CD44 variant isoform 9 (CD44v9)

CD44 variant isoform 9 (CD44v9) is a cell surface transmembrane glycoprotein generated through alternative splicing of the CD44 gene, incorporating the variant exon v9 into the mature mRNA transcript. CD44v9 is part of the CD44 receptor family, which mediates cellular adhesion, migration, and interaction with multiple extracellular matrix components (such as hyaluronan, osteopontin, and fibronectin)[1][4]. As with other CD44 variants, CD44v9 serves as a co-receptor for various growth factors and receptor tyrosine kinases, contributing to cellular signaling that influences tumor progression, metastasis, and stemness properties[1][2][5][6]. Uniquely, CD44v9 has been shown to stabilize the cystine/glutamate antiporter xCT, helping tumor cells resist oxidative stress and chemotherapy-induced ferroptosis, thus acting as a driver of chemoresistance in several cancers[1]. Its expression is associated with increased metastatic potential and poor prognosis in multiple tumors[1][2][5][6]. While CD44v9 is a compelling therapeutic and diagnostic target, its presence in some normal tissues raises safety considerations for targeted therapy[2][4].

Other names

CD44 variant v9CD44v9CD44 exon v9CD44v9 isoformCD44-variant 9

Antibody-mediated inhibition: function-blocking antibodies prevent ligand-receptor binding or disrupt co-receptor functionality, leading to reduced cell migration and invasion[6]. Decreasing chemoresistance: Interference with CD44v9-xCT-OTUB1 complex destabilizes xCT and sensitizes cells to ferroptosis[1].