Effects of HER2-binding affibody molecules on intracellular signaling pathways.
BACKGROUND
HER2, which is overexpressed in 25-30% of human breast cancers, is a tyrosine kinase receptor critical for the signal transduction network that regulates proliferation, migration and apoptosis of cells.


METHODS
We report the effects of two novel HER2-binding affibody molecules (Affibody), (ZHER2:4)2 and ZHER2:342, on intracellular signal transduction pathways (Erk1/2, Akt and PLCgamma1) using quantitative immunoblotting techniques and their biological effects in cell culture. The clinically approved antibody trastuzumab (Herceptin) was used as reference substance.


RESULTS
Our data showed that, although all substances target HER2, the effects on the receptor and signaling molecules differed. For example, HER2 phosphorylation was induced by trastuzumab and (ZHER2:4)2 but inhibited by ZHER2:342. The effects these substances had on signal transduction correlated to some degree with changes in growth and migration, e.g. (ZHER2:4)2 stimulated phosphorylation of Erk1/2 and PLCgamma1, as well as growth and migration, while ZHER2:342 did not. ZHER2:342 even inhibited phosphorylation of PLCgamma1 and migration.


CONCLUSIONS
Our data suggest that ZHER2:342 is a promising small agent (7 kDa) that may be used as an alternative, or complement, to trastuzumab. If radiolabelled, it can hopefully also be used for HER2 imaging and radionuclide therapy.
Ekerljung
Lina
L
Department of Oncology, Radiology and Clinical Immunology, Rudbeck Laboratory, Uppsala, Sweden.
Steffen
Ann-Charlott
AC
Carlsson
Jorgen
J
Lennartsson
Johan
J
D000911:Antibodies, Monoclonal / Q000494:pharmacology; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000494:pharmacology; D001943:Breast Neoplasms / Q000235:genetics; D002455:Cell Division; D045744:Cell Line, Tumor; D002465:Cell Movement; D005260:Female; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D010051:Ovarian Neoplasms; D051966:Phospholipase C gamma / Q000187:drug effects / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D000068878:Trastuzumab
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D051966:Phospholipase C gamma; D018719:Erb-b2 Receptor Tyrosine Kinases; D000068878:Trastuzumab