Relationship between protein levels and gene expression of dihydropyrimidine dehydrogenase in human tumor cells during growth in culture and in nude mice.

摘要: Protein levels and gene expression of dihydropyrimidine dehydrogenase (DPD), the rate-limiting enzyme for degradation 5-fluorouracil, were studied in two human tumor cell lines (fibrosarcoma HT-1080 pancreatic carcinoma MIAPaCa-2) various growth phases cultured cells xenografts implanted into nude mice. DPD catalytic activity protein content cytosolic preparations determined by means radioenzymatic assay western blot analysis, respectively. Relative mRNA was using a semi-quantitative reverse transcription-polymerase chain reaction which glyceraldehyde-3-phosphate used as an internal standard. cultures both increased proportion to density (DPD activities ranged from undetectable 84 pmol/min/mg 335 MIAPaCa-2 cells). levels, on other hand, tended decrease slightly during growth. weight 7 131 protein), but did not correlate with weight. change much, seemed have already plateaued, since tumors small (weighing about 30 mg). These findings suggest that is controlled at post-transcriptional level.