Parathyroid Hormone-related Protein Levels Research Articles

Association Between Parathyroid Hormone-Related Peptide Levels and Mortality in Patients With Malignancy

ObjectiveHypercalcemia of malignancy is a risk factor for mortality in patients with malignancies. Although the parathyroid hormone-related protein (PTHrP) secreted by tumor cells induces hypercalcemia, the association between serum PTHrP levels and mortality remains unclear. This study aimed to investigate the association between serum PTHrP levels and mortality in patients with malignancies. MethodsWe included patients with hypercalcemia (>10 mg/dL) and elevated PTHrP levels (>1.1 pmol/L) and analyzed mortality (overall survival after cancer diagnosis, PTHrP measurement, and 5-year survival rate). Moreover, using Cox proportional hazard model analysis, we investigated the impact of PTHrP levels on survival prognosis, assessing whether this effect varied depending on calcium concentration. ResultsWe analyzed the data of 183 patients. The median PTHrP level, corrected calcium level, and age were 5.5 (3.0-10.6) pmol/L, 12.5 (11.5-13.4) mg/dl, and 70 (61-76) years, respectively. PTHrP was significantly and linearly associated with serum calcium levels (correlation coefficient, 0.06; 95% CI: 0.039-0.081, t: 5.69; P < .001). The group with the highest PTHrP levels had significantly worse survival rates than the group with the lowest PTHrP levels (hazard ratio: 1.68, 95% CI 1.03-2.77, P = .038). ConclusionThis study showed an association between PTHrP and mortality in patients with malignancy after adjusting for serum calcium levels.

PTHrP participates in the bone destruction of middle ear cholesteatoma via promoting macrophage differentiation into osteoclasts induced by RANKL.

Progressive bone resorption and destruction is one of the most critical clinical features of middle ear cholesteatoma, potentially leading to various intracranial and extracranial complications. However, the mechanisms underlying bone destruction in middle ear cholesteatoma remain unclear. This study aims to explore the role of parathyroid hormone-related protein (PTHrP) in bone destruction associated with middle ear cholesteatoma. A total of 25 cholesteatoma specimens and 13 normal external auditory canal skin specimens were collected from patients with acquired middle ear cholesteatoma. Immunohistochemical staining was used to detect the expressions of PTHrP, receptor activator for nuclear factor-kappa B ligand (RANKL), and osteoprotegerin (OPG) in cholesteatoma and normal tissues. Tartrate-resistant acid phosphatase (TRAP) staining was used to detect the presence of TRAP positive multi-nucleated macrophages in cholesteatoma and normal tissues. Mono-nuclear macrophage RAW264.7 cells were subjected to interventions, divided into a RANKL intervention group and a PTHrP+ RANKL co-intervention group. TRAP staining was used to detect osteoclast formation in the 2 groups. The mRNA expression levels of osteoclast-related genes, including TRAP, cathepsin K (CTSK), and nuclear factor of activated T cell cytoplasmic 1 (NFATc1), were measured using real-time polymerase chain reaction (real-time PCR) after the interventions. Bone resorption function of osteoclasts was assessed using a bone resorption pit analysis. Immunohistochemical staining showed significantly increased expression of PTHrP and RANKL and decreased expression of OPG in cholesteatoma tissues (all P<0.05). PTHrP expression was significantly positively correlated with RANKL, the RANKL/OPG ratio, and negatively correlated with OPG expression (r=0.385, r=0.417, r=-0.316, all P<0.05). Additionally, the expression levels of PTHrP and RANKL were significantly positively correlated with the degree of bone destruction in cholesteatoma (r=0.413, r=0.505, both P<0.05). TRAP staining revealed a large number of TRAP-positive cells, including multi-nucleated osteoclasts with three or more nuclei, in the stroma surrounding the cholesteatoma epithelium. After 5 days of RANKL or PTHrP+RANKL co-intervention, the number of osteoclasts was significantly greater in the PTHrP+RANKL co-intervention group than that in the RANKL group (P<0.05), with increased mRNA expression levels of TRAP, CTSK, and NFATc1 (all P<0.05). Scanning electron microscopy of bone resorption pits showed that the number (P<0.05) and size of bone resorption pits on bone slices were significantly greater in the PTHrP+RANKL co-intervention group compared with the RANKL group. PTHrP may promote the differentiation of macrophages in the surrounding stroma of cholesteatoma into osteoclasts through RANKL induction, contributing to bone destruction in middle ear cholesteatoma.

Parathyroid hormone related-protein (PTHrP) in tissues with poor prognosis in prostate cancer patients.

Parathyroid hormone-related peptide (PTHrP) is known to have a pivotal role in the progression of various solid tumors, among which prostate cancer stands out. However, the extent of PTHrP expression and its clinical implications in prostate cancer patients remain shrouded in obscurity. The primary objective of this research endeavor was to shed light on the relevance of PTHrP in the context of prostate cancer patients and to uncover the potential underlying mechanisms. The expression of PTHrP, E-cadherin, and vimentin in tumor tissues of 88 prostate cancer patients was evaluated by immunohistochemical technique. Subsequently, the associations between PTHrP and clinicopathological parameters and prognosis of patients with prostate cancer were analyzed. Immunohistochemical analysis showed that the expression rates of PTHrP, E-cadherin, and vimentin in prostate cancer tissues were 95.5%, 88.6%, and 84.1%, respectively. Patients with a high level of PTHrP had a decreased expression of E-cadherin (P = .013) and an increased expression of vimentin (P = .010) compared with patients with a low level of PTHrP. Besides, the high expression of PTHrP was significantly correlated with a higher level of initial prostate-specific antigen (P = .026), positive lymph node metastasis (P = .010), osseous metastasis (P = .004), and Gleason score (P = .026). Moreover, patients with a high level of PTHrP had shorter progression-free survival (P = .002) than patients with a low level of PTHrP. The present study indicates that PTHrP is associated with risk factors of poor outcomes in prostate cancer, while epithelial-mesenchymal transition may be involved in this process.

Differences in Parathyroid Hormone-Related Peptide and Serum Electrolytes in Acute Leukemia Patients

Acute leukemia is a clonal malignancy of myeloid or lymphoid precursor cells. Parathyroid hormone-related protein (PTHrp) is an 84 amino acid protein released by the parathyroid glands. Serum electrolyte disturbances are common in acute leukemia patients. This study aimed to determine the difference in the levels of PTHrp and serum electrolytes (sodium, potassium, calcium ion) in acute leukemia patients. An observational analytic research, cross-sectional approach was performed at the Dr. Moewardi Hospital in Surakarta between June and August 2019 with 43 subjects. Acute leukemia, based on the FAB classification, is divided into two groups (myeloid and lymphoid lineage). The serum was used for measurement of PTHrp levels with enzyme immunoassay (ELISA) principle (the Rayto RT-2100C) and serum electrolyte with the Ion Selective Electrode (ISE) method (AVL analyzer). The data were tested by comparison test and ROC curve, p was significant if &lt;0.05, and the confidence interval was 95%. Acute leukemia subjects comprised 24 lymphoid lineages (55.8%) and 19 (44.2%) myeloid lineages subjects. The mean age was 25 (7-47) years, with 18 (41.9%) male subjects and 25 (58.1%) female subjects. The mean sodium level was 136 (132-140) mmol/L, with a mean level of 134.38±4.75 mmol/L and 137.00 (121-143) mmol/L in the lymphoid and myeloid lineage groups, respectively. The cut-off point for serum sodium levels was 135.5 mmol/L, with an AUC of 0.679, a sensitivity of 73.7%, and a specificity of 67.7%. There was a significant difference in serum sodium electrolyte levels in acute leukemia patients (p=0.046) but not in acute leukemia patients' serum potassium, calcium ion, and PTHrp levels (p=0.415; p=0.912 and p=0.293, respectively). Further research was needed in the chronic leukemia population and other research variables related to electrolyte balance.

SAT610 Multiple Endocrine Neoplasia Type 1 - The First Reported Case In An Indigenous Australian

Abstract Disclosure: E. Mignone: None. K. Neal: None. Background: Multiple Endocrine Neoplasia type 1 (MEN1) is a rare and under recognised syndrome. It has not been previously reported in Indigenous Australians for this reason. Clinical Case: A 48-year-old Indigenous Australian female was consulted on by an inpatient endocrine team in March 2020 for persistent hypercalcaemia on a background of a parathyroidectomy in 2011 for primary hyperparathyroidism (PHPTH). She was admitted to a remote Australian hospital for investigation and management of acute on chronic abdominal pain. Relevant medical history included a parathyroidectomy at age 40, multiple PE/DVT, MI, AF, CTEPH, right heart failure, HTLV-1 and recurrent abdominal pain presumed secondary to GORD. Gastroscopy from 2013 revealed chronic gastritis with hundreds of gastric polyps discovered on subsequent gastroscopy in 2015. The young age of PHPTH combined with her chronic gastritis and polyps prompted neuroendocrine tumour (NET) screening, including MEN1. At time of consult in 2020, laboratory studies were consistent with recurrence of PHPTH with a corrected calcium of 2.9 mmol/L (2.15-2.57mmol/L), serum PTH level 31.5 pmol/L (1-7pmol/L), vitamin D level 30 nmol/L, 24-hour urinary calcium variable between low and high. NET markers were markedly elevated with a gastrin level of 14042 ng/L (&amp;lt;100 ng/L), pancreatic polypeptide 2905 pmol/L (&amp;lt;55 pmol/L), urine 5HIAA ratio 8 mmol/L (&amp;lt;4 mmol/L), vasoactive intestinal peptide and glucagon levels normal. Pituitary studies, serum calcitonin, plasma metanephrines and PTH related protein levels were within normal limits. A CT of the abdomen showed thickened gastric folds, and persistent liver and IVC lesions from 2018. A diagnosis of Zollinger Ellison Syndrome (ZES) was made. Eventually, genetic testing was positive for a rare heterozygous variant of c.207dupC in exon 2 of MEN1 gene. A 68-gallium-DOTATATE PET/CT showed multiple avid pancreatic, gastric, nodal and liver lesions with high somatostatin receptor expression, suggestive of a neuroendocrine malignancy. Treatment was based largely on symptom control due to poor overall prognosis from underlying cardiorespiratory comorbidities. Abdominal pain from ZES was managed with a high dose PPI, H2 receptor antagonist and subcutaneous somatostatin analogue were trialled. Hypercalcaemia was treated with IV bisphosphonate therapy. Calcimimetic analogues were considered however patient declined. Genetic counselling was attempted however many cultural and logistical barriers were identified and family declined further testing. Unfortunately, our patient died in 2021 from presumed multifactorial respiratory failure. Conclusion: High index of suspicion is required to diagnose MEN1. This is particularly true within the Indigenous Australian population, with no prior documented cases reported. Presentation: Saturday, June 17, 2023

Parathyroid hormone related protein (PTHrP) in patients with pancreatic carcinoma and overt signs of disease progression and host tissue wasting

BackgroundCancer-cachexia is a complex syndrome secondary to physiological mechanisms related to classical hormone and immune alterations, where contributions of neuro-endocrine involvement have been less evaluated. Therefore, the aim of our study was to explore relationships between PTHrP and whole body metabolism in patients with progressive pancreatic carcinoma; relevant to “fat tissue browning”. MethodsPatient serum samples and clinical information were retrieved from earlier translational projects (1995-2005), at Sahlgrenska University Hospital in Gothenburg. Blood PTHrP levels were determined at Harvard medical School (2014). Patient data included: medical history, clinical laboratory tests, food diaries, resting metabolic expenditure, body composition, exercise capacity, Health-Related Quality of Life (SF-36) and mental disorders (HAD-scales). ResultsSerum PTHrP was detectable in 17 % of all samples without significance to tumor stage. PTHrP-negativity at inclusion remained during follow-up. Mean PTHrP concentration was 262±274 pg/ml, without sex difference and elevation over time.PTHrP-positive and negative patients experienced similar body weight loss (%) at inclusion, with a trend to deviate at follow ups (16.8±8.2% vs. 13.1±8.2%, p<0.06), where PTHrP concentrations showed correlations to weight loss, handgrip strength and Karnofsky performance, without difference in exercise capacity.PTHrP-positivity was related to increased whole body fat oxidation (p<0.006-0.01) and reduced carbohydrate oxidation (p<0.01-0.03), independently of peripheral lipolysis. Metabolic alterations in PTHrP-positive patients were related to reduced Health Related Quality of life (SF: p<0.08, MH: p<0.02), and increased anxiety and depression (HAD 1-7: p<0.004; HAD 8-14: p<0.008). ConclusionSerum PTHrP positivity in patients with pancreatic carcinoma was related to altered whole body oxidative metabolism; perhaps induced by “browning” of fat cells?

PTHrP Modulates the Proliferation and Osteogenic Differentiation of Craniofacial Fibrous Dysplasia-Derived BMSCs.

Fibrous dysplasia (FD) is a skeletal stem cell disease caused by mutations in the guanine nucleotide-binding protein, alpha-stimulating activity polypeptide (GNAS) gene, which results in the abnormal accumulation of cyclic adenosine monophosphate (cAMP) and hyperactivation of downstream signaling pathways. Parathyroid hormone-related protein (PTHrP) is secreted by the osteoblast lineage and is involved in various physiological and pathological activities of bone. However, the association between the abnormal expression of PTHrP and FD, as well as its underlying mechanism, remains unclear. In this study, we discovered that FD patient-derived bone marrow stromal cells (FD BMSCs) expressed significantly higher levels of PTHrP during osteogenic differentiation and exhibited greater proliferation capacity but impaired osteogenic ability compared to normal control patient-derived BMSCs (NC BMSCs). Continuous exogenous PTHrP exposure on the NC BMSCs promoted the FD phenotype in both in vitro and in vivo experiments. Through the PTHrP/cAMP/PKA axis, PTHrP could partially influence the proliferation and osteogenesis capacity of FD BMSCs via the overactivation of the Wnt/β-Catenin signaling pathway. Furthermore, PTHrP not only directly modulated cAMP/PKA/CREB transduction but was also demonstrated as a transcriptional target of CREB. This study provides novel insight into the possible pathogenesis involved in the FD phenotype and enhances the understanding of its molecular signaling pathways, offering theoretical evidence for the feasibility of potential therapeutic targets for FD.

LBSAT142 Discovery And Characterization Of A Potent And Orally Bioavailable Parathyroid Hormone Receptor Type-1 (PTHR1) Antagonist For The Treatment Of Hypercalcemia

Abstract Hypercalcemia is a common disorder defined as a serum calcium concentration higher than the normal range of 8.5 - 10.5 mg/dL. The most common causes of hypercalcemia are over-secretion of parathyroid hormone (PTH) from one or more enlarged parathyroid glands, which can lead to primary hyperparathyroidism (PHPT), or over-secretion of parathyroid hormone related protein (PTHrP) from a cancerous tumor, which leads to humoral hypercalcemia of malignancy (HHM). PTH is an 84 amino acid peptide that regulates calcium and phosphate homeostasis through activation of its receptor, PTHR1. PTHrP has close homology to the N-terminal region of PTH and also activates PTHR1, inducing similar biological actions. Activation of PTHR1, a class B G-protein coupled receptor expressed in bone and kidney, leads to an increase in cAMP and PKA activation, inducing gene expression changes of important modulators of bone homeostasis. In the kidney, it increases renal phosphate excretion and calcium reabsorption. Hyperactivation of PTHR1 due to high levels of either PTH or PTHrP results in increased calcium release from the bone matrix, as well as increased calcium reabsorption in the kidney, causing hypercalcemia. Surgery is the first line therapy for PHPT, but patients that cannot or choose not to have surgery are prescribed calcimimetics and/or bisphosphonates. Calcimimetics decrease circulating calcium levels but have no effect on bone homeostasis, while bisphosphonates improve bone homeostasis but have little effect on circulating calcium levels. HHM patients are prescribed bisphosphonates or denosumab, both of which possess undesirable side effects. We hypothesize that blocking PTH/PTHrP action via a PTHR1 antagonist may provide an improved therapeutic mechanism to treat PHPT and HHM, and potentially other diseases of hypercalcemia. Using an iterative medicinal chemistry approach, Crinetics has identified several nonpeptide PTHR1 antagonists via both binding and functional in vitro assays. One of these compounds, Antagonist 1 (ANT-1), has low nanomolar binding affinity for both human and rat PTHR1 and is potent in human, monkey, rat, mouse and canine PTHR1 functional antagonist assays in vitro. ANT-1 has good oral exposure in preclinical species and desirable drug-like properties, including lack of inhibition of cytochromes P450 and the hERG ion channel, and stability in liver microsomes. In rat models of PTH- and PTHrP-induced hypercalcemia, ANT-1 dose-dependently suppresses ionized blood calcium, providing support that a nonpeptide PTH antagonist has potential use as an effective therapeutic for hypercalcemia caused by PHPT and HHM. Currently, ANT-1 and other potential candidate molecules are being evaluated in a battery of safety studies to select the optimal molecule(s) suitable for evaluation in human clinical trials. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.

ODP564 Hypercalcemia in the Setting of HTLV-1 Infection and Normal PTHrP Levels

Abstract A 53 year old male with history of HTLV-1 infection associated myelopathy but with unknown mode of transmission, presented with acute on chronic bilateral lower extremity weakness and numbness with no other deficits. Examination revealed decreased strength (grade 1/5) in lower extremities with normal bulk, tone and sensations. Initial blood work revealed hypercalcemia with corrected Calcium of 16.2mg/dl(8.5-11.5), Phosphorus of 2.7mg/dl (2.5- 4.5) and Alkaline Phosphatase of 126mg/dl(20-140). Workup for hypercalcemia revealed Parathyroid hormone (PTH) level of 14pg/ml (10-65), 25 hydroxy vitamin D at 19.6 ng/ml(30-100), 1,25 dihydroxy vitamin D at 6.7pg/ml(19.9-79.3) and TSH of 1.265 microIU/ml(0.5-5). The Parathyroid hormone related protein(PTHrP) level was low at &amp;lt; 2pmol/L while Lactate Dehydrogenase (LDH) was 433U/L(100-220). Urine calcium creatinine ratio was 0.388. Reverse Transcriptase PCR was positive for HTLV-1 but negative for HTLV-2. Smudge cells and atypical lymphocytes were noted on peripheral smear. Imaging revealed generalized lymphadenopathy with splenomegaly but no spinal cord compression. Flow cytometry showed 7.8% atypical helper T cells, positive for CD3, CD4, CD5 and CD45. Clonal T cell receptor gene rearrangements were found, suggesting an underlying T cell neoplasm. Lymph node biopsy confirmed ATLL. He received treatment with fluids, Calcitonin and Denosumab after which serum Calcium levels fell (nadir 7.7mg/dl) and then normalized. He developed another episode of hypercalcemia 5 weeks later which was treated similarly. Discussion Human T cell Lymphotropic Virus-1 (HTLV-1) is a retrovirus causing asymptomatic infections, symptomatic systemic disorders and adult T cell Leukemia and lymphoma(ATLL). HTLV-1 infections, whether in asymptomatic or symptomatic patients, and ATLL are rare but important causes of hypercalcemia and hypercalcemic crises. Individuals with ATLL have the highest incidence of hypercalcemia(50-70%) among all hematologic malignancies. Hypercalcemia is a poor prognostic factor and predicts lower overall survival. It is caused by increased bone resorption, mediated by various factors with the largest role being played by Receptor Activator of Nuclear Factor Kappa B ligand (RANKL), followed by PTHrP, Interleukins, Macrophage Inflammatory Protein 1 alpha and gp 46. RANKL expression is increased upon transactivation by the viral TAX gene product and mediates conversion of osteoclast precursors to mature osteoclasts engaging in bone resorption. PTHrP expression is variable among patients, relating to levels of the TAX gene product that transactivates the PTHrP gene promoter. Thus, a low level, like in our patient, does not rule out HTLV infection as the cause of hypercalcemia. Management of hypercalcemia is in keeping with guidelines for management of other causes of hypercalcemia but may be better responsive to monoclonal antibodies against RANKL than bisphosphonates given the role of the ligand in mediating hypercalcemia in these cases. It can also be used in the setting of poor renal function, which is commonly encountered in hypercalcemic patients. Presentation: No date and time listed

ODP123 Severe Hypercalcemia During Lactation In A Patient With Pre-Existing Hypoparathyroidism

Abstract Background Pregnancy and lactation are associated with profound changes in calcium homeostasis that can complicate the management of primary hypoparathyroidism. Clinical Case A 35-year-old woman with a history of post-operative hypoparathyroidism aftertotal thyroidectomy for metastatic papillary thyroid carcinomawas found to have hypercalcemia during lactation, two months after delivery of her first pregnancy. She was taking calcitriol 0.5mcgtwo times daily prepartum, which she continued throughout pregnancy and postpartum. Two weeks prior to delivery, her serum calcium was 9.7 mg/dL (n: 8.6-10.3 mg/dL). However, testingtwo months postpartum revealed a markedly elevated serum calcium 13.7 mg/dL and ionized calcium 1.70 mmol/L (n: 1. 09-1.29 mmol/L). Subsequent workup was notable for low parathyroid hormone (PTH) 4 pg/mL (n: 11-51 pg/mL), and normal PTH-related protein (PTHrP) 0.3 pmol/L (n: &amp;lt;2 pmol/L), 25-hydroxy-vitamin D 60 ng/mL (n: 30-80 ng/mL), and 1,25-dihydroxy-vitamin D 38. 0 pg/mL (n: 19.9-79.3 pg/mL). Her calcitriol was reducedto 0.25mcg once daily, and her serum and ionized calcium improved to 10.2 mg/dL and 1.18 mmol/L, respectively, within 10 days. Two years later, after her second pregnancy, she again developed hypercalcemia during lactation. One month prior to delivery, her serum calcium was 8. 0 mg/dL and her ionized calcium was 1. 04 mmol/L on a regimen of calcium carbonate 1000mg three times daily and calcitriol 0.5mcg twice daily. However, two months after delivery and during lactation, her serum and ionized calcium increased to 10.4 mg/dL and 1.31 mmol/L, respectively. Evaluation of her PTHrP levels revealed an increase from 13 pg/mL (n: 14-27 pg/mL) one-year prepartum to 22 pg/mL during her third trimester, and then to17 pg/mL two months postpartum. In addition, her 1,25-dihydroxy-vitamin D increased from 60.2 pg/mL one-year prepartum to 108. 0 pg/mL during her third trimester and decreased to 70.2 pg/mL two months postpartum. Reductions in her calcium and calcitriol regimen improved her serum and ionized calcium levels. Conclusion This rare case highlights the changes in calcium physiology during pregnancy and lactation that can significantly alter calcium and calcitriol requirements in women with primary hypoparathyroidism. During pregnancy, calcium demand is met by increased placental and fetal PTHrP secretion and increased 1,25-dihydroxy-vitamin D production from placental 1-alpha-hydroxylase activity. Conversely, during lactation, this demand is met by increased net bone resorption from PTHrP produced by the mother's mammary tissue and decreased estrogen levels postpartum. As illustrated in this case, continuation of prepartum calcium and calcitriol regimens during pregnancy and lactation can result in maternal hypercalcemia. Thus, close monitoring of calcium levels during pregnancy and lactation in women with hypoparathyroidism is essential to adjust calcium and calcitriol supplementation and maintain adequate calcium homeostasis in the mother and fetus. Presentation: No date and time listed

Analysis of Saliva Composition: Parathyroid Hormone-Related Protein, Total Protein, and Secretory Immunoglobulin A (sIgA) in Rattus norvegicus with Stunted Growth.

This study aimed to determine total protein, secretory immunoglobulin A (sIgA) and parathyroid hormone-related protein (PTHrP) levels in the saliva of rats with stunted growth. Experimental laboratory research with a pre-and posttest control group design was conducted. Seventeen albino rats (Rattus norvegicus) were divided into the control group (eight rats) and the treatment group (nine rats). Rats in the treatment group were exposed to aflatoxin B1 5µg/kg orally for 5 weeks. Anthropometry data (body length, body weight) and saliva of R. norvegicus were collected. The levels of PTHrP and sIgA in the saliva were measured using an enzyme-linked immunosorbent assay kit for rats and the Bradford test for total protein and analyzed using SPSS 25.0. Aflatoxin caused stunted growth in rats in the treatment group. There was a significant difference in body length, salivary flow, PTHrP, sIgA, and total protein in the treatment group compared with the control group. The average rat's body length change in the control group was 6.4 ± 1.1mm/5 weeks, while in the treatment group, the change was 3.7 ± 0.9 mm /5 weeks. There was no significant weight gain in the treatment group compared with the normal group. The average values of PTHrP, sIgA, and total protein in the control group were x̄0.9, x̄18, and x̄0.7 m./L, respectively, while in the treatment group, they measured x̄0.4, x̄10.7, and x̄0.5 mg/L, respectively. This study showed that salivary flow, PTHrP, sIgA, and total protein levels in the saliva were significantly lower in stunted rats compared with normal rats.

Hypercalcemia in the setting of HTLV-1 infection and a normal PTHrP level

SummaryHuman T-cell lymphotropic virus-1 (HTLV-1) causes adult T-cell leukemia and lymphoma (ATLL) and is a rare but important cause of hypercalcemia. A 53-year-old male with HTLV-1-associated myelopathy presented with acute on chronic bilateral lower extremity weakness and numbness. Initial blood work revealed hypercalcemia with corrected calcium of 16.2 mg/dL (8.5–11.5) with normal levels of phosphorus and alkaline phosphatase. Workup for hypercalcemia revealed parathyroid hormone (PTH) of 14 pg/mL (10–65), 25 hydroxy vitamin D at 19.6 ng/mL (30–100), 1,25 dihydroxy vitamin D at 6.7 pg/mL (19.9–79.3), thyroid-stimulating hormone of 1.265 μIU/mL (0.5–5), undetectable PTH-related protein (PTHrP) and lactate dehydrogenase of 433 U/L (100–220). The urine calcium creatinine ratio was 0.388. Reverse transcriptase PCR was positive for HTLV-1 and negative for HTLV-2. Peripheral blood flow cytometry and lymph node biopsy confirmed ATLL. He received treatment with fluids, calcitonin and denosumab after which serum calcium levels fell (nadir: 7.7 mg/dL) and then normalized. Humoral hypercalcemia in this setting is mediated by receptor activator of nuclear factor-kappa B ligand (RANKL), PTHrP and other cytokines. PTHrP levels depend on levels of the TAX gene product, cell type and lymphocyte-specific factors. Thus, a low level, like in our patient, does not rule out HTLV-1 infection/ATLL as the cause of hypercalcemia. Hypercalcemia is known to be responsive to monoclonal antibodies against RANKL given the compound’s role in mediating hypercalcemia in these cases.Learning pointsHuman T-cell lymphotropic virus-1 infection and adult T-cell leukemia and lymphoma are associated with high rates of hypercalcemia and hypercalcemic crises.Hypercalcemia in these cases is mediated by osteoclastic bone resorption carried out by several agents including receptor activator of nuclear factor-kappa B ligand, parathyroid hormone-related protein (PTHrP), macrophage inflammatory protein 1 alpha, interleukins, etc. A normal PTHRrP does not rule out humoral hypercalcemia of malignancy in this setting, as indicated by this case.Hypercalcemia in such settings is highly responsive to monoclonal antibodies against RANKL given the role the ligand plays in resorptive hypercalcemia.

Parathyroid hormone-related protein and primary teeth eruption in stunting children

Stunting is a linear growth failure as an indicator of malnutrition status which is identified by comparing the height of children with normal height according to the same age and sex. Children are categorized as stunting if the child`s height is shorter than the average height of the same age and sex and has a standard deviation of below minus 2 according to the standard who. The cause of stunting is multifactorial, including disruption of hormone function, one of which is a parathyroid hormone. Parathyroid Hormone-related Protein (PTHrP) plays a role in the tooth-eruption process. This literature review aims to study the role of PTHrP on the eruption rate of primary teeth in stunting children. Malfunction of the parathyroid glands in stunted children can cause a deficiency of PTHrP levels. PTHrP and vitamin D play a role in the maintenance and affect calcium levels. Deficiency levels of PTHrP and vitamin d can lead to decreased absorption of calcium in the blood. Calcium deficiency in children can cause osteoclasts and osteoblasts to decrease, which can affect bone growth and tooth eruption patterns. In stunting children, the level of PTHrP will decrease so that tooth eruption will be inhibited.

Abstract #1183557: Parathyroid Hormone-Related Protein Causing Hypercalcemia in a Patient with Large Cell Lung Cancer

Secretion of parathyroid hormone-related protein (PTHrP) accounts for up to 80% of cases with hypercalcemia of malignancy. It is most commonly associated with lung cancer, with a reported incidence up to 12.5% in those at advanced stages. While elevated PTHrP levels have been reported with all histologic types of lung cancer, it is rare in large cell carcinoma, with only 3 previously reported cases.

Polygonum cuspidatum Extract (Pc-Ex) Containing Emodin Suppresses Lung Cancer-Induced Cachexia by Suppressing TCF4/TWIST1 Complex-Induced PTHrP Expression.

Cachexia, which is characterised by the wasting of fat and skeletal muscles, is the most common risk factor for increased mortality rates among patients with advanced lung cancer. PTHLH (parathyroid hormone-like hormone) is reported to be involved in the pathogenesis of cancer cachexia. However, the molecular mechanisms underlying the regulation of PTHLH expression and the inhibitors of PTHLH have not yet been identified. The PTHLH mRNA levels were measured using quantitative real-time polymerase chain reaction, while the PTHrP (parathyroid hormone-related protein) expression levels were measured using Western blotting and enzyme-linked immunosorbent assay. The interaction between TCF4 (Transcription Factor 4) and TWIST1 and the binding of the TCF4–TWIST1 complex to the PTHLH promoter were analysed using co-immunoprecipitation and chromatin immunoprecipitation. The results of the mammalian two-hybrid luciferase assay revealed that emodin inhibited TCF4–TWIST1 interaction. The effects of Polygonum cuspidatum extract (Pc-Ex), which contains emodin, on cachexia were investigated in vivo using A549 tumour-bearing mice. Ectopic expression of TCF4 upregulated PTHLH expression. Conversely, TCF4 knockdown downregulated PTHLH expression in lung cancer cells. The expression of PTHLH was upregulated in cells ectopically co-expressing TCF4 and TWIST1 when compared with that in cells expressing TCF4 or TWIST1 alone. Emodin inhibited the interaction between TCF4 and TWIST1 and consequently suppressed the TCF4/TWIST1 complex-induced upregulated mRNA and protein levels of PTHLH and PTHrP. Meanwhile, emodin-containing Pc-Ex significantly alleviated skeletal muscle atrophy and downregulated fat browning-related genes in A549 tumour-bearing mice. Emodin-containing Pc-Ex exerted therapeutic effects on lung cancer-associated cachexia by inhibiting TCF4/TWIST1 complex-induced PTHrP expression.

Involvement of the Parathyroid Hormone-Related Protein on Changes in the CYP3A Expression in Cancer Cachexia.

Parathyroid hormone-related protein (PTHrP), which is secreted from a tumor, contributes to the progression of cachexia, a condition that is observed in half of all cancer patients. Although drug clearance was reported to decrease in patients with cancer cachexia, the details have not been clarified. The present study reports on an investigation of whether PTHrP is involved in the alternation of drug metabolism in cases of cancer cachexia. Cancer cachexia model rats with elevated serum PTHrP levels showed a significant decrease in hepatic and intestinal CYP3A2 protein expression. When midazolam, a CYP3A substrate drug, was administered intravenously or orally to the cancer cachexia rats, its area under the curve (AUC) was increased by about 2 and 5 times, as compared to the control group. Accordingly, the bioavailability of midazolam was increased by about 3 times, thus enhancing its pharmacological effect. In vitro experiments using HepG2 cells and Caco-2 cells showed that the addition of serum from cancer cachexia rats or active PTHrP (1-34) to each cell resulted in a significant decrease in the expression of CYP3A4 mRNA. Treatment with a cell-permeable cAMP analog also resulted in a decreased CYP3A4 expression. Pretreatment with protein kinase A (PKA), protein kinase C (PKC), and nuclear factor-kappa B (NF-κB) inhibitors recovered the decrease in CYP3A4 expression that was induced by PTHrP (1-34). These results suggest that PTHrP suppresses CYP3A expression via the cAMP/PKA/PKC/NF-κB pathway. Therefore, it is likely that PTHrP would be involved in the changes in drug metabolism observed in cancer cachexia.

Cyclooxygenase-2 regulates PTHrP transcription in human articular chondrocytes and is involved in the pathophysiology of osteoarthritis in rats.

BackgroundCyclooxygenase-2 (COX-2) inhibitors are prescribed for the management of osteoarthritis (OA)-associated pain and inflammation. However, the role of COX-2 in normal and osteoarthritic articular chondrocytes has not been well investigated. We hypothesize that COX-2 plays a role in articular chondrocytes under normal conditions and during OA progression.MethodsIn vivo COX-2 levels in articular cartilage of normal and papain-induced osteoarthritic rats were compared. The role of COX-2 in human articular chondrocytes (HACs) was tested in vitro by COX-2 overexpression or activity inhibition. The levels of COX-2 and marker gene for normal function or articular cartilage degeneration were evaluated: mRNA by qRT-PCR; proteins by western blotting or immunohistochemistry; and glycosaminoglycan (GAG) by Safranin O–fast green staining. Parathyroid hormone-related protein (PTHrP) promoter activity was detected with luciferase reporter assays.ResultsIn the OA rat study, COX-2 and PTHrP were simultaneously increased in osteoarthritic rat chondrocytes, while increased PTHrP levels were reduced by celecoxib, a COX-2 selective inhibitor. The levels of normal cartilage matrices, GAG and type II collagen decreased, while markers of degeneration, collagen type X and MMP13 were elevated in osteoarthritic articular chondrocytes. Celecoxib rescued the loss of GAG and the increased collagen type X and MMP13 levels. In vitro, COX-2 overexpression in HACs significantly increased Col2a1, Col10a1, PTHrP and MMP13 mRNA expression, which was decreased when COX-2 activity was suppressed. More importantly, COX-2 overexpression upregulated the PTHrP transcription, mRNA expression and protein levels.ConclusionCOX-2 plays a pathophysiological role by preventing terminal differentiation of articular chondrocytes by upregulating PTHrP expression at the early stage of OA progression.The Translational potential of this articleCOX2 up-regulates PTHrP expression in normal and OA articular chondrocytes.

Calcitriol-mediated hypercalcemia as an immune-related adverse event in a patient receiving nivolumab and ipilimumab for metastatic renal cell carcinoma, case report

BackgroundSevere hypercalcemia is often associated with uncontrolled malignancy through several mechanisms. However, calcitriol-mediated hypercalcemia is a rare etiology for advanced solid tumors.Case presentationWe report a case of calcitriol-mediated hypercalcemia secondary to immune checkpoint inhibition in a responder with metastatic clear cell renal cell carcinoma (ccRCC). In this case, a 68 year old male with metastatic ccRCC to the liver within 4 months of right radical nephrectomy went on to develop hypercalcemia (12.8 mg/dL) shortly following 2 cycles of nivolumab and ipilimumab. Additional testing showed an elevated calcitriol level (142 pg/mL), low parathyroid hormone (PTH) and parathyroid hormone-related protein (PTHrP) levels, and a normal 25-hydroxyvitamin D level. FDG-PET imaging showed hypermetabolic mediastinal, hilar, and intra-abdominal lymphadenopathy, however the subsequent lymph node biopsy only showed reactive lymphoid cells without malignancy or granuloma. The hypercalcemia was resistant to initial therapy with calcitonin, hydration, and zoledronic acid but quickly responded to high-dose prednisone (1 mg/kg), followed by normalization of calcitriol levels. The patient was rechallenged with nivolumab and ipilimumab which provided a partial response after 4 cycles. He was maintained on low dose prednisone (10 mg daily) leading to a sustained resolution of his hypercalcemia.ConclusionThis case suggests calcitriol-mediated hypercalcemia as a novel immune-related adverse event.

Определение концентрации маркеров кальциевого метаболизма у пациентов с кальций-оксалатным нефролитиазом

THE AIM OF THE RESEARCH: to reveal the relationship of various markers of calcium metabolism (osteopontin (OPN), parathyroid hormone-related protein (PTHrP), vitamin D, parathyroid hormone (PTH)) on the course of urolithiasis (Urolithiasis) in patients with calcium oxalate nephrolithiasis. Materials and methods 100 people were examined, the following groups were included: group 1 - patients with calcium oxalate primary nephrolithiasis (n=41), group 2 - with calcium oxalate recurrent nephrolithiasis (n=39). Group 3 included conditionally healthy volunteers (n=20). The studies were carried out by the immunoenzymometric ELIZA and biochemical methods using appropriate test systems. Results in patients with recurrent nephrolithiasis, the serum PTHrP level is 54.6 (25.4-78.2) pg / ml, which is 3.7 times higher than in conventionally healthy individuals; the level of osteopontin is more than 1.5 times higher and amounts to 1.820 (0.991-2.212) pg / ml. In the group of primary nephrolithiasis, the level of PTHrP is 2-2.5 times higher than in conventionally healthy people. In patients with primary nephrolithiasis, the blood calcium level does not correlate with the level of PTHrP in the blood (r=- 0.0173, p> 0.05), as in the group with recurrent nephrolithiasis (r=0.0223, p>0.05). Discussion in patients with recurrent nephrolithiasis in the preoperative period, the serum levels of osteopontin and PTHrP in the blood serum were higher than in patients who were first diagnosed with urolithiasis, the data obtained can be used as a criterion for predicting the risk of recurrence of urolithiasis in the postoperative period. The blood calcium level does not have a statistically significant relationship with PTHrP, which allows us to assume that PTHrP has other mechanisms of influence on the development of urolithiasis, given the data obtained that the PTHrP level in patients with primary and recurrent nephrolithiasis is higher than in conditionally healthy people. Conclusion Determination of the level of PTHrP and osteopontin in patients with urolithiasis allows predicting the risk of recurrence of urolithiasis at the stage of primary calcium oxalate nephrolithiasis. Determination of the level of PTHrP makes it possible to predict the risks of developing urolithiasis in conventionally healthy individuals, which can be used for targeted prevention of an unfavorable course of urolithiasis by prescribing timely adequate rational therapy and correcting the patients diet. At the same time, no correlation was found between the level of PTHrP and the level of blood calcium in patients with calcium oxalate nephrolithiasis; therefore, further studies of the role of this protein in the pathogenesis of urolithiasis are needed.

Dmp1Cre-directed knockdown of parathyroid hormone-related protein (PTHrP) in murine decidua is associated with a life-long increase in bone mass, width, and strength in male progeny.

Parathyroid hormone-related protein (PTHrP, gene name Pthlh) is a pleiotropic regulator of tissue homeostasis. In bone, Dmp1Cre-targeted PTHrP deletion in osteocytes causes osteopenia and impaired cortical strength. We report here that this outcome depends on parental genotype. In contrast to our previous report using mice bred from heterozygous (flox/wild type) Dmp1Cre.Pthlhf/w parents, adult (16-week-old and 26-week-old) flox/flox (f/f) Dmp1Cre.Pthlhf/f mice from homozygous parents (Dmp1Cre.Pthlhf/f(hom) ) have stronger bones, with 40% more trabecular bone mass and 30% greater femoral width than controls. This greater bone size was observed in Dmp1Cre.Pthlhf/f(hom) mice as early as 12 days of age, when greater bone width was also found in male and female Dmp1Cre.Pthlhf/f(hom) mice compared to controls, but not in gene-matched mice from heterozygous parents. This suggested a maternal influence on skeletal size prior to weaning. Although Dmp1Cre has previously been reported to cause gene recombination in mammary gland, milk PTHrP protein levels were normal. The wide-bone phenotype was also noted in utero: Dmp1Cre.Pthlhf/f(hom) embryonic femurs were more mineralized and wider than controls. Closer examination revealed that Dmp1Cre caused PTHrP recombination in placenta, and in the maternal-derived decidual layer that resides between the placenta and the uterus. Decidua from mothers of Dmp1Cre.Pthlhf/f(hom) mice also exhibited lower PTHrP levels by immunohistochemistry and were smaller than controls. We conclude that Dmp1Cre leads to gene recombination in decidua, and that decidual PTHrP might, through an influence on decidual cells, limit embryonic bone radial growth. This suggests a maternal-derived developmental origin of adult bone strength. © 2021 American Society for Bone and Mineral Research (ASBMR).