SIGLEC-G deficiency increases susceptibility to develop B-cell lymphoproliferative disorders

Area of Science:

• Immunology
• Molecular Biology
• Oncology

Background:

• SIGLEC-G negatively regulates B-cell receptor signaling.
• SIGLEC-G deficiency causes B-1a cell expansion and premature CD5(+) B cell proliferation.
• The long-term effects of SIGLEC-G deficiency on B lymphocyte fate are unknown.

Purpose of the Study:

• To investigate the fate of B lymphocytes in aging Siglecg(-/-) mice.
• To determine if SIGLEC-G deficiency predisposes to B-cell lymphoproliferative disorders.
• To explore the role of SIGLEC-G/SIGLEC10 in B-cell lymphoma pathogenesis.

Main Methods:

• Longitudinal study of B lymphocyte populations in Siglecg(-/-) mice.
• Histopathological and molecular analysis of lymphoid tumors.
• Analysis of human B-cell lymphoma and leukemia cell lines for SIGLEC10 expression.

Main Results:

• SIGLEC-G deficiency promotes progressive accumulation of monoclonal B lymphocytes in aging mice.
• Aged Siglecg(-/-) mice develop heterogeneous monoclonal B-cell lymphomas, including diffuse large B-cell lymphoma and follicular lymphoma.
• Tumors express high BCL-2 levels and are transplantable; human SIGLEC10 is downregulated in B-cell malignancies.
• Chronic lymphocytic leukemia was not observed in these mice.

Conclusions:

• SIGLEC-G deficiency contributes to the development of B-cell lymphoproliferative disorders.
• Down-regulation of negative B-cell receptor regulators like SIGLEC-G/SIGLEC10 is implicated in B-cell lymphoma pathogenesis.
• SIGLEC-G/SIGLEC10 may represent novel therapeutic targets for B-cell lymphomas.