Characterization of a polymorphism in NAD(P)H: quinone oxidoreductase (DT-diaphorase).

摘要: NAD(P)H:quinone oxidoreductase (NQO1, EC 1.6.99.2) is an obligate two-electron reductase that can either bioactivate or detoxify quinones and has been proposed to play important role in chemoprevention. We have previously characterized a homozygous point mutation the BE human colon carcinoma cell line leads loss of NQO1 activity. Sequence analysis showed this was at position 609 cDNA, conferring proline serine substitution 187 enzyme. Using polymerase chain reaction (PCR) analysis, we found H596 non-small-cell lung cancer (NSCLC) elevated mRNA, but no detectable enzyme Sequencing coding region from cells presence identical present line. Expression purification recombinant wild-type mutant protein E. coli could be detected using immunoblot had 2% enzymatic activity protein. PCR Northern blot moderate low levels expression correctly sized transcript cells. Immunoblot also revealed immunoreactive; however, not cytosol cells, suggesting proteins were translated rapidly degraded. The absence any detectable, active protein, therefore, appears responsible for lack mutation. A reaction-restriction fragment length polymorphism (PCR-RFLP) conducted on 90 tissue samples (45 matched sets tumour uninvolved tissue) 7% incidence individuals mutation, 42% heterozygous These data suggest represents xenobiotic metabolizing enzyme, which implications therapy, chemoprevention chemoprotection.