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McNeil BL, Robertson AKH, Fu W, Yang H, Hoehr C, Ramogida CF, Schaffer P. Production, purification, and radiolabeling of the 203Pb/ 212Pb theranostic pair. EJNMMI Radiopharm Chem 2021; 6:6. [PMID: 33527221 PMCID: PMC7851237 DOI: 10.1186/s41181-021-00121-4] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 01/11/2021] [Indexed: 11/26/2022] Open
Abstract
Background Lead-212 (212Pb, t1/2 = 10.6 h) and lead-203 (203Pb, t1/2 = 51.9 h) are an element-equivalent, or a matched theranostic radioisotope pair that show great potential for application in targeted radionuclide therapy (TRT) and single-photon emission computed tomography (SPECT), respectively. At TRIUMF we have produced both 203Pb and 212Pb using TRIUMF’s TR13 (13 MeV) and 500 MeV cyclotrons, and subsequently purified and evaluated both radioisotopes using a series of pyridine-modified DOTA analogues in comparison to the commercially available chelates DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) and TCMC (1,4,7,10-tetraaza-1,4,7,10-tetra(2-carbamoylmethyl)cyclododecane). Results Proton irradiation (12.8 MeV) of natural and enriched thallium-203 (203Tl) targets gave 203Pb saturation yields of 134 ± 25 and 483 ± 3 MBq/μA, respectively. Thorium-228 (228Th, t1/2 = 1.9 y), a by-product of 232Th proton spallation on TRIUMF’s main 500 MeV beamline (beamline 1A, BL1A), was recovered to build a 228Th/212Pb generator with the ability to deliver up to 9–10 MBq of 212Pb daily. Both lead isotopes were purified via solid phase extraction chromatography (Pb resin), and isolated in an acetate form ([203/212Pb]Pb(OAc)2) suitable for direct radiolabeling of chelators and bioconjugates. A series of cyclen-based chelators (herein referred to as DOTA-1Py, -2Py, and -3Py) along with established chelates DOTA and TCMC were evaluated for their ability to complex both 203Pb and 212Pb. All chelates incorporated 212Pb/203Pb efficiently, with higher radiolabeling yields observed for the 212Pb-complexes. Conclusion The production of 203Pb and 212Pb was established using TRIUMF 13 MeV and 500 MeV cyclotrons, respectively. Both production methods provided radiometals suitable for subsequent radiolabeling reactions using known and novel chelates. Furthermore, the novel chelate DOTA-3Py may be a good candidate for biomolecule conjugation and further theranostic 212Pb/203Pb studies. Supplementary Information The online version contains supplementary material available at 10.1186/s41181-021-00121-4.
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Affiliation(s)
- Brooke L McNeil
- Life Sciences Division, TRIUMF, Vancouver, BC, Canada.,Department of Chemistry, Simon Fraser University, Burnaby, BC, Canada
| | - Andrew K H Robertson
- Life Sciences Division, TRIUMF, Vancouver, BC, Canada.,Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada
| | - Winnie Fu
- Life Sciences Division, TRIUMF, Vancouver, BC, Canada
| | - Hua Yang
- Life Sciences Division, TRIUMF, Vancouver, BC, Canada
| | | | - Caterina F Ramogida
- Life Sciences Division, TRIUMF, Vancouver, BC, Canada. .,Department of Chemistry, Simon Fraser University, Burnaby, BC, Canada.
| | - Paul Schaffer
- Life Sciences Division, TRIUMF, Vancouver, BC, Canada. .,Department of Chemistry, Simon Fraser University, Burnaby, BC, Canada. .,Department of Radiology, University of British Columbia, Vancouver, BC, Canada.
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RecQ and Fe-S helicases have unique roles in DNA metabolism dictated by their unwinding directionality, substrate specificity, and protein interactions. Biochem Soc Trans 2017; 46:77-95. [PMID: 29273621 DOI: 10.1042/bst20170044] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 11/15/2017] [Accepted: 11/17/2017] [Indexed: 12/11/2022]
Abstract
Helicases are molecular motors that play central roles in nucleic acid metabolism. Mutations in genes encoding DNA helicases of the RecQ and iron-sulfur (Fe-S) helicase families are linked to hereditary disorders characterized by chromosomal instabilities, highlighting the importance of these enzymes. Moreover, mono-allelic RecQ and Fe-S helicase mutations are associated with a broad spectrum of cancers. This review will discuss and contrast the specialized molecular functions and biological roles of RecQ and Fe-S helicases in DNA repair, the replication stress response, and the regulation of gene expression, laying a foundation for continued research in these important areas of study.
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Bharti SK, Khan I, Banerjee T, Sommers JA, Wu Y, Brosh RM. Molecular functions and cellular roles of the ChlR1 (DDX11) helicase defective in the rare cohesinopathy Warsaw breakage syndrome. Cell Mol Life Sci 2014; 71:2625-39. [PMID: 24487782 PMCID: PMC4537069 DOI: 10.1007/s00018-014-1569-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 01/07/2014] [Accepted: 01/16/2014] [Indexed: 02/08/2023]
Abstract
In 2010, a new recessive cohesinopathy disorder, designated Warsaw breakage syndrome (WABS), was described. The individual with WABS displayed microcephaly, pre- and postnatal growth retardation, and abnormal skin pigmentation. Cytogenetic analysis revealed mitomycin C (MMC)-induced chromosomal breakage; however, an additional sister chromatid cohesion defect was also observed. WABS is genetically linked to bi-allelic mutations in the ChlR1/DDX11 gene which encodes a protein of the conserved family of Iron-Sulfur (Fe-S) cluster DNA helicases. Mutations in the budding yeast ortholog of ChlR1, known as Chl1, were known to cause sister chromatid cohesion defects, indicating a conserved function of the gene. In 2012, three affected siblings were identified with similar symptoms to the original WABS case, and found to have a homozygous mutation in the conserved Fe-S domain of ChlR1, confirming the genetic linkage. Significantly, the clinically relevant mutations perturbed ChlR1 DNA unwinding activity. In addition to its genetic importance in human disease, ChlR1 is implicated in papillomavirus genome maintenance and cancer. Although its precise functions in genome homeostasis are still not well understood, ongoing molecular studies of ChlR1 suggest the helicase plays a critically important role in cellular replication and/or DNA repair.
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Affiliation(s)
- Sanjay Kumar Bharti
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, Baltimore, MD 21224 USA
| | - Irfan Khan
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, Baltimore, MD 21224 USA
| | - Taraswi Banerjee
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, Baltimore, MD 21224 USA
| | - Joshua A. Sommers
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, Baltimore, MD 21224 USA
| | - Yuliang Wu
- Department of Biochemistry, University of Saskatchewan, Saskatoon, SK S7N 5E5 Canada
| | - Robert M. Brosh
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, Baltimore, MD 21224 USA
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