Toggle Main Menu Toggle Search

Open Access padlockePrints

DNA-dependent protein kinase is a therapeutic target and an indicator of poor prognosis in B-cell chronic lymphocytic leukemia

Lookup NU author(s): Dr Elaine Willmore, Dr Sarah Johnson, Dr Tryfonia Mainou-Fowler, Professor Graham Jackson, Dr Celine Cano, Professor Roger Griffin, Dr Ian Cowell, Professor Caroline Austin, Emeritus Professor Barbara Durkacz

Downloads

Full text for this publication is not currently held within this repository. Alternative links are provided below where available.


Abstract

Purpose: del(17p), del(11q), and associated p53 dysfunction predict for short survival and chemoresistance in B-cell chronic lymphocytic leukemia (CLL). DNA-dependent protein kinase (DNA-PK) is activated by DNA damage and mediates DNA double-strand break repair. We hypothesized that inhibiting DNA-PK would sensitize CLL cells to drug-induced DNA damage and that this approach could increase the therapeutic index of agents used to treat CLL. Experimental Design: Fifty-four CLL cases were characterized for poor prognosis markers [del(17p), del(11q), CD38, and ZAP-70]. In selected cases, DNA-PK catalytic subunit (DNA-PKcs) expression and activity and p53 function were also measured. Ex vivo viability assays established sensitivity to fludarabine and chlorambucil and also tested the ability of a novel DNA-PK inhibitor (NU7441) to sensitize CLL cells to these drugs. The effects of NU7441 on fludarabine-induced DNA damage repair were also assessed (Comet assays and detection of γH2AX). Results: DNA-PKcs levels correlated with DNA-PK activity and varied 50-fold between cases but were consistently higher in del(17p) (P = 0.01) and del(11q) cases. NU7441 sensitized CLL cells to chlorambucil and fludarabine, including cases with del(17p), del(11q), p53 dysfunction, or high levels of DNA-PKcs. NU7441 increased fludarabine-induced double-strand breaks and abrogated drug-induced autophosphorylation of DNA-PKcs at Ser2056. High DNA-PK levels predicted for reduced treatment-free interval. Conclusions: These data validate the concept of targeting DNA-PKcs in poor risk CLL, and demonstrate a mechanistic rationale for use of a DNA-PK inhibitor. The novel observation that DNA-PKcs is overexpressed in del(17p) and del(11q) cases indicates that DNA-PK may contribute to disease progression in CLL.


Publication metadata

Author(s): Willmore E, Elliott SL, Mainou-Fowler T, Summerfield GP, Jackson GH, O'Neill F, Lowe C, Carter A, Harris R, Pettitt AR, Cano-Soumillac C, Griffin RJ, Cowell IG, Austin CA, Durkacz BW

Publication type: Article

Publication status: Published

Journal: Clinical Cancer Research

Year: 2008

Volume: 14

Issue: 12

Pages: 3984-3992

ISSN (print): 1078-0432

ISSN (electronic): 1557-3265

Publisher: American Association for Cancer Research

URL: http://dx.doi.org/10.1158/1078-0432.CCR-07-5158

DOI: 10.1158/1078-0432.CCR-07-5158


Altmetrics

Altmetrics provided by Altmetric


Actions

Find at Newcastle University icon    Link to this publication


Share