TY - JOUR

T1 - Quantification of Urinary Thymidine Dimers in Volunteers After Ultraviolet Radiation Using a New UPLC-MS/MS-based Method

AU - Lerche, Catharina M.

AU - Philipsen, Peter A.

AU - Hermansson, Sigurd

AU - Heydenreich, Jakob

AU - Wulf, Hans Christian

N1 - Funding Information: The Authors would like to thank laboratory coordinator Kirsten Andersen, Department of Pharmacy, University of Copenhagen, Copenhagen, Denmark for valuable help during innumerable studies during the method development. The research was supported by the Danish Research Center for Skin Cancer, Denmark (https://vfhk.org/en) and the Skin Cancer Innovation Clinical Academic Group (SCIN CAG), Greater Copenhagen Health Science Partners (GCHSP), Copenhagen, Denmark. The work was funded by Copenhagen University Hospital, Bispebjerg and Frederiksberg, Copenhagen, Denmark. C.M.L is funded by the Lundbeck Foundation, Copenhagen, Denmark (R307-2018-3318).

PY - 2022

Y1 - 2022

N2 - Background/Aim: Solar ultraviolet radiation (UVR) is a carcinogen and irradiation of the skin results in DNA damage. Cyclobutane pyrimidine dimers (CPDs), including thymidine dimers, are among the most frequent forms of DNA damage. When CPDs are formed, the nucleotide excision repair system is activated and CPDs are excreted in the urine. Here, we developed a mass spectrometry-based method to quantify thymidine dimers in the urine and tested the method on a small group of volunteers after whole-body UVR exposure. Patients and Methods: Years of research resulted in a method based on the “dilute-and-shoot” principle and ultra-performance liquid chromatography (UPLC) coupled to mass spectrometry. The whole body of each of eight healthy volunteers was exposed to 1.5-2.0 standard erythema doses (SEDs) of UVR for 3 consecutive days. Morning urine was collected on Day 1 (before irradiation) and on the following 7-9 days. Prior to analysis, sample preparation consisted of a simple dilution. A tandem quadrupole mass spectrometer coupled to UPLC was used for quantitative analysis in the multiple reaction monitoring mode. Results: After 3 consecutive days of 1.5-2 SEDs, the highest level of thymidine dimer excretion occurred on Day 6 (0.7 ng/ml urine). Compared with baseline, significantly more thymidine dimers were excreted every day until Day 8 (p<0.016). Our method quantifies thymidine dimers that are excreted as dimers (i.e., not degraded further) after nucleotide excision repair. Conclusion: This is the first published mass spectrometry-based method for quantifying thymidine dimers in the urine after whole-body UVR exposure.

AB - Background/Aim: Solar ultraviolet radiation (UVR) is a carcinogen and irradiation of the skin results in DNA damage. Cyclobutane pyrimidine dimers (CPDs), including thymidine dimers, are among the most frequent forms of DNA damage. When CPDs are formed, the nucleotide excision repair system is activated and CPDs are excreted in the urine. Here, we developed a mass spectrometry-based method to quantify thymidine dimers in the urine and tested the method on a small group of volunteers after whole-body UVR exposure. Patients and Methods: Years of research resulted in a method based on the “dilute-and-shoot” principle and ultra-performance liquid chromatography (UPLC) coupled to mass spectrometry. The whole body of each of eight healthy volunteers was exposed to 1.5-2.0 standard erythema doses (SEDs) of UVR for 3 consecutive days. Morning urine was collected on Day 1 (before irradiation) and on the following 7-9 days. Prior to analysis, sample preparation consisted of a simple dilution. A tandem quadrupole mass spectrometer coupled to UPLC was used for quantitative analysis in the multiple reaction monitoring mode. Results: After 3 consecutive days of 1.5-2 SEDs, the highest level of thymidine dimer excretion occurred on Day 6 (0.7 ng/ml urine). Compared with baseline, significantly more thymidine dimers were excreted every day until Day 8 (p<0.016). Our method quantifies thymidine dimers that are excreted as dimers (i.e., not degraded further) after nucleotide excision repair. Conclusion: This is the first published mass spectrometry-based method for quantifying thymidine dimers in the urine after whole-body UVR exposure.

KW - bioanalysis

KW - CPD

KW - cyclobutane pyrimidine dimer

KW - DNA damage

KW - LC-MS/MS

KW - thymidine dimer

KW - urine

U2 - 10.21873/anticanres.16015

DO - 10.21873/anticanres.16015

M3 - Journal article

C2 - 36191964

AN - SCOPUS:85139159407

VL - 42

SP - 5069

EP - 5076

JO - Anticancer Research

JF - Anticancer Research

SN - 0250-7005

IS - 10

ER -