title: Single-cell functional analysis of parathyroid adenomas reveals distinct classes of calcium sensing behaviour in primary hyperparathyroidism.
abstract: Primary hyperparathyroidism (PHPT) is a common endocrine neoplastic disorder caused by a failure of calcium sensing secondary to tumour development in one or more of the parathyroid glands. Parathyroid adenomas are comprised of distinct cellular subpopulations of variable clonal status that exhibit differing degrees of calcium responsiveness. To gain a clearer understanding of the relationship among cellular identity, tumour composition and clinical biochemistry in PHPT, we developed a novel single cell platform for quantitative evaluation of calcium sensing behaviour in freshly resected human parathyroid tumour cells. Live-cell intracellular calcium flux was visualized through Fluo-4-AM epifluorescence, followed by in situ immunofluorescence detection of the calcium sensing receptor (CASR), a central component in the extracellular calcium signalling pathway. The reactivity of individual parathyroid tumour cells to extracellular calcium stimulus was highly variable, with discrete kinetic response patterns observed both between and among parathyroid tumour samples. CASR abundance was not an obligate determinant of calcium responsiveness. Calcium EC50 values from a series of parathyroid adenomas revealed that the tumours segregated into two distinct categories. One group manifested a mean EC50 of 2.40 mM (95% CI: 2.37-2.41), closely aligned to the established normal range. The second group was less responsive to calcium stimulus, with a mean EC50 of 3.61 mM (95% CI: 3.45-3.95). This binary distribution indicates the existence of a previously unappreciated biochemical sub-classification of PHPT tumours, possibly reflecting distinct etiological mechanisms. Recognition of quantitative differences in calcium sensing could have important implications for the clinical management of PHPT.
authors.affiliation: Department of Surgery, Duke University Medical Center, Durham, NC, USA.
authors.forename: James
authors.initials: J
authors.lastname: Koh
authors.affiliation: Department of Surgery, Duke University Medical Center, Durham, NC, USA.
authors.forename: Joyce A
authors.initials: JA
authors.lastname: Hogue
authors.affiliation: Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC, USA.|North Carolina State University, Raleigh, NC, USA.
authors.forename: Yuli
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC, USA.|North Carolina State University, Raleigh, NC, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: DiSalvo
authors.affiliation: Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC, USA.|North Carolina State University, Raleigh, NC, USA.
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Allbritton
authors.affiliation: Departments of Surgery and Biochemistry, University of Maryland School of Medicine, Baltimore, MD, USA.
authors.forename: Yuhong
authors.initials: Y
authors.lastname: Shi
authors.affiliation: Departments of Surgery and Biochemistry, University of Maryland School of Medicine, Baltimore, MD, USA.|Departments of Surgery and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, USA.
authors.forename: John A
authors.initials: JA
authors.lastname: Olson
authors.affiliation: Department of Surgery, Duke University Medical Center, Durham, NC, USA.|Duke Cancer Institute and Duke Clinical Research Institute, Duke University Medical Center, Durham, NC, USA.
authors.forename: Julie A
authors.initials: JA
authors.lastname: Sosa
mesh_terms: D000236:Adenoma / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D002460:Cell Line; D006801:Humans; D049950:Hyperparathyroidism, Primary / Q000378:metabolism*; D010282:Parathyroid Neoplasms / Q000378:metabolism*; D044169:Receptors, Calcium-Sensing / Q000378:metabolism; D059010:Single-Cell Analysis / Q000379:methods
chemical_list: D044169:Receptors, Calcium-Sensing; D002118:Calcium
keywords: adenoma; calcium; hyperparathyroidism; parathyroid; single-cell analysis