Identification of small molecule inhibitors of the human DNA repair enzyme polynucleotide kinase/phosphatase

• Author / Creator

  Freschauf, Gary

• Human polynucleotide kinase/phosphatase (hPNKP) is a bifunctional DNA repair enzyme that phosphorylates DNA 5’-termini and dephosphorylates DNA 3’-termini. hPNKP has been shown to be involved in both single- and double-strand break repair, and cancer cells depleted of hPNKP show significant sensitivity to ionizing radiation and various other genotoxic agents, including the chemotherapeutic drug camptothecin. Based on these findings, we hypothesized that small molecule inhibitors could also potentiate the sensitivity of human tumors to γ-radiation or camptothecin.
  A12B4C3 was the most effective inhibitor and was able to enhance the radiosensitivity of human A549 lung adenocarcinoma and MDA-MB-231 breast carcinoma cells by a factor of two. Kinetic analysis of A12B4C3 showed it to be a noncompetitive inhibitor. Conformational investigation using circular dichroism, UV difference spectroscopy and fluorescence resonance energy transfer all indicate that A12B4C3 disrupts the secondary structure of PNKP causing an allosteric conformational change resulting in PNKP phosphatase inhibition.

• Subjects / Keywords

  • Small molecule inhibitors
  • Polynucleotide kinase/phosphatase
  • DNA repair

• Graduation date

  Fall 2011

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R36T68

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.