Lymphocyte antigen 6 complex locus K protein (LY6K)

Lymphocyte antigen 6 complex locus K protein (LY6K) is a glycosylphosphatidylinositol (GPI)-anchored membrane protein belonging to the Ly6/uPAR superfamily. It is encoded on chromosome 8q24.3 and characterized by conserved cysteine-rich LU domains typical of this family.[4] Normally expressed at high levels only in testicular tissue but aberrantly upregulated across various cancers—including lung, esophageal squamous cell carcinoma, cervical cancer, breast cancer, bladder cancer—LY6K promotes tumor progression through enhancement of cellular proliferation, migration/invasion via modulation of TGF‐β/EGF signaling pathways and ERK activation.[2][3][4] High expression serves as an independent prognostic marker for poor survival outcomes across several malignancies,[2] making it both a promising therapeutic target and diagnostic/prognostic biomarker candidate. Experimental silencing reduces tumor growth *in vitro* by disrupting key oncogenic pathways without affecting EGFR localization or binding directly,[3] highlighting its role as an accessory modulator rather than primary receptor.

Other names

LY6KCancer-testis antigen 103 (CT103)Lymphocyte antigen 6 family member KGPI-anchored protein LY6K

Experimental inhibition or depletion of LY6K suppresses tumor cell growth by impairing TGF‐β-induced migration/invasion and EGF-induced proliferation; it also disrupts downstream ERK signaling and endocytic trafficking relevant to receptor function.