MiR-126-3p contributes to parathyroid tumor angiogenesis. Issue 1 (January 2021)

• Record Type: Journal Article
• Authors: Verdelli, Chiara; Forno, Irene; Morotti, Annamaria; Maggiore, Riccardo; Mari, Gilberto; Vicentini, Leonardo; Ferrero, Stefano; Kuhn, Elisabetta; Vaira, Valentina; Corbetta, Sabrina
• Is Part Of: Endocrine-related cancer. Volume 28:Issue 1(2021)
• Page Start: 53
• Page End: 63
• Publication Date: 2021-01
• Subjects: parathyroid tumors -- miR-126-3p -- parathormone -- αSMA -- CD34; Endocrine glands -- Cancer -- Periodicals; Endocrinology -- Periodicals; Cancer -- Endocrine aspects -- Periodicals; 616.9944005
• DOI: 10.1530/ERC-20-0313
• Languages: English
• ISSNs: 1351-0088

Abstract

Abstract : Tumors of the parathyroid glands are highly vascularized and display a microRNA (miRNA) profile divergent from normal parathyroid glands (PaNs). Angiogenic miRNAs, namely miR-126-3p, miR-126-5p, and miR-296-5p, have been found downregulated in parathyroid tumors. Here, we show that miR-126-3p expression levels are reduced in parathyroid adenomas (PAds; n = 12) compared with PaNs ( n = 4). In situ hybridization (ISH) of miR-126-3p and miR-296-5p in 10 PAds show that miR-126-3p is expressed by endothelial cells lining the walls of great vessels and by cells within the thin stroma surrounding acinar structures. At variance, miR-296-5p was detectable in most PAd epithelial cells. Combining ISH for miR-126-3p with immunohistochemistry for the endothelial and mesenchymal markers CD34, CD31 and α-smooth muscle actin (αSMA), we could identify that miR-126-3p is localized in the αSMA-positive thin stroma. Further, miR-126-3p-expressing cells are enriched in the CD34-positive stromal cells surrounding epithelial cell acinar structures, a cellular pattern consistent with tumor-associated myofibroblasts (TAMs). In line with this, CD34-positive cells, sorted by FACS from PAds tissues, express miR-126-3p at higher levels than CD34-negative cells, suggesting that miR-126-3p downregulation promotes the endothelial-to-αSMA+ mesenchymal transition. In human mesenchymal stem cells derived from bone marrow (hBM-MSCs), a model of TAMs, the co-culture with PAds-derived cells for 5 days decreases miR-126-3p, while it increases VEGFA expression. At variance, adrenomedullin ( ADM ) expression is unaffected. Finally, overexpression of the miR-126-3p mimic in both hBM-MSCs and PAds-derived explants downregulates VEGFA expression levels. In conclusion, miR-126-3p is expressed by both endothelial cells and TAMs in PAds, and its downregulation promotes neoangiogenesis, possibly through VEGFA overexpression.