Giuseppe
Emeritus
[Source: PNAS, full text: (LINK). Abstract, edited.]
Gain of chromosome band 7q11 in papillary thyroid carcinomas of young patients is associated with exposure to low-dose irradiation
Abstract
The main consequence of the Chernobyl accident has been an increase in papillary thyroid carcinomas (PTCs) in those exposed to radioactive fallout as young children. Our aim was to identify genomic alterations that are associated with exposure to radiation. We used array comparative genomic hybridization to analyze a main (n = 52) and a validation cohort (n = 28) of PTC from patients aged <25 y at operation and matched for age at diagnosis and residency. Both cohorts consisted of patients exposed and not exposed to radioiodine fallout. The study showed association of a gain on chromosome 7 (7q11.22?11.23) with exposure (false discovery rate = 0.035). Thirty-nine percent of the exposed group showed the alteration; however, it was not found in a single case from the unexposed group. This was confirmed in the validation set. Because only a subgroup of cases in the exposed groups showed gain of 7q11.22?11.23, it is likely that different molecular subgroups and routes of radiation-induced carcinogenesis exist. The candidate gene CLIP2 was specifically overexpressed in the exposed cases. In addition, the expression of the genes PMS2L11, PMS2L3, and STAG3L3 correlated with gain of 7q11.22?11.23. An enrichment of Gene Ontology terms ?DNA repair? (PMS2L3, PMS2L5), ?response to DNA damage stimulus? (BAZ1B, PMS2L3, PMS2L5, RFC2), and ?cell?cell adhesion? (CLDN3, CLDN4) was found. This study, using matched exposed and unexposed cohorts, provides insights into the radiation-related carcinogenesis of young-onset PTC and, with the exposure-specific gain of 7q11 and overexpression of the CLIP2 gene, radiation-specific molecular markers.
Footnotes
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- Julia He?<SUP>a</SUP>, Gerry Thomas<SUP>b</SUP>, Herbert Braselmann<SUP>a</SUP>, Verena Bauer<SUP>a</SUP>, Tatjana Bogdanova<SUP>c</SUP>, Johannes Wienberg<SUP>d</SUP>, Horst Zitzelsberger<SUP>a</SUP>, and Kristian Unger<SUP>b</SUP>,<SUP>1</SUP>
- <SUP>a</SUP>Research Unit of Radiation Cytogenetics, Helmholtz Zentrum M?nchen, German Research Center for Environmental Health GmbH, 85764 Neuherberg, Germany; <SUP>b</SUP>Human Cancer Studies Group, Department of Surgery and Cancer, Hammersmith Hospital, London W12 0HS, United Kingdom; <SUP>c</SUP>Institute of Endocrinology and Metabolism, Academy of Medical Sciences of the Ukraine, 254114 Kiev, Ukraine; and <SUP>d</SUP>Department Biologie II, Anthropologie und Humangenetik, Ludwig-Maximilians-University, 82152 Martinsried, Germany
- Edited* by Janet D. Rowley, University of Chicago, Chicago, IL, and approved April 26, 2011 (received for review November 21, 2010)
Abstract
The main consequence of the Chernobyl accident has been an increase in papillary thyroid carcinomas (PTCs) in those exposed to radioactive fallout as young children. Our aim was to identify genomic alterations that are associated with exposure to radiation. We used array comparative genomic hybridization to analyze a main (n = 52) and a validation cohort (n = 28) of PTC from patients aged <25 y at operation and matched for age at diagnosis and residency. Both cohorts consisted of patients exposed and not exposed to radioiodine fallout. The study showed association of a gain on chromosome 7 (7q11.22?11.23) with exposure (false discovery rate = 0.035). Thirty-nine percent of the exposed group showed the alteration; however, it was not found in a single case from the unexposed group. This was confirmed in the validation set. Because only a subgroup of cases in the exposed groups showed gain of 7q11.22?11.23, it is likely that different molecular subgroups and routes of radiation-induced carcinogenesis exist. The candidate gene CLIP2 was specifically overexpressed in the exposed cases. In addition, the expression of the genes PMS2L11, PMS2L3, and STAG3L3 correlated with gain of 7q11.22?11.23. An enrichment of Gene Ontology terms ?DNA repair? (PMS2L3, PMS2L5), ?response to DNA damage stimulus? (BAZ1B, PMS2L3, PMS2L5, RFC2), and ?cell?cell adhesion? (CLDN3, CLDN4) was found. This study, using matched exposed and unexposed cohorts, provides insights into the radiation-related carcinogenesis of young-onset PTC and, with the exposure-specific gain of 7q11 and overexpression of the CLIP2 gene, radiation-specific molecular markers.
Footnotes
- <SUP>1</SUP>To whom correspondence should be addressed. E-mail: unger@helmholtz-muenchen.de.
- Author contributions: G.T., H.Z., and K.U. designed research; J.H., V.B., T.B., J.W., and K.U. performed research; H.B. contributed new reagents/analytic tools; J.H., G.T., H.B., and K.U. analyzed data; and J.H., G.T., V.B., H.Z., and K.U. wrote the paper.
- The authors declare no conflict of interest.
- *This Direct Submission article had a prearranged editor.
- This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1017137108/-/DCSupplemental.
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