TY - JOUR
T1 - Proteasome activator complex PA28 identified as an accessible target in prostate cancer by in vivo selection of human antibodies
AU - Sánchez-Martín, David
AU - Martínez-Torrecuadrada, Jorge
AU - Teesalu, Tambet
AU - Sugahara, Kazuki N.
AU - Alvarez-Cienfuegos, Ana
AU - Ximénez-Embún, Pilar
AU - Fernández-Periáñez, Rodrigo
AU - Teresa Martín, M.
AU - Molina-Privado, Irene
AU - Ruppen-Cañás, Isabel
AU - Blanco-Toribio, Ana
AU - Cañamero, Marta
AU - Cuesta, Ángel M.
AU - Compte, Marta
AU - Kremer, Leonor
AU - Bellas, Carmen
AU - Alonso-Camino, Vanesa
AU - Guijarro-Muñoz, Irene
AU - Sanz, Laura
AU - Ruoslahti, Erkki
AU - Alvarez-Vallina, Luis
PY - 2013
Y1 - 2013
N2 - Antibody cancer therapies rely on systemically accessible targets and suitable antibodies that exert a functional activity or deliver a payload to the tumor site. Here, we present proof-of-principle of in vivo selection of human antibodies in tumor-bearing mice that identified a tumor-specific antibody able to deliver a payload and unveils the target antigen. By using an ex vivo enrichment process against freshly disaggregated tumors to purge the repertoire, in combination with in vivo biopanning at optimized phage circulation time, we have identified a human domain antibody capable of mediating selective localization of phage to human prostate cancer xenografts. Affinity chromatography followed by mass spectrometry analysis showed that the antibody recognizes the proteasome activator complex PA28. The specificity of soluble antibody was confirmed by demonstrating its binding to the active human PA28αβ complex. Whereas systemically administered control phage was confined in the lumen of blood vessels of both normal tissues and tumors, the selected phage spread from tumor vessels into the perivascular tumor parenchyma. In these areas, the selected phage partially colocalized with PA28 complex. Furthermore, we found that the expression of the α subunit of PA28 [proteasome activator complex subunit 1 (PSME1)] is elevated in primary and metastatic human prostate cancer and used anti- PSME1 antibodies to show that PSME1 is an accessible marker in mouse xenograft tumors. These results support the use of PA28 as a tumor marker and a potential target for therapeutic intervention in prostate cancer.
AB - Antibody cancer therapies rely on systemically accessible targets and suitable antibodies that exert a functional activity or deliver a payload to the tumor site. Here, we present proof-of-principle of in vivo selection of human antibodies in tumor-bearing mice that identified a tumor-specific antibody able to deliver a payload and unveils the target antigen. By using an ex vivo enrichment process against freshly disaggregated tumors to purge the repertoire, in combination with in vivo biopanning at optimized phage circulation time, we have identified a human domain antibody capable of mediating selective localization of phage to human prostate cancer xenografts. Affinity chromatography followed by mass spectrometry analysis showed that the antibody recognizes the proteasome activator complex PA28. The specificity of soluble antibody was confirmed by demonstrating its binding to the active human PA28αβ complex. Whereas systemically administered control phage was confined in the lumen of blood vessels of both normal tissues and tumors, the selected phage spread from tumor vessels into the perivascular tumor parenchyma. In these areas, the selected phage partially colocalized with PA28 complex. Furthermore, we found that the expression of the α subunit of PA28 [proteasome activator complex subunit 1 (PSME1)] is elevated in primary and metastatic human prostate cancer and used anti- PSME1 antibodies to show that PSME1 is an accessible marker in mouse xenograft tumors. These results support the use of PA28 as a tumor marker and a potential target for therapeutic intervention in prostate cancer.
KW - Phage display
KW - Phage library
KW - Physiological selection
KW - Single domain antibody
KW - Tumor-associated antigen
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U2 - 10.1073/pnas.1300013110
DO - 10.1073/pnas.1300013110
M3 - Article
C2 - 23918357
AN - SCOPUS:84882793602
SN - 0027-8424
VL - 110
SP - 13791
EP - 13796
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 34
ER -