Novel N2-substituted pyrazolo[3,4-d]pyrimidine adenosine A3 receptor antagonists: inhibition of A3-mediated human glioblastoma cell proliferation

J Med Chem. 2010 May 27;53(10):3954-63. doi: 10.1021/jm901785w.


Adenosine induces glioma cell proliferation by means of an antiapoptotic effect, which is blocked by cotreatment with selective A(3) AR antagonists. In this study, a novel series of N(2)-substituted pyrazolo[3,4-d]pyrimidines 2a-u was developed as highly potent and selective A(3) AR antagonists. The most performing compounds were derivatives 2a (R(1) = CH(3) and R(2) = COC(6)H(5); K(i) 334, 728, and 0.60 nM at the human A(1), A(2A), and A(3) ARs, respectively) and 2b (R(1) = CH(3) and R(2) = COC(6)H(4)-4-OCH(3); K(i) 1037, 3179, and 0.18 nM at the human A(1), A(2A), and A(3) ARs, respectively), which counteracted the effect of the A(3) AR agonists Cl-IB-MECA and IB-MECA on human glioma U87MG cell proliferation. This effect was concentration-dependent, with IC(50) values comparable to A(3) AR binding affinity values of 2a and 2b, thereby suggesting that their effects were receptor-mediated. Furthermore, the antiproliferative activity of the new compounds was demonstrated to be mediated by the block of A(3) AR agonist activation of intracellular kinases ERK 1/2.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine A3 Receptor Agonists
  • Adenosine A3 Receptor Antagonists*
  • Animals
  • Antineoplastic Agents / chemical synthesis*
  • Antineoplastic Agents / chemistry
  • Antineoplastic Agents / pharmacology
  • Binding, Competitive
  • CHO Cells
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Chemotherapy, Adjuvant
  • Cricetinae
  • Cricetulus
  • Cyclic AMP / metabolism
  • Enzyme Activation
  • Glioblastoma
  • Humans
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • Mitogen-Activated Protein Kinase 3 / metabolism
  • Models, Molecular
  • Phosphorylation
  • Pyrazoles / chemical synthesis*
  • Pyrazoles / chemistry
  • Pyrazoles / pharmacology
  • Pyrimidines / chemical synthesis*
  • Pyrimidines / chemistry
  • Pyrimidines / pharmacology
  • Radioligand Assay
  • Structure-Activity Relationship


  • Adenosine A3 Receptor Agonists
  • Adenosine A3 Receptor Antagonists
  • Antineoplastic Agents
  • Pyrazoles
  • Pyrimidines
  • Cyclic AMP
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3