Comparison of serum and urinary levels of modified nucleoside, 1-methyladenosine, in cancer patients using a monoclonal antibody-based inhibition ELISA.
To evaluate the clinical usefulness of serum 1-methyladenosine, several modifications have been made in our previously established inhibition ELISA system. Horseradish peroxidase (HRP) labeled anti-mouse IgG and 3,3',5,5'-tetramethylbenzidine (TMBZ) were used as a secondary antibody and a substrate, respectively. The second blocking was done just before the addition of the secondary antibody. The standard curve of the modified ELISA system showed good linearity between 1 and 1,000 ng/ml, and the detection limit was 50 pg/well. Using the ultrafiltrated-serum samples, serum 1-methyladenosine levels in healthy individuals and cancer patients were determined. The mean level of 1-methyladenosine in 31 healthy individuals was 28.3 +/- 7.9 ng/ml, and cut off value was set at 44.1 ng/ml (Mean+ 2SD). In cancer patients, elevated levels of serum 1-methyladenosine above the cut off value were detected in 4 out of 25 cases tested, though 11 cases had elevated urinary 1-methyladenosine levels above the cut off value (3.23 nmol/mumol creatinine). Since 1-methyladenosine has no interaction with serum proteins and its molecular weight is quite low, it might be rapidly excreted into the urine.
D000241:Adenosine / Q000031:analogs & derivatives* / Q000097:blood / Q000652:urine; D000293:Adolescent; D000328:Adult; D000368:Aged; D000911:Antibodies, Monoclonal; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000097:blood* / Q000652:urine*; D012016:Reference Values
D000911:Antibodies, Monoclonal; C002230:1-methyladenosine; D000241:Adenosine