CEACAM5/CD66e: From Normal Tissue Polarity Expression to the Molecular Basis of Tumor-Targeted Therapy

Author: Senior Product Manager of UA Views：34

This article systematically elaborates on the molecular characteristics and biological functions of CEACAM5 (CEA/CD66e), focusing on its molecular structure as the first member of the CEACAM family, its polarized expression patterns in normal tissues, and its aberrant overexpression in various epithelial-derived tumors. It further analyzes its clinical value as a broad-spectrum tumor marker and a target for immunotherapy.

Recent Advances
Product Information

Recent Advances

CEACAM5/CD66e: Molecular Basis from Normal Tissue Polarity Expression to Tumor-Targeted Therapy

Summary
This article focuses on the molecular characteristics and biological functions of CEACAM5 (CEA/CD66e), systematically elaborating its molecular structure as the first member of the CEACAM family, its polarized expression pattern in normal tissues, and its aberrant overexpression in various epithelial-derived tumors. It analyzes its clinical value as a broad-spectrum tumor marker and immunotherapy target.

I. Composition of the CEACAM Family and the Position of CEACAM5

The carcinoembryonic antigen-related cell adhesion molecule family is a group of cell surface glycoproteins comprising 12 members, widely expressed in normal and tumor tissues. They play key roles in mediating critical pathological processes such as cancer progression, metastasis, angiogenesis, and inflammation. Among them, CEACAM1, CEACAM5 (the classical carcinoembryonic antigen), CEACAM6, and CEACAM7 have been the most extensively studied and are most closely related to tumor development. CEACAM5 is the earliest identified and applied member of this family and has long been widely studied as a clinical tumor marker.

II. Molecular Structural Features of CEACAM5

The molecular structure of CEACAM5 includes a 34-amino-acid signal peptide at the N-terminus, guiding the protein into the secretory pathway; an N-terminal variable region-like immunoglobulin domain responsible for primary molecular recognition; and six constant region-like immunoglobulin domains arranged in three repeat units (A1-B1-A2-B2-A3-B3), collectively maintaining protein conformational stability and participating in intermolecular interactions. CEACAM5 is anchored to the cell membrane surface via glycosylphosphatidylinositol (GPI), lacking an intracellular domain. Its signal transduction relies on membrane proteins near the GPI anchor or cis-interactions with other transmembrane receptors. CEACAM5 is highly glycosylated, with a theoretical molecular weight of approximately 70 kDa, but its apparent molecular weight in SDS-PAGE can expand to about 180 kDa.

III. Polarized Expression of CEACAM5 in Normal Tissues

During early human embryonic development (weeks 9–14), CEA can be detected and remains expressed in certain cells for life. In adult normal tissues, CEACAM5 is primarily expressed in columnar epithelial cells and goblet cells of the colon (especially the upper third of the crypts and luminal surface), as well as in epithelial cells of the stomach, tongue, esophagus, cervix, sweat glands, and prostate. CEACAM5 expression exhibits strict polarized distribution—localized only to the apical membrane surface of epithelial cells facing the lumen, with no expression on the basolateral membrane. This polarized distribution prevents CEACAM5 from being exposed to interstitial fluid and the circulatory system under physiological conditions, making it unrecognizable by immune cells.

IV. Aberrant Expression of CEACAM5 in Tumor Tissues

During tumorigenesis, the expression profile and distribution characteristics of CEACAM5 undergo significant changes. Tumor cells lose the polarized distribution of CEACAM5, causing it to redistribute across the entire cell membrane surface, directly exposing it to the interstitial space and circulatory system, where it can be recognized by the immune system and shed into the bloodstream. CEACAM5 is overexpressed in various epithelial-derived malignancies, including colon, gastric, pancreatic, ovarian, and lung cancers. CEACAM5 is positively expressed in approximately 90% of colorectal cancers, with expression levels in normal tissues averaging about 60 times lower than in tumor tissues. This significant differential expression makes it an ideal tumor marker and therapeutic target.

V. Applications of CEACAM5 as a Tumor Marker and Therapeutic Target

Based on the high expression of CEACAM5 in tumors and its restricted expression in normal tissues, CEACAM5 has become an important target for various immunotherapy strategies. In CAR-T cell therapy, CEACAM5-targeting CAR-T cells have demonstrated specific cytotoxic activity against CEACAM5-positive tumors in preclinical studies. In the field of antibody-drug conjugates (ADCs), CEACAM5-targeting ADC drugs have shown efficacy in clinical studies for non-small cell lung cancer and colorectal cancer. Additionally, as a serum tumor marker, CEACAM5 level detection is widely used for auxiliary diagnosis, efficacy monitoring, and recurrence warning in various malignancies, including colorectal cancer.

VI. Conclusion

As the most extensively studied and applied member of the CEACAM family, CEACAM5 has established its dual clinical value as a broad-spectrum tumor marker and immunotherapy target, owing to its unique GPI anchoring, precise arrangement of seven immunoglobulin-like domains, highly glycosylated molecular features, and differential distribution pattern—polarized and restricted in normal tissues but non-polarized and overexpressed in various epithelial-derived tumors. Fluorescently labeled recombinant CEACAM5 proteins provide reliable detection tools to support related research and drug development.

In CEACAM5-targeted therapies and related research, high-quality fluorescently labeled recombinant proteins are key tools for flow cytometry detection. To meet this research need, Univ offers PE-Labeled CEACAM-5/CD66e Fc&Avi Tag Protein, Human, suitable for applications such as CEACAM5 CAR-T cell positivity rate detection, binding activity evaluation of CEACAM5-targeting antibody drugs, and flow cytometry analysis of CEACAM5 expression levels on tumor cell lines.

This article is reviewed and published by the technical expert team of UA

Disclaimer: This article partially utilizes artificial intelligence assistance in its creation. If any content involves copyright or intellectual property issues, please let us know and we promise to verify and remove it as soon as possible.

Purchase recombinant protein, choose Nanjing UA-Bio

UA protein focuses on providing various protein reagents, raw materials, and services required for drug research and development, cell therapy, gene therapy, and basic scientific research, including drug target proteins, immune checkpoint proteins, cytokines, tool enzymes, customized protein expression, and full-length transmembrane protein development. Youai is committed to providing customers with high-quality products and professional services, and building a High-tech Biological Enterprise with International Competitiveness.

Buy antibodiesFind UA www.ua-bio.com | 15 years of protein development experience

Nanjing UA Biotechnology Co., Ltd. Email：order@ua-bio.com Phone：+86-25-56221161

more products

Product Information

The Last The Next