ADGRD1 promotes bladder cancer progression and angiogenesis via the PI3K/AKT/mTOR-mediated pro-angiogenic secretome.

BACKGROUND

Bladder cancer (BLCA) remains a major cause of cancer-related mortality, particularly in advanced and metastatic stages. Identifying molecular drivers of tumor aggressiveness is critical for developing targeted therapies. Adhesion G protein-coupled receptor D1 (ADGRD1, also known as GPR133) is an orphan aGPCR recently implicated in tumorigenesis. However, its role in bladder cancer and underlying signaling mechanisms remain unknown.

METHODS

The clinical significance of ADGRD1 was analyzed using GEPIA3 datasets, focusing on clinical stage and prognosis. Stable ADGRD1-knockdown and overexpression BLCA cell lines were established. qPCR, Western blot, CCK-8, colony formation, wound-healing, Transwell, and HUVEC tube formation assays were used to assess proliferation, migration, invasion, and angiogenesis. Xenograft models were used to evaluate in vivo tumor growth. PI3K/AKT/mTOR pathway activity was examined by Western blot, and its function validated using SC79 (AKT activator) and LY294002 (PI3K inhibitor).

RESULTS

ADGRD1 expression was significantly enriched in advanced-stage and high-grade BLCA, where it serves as a robust predictor of poor overall survival and progression-free interval. Functional assays demonstrated that ADGRD1 promotes BLCA cell proliferation, migration, invasion, and endothelial tube formation in vitro, and enhances tumor growth and angiogenesis in vivo. Importantly, ADGRD1-high cells enhanced endothelial tube formation by upregulating a secretome rich in VEGF, PDGF, and IL-8. Mechanistically, ADGRD1 activated the PI3K/AKT/mTOR signaling cascade, as evidenced by increased phosphorylation of pathway components. Pharmacological inhibition of PI3K/AKT/mTOR reversed the oncogenic and pro-angiogenic effects of ADGRD1.

CONCLUSIONS

This study identifies ADGRD1 as a key progression-associated driver in BLCA. By modulating the PI3K/AKT/mTOR signaling axis and the pro-angiogenic microenvironment, ADGRD1 facilitates tumor growth and neovascularization. ADGRD1 may serve as a promising prognostic biomarker and therapeutic target for advanced BLCA.