroborated by Western blot and ELISA analyses of tumor lysates from CD44-expressing tumors. Short-term treatment of tumor-bearing mice with RG7356 resulted in modifications of the MAPK pathway in the responsive model, although no effects on downstream phosphorylation were observed in a nonresponsive xenograft model. Taken together, our approach augments the value of other high throughput techniques to identify biomarkers for clinical development of targeted agents.
Discovery Oncology, Pharma Research and Early Development, Roche Diagnostics GmbH, Penzberg, Germany. Stefan.weigand@roche.com
Stefan
S
Weigand
Frank
F
Herting
Daniela
D
Maisel
Adam
A
Nopora
Edgar
E
Voss
Christoph
C
Schaab
Martin
M
Klammer
Andreas
A
Tebbe
D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage / Q000494:pharmacology*; D061067:Antibodies, Monoclonal, Humanized / Q000008:administration & dosage / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D019295:Computational Biology / Q000379:methods; D005260:Female; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D016513:Mice, SCID; D009369:Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D020543:Proteome / Q000378:metabolism*; D040901:Proteomics; D023041:Xenograft Model Antitumor Assays
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D018960:Hyaluronan Receptors; D010750:Phosphoproteins; D020543:Proteome; C576196:RG7356