[CD44, the hyaluronic acid cell receptor. Its role in neoplastic invasion and metastatic dissemination].

The CD44 group of transmembrane glycoproteins encompasses several isoforms expressed in a variety of tissues. All isoforms are encoded by the same gene on chromosome 11 and are formed by alternative splicing of their mRNA. CD44 isoforms belong to the family of cell adhesion molecules and to the sub-family of the hyaladherins in consideration of their affinity for hyaluronate and their structural homology with the cartilage link protein. The standard form of CD44, CD44H exhibits a high affinity for hyaluronate, plays a role in the uptake and degradation of this glycosaminoglycan and participates in cell locomotion in its presence. In physiology, CD44H plays a role in the homing of lymphocytes into Peyer's patches, in organogenesis and in the degradation of hyaluronate in lung or lymphoid tissue. In pathology, CD44H probably enhances the tumorigenic properties of some lymphomas and melanomas. The variant form CD44E exhibits low affinity for hyaluronate and its role in cell-cell adhesion in epithelia is suspected. The variant form CD44V (or CD44M) confers metastatic properties to rat carcinoma cells and is expressed in human breast and colorectal cancer and in adenomatous polyps.