Distribution of DT-diaphorase and reduced nicotinamide adenine dinucleotide phosphate: cytochrome p450 oxidoreductase in bladder tissues and tumors.
OBJECTIVE
We previously showed that mitomycin C activity in human bladder tumors is inversely related to tumor stage and muscle invasive tumors are less sensitive than superficial tumors. Because DT-diaphorase and reduced nicotinamide adenine dinucleotide phosphate:cytochrome P450 oxidoreductase (P450R) have a role in mitomycin C bioactivation, we investigated the distribution of these enzymes as a function of depth in the bladder wall and in human bladder tumors located at different parts of the bladder.


METHODS
Gene expression of DT-diaphorase and P450R relative to the expression of beta-actin was measured by reverse transcriptase-polymerase chain reaction in 4 dog and 8 human bladder tissue specimens, and in 46 human bladder tumors. DT-diaphorase activity was measured by enzymatic assay in dog and human bladders.


RESULTS
Data showed decreasing expression of DT-diaphorase and P450R from urothelium to muscle layer in the normal bladder wall with higher interindividual variation in humans than in dogs (greater than 40-fold versus approximately 3-fold). The expression of DT-diaphorase and P450R in bladder tumors correlated inversely with tumor stage (p <0.05) and was significantly higher in superficial than in muscle invasive bladder disease. DT-diaphorase and P450R expression in bladder tumors was approximately 6-fold higher than in normal bladder tissue. In normal and tumor tissues DT-diaphorase expression correlated significantly with P450R (r2 = 0.33, p <0.01), while DT-diaphorase expression correlated with its enzyme activity (r2 = 0.84, p <0.01).


CONCLUSIONS
Our results indicate a higher distribution of DT-diaphorase and P450R in superficial bladder tumors and tissues. Preferential enzyme distribution in superficial tumors may be a cause of the higher efficacy of intravesical mitomycin C therapy for superficial versus muscle invasive disease.
Li
D
D
College of Pharmacy, Ohio State University, Columbus, Ohio, USA.
Gan
Y
Y
Wientjes
M G
MG
Badalament
R A
RA
Au
J L
JL
D000818:Animals; D004285:Dogs; D006801:Humans; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000378:metabolism*; D009251:NADPH-Ferrihemoprotein Reductase / Q000378:metabolism*; D001743:Urinary Bladder / Q000201:enzymology*; D001749:Urinary Bladder Neoplasms / Q000201:enzymology*
D009251:NADPH-Ferrihemoprotein Reductase; D016660:NAD(P)H Dehydrogenase (Quinone)