Antigen binding of human IgG Fabs mediate ERK-associated proliferation of human breast cancer cells.
Serum-circulating antibody can be linked to poor outcomes in some cancer patients. To investigate the role of human antibodies in regulating tumor cell growth, we constructed a recombinant cDNA expression library of human IgG Fab from a patient with breast cancer. Clones were screened from the library with breast tumor cell lysate. Sequence analysis of the clones showed somatic hypermutations when compared to their closest VH/VL germ-line genes. Initial characterizations focused on five clones. All tested clones displayed stronger binding to antigen derived from primary breast cancers and established breast cancer cell lines than to normal breast tissues. In vitro functional studies showed that four out of five tested clones could stimulate the growth of MDA-MB-231 breast cancer cell lines, and one out of five was able to promote MCF-7 cell growth as well. Involvement of ERK2 pathway was observed. By 1H-NMR spectra and Western blot analysis, it was evident that two tested antibody Fabs are capable of interacting with sialic acid. Our study suggests a possible role for human antibody in promoting tumor cell growth by direct binding of IgG Fab to breast tumor antigen. Such studies prompt speculation regarding the role of serum antibodies in mediating tumor growth as well as their contribution to disease progression.
Wen
Yue-Jin
YJ
Department of Pathology, Arkansas Cancer Research Center, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA.
Mancino
Anne
A
Pashov
Anastas
A
Whitehead
Tracy
T
Stanley
Joseph
J
Kieber-Emmons
Thomas
T
D000595:Amino Acid Sequence; D000951:Antigens, Neoplasm / Q000276:immunology*; D001323:Autoantibodies / Q000276:immunology / Q000494:pharmacology; D001943:Breast Neoplasms / Q000201:enzymology / Q000276:immunology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D005419:Flavonoids / Q000494:pharmacology; D015723:Gene Library; D005854:Germ Cells; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000235:genetics / Q000276:immunology* / Q000494:pharmacology; D007074:Immunoglobulin G / Q000235:genetics / Q000276:immunology* / Q000494:pharmacology; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007147:Immunoglobulin Light Chains / Q000235:genetics; D007135:Immunoglobulin Variable Region / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D019158:N-Acetylneuraminic Acid / Q000276:immunology; D010766:Phosphorylation
D000951:Antigens, Neoplasm; D001323:Autoantibodies; D005419:Flavonoids; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G; D007143:Immunoglobulin Heavy Chains; D007147:Immunoglobulin Light Chains; D007135:Immunoglobulin Variable Region; D048049:Extracellular Signal-Regulated MAP Kinases; D019158:N-Acetylneuraminic Acid; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one