GCM2 Silencing in Parathyroid Adenoma is associated with Promoter Hypermethylation and Gain of Methylation on Histone 3

PURPOSE: Glial cells missing 2 (GCM2), a zinc finger-transcription factor, is essentially required for the development of parathyroid glands. We sought to identify if the epigenetic alterations in the GCM2 transcription are involved in the pathogenesis of sporadic parathyroid adenoma. In addition, we examined the association between promoter methylation and histone modifications with disease indices. EXPERIMENTAL DESIGN: mRNA and protein expression of GCM2 were analyzed by RT-qPCR and immunohistochemistry in 33 adenomatous and 10 control parathyroid tissues. DNA methylation and histone methylation/acetylation of GCM2 promoter were measured by bisulfite sequencing and ChIP-qPCR. Additionally, we investigated the role of epigenetic modifications on GCM2 and DNA methyltransferase 1 (DNMT1) expression in PTH-C1 cells by treating with 5-aza 2\u27deoxycytidine (DAC) and BRD4770 and assessed for GCM2 mRNA and DNMT1 protein levels. RESULTS: mRNA and protein expression of GCM2 were lower in sporadic adenomatous than in control parathyroid tissues. This reduction correlated with hypermethylation (P\u3c0.001) and higher H3K9me3 levels in GCM2 promoter (P\u3c0.04) in adenomas. In PTH-C1 cells, DAC treatment resulted in increased GCM2 transcription and decreased DNMT1 protein expression, while cells treated with the BRD4770 showed reduced H3K9me3 levels but a non-significant change in GCM2 transcription. CONCLUSION: These findings suggest the concurrent association of promoter hypermethylation and higher H3K9me3 with the repression of GCM2 expression in parathyroid adenomas. Treatment with DAC restored GCM2 expression in PTH-C1 cells. Our results showed a possible epigenetic landscape in the tumorigenesis of parathyroid adenoma and also that DAC may be promising avenues of research for parathyroid adenoma therapeutics

Differences in Primary Hyperparathyroidism Between Pre- and Postmenopausal Women in India

OBJECTIVE: Primary hyperparathyroidism (PHPT) is a common endocrine disorder in women which becomes more prevalent after menopause. In this study, we compared the demographic, clinical, and biochemical variables between premenopausal (pre-M) and postmenopausal (post-M) women with PHPT. METHODS: A retrospective analysis (from 2005 to 2019) of enrolled women PHPT patients from an online Indian PHPT registry. RESULTS: Of the women with PHPT, 232 and 122 were pre-M and post-M, respectively. The number of post-M PHPT cases registered had a 3.3-fold increase in 2015-2019 from 2005-2009 compared with only a 2.5-fold increase in pre-M cases in the same duration. The majority were symptomatic (90%), although pre-M had a higher proportion of symptomatic than post-M (92% vs 85%; P = .04). Pre-M women showed more prevalence of osteitis fibrosa cystica than post-M women (28% vs 13%; P = .03), although hypertension and gallstone disease were seen more frequently in post-M PHPT women. Pre-M women had a significantly higher median PTH (403 vs 246 pg/mL; P = .02) and median alkaline phosphatase (202 vs 145 pg/mL; P = .02) than post-M women, and vitamin D deficiency was more common in pre-M women (58% vs 45%; P = .03). Gland localization, tumor weight, and disease cure rates did not differ according to menopausal status. CONCLUSION: PHPT was more prevalent in pre-M women, although the number of post-M cases had significantly increased in the last 10 years. Pre-M women had generally more severe clinical and biochemical variables than post-M PHPT women

Progressive rise in the prevalence of asymptomatic primary hyperparathyroidism in India: Data from PHPT registry

INTRODUCTION: Primary hyperparathyroidism (PHPT), a third common endocrine disorder, varies from asymptomatic disease, mostly seen in the West where routine biochemical screening is practiced, to the classical symptomatic disease mostly seen in the Eastern countries. We aimed to compare the demographic, clinical, biochemical measurements in patients with asymptomatic and symptomatic PHPT from the Indian PHPT registry. MATERIAL AND METHODS: Data of PHPT patients from the last 25 years (1995-2019) were analyzed for demographic, clinical presentation and biochemical measurements, and compared these characteristics between asymptomatic and symptomatic PHPT patients. RESULTS: Of the 554 patients, 54 (10%) patients had asymptomatic PHPT. There was a sharp rise in the proportion of asymptomatic PHPT patients of 3% in the first decade to 13% in the second decade of the century (p = 0.003). Patients with asymptomatic PHPT were significantly older (50 vs. 42 years; p \u3c 0.0001) and had higher mean body mass index (27.8 vs. 23.5 kg/m(2); p \u3c 0.0001) compared to the symptomatic PHPT group. In addition, asymptomatic PHPT patients had significantly lower median plasma iPTH (180 vs. 370 pg/mL; p \u3c 0.0001), serum alkaline phosphatase (119 vs. 172 IU/L; p \u3c 0.0001), and parathyroid adenoma weight (1.0 vs. 2.62 g; p = 0.006) compared to the symptomatic PHPT group. CONCLUSION: Although symptomatic PHPT is still most prevalent (\u3e 90%) in India with higher indices of the disease and tumor weights, there is a progressive rise in the prevalence of asymptomatic PHPT patients in the last decade. Improvements in calcium and vitamin D nutrition might account for this change as in the Western series

Characterization of primary hyperparathyroidism based on target organ involvement: An analysis from the Indian PHPT registry

BACKGROUND: It has been a matter of debate for long time about the existence of two distinct phenotypes of primary hyperparathyroidism (PHPT) predisposed to either renal or skeletal manifestation. OBJECTIVE: To differentiate characteristics of symptomatic PHPT patients based on the presence of skeletal or renal involvement. DESIGN: Retrospective analysis of data from the Indian PHPT registry. PATIENTS: PHPT patients were divided into four discrete groups: asymptomatic, presenting with renal manifestations alone, skeletal manifestations alone, and both skeletal and renal manifestations. MEASUREMENTS: Clinical, biochemical, and tumour weight and histopathological characteristics of these groups were compared. RESULTS: Of the 229 eligible patients, 45 were asymptomatic, 62 had renal manifestations, 55 had skeletal manifestations, and 67 had both skeletal and renal manifestations. Patients with both skeletal and renal manifestations had higher serum calcium levels than those with isolated skeletal involvement [12.5 (11.1-13.7) mg/dL, 11.2 (10.6-12.3) mg/dL, respectively; p \u3c .05]. Serum alkaline phosphatase (AP), plasma parathyroid hormone (PTH) levels, and parathyroid tumour weight were significantly higher in patients with isolated skeletal, and both skeletal and renal manifestations, compared to the other two groups. A preoperative PTH and AP level of 300 pg/mL and 152 U/L, predicted the risk of developing skeletal involvement with sensitivity and specificity of 71%, 70%, and 69%, 67%, respectively. CONCLUSIONS: We observed distinct skeletal and renal phenotypic subgroups among PHPT patients with characteristic biochemical and hormonal patterns with higher parathyroid disease burden in patients with skeletal complications compared to those with isolated renal manifestation

Promoter hypermethylation inactivates CDKN2A, CDKN2B and RASSF1A genes in sporadic parathyroid adenomas

Cyclin D1, a G1-S phase regulator, is upregulated in parathyroid adenomas. Since cyclin-dependent kinase (CDK) inhibitors, CDKN2A and CDKN2B, and RASSF1A (Ras-association domain family 1, isoform A) are involved in G1-S phase arrest and act as potential tumor suppressor genes, we aimed to study potential methylation-mediated inactivation of these genes in parathyroid adenomas. Gene expressions of cyclin D1 (CCND1) and regulatory molecules (CDKN2A, CDKN2B and RASSF1A) was analysed in parathyroid adenoma tissues (n = 30). DNA promoter methylation of cyclin D1 regulators were assessed and correlated with clinicopathological features of the patients. Gene expression analysis showed a relative fold reductions of 0.35 for CDKN2A (p = 0.01), 0.45 for CDKN2B (P = 0.02), and 0.39 for RASSF1A (p \u3c 0.01) in adenomatous compared to normal parathyroid tissue. There was an inverse relationship between the expressions of CDKN2A and CDKN2B with CCND1. In addition, the promoter regions of CDKN2A, CDKN2B, and of RASSF1A were significantly hyper-methylated in 50% (n = 15), 47% (n = 14), and 90% (n = 27) of adenomas respectively. In contrast, no such aberrant methylation of these genes was observed in normal parathyroid tissue. So, promoter hypermethylation is associated with down-regulation of CCND1 regulatory genes in sporadic parathyroid adenomas. This dysregulated cell cycle mechanism may contribute to parathyroid tumorigenesis