Receptor-binding cancer antigen expressed on SiSo cells (RCAS1)

Receptor-binding cancer antigen expressed on SiSo cells (RCAS1), also known as estrogen receptor binding site associated antigen 9 (EBAG9), is a tumor-associated antigen encoded by the EBAG9 gene in humans. The gene is estrogen-responsive and its transcription is regulated by estrogen receptor interaction with an estrogen-responsive element upstream of the gene. RCAS1 is overexpressed in a wide variety of cancers—including breast, ovarian, uterine, endometrial, and liver tumors—where it is thought to play a role in immune evasion by inducing apoptosis in activated immune cells. It is used as a biomarker for certain cancers and may serve as a prognostic indicator for tumor aggressiveness. The protein localizes to the Golgi apparatus and exerts effects via caspase activation, suppressing cell proliferation and inducing apoptosis. While clinically relevant as a diagnostic and prognostic biomarker, there are currently no therapeutics directly targeting RCAS1 in clinical use[1][2][4][8][9][10][12].

Other names

Estrogen receptor binding site associated antigen 9EBAG9Estrogen receptor-binding fragment-associated antigen 9PDAFEB9Cancer-associated surface antigen RCAS1Estrogen receptor binding site associated antigen 9 protein

May induce apoptosis of immune cells by activating caspase (ICE-like protease) pathways[4][12] Action may contribute to tumor immune evasion and progression[4][12]