title: 26,26,26,27,27,27-Hexadeuterated-1,25-Dihydroxyvitamin D3 (1,25D-d6) As Adjuvant of Chemotherapy in Breast Cancer Cell Lines.
abstract: It has been demonstrated that 1,25-dihydroxyvitamin D3 (1,25D) and some of its analogues have antitumor activity. 1,25D labeled with deuterium (26,26,26,27,27,27-hexadeuterated 1a,25-dihydroxyvitamin D3, or 1,25D-d6) is commonly used as internal standard for 1,25D liquid chromatography-mass spectrometry (LC-MS) quantification. In the present study using human breast cancer cell lines, the biological activity of 1,25D-d6 administered alone and in combination with two commonly used antineoplastic agents, 5-fluorouracil and etoposide, was evaluated. Using an MTT assay, flow cytometry, and western blots, our data demonstrated that 1,25D-d6 has effects similar to the natural hormone on cell proliferation, cell cycle, and apoptosis. Furthermore, the combination of 1,25D-d6 and etoposide enhances the antitumoral effects of both compounds. Interestingly, the antitumoral effect is higher in the more aggressive MDA-MB-231 breast cancer cell line. Our data indicate that 1,25D-d6 administered alone or in combination with chemotherapy could be a good experimental method for accurately quantifying active 1,25D levels in cultures or in biological fluids, on both in vitro breast cancer cell lines and in vivo animal experimental models.
authors.affiliation: Department of Physiology-CIMUS, Endocrine Oncology Laboratories (P1L3), Avda. Barcelona s/n, Campus Vida-University of Santiago de Compostela, Santiago de Compostela 15782, Spain. samuel.seoane@usc.es.
authors.forename: Samuel
authors.initials: S
authors.lastname: Seoane
authors.affiliation: Department of Physiology-CIMUS, Endocrine Oncology Laboratories (P1L3), Avda. Barcelona s/n, Campus Vida-University of Santiago de Compostela, Santiago de Compostela 15782, Spain. maria.bermudez@usc.es.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Bermudez
authors.affiliation: Department of Physiology-CIMUS, Endocrine Oncology Laboratories (P1L3), Avda. Barcelona s/n, Campus Vida-University of Santiago de Compostela, Santiago de Compostela 15782, Spain. juanjose.sendon@usc.es.
authors.forename: Juan
authors.initials: J
authors.lastname: Sendon-Lago
authors.affiliation: Department of Physiology-CIMUS, Endocrine Oncology Laboratories (P1L3), Avda. Barcelona s/n, Campus Vida-University of Santiago de Compostela, Santiago de Compostela 15782, Spain. anxo.martinez.ordonez@rai.usc.es.
authors.forename: Anxo
authors.initials: A
authors.lastname: Martinez-Ordoñez
authors.affiliation: Department of Physiology-CIMUS, Endocrine Oncology Laboratories (P1L3), Avda. Barcelona s/n, Campus Vida-University of Santiago de Compostela, Santiago de Compostela 15782, Spain. ahadi92@gmail.com.
authors.forename: Soraya
authors.initials: S
authors.lastname: Abdul-Hadi
authors.affiliation: Department of Physiology-CIMUS, Endocrine Oncology Laboratories (P1L3), Avda. Barcelona s/n, Campus Vida-University of Santiago de Compostela, Santiago de Compostela 15782, Spain. qfmaestr@udc.es.
authors.forename: Miguel
authors.initials: M
authors.lastname: Maestro
authors.affiliation: Department of Physiology-CIMUS, Endocrine Oncology Laboratories (P1L3), Avda. Barcelona s/n, Campus Vida-University of Santiago de Compostela, Santiago de Compostela 15782, Spain. antonio.mourino@usc.es.
authors.forename: Antonio
authors.initials: A
authors.lastname: Mouriño
authors.affiliation: Department of Physiology-CIMUS, Endocrine Oncology Laboratories (P1L3), Avda. Barcelona s/n, Campus Vida-University of Santiago de Compostela, Santiago de Compostela 15782, Spain. roman.perez.fernandez@usc.es.
authors.forename: Roman
authors.initials: R
authors.lastname: Perez-Fernandez