LY6K

LY6K stands for lymphocyte antigen 6 family member K, a small glycosylphosphatidylinositol (GPI)-anchored cell surface protein of the Ly6/uPAR family; it is embedded in the plasma membrane and has an extracellular LU-domain.

In humans, LY6K expression is normally restricted, with notable expression in testis; studies have reported elevated LY6K transcripts or protein in various cancers, including cervical cancer, breast cancer, lung cancer, glioma, and others; thus it is considered a cancer-testis antigen (CTA) in many contexts.

The precise physiological function is not fully defined; Ly6 family proteins are involved in signaling, cell adhesion, and immune modulation; LY6K may influence tumor cell interactions with the immune system or microenvironment, but mechanistic details are not well established.

Because LY6K is overexpressed in tumors and limited in normal tissues, it is explored as an immunotherapy target, including cancer vaccines and T cell– or antibody-based approaches; some preclinical evidence suggests that LY6K-directed immune responses can be elicited; its expression level may have prognostic value in certain cancers, though findings vary by cancer type.

Detection methods include immunohistochemistry and RT-PCR; expression can be regulated epigenetically, contributing to CT antigen status.