The Significance Of Adenosine A_2b Receptor Expression In Hepatocellular Carcinoma And Its Contributions To Hepatomacell Lines After RNAi

Adenosine is an intermediate product of adenine nucleotide metabolism. In many organs, adenosine is released into the extracellular space, when oxygen supply is decreased or energy consumption increased, as a signal to restore the balance between energy supply and local energy requirements. In particular, significant levels of adenosine have been found in the extracellular fluid of solid rumors, suggesting a role for adenosine in tumor growth. Adenosine, an endogenous nucleoside, has also been suggested to modulate many physiological processes through its interaction with at least four membrane receptors: A₁, A_2a, A_2b and A₃. The classification of A₂ receptors into two subtypes was originally based on different affinity levels: A_2a , or high-affinity and A_2b ,, or low-affinity receptors. Much of the current research has focused on A_2a receptors, given the perception that the relatively low affinity of A_2b for adenosine suggested A_2b receptors were of lesser physiological relevance. Only recently have potentially important functions have been associated with A_2b , prompting a renewed interest...