Determination of deoxyribonucleoside triphosphate pool sizes in ribonucleotide reductase cDNA transfected human KB cells

Bing Sen Zhou, Rhonda Ker, Roger Ho, Jonathan Yu, Yong Ren Zhao, Jennifer Shih, Yun Yen

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21 Citations (Scopus)


Ribonucleotide reductase (RR) is a rate-limiting enzyme in DNA synthesis, which is responsible for controlling deoxyribonucleoside triphosphate (dNTP) pool size. It has been shown that transfection of RR M2 cDNA in human KB cells (M2-D clone) results in overexpression for the M2 subunit and resistance to hydroxyurea (HU). In this study, dNTP pool assays were performed to measure the pool sizes in six cell lines: two controls, three transfectants, and drug-induced HU-resistant (HUR) cells. Total dNTP levels among the six cell lines rose in the following order: KB wild-type, KB vector-only transfectant, M1 cDNA transfectant, M2 cDNA transfectant, M1/M2 cDNA transfectant, and HU-induced resistant clone. The dCTP levels of the cells mimicked the total dNTP pools on a smaller scale. The significant increases in the dCIT pool sizes of the M2-D, X-D, and HUR clones were proportional to their respective increases in RR activity. Relative to all other transfectants, the M1-D clone demonstrated lower dCTP levels but increased dATP pools. The M1-D clone demonstrated a significant resistance to dNTP inhibition of RR activity compared with the control KB wild-type cells. In contrast, a profound inhibition of dCTP and a decreased sensitivity to dATP inhibition was observed in M2-D, X-D, and HUR clones. In summary, M2 cDNA transfectants and HUR clones had increased RR activity as well as expanded dNTP pools, particularly dCTP, when compared with wild-type KB cells. These data provide evidence for the intertwined relationship between RR activity and dNTP pools.

Original languageEnglish
Pages (from-to)1657-1665
Number of pages9
JournalBiochemical Pharmacology
Issue number10
Publication statusPublished - May 15 1998
Externally publishedYes


  • Deoxyribonucleoside triphosphate pools
  • Drug resistance
  • Hydroxyurea
  • Ribonucleotide reductase

ASJC Scopus subject areas

  • Biochemistry
  • Pharmacology


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