Colocalization of Wnt/β-catenin and ACTH signaling pathways and paracrine regulation in aldosterone producing adenoma.

Abstract

CONTEXT\nAldosterone-producing adenomas (APA) are a common cause of primary aldosteronism. Despite the discovery of somatic mutations in APA and characterization of multiple factors regulating adrenal differentiation and function, the sequence of events leading to APA formation remains to be determined.\n\n\nOBJECTIVE\nWe investigated the role of Wnt/β-catenin and ACTH signaling, as well as elements of paracrine regulation of aldosterone biosynthesis in adrenals with APA and their relationship to intratumoral heterogeneity and mutational status.\n\n\nDESIGN\nWe analyzed expression of CYP11B2, CYP17A1, β-catenin, MC2R, pCREB, Tryptase, S100, CD34 by multiplex immunofluorescence and IHC guided RT-qPCR.\n\n\nSETTING\n11 adrenals with APA and one with micronodular hyperplasia from patients with PA were analysed.\n\n\nMAIN OUTCOME MEASURE(S)\nLocalization of CYP11B2, CYP17A1, β-catenin, MC2R, pCREB, Tryptase, S100, CD34 in APA and aldosterone producing cell clusters (APCC).\n\n\nRESULTS\nImmunofluorescence revealed abundant mast cells and a dense vascular network in APA, independent of mutational status. Within APA, mast cells were localized in areas expressing CYP11B2 and were rarely co-localized with nerve fibers, suggesting that their degranulation is not controlled by innervation. In these same areas, ß-catenin was activated, suggesting a zona glomerulosa cell identity. In heterogeneous APA with KCNJ5 mutations, MC2R and VEGFA expression was higher in areas expressing CYP11B2. A similar pattern was observed in APCC, with high expression of CYP11B2, activated β-catenin, and numerous mast cells.\n\n\nCONCLUSIONS\nOur results suggest that aldosterone producing structures in adrenals with APA share common molecular characteristics and cellular environment, despite different mutation status, suggesting common developmental mechanisms.