Digital spatial profiling of human parathyroid tumors reveals cellular and molecular alterations linked to vitamin D deficiency

Abstract

Primary hyperparathyroidism (PHPT) is a common endocrine neoplastic disorder characterized by disrupted calcium homeostasis secondary to inappropriately elevated parathyroid hormone (PTH) secretion. Low levels of serum 25-hydroxyvitamin D (25OHD) are significantly more prevalent in PHPT patients than in the general population (1-3), but the basis for this association remains unclear. We employed a spatially-defined in situ whole-transcriptomics and selective proteomics profiling approach to compare gene expression patterns and cellular composition in parathyroid adenomas from vitamin D-deficient or vitamin D-replete PHPT patients. A cross-sectional panel of eucalcemic cadaveric donor parathyroid glands were examined in parallel as normal tissue controls. Here, we report that parathyroid tumors from vitamin D-deficient PHPT patients (Def-Ts) are intrinsically different from those of vitamin D-replete patients (Rep-Ts) of similar age and pre-operative clinical presentation. Parathyroid oxyphil cell content is markedly higher in Def-Ts (47.8%) relative to Rep-Ts (17.8%) and normal donor glands (7.7%). Vitamin D-deficiency is associated with increased expression of electron transport chain and oxidative phosphorylation pathway components. Parathyroid oxyphil cells, while morphologically distinct, are comparable to chief cells at the transcriptional level, and vitamin D-deficiency affects the transcriptional profiles of both cell types in a similar manner. These data suggest that oxyphil cells are derived from chief cells and imply that their increased abundance may be induced by low vitamin D status. Geneset enrichment analysis reveals that pathways altered in Def-Ts are distinct from Rep-Ts, suggesting alternative tumor etiologies in these groups. Increased oxyphil content may thus be a morphological indicator of tumor-predisposing cellular stress.

Cancer-Associated Hypercalcemia Signals Through the Hindbrain to cause Anorexia

“…Immunofluorescent staining of CaSR was detected using an AlexaFluor647-conjugated mouse monoclonal antibody (clone 3H8E9) raised against a peptide ( DYGRPGIEKFREEAEE ) in the extracellular domain of the CaSR at a concentration of 5 μg/ml and counterstained with SYTO13 fluorescent nucleic acid dye (ThermoFisher, S7575) as previously described 33 . Fluorescent images of whole brain sections were acquired with a 20x objective and exported as dual-channel TIFF files from a GeoMx Digital Spatial Profiler instrument (NanoString Technologies) and presented in digitally assigned pseudo colors (CaSR in red and nucleus in blue).…”