Cluster of differentiation 44 (CD44)

Cluster of differentiation 44 (CD44) is a transmembrane glycoprotein that functions primarily as a cell-surface receptor mediating cell-cell and cell-matrix interactions. It binds hyaluronic acid—a major component of the extracellular matrix—as well as other ligands such as osteopontin, collagens, integrins, laminins, fibronectin, and matrix metalloproteases. Through these interactions it regulates diverse biological processes including cell adhesion, migration, proliferation, angiogenesis, immune responses, presentation/docking of cytokines/growth factors at the membrane surface for signal transduction pathways critical for both normal physiology and disease states. CD44 exists in multiple isoforms generated by alternative splicing; its standard form (CD44s) is widely expressed on most vertebrate cells while variant forms show more restricted distribution. Overexpression or altered splicing patterns are implicated in various cancers where it can promote metastasis by enhancing motility/invasion. Targeting CD44 has shown promise experimentally but clinical translation faces challenges due to its broad tissue distribution and functional diversity.

Other names

Homing cell adhesion molecule (HCAM)Phagocytic glycoprotein-1 (Pgp-1)Hermes antigenLymphocyte homing receptorECM-III (Extracellular matrix receptor III)HUTCH-1/HUTCH-ICDw44Hermes-1HCELL (Hematopoietic cell E-and L-selectin ligand)CSPG8 (Chondroitin sulfate proteoglycan 8)H-CAMMC56MDU2, MDU3, MIC4INGP90 lymphocyte homing/adhesion receptorChondroitin sulfate proteoglycan VIII

Blockade of ligand binding to inhibit cell adhesion/migration. Disruption of hyaluronic acid-CD44 interaction to reduce tumor invasion/metastasis. Modulation of downstream signaling pathways such as PI3K/E2F1/SVV, NF-kB/CTN, CREB/TGF-beta2 involved in tumor progression.