Human Genetics

, Volume 123, Issue 6, pp 643–653

Sensitivity of RECQL4-deficient fibroblasts from Rothmund–Thomson syndrome patients to genotoxic agents

  • Weidong Jin
  • Hao Liu
  • Yiqun Zhang
  • Subhendu K. Otta
  • Sharon E. Plon
  • Lisa L. Wang
Original Investigation

DOI: 10.1007/s00439-008-0518-4

Cite this article as:
Jin, W., Liu, H., Zhang, Y. et al. Hum Genet (2008) 123: 643. doi:10.1007/s00439-008-0518-4

Abstract

RECQ helicase protein-like 4 (RECQL4) is a member of the human RECQ family of DNA helicases. Two-thirds of patients with Rothmund–Thomson syndrome (RTS) carry biallelic inactivating mutations in the RECQL4 gene. RTS is an autosomal recessive disorder characterized by poikiloderma, sparse hair, small stature, skeletal abnormalities, cataracts, and an increased risk of cancer. Mutations in two other RECQ helicases, BLM and WRN, are responsible for the cancer predisposition conditions Bloom and Werner syndromes, respectively. Previous studies have shown that BLM and WRN-deficient cells demonstrate increased sensitivity to hydroxyurea (HU), camptothecin (CPT), and 4-nitroquinoline 1-oxide (4NQO). Little is known about the sensitivity of RECQL4-deficient cells to these and other genotoxic agents. The purpose of this study was to determine if RTS cells display any distinct cellular phenotypes in response to DNA damaging agents or replication blocks that could provide insight into the molecular function of the RECQL4 protein. Our results show that primary fibroblasts from RTS patients carrying two deleterious RECQL4 mutations, compared to wild type (WT) fibroblasts, have increased sensitivity to HU, CPT, and doxorubicin (DOX), modest sensitivity to other DNA damaging agents including ultraviolet (UV) irradiation, ionizing radiation (IR), and cisplatin (CDDP), and relative resistance to 4NQO. The RECQ family of DNA helicases has been implicated in the regulation of DNA replication, recombination, and repair. Because HU, CPT, and DOX exert their effects primarily during S phase, these results support a greater role for the RECQL4 protein in DNA replication as opposed to repair of exogenous damage.

Supplementary material

439_2008_518_MOESM1_ESM.doc (97 kb)
Sensitivity of individual RTS fibroblast samples to CPT compared to WT, BS, and WS controls a Log percentage survival curves and standard deviations for three independent WT controls and one sample each for RTS, WS, and BS fibroblasts b Log percentage survival curves and standard deviations for three independent RTS samples and one WT control and one BS control c Same as b except using three other independent RTS samples (MOESM1 DOC 97kb).
439_2008_518_MOESM2_ESM.doc (198 kb)
Plots of survival fraction curves as a function of various doses of genotoxic agent for indicated fibroblasts. Curves were estimated by the generalized linear regression models fitted for the probability of surviving colonies. LD10 levels for each agent are indicated by the horizontal lines. Fibroblasts were treated with the following agents: a HU; b CPT; c DOX; d UV; e IR; f CDDP; g 4NQO (MOESM2 198kb).

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Weidong Jin
    • 1
  • Hao Liu
    • 2
  • Yiqun Zhang
    • 2
  • Subhendu K. Otta
    • 1
  • Sharon E. Plon
    • 3
  • Lisa L. Wang
    • 1
  1. 1.Department of Pediatrics, Section of Hematology/OncologyTexas Children’s Cancer Center, Baylor College of MedicineHoustonUSA
  2. 2.Division of BiostatisticsDan L. Duncan Cancer Center, Baylor College of MedicineHoustonUSA
  3. 3.Departments of Human and Molecular Genetics and Pediatrics, Section of Hematology/OncologyTexas Children’s Cancer Center, Baylor College of MedicineHoustonUSA