P2Y2- and P2Y4 purinergic receptors are over-expressed in human colon cancer.

1. A characteristic of cancer is altered signal transduction leading to uninhibited growth. Adenosine-5'-triphosphate (ATP), a natural ligand at P2X- and P2Y purinergic receptors may regulate cell growth in non-neoplastic, as well as neoplastic tissues. In the human colon cancer cell line, HT-29, we previously demonstrated the expression of purinergic receptors of the P2Y(2)- and P2Y(4) subclasses. 2. The aim of the current study was to investigate whether these two purinergic receptors are expressed also in human colon cancer, and, if so, how such expression is related to that in tumour-free colonic tissue. 3. The immunohistochemical findings of both P2Y(2)- and P2Y(4) receptors in the tumours from three patients, prompted us to conduct an investigation of a consecutive series of patients utilizing Western blotting for protein detection and densitometry for quantitation. 4. Both P2Y(2)- and P2Y(4) purinergic receptors could be identified in tumour-free tissue, and both were significantly over-expressed in each of the 10 colon cancers.