Background: Skeletal muscle mass wasting almost invariably accompanies bone loss in elderly, and the coexistence of these two conditions depends on the tight endocrine crosstalk existing between the two organs, other than the biomechanical coupling. Since the current diagnostics limitation in this field, and given the progressive population aging, more effective tools are needed. The aim of this study was to identify circulating microRNAs (miRNAs) as potential biomarkers for muscle mass wasting in post‐menopausal osteoporotic women.Methods: One hundred seventy‐nine miRNAs were assayed by quantitative real‐time polymerase chain reaction in plasma samples from 28 otherwise healthy post‐menopausal osteoporotic women (73.4 ± 6.6 years old). The cohort was divided in tertiles based on appendicular skeletal muscle mass index (ASMMI) to better highlight the differences on skeletal muscle mass (first tertile: n = 9, ASMMI = 4.88 ± 0.40 kg·m⁻²; second tertile: n = 10, ASMMI = 5.73 ± 0.23 kg·m⁻²; third tertile: n = 9, ASMMI = 6.40 ± 0.22 kg·m⁻²). Receiver operating characteristic (ROC) curves were calculated to estimate the diagnostic potential of miRNAs. miRNAs displaying a statistically significant fold change ≥ ±1.5 and area under the curve (AUC) > 0.800 (P < 0.05) between the first and third tertiles were considered. A linear regression model was applied to estimate the association between miRNA expression and ASMMI in the whole population, adjusting for body mass index, age, total fat (measured by total‐body dual‐energy X‐ray absorptiometry [DXA]) and bone mineral density (measured by femur DXA). Circulating levels of adipo‐myokines were evaluated by bead‐based immunofluorescent assays and enzyme‐linked immunosorbent assays.Results: Five miRNAs (hsa‐miR‐221‐3p, hsa‐miR‐374b‐5p, hsa‐miR‐146a‐5p, hsa‐miR‐126‐5p and hsa‐miR‐425‐5p) resulted down‐regulated and two miRNAs (hsa‐miR‐145‐5p and hsa‐miR‐25‐3p) were up‐regulated in the first tertile (relative‐low ASMMI) compared with the third tertile (relative‐high ASMMI) (fold change ≥ ±1.5; P‐value < 0.05). All the corresponding ROC curves had AUC > 0.8 (P < 0.05). Two signatures hsa‐miR‐126‐5p, hsa‐miR‐146a‐5p and hsa‐miR‐425‐5p; and hsa‐miR‐126‐5p, hsa‐miR‐146a‐5p, hsa‐miR‐145‐5p and hsa‐miR‐25‐3p showed the highest AUC, 0.914 (sensitivity = 77.78%; specificity = 100.00%) and 0.901 (sensitivity = 88.89%; specificity = 100.00%), respectively.Conclusions: In this study, we identified, for the first time, two miRNA signatures, hsa‐miR‐126‐5p, hsa‐miR‐146a‐5p and hsa‐miR‐425‐5p; and hsa‐miR‐126‐5p, hsa‐miR‐146a‐5p, hsa‐miR‐145‐5p and hsa‐miR‐25‐3p, specifically associated with muscle mass wasting in post‐menopausal osteoporotic women.

Adenine phosphoribosyltransferase deficiency (APRTD) is an under estimated genetic form of kidney stones and/or kidney failure, characterized by intratubular precipitation of 2,8-dihydroxyadenine crystals (2,8-DHA). Currently, five pathologic allelic variants have been identified as responsible of the complete inactivation of APRT protein. In this study, we report a novel nonsense mutation of the APRT gene from a 47- year old Italian patient. The mutation, localized in the exon 5, leads to the replacement of a cytosine with a thymine (g.2098C > T), introducing a stop codon at amino acid position 147 (p.Gln147X).This early termination was deleterious for the enzyme structural and functional integrity, as demonstrated by the structure analysis and the activity assay of the mutant APRT protein. These data revealed that the p.Gln147X mutation in APRT gene might be a new cause of APRT disease.

Tumors of the parathyroid glands are the second most common endocrine neoplasia. Epigenetic studies revealed an embryonic signature involved in parathyroid tumorigenesis. Here, we investigated the expression of the stem core genes SOX2, POU5F1/OCT4, and NANOG. Rare cells within normal parathyroid glands expressed POU5F1/OCT4 and NANOG, while SOX2 was undetectable. Nuclear SOX2 expression was detectable in 18% of parathyroid adenomas (PAds, n = 34) involving 5–30% of cells, while OCT4 and NANOG were expressed at the nuclear level in a more consistent subset of PAds involving 15–40% of cells. Most parathyroid carcinomas expressed the core stem genes. SOX2-expressing cells co-expressed parathormone (PTH). In PAds-derived primary cultures, silencing of the tumor suppressor gene MEN1 induced the expression of SOX2, likely through a MEN1/HAR1B/SOX2 axis, while calcium-sensing receptor activation increased SOX2 mRNA levels through YAP1 activation. In addition, inducing nuclear β-catenin accumulation in PAds-derived primary cultures by short-term incubation with lithium chloride (LiCl), SOX2 and POU5F1/OCT4 expression levels increased, while NANOG transcripts were reduced, and LiCl long-term incubation induced an opposite pattern of gene expression. In conclusion, detection of the core stem genes in parathyroid tumors supports their embryogenic signature, which is modulated by crucial genes involved in parathyroid tumorigenesis.

The Hippo pathway is involved in human tumorigenesis and tissue repair. Here, we investigated the Hippo coactivator Yes-associated protein 1 (YAP1) and the kinase large tumor suppressor 1/2 (LATS1/2) in tumors of the parathyroid glands, which are almost invariably associated with primary hyperparathyroidism. Compared with normal parathyroid glands, parathyroid adenomas (PAds) and carcinomas show variably but reduced nuclear YAP1 expression. The kinase LATS1/2, which phosphorylates YAP1 thus promoting its degradation, was also variably reduced in PAds. Further, YAP1 silencing reduces the expression of the key parathyroid oncosuppressor multiple endocrine neoplasia type 1(MEN1), while MEN1 silencing increases YAP1 expression. Treatment of patient-derived PAds-primary cell cultures and Human embryonic kidney 293A (HEK293A) cells expressing the calcium-sensing receptor (CASR) with the CASR agonist R568 induces YAP1 nuclear accumulation. This effect was prevented by the incubation of the cells with RhoA/Rho-associated coiled-coil-containing protein kinase (ROCK) inhibitors Y27632 and H1152. Lastly, CASR activation increased the expression of the YAP1 gene targets CYR61, CTGF, and WNT5A, and this effect was blunted by YAP1 silencing. Concluding, here we provide preliminary evidence of the involvement of the Hippo pathway in human tumor parathyroid cells and of the existence of a CASR-ROCK-YAP1 axis. We propose a tumor suppressor role for YAP1 and LATS1/2 in parathyroid tumors.

The expression of several key molecules is altered in parathyroid tumors due to gene mutations, the loss of heterozygosity, and aberrant gene promoter methylation. A set of genes involved in parathyroid tumorigenesis has been investigated in sporadic parathyroid adenomas (PAds). Thirty-two fresh PAd tissue samples surgically removed from patients with primary hyperparathyroidism (PHPT) were collected and profiled for gene, microRNA, and lncRNA expression (n = 27). Based on a gene set including MEN1, CDC73, GCM2, CASR, VDR, CCND1, and CDKN1B, the transcriptomic profiles were analyzed using a cluster analysis. The expression levels of CDC73 and CDKN1B were the main drivers for clusterization. The samples were separated into two main clusters, C1 and C2, with the latter including two subgroups of five PAds (C2A) and nineteen PAds (C2B), both differing from C1 in terms of their lower expression of CDC73 and CDKN1B. The C2A PAd profile was also associated with the loss of TP73, an increased expression of HAR1B, HOXA-AS2, and HOXA-AS3 lncRNAs, and a trend towards more severe PHPT compared to C1 and C2B PAds. C2B PAds were characterized by a general downregulated gene expression. Moreover, CCND1 levels were also reduced as well as the expression of the lncRNAs NEAT1 and VLDLR-AS1. Of note, the deregulated lncRNAs are predicted to interact with the histones H3K4 and H3K27. Patients harboring C2B PAds had lower ionized and total serum calcium levels, lower PTH levels, and smaller tumor sizes than patients harboring C2A PAds. In conclusion, PAds display heterogeneous transcriptomic profiles which may contribute to the modulation of clinical and biochemical features. The general downregulated gene expression, characterizing a subgroup of PAds, suggests the tumor cells behave as quiescent resting cells, while the severity of PHPT may be associated with the loss of p73 and the lncRNA-mediated deregulation of histones.