DIFFERENTIAL EXPRESSION OF ADENOSINE-A1-RECEPTORS IN COLORECTAL-CANCER AND RELATED MUCOSA

Adenosine A1 receptors (A1R) are known to inhibit while the A2 recepto rs (A2R) stimulate the G-protein cAMP second messenger system and may play a role in cell growth and carcinogenesis. Using a quantitative re verse transcription-polymerase chain reaction (RT-PCR) method, mRNA fo r A1R and A2R was measured in human colorectal adenocarcinomas and ind ividual peritumoural colon tissues. There was differential expression of the mRNA for A1R with tumour tissues having significantly higher am ounts compared to peritumoural normal tissues. The mRNA for A2R was no t found to be differentially expressed. The increase in the inhibitory A1 receptor in tumour tissues may be in response to increased adenosi ne release from the hypoxic cells found in malignant tumour tissues, t hus indicating a possible role for the adenosine A1 receptor in carcin ogenesis.