Adenosine receptor 2B activity promotes autonomous growth, migration as well as vascularization of head and neck squamous cell carcinoma cells

Adenosine is a signaling molecule that exerts dual effects on tumor growth: it inhibits immune cell function and thereby prevents immunosurveillance and also influences tumorigenesis directly via activation of its receptors on tumor cells. However, the adenosine-mediated mechanisms affecting oncogenic processes particularly in head and neck squamous cell carcinomas (HNSCC) are not fully understood. We investigated the role of ADORA2B (adenosine receptor A2B) in HNSCC-derived cell lines. The ADORA2B expression profile was analyzed by RT-PCR and Western-Blot and the effects of ADORA modulation by receptor ligands on proliferation, migration, invasion and angiogenesis were investigated. In vitro experiments involved MTT assays, scratch assays, transwell migration assays as well as VEGF-ELISA. Additionally, the influence of ADORA2B activity on cell cycle progression as well as on apoptotic pathways was investigated by Western Blotting and flow-cytometry based cell cycle analysis. Targeting ADORA2B with the inverse agonist PSB-603 on HNSSC-derived cell lines leads to inhibition of proliferation, transmigration and VEGFA secretion in vitro. At the molecular level, these effects were associated with cell cycle arrest (downregulation of cyclin D1 (CCND1) and phospho-RB (pRB1) expression) and the induction of apoptosis (downregulation of Bcl-xL (BCL2L) and upregulation of cleaved Caspase 9 (cleaved CASP9)) expression at protein level. Also, shRNA-mediated down-modulation of ADORA2B expression caused decreased proliferation. We found that ADORA2B is upregulated in HNSCC-derived cell lines, which promotes autonomous cell growth, migration. Our data suggest ADORA2B being an important biomarker and an interesting therapeutic target for treatment of HNSCC.

Poster-PDF A-1255.PDF