Three-dimensional cell growth confers radioresistance by chromatin density modification.

TY - JOUR

T1 - Three-dimensional cell growth confers radioresistance by chromatin density modification.

AU - Storch, Katja

AU - Eke, Iris

AU - Borgmann, Kerstin

AU - Krause, Mechthild

AU - Richter, Christian

AU - Becker, Kerstin

AU - Schröck, Evelin

AU - Cordes, Nils

PY - 2010

Y1 - 2010

N2 - Cell shape and architecture are determined by cell-extracellular matrix interactions and have profound effects on cellular behavior, chromatin condensation, and tumor cell resistance to radiotherapy and chemotherapy. To evaluate the role of chromatin condensation for radiation cell survival, tumor cells grown in three-dimensional (3D) cell cultures as xenografts and monolayer cell cultures were compared. Here, we show that increased levels of heterochromatin in 3D cell cultures characterized by histone H3 deacetylation and induced heterochromatin protein 1alpha expression result in increased radiation survival and reduced numbers of DNA double strand breaks (DSB) and lethal chromosome aberrations. Intriguingly, euchromatin to heterochromatin-associated DSBs were equally distributed in irradiated 3D cell cultures and xenograft tumors, whereas irradiated monolayer cultures showed a 2:1 euchromatin to heterochromatin DSB distribution. Depletion of histone deacetylase (HDAC) 1/2/4 or application of the class I/II pharmacologic HDAC inhibitor LBH589 induced moderate or strong chromatin decondensation, respectively, which was translated into cell line-dependent radiosensitization and, in case of LBH589, into an increased number of DSBs. Neither growth conditions nor HDAC modifications significantly affected the radiation-induced phosphorylation of the important DNA repair protein ataxia telangiectasia mutated. Our data show an interrelation between cell morphology and cellular radiosensitivity essentially based on chromatin organization. Understanding the molecular mechanisms by which chromatin structure influences the processing of radiation-induced DNA lesions is of high relevance for normal tissue protection and optimization of cancer therapy.

AB - Cell shape and architecture are determined by cell-extracellular matrix interactions and have profound effects on cellular behavior, chromatin condensation, and tumor cell resistance to radiotherapy and chemotherapy. To evaluate the role of chromatin condensation for radiation cell survival, tumor cells grown in three-dimensional (3D) cell cultures as xenografts and monolayer cell cultures were compared. Here, we show that increased levels of heterochromatin in 3D cell cultures characterized by histone H3 deacetylation and induced heterochromatin protein 1alpha expression result in increased radiation survival and reduced numbers of DNA double strand breaks (DSB) and lethal chromosome aberrations. Intriguingly, euchromatin to heterochromatin-associated DSBs were equally distributed in irradiated 3D cell cultures and xenograft tumors, whereas irradiated monolayer cultures showed a 2:1 euchromatin to heterochromatin DSB distribution. Depletion of histone deacetylase (HDAC) 1/2/4 or application of the class I/II pharmacologic HDAC inhibitor LBH589 induced moderate or strong chromatin decondensation, respectively, which was translated into cell line-dependent radiosensitization and, in case of LBH589, into an increased number of DSBs. Neither growth conditions nor HDAC modifications significantly affected the radiation-induced phosphorylation of the important DNA repair protein ataxia telangiectasia mutated. Our data show an interrelation between cell morphology and cellular radiosensitivity essentially based on chromatin organization. Understanding the molecular mechanisms by which chromatin structure influences the processing of radiation-induced DNA lesions is of high relevance for normal tissue protection and optimization of cancer therapy.

M3 - SCORING: Zeitschriftenaufsatz

VL - 70

SP - 3925

EP - 3934

JO - CANCER RES

JF - CANCER RES

SN - 0008-5472

IS - 10

M1 - 10

ER -