Inhibition of tumorigenesis driven by different Wnt proteins requires blockade of distinct ligand-binding regions by LRP6 antibodies.
Disregulated Wnt/beta-catenin signaling has been linked to various human diseases, including cancers. Inhibitors of oncogenic Wnt signaling are likely to have a therapeutic effect in cancers. LRP5 and LRP6 are closely related membrane coreceptors for Wnt proteins. Using a phage-display library, we identified anti-LRP6 antibodies that either inhibit or enhance Wnt signaling. Two classes of LRP6 antagonistic antibodies were discovered: one class specifically inhibits Wnt proteins represented by Wnt1, whereas the second class specifically inhibits Wnt proteins represented by Wnt3a. Epitope-mapping experiments indicated that Wnt1 class-specific antibodies bind to the first propeller and Wnt3a class-specific antibodies bind to the third propeller of LRP6, suggesting that Wnt1- and Wnt3a-class proteins interact with distinct LRP6 propeller domains. This conclusion is further supported by the structural functional analysis of LRP5/6 and the finding that the Wnt antagonist Sclerostin interacts with the first propeller of LRP5/6 and preferentially inhibits the Wnt1-class proteins. We also show that Wnt1 or Wnt3a class-specific anti-LRP6 antibodies specifically block growth of MMTV-Wnt1 or MMTV-Wnt3 xenografts in vivo. Therapeutic application of these antibodies could be limited without knowing the type of Wnt proteins expressed in cancers. This is further complicated by our finding that bivalent LRP6 antibodies sensitize cells to the nonblocked class of Wnt proteins. The generation of a biparatopic LRP6 antibody blocks both Wnt1- and Wnt3a-mediated signaling without showing agonistic activity. Our studies provide insights into Wnt-induced LRP5/6 activation and show the potential utility of LRP6 antibodies in Wnt-driven cancer.
Ettenberg
Seth A
SA
Novartis Institutes for Biomedical Research, Cambridge, MA 02139, USA.
Charlat
Olga
O
Daley
Michael P
MP
Liu
Shanming
S
Vincent
Karen J
KJ
Stuart
Darrin D
DD
Schuller
Alwin G
AG
Yuan
Jing
J
Ospina
Beatriz
B
Green
John
J
Yu
Qunyan
Q
Walsh
Renee
R
Li
Sharon
S
Schmitz
Rita
R
Heine
Holger
H
Bilic
Sanela
S
Ostrom
Lance
L
Mosher
Rebecca
R
Hartlepp
K Felix
KF
Zhu
Zhenping
Z
Fawell
Stephen
S
Yao
Yung-Mae
YM
Stover
David
D
Finan
Peter M
PM
Porter
Jeffery A
JA
Sellers
William R
WR
Klagge
Ingo M
IM
Cong
Feng
F
D000818:Animals; D000906:Antibodies / Q000276:immunology / Q000494:pharmacology*; D002460:Cell Line; D002472:Cell Transformation, Viral; D005260:Female; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D026502:LDL-Receptor Related Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D008024:Ligands; D060488:Low Density Lipoprotein Receptor-Related Protein-6; D008324:Mammary Tumor Virus, Mouse / Q000235:genetics; D051379:Mice; D008819:Mice, Nude; D009374:Neoplasms, Experimental / Q000473:pathology / Q000517:prevention & control; D011485:Protein Binding / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D047368:Tumor Burden / Q000187:drug effects; D051153:Wnt Proteins / Q000235:genetics / Q000378:metabolism*; D051155:Wnt1 Protein / Q000235:genetics / Q000378:metabolism; D060508:Wnt3 Protein; D060509:Wnt3A Protein; D023041:Xenograft Model Antitumor Assays; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism
D000906:Antibodies; D026502:LDL-Receptor Related Proteins; C555475:LRP6 protein, human; D008024:Ligands; D060488:Low Density Lipoprotein Receptor-Related Protein-6; C555476:Lrp6 protein, mouse; C555507:WNT3 protein, human; C555510:WNT3A protein, human; D051153:Wnt Proteins; D051155:Wnt1 Protein; D060508:Wnt3 Protein; C555508:Wnt3 protein, mouse; D060509:Wnt3A Protein; C555511:Wnt3a protein, mouse; D051176:beta Catenin; D049452:Green Fluorescent Proteins