CEACAM1

CEACAM1 Full Name

carcinoembryonic antigen-related cell adhesion molecule 1 (biliary glycoprotein)

CEACAM1 Introduction

Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1), also known as CD66a, is a transmembrane glycoprotein belonging to the carcinoembryonic antigen (CEA) family within the immunoglobulin superfamily. It exists in multiple isoforms due to alternative splicing, primarily differing in the number of extracellular immunoglobulin-like domains (either 4 or 3) and the length of their cytoplasmic tails. A key feature is the presence of either a long (L) or short (S) cytoplasmic domain, which dictates its signaling capacity. CEACAM1 is expressed on epithelial cells, endothelial cells, and various immune cells, including activated T cells, B cells, natural killer (NK) cells, and myeloid cells, playing a pivotal role in intercellular communication.

Figure 1. Crystal structure of the N terminal domain of human CEACAM1.

Dual Functions in Cell Adhesion and Immune Regulation
CEACAM1 mediates homophilic (CEACAM1-CEACAM1) and heterophilic interactions with other family members. Its primary functions are twofold. First, it regulates cell adhesion, proliferation, and differentiation in epithelial tissues, contributing to tissue architecture and lumen formation in glands. Second, and most prominently, it is a potent co-inhibitory immune checkpoint receptor. Upon homophilic engagement on interacting T cells or through binding to specific ligands on antigen-presenting cells, its long cytoplasmic domain transmits inhibitory signals that dampen lymphocyte activation, proliferation, and effector functions. This is crucial for maintaining immune tolerance and resolving inflammation.

Clinical Significance and Therapeutic Potential
Given its roles in immune inhibition and pathogen entry, CEACAM1 is a compelling target for therapy. In oncology, blocking CEACAM1 with monoclonal antibodies is being investigated to disrupt its immunosuppressive signals and reactivate anti-tumor immunity, potentially in combination with other checkpoint inhibitors like anti-PD-1. In infectious disease, strategies aim to block pathogenic adhesion to CEACAM1 to prevent infection. Additionally, soluble CEACAM1 levels are being studied as a potential diagnostic or prognostic biomarker in inflammatory diseases and certain cancers. Its multifaceted nature makes it a critical molecule at the intersection of immunology, cancer biology, and microbiology.

Alternate Names for CEACAM1

CEACAM1; carcinoembryonic antigen-related cell adhesion molecule 1 (biliary glycoprotein); BGP; carcinoembryonic antigen-related cell adhesion molecule 1; BGP1; CD66a; antigen CD66; CD66a antigen; BGPI