NR4A3 regulates anoikis resistance and metastasis of bladder cancer through EWSR1.

Bladder cancer (BLCA) is a common urinary malignancy with high metastatic potential. However, the mechanisms underlying its progression remain unclear. This study aimed to investigate the role and regulatory mechanisms of NR4A3, a nuclear receptor involved in apoptosis and tumor suppression, in BLCA progression, particularly its impact on anoikis resistance and metastasis. NR4A3 expression levels were analyzed using the GEPIA database. Functional studies were conducted by overexpressing NR4A3 in adherent and suspension-cultured BLCA cells. Apoptosis, invasion, migration, and ER stress marker (Bip and CHOP) expression were evaluated. Subcutaneous and lung metastasis models in BALB/c nude mice were used for in vivo validation. GEPIA analysis showed that NR4A3 is significantly downregulated in BLCA. NR4A3 overexpression increased apoptosis, reduced invasion and migration, and upregulated Bip and CHOP expression. In vivo, NR4A3 overexpression significantly reduced lung metastasis in BALB/c nude mice (n = 8 per group, p < .001). Mechanistically, NR4A3 promoted ER stress by regulating the EWSR1/Ezrin pathway, thereby suppressing anoikis resistance. NR4A3 functions as a tumor suppressor in BLCA by enhancing endoplasmic reticulum stress and inhibiting anoikis resistance through the EWSR1/Ezrin pathway. It may serve as a promising therapeutic target for metastatic BLCA.