Base excision repair activities differ in human lung cancer cells and corresponding normal controls

TY - JOUR

T1 - Base excision repair activities differ in human lung cancer cells and corresponding normal controls

AU - Karahalil, Bensu

AU - Bohr, Vilhelm A

AU - De Souza-Pinto, Nadja C

PY - 2010/12/1

Y1 - 2010/12/1

N2 - Oxidative damage to DNA is thought to play a role in carcinogenesis by causing mutations, and indeed accumulation of oxidized DNA bases has been observed in samples obtained from tumors but not from surrounding tissue within the same patient. Base excision repair (BER) is the main pathway for the repair of oxidized modifications both in nuclear and mitochondrial DNA. In order to ascertain whether diminished BER capacity might account for increased levels of oxidative DNA damage in cancer cells, the activities of BER enzymes in three different lung cancer cell lines and their non-cancerous counterparts were measured using oligonucleotide substrates with single DNA lesions to assess specific BER enzymes. The activities of four BER enzymes, OGG1, NTH1, UDG and APE1, were compared in mitochondrial and nuclear extracts. For each specific lesion, the repair activities were similar among the three cell lines used. However, the specific activities and cancer versus control comparison differed significantly between the nuclear and mitochondrial compartments. OGG1 activity, as measured by 8-oxodA incision, was up-regulated in cancer cell mitochondria but down-regulated in the nucleus when compared to control cells. Similarly, NTH1 activity was also up-regulated in mitochondrial extracts from cancer cells but did not change significantly in the nucleus. Together, these results support the idea that alterations in BER capacity are associated with carcinogenesis.

AB - Oxidative damage to DNA is thought to play a role in carcinogenesis by causing mutations, and indeed accumulation of oxidized DNA bases has been observed in samples obtained from tumors but not from surrounding tissue within the same patient. Base excision repair (BER) is the main pathway for the repair of oxidized modifications both in nuclear and mitochondrial DNA. In order to ascertain whether diminished BER capacity might account for increased levels of oxidative DNA damage in cancer cells, the activities of BER enzymes in three different lung cancer cell lines and their non-cancerous counterparts were measured using oligonucleotide substrates with single DNA lesions to assess specific BER enzymes. The activities of four BER enzymes, OGG1, NTH1, UDG and APE1, were compared in mitochondrial and nuclear extracts. For each specific lesion, the repair activities were similar among the three cell lines used. However, the specific activities and cancer versus control comparison differed significantly between the nuclear and mitochondrial compartments. OGG1 activity, as measured by 8-oxodA incision, was up-regulated in cancer cell mitochondria but down-regulated in the nucleus when compared to control cells. Similarly, NTH1 activity was also up-regulated in mitochondrial extracts from cancer cells but did not change significantly in the nucleus. Together, these results support the idea that alterations in BER capacity are associated with carcinogenesis.

KW - Cell Line, Tumor

KW - Cell Nucleus

KW - Cell Transformation, Neoplastic

KW - DNA Damage

KW - DNA Glycosylases

KW - DNA Repair

KW - DNA, Mitochondrial

KW - DNA, Neoplasm

KW - DNA-(Apurinic or Apyrimidinic Site) Lyase

KW - Deoxyribonuclease (Pyrimidine Dimer)

KW - Genomic Instability

KW - Humans

KW - Lung Neoplasms

KW - Mitochondria

KW - Uracil-DNA Glycosidase

M3 - Journal article

C2 - 21187477

SN - 0250-7005

VL - 30

SP - 4963

EP - 4971

JO - Anticancer Research

JF - Anticancer Research

IS - 12

ER -