MARCH Proteins Mediate Responses to Antitumor Antibodies

Area of Science:

• Immunology
• Molecular Biology
• Oncology

Background:

• CD98 and MET are cell surface proteins crucial for normal and cancer cell proliferation.
• Antitumor antibodies targeting CD98 and MET are under investigation for cancer therapy.
• The role of E3 ubiquitin ligases in antibody-mediated antitumor responses is not fully understood.

Purpose of the Study:

• To investigate the mechanism by which anti-CD98 antibody UM7F8 exerts its antiproliferative effects.
• To determine if MARCH E3 ubiquitin ligases mediate the antiproliferative response to antitumor antibodies targeting cell surface proteins.
• To explore the role of MARCH proteins in the efficacy of the anti-MET antibody emibetuzumab.

Main Methods:

• Utilized antibody-induced ubiquitination assays to study CD98 and MET.
• Assessed the impact of MARCH E3 ligase activity on cell surface protein expression and ubiquitination.
• Evaluated the antiproliferative effects of antibodies in murine T cells and leukemia-initiating cells, as well as human tumor cells.

Main Results:

• UM7F8 antibody induces ubiquitination and downregulation of cell surface CD98 via MARCH1, inhibiting proliferation of T cells and leukemia cells.
• MARCH1, 4, or 8-mediated ubiquitination reduces MET surface expression.
• Emibetuzumab-induced MET ubiquitination contributes to MET downregulation and inhibition of human tumor cell proliferation.

Conclusions:

• MARCH E3 ubiquitin ligases act as cofactors for antitumor antibodies targeting cell surface proteins.
• The cellular repertoire of MARCH proteins influences the response to such antibodies.
• This finding suggests a potential strategy for enhancing antibody-based cancer therapies.