Bone Metabolism and Vitamin D Implication in Gastroenteropancreatic Neuroendocrine Tumors

Bone and muscle mass characteristics in patients with gastroenteropancreatic neuroendocrine neoplasms

BACKGROUND

Neuroendocrine neoplasms (NEN) are rare tumors arising from neuroendocrine cells most commonly in the gastrointestinal-tract. In recent years, advancements in therapeutics have increased survival rates in patients with NEN leading to a greater clinical burden compared to the general population.

METHODS

The aim of this single-center case-control study was to investigate the incidence of low bone mass and changes in body composition in adult patients diagnosed with gastroenteropancreatic neuroendocrine tumors (GEPNET). Enrolled participants underwent measurements of bone mineral density (BMD) at the lumbar spine (LS), femoral neck (FN), and total hip (TH) and body composition analysis with calculation of total fat-mass (TFM) and relative skeletal mass index (RSMI), by dual X-ray absorptiometry.

RESULTS

Ninety GEPNET patients (28 with Pancreatic-NET, 20 with small-intestine-NET, 42 with gastric-NET), and 50 age and sex-matched controls were enrolled. The mean disease duration was 5±4.4 years, the majority of patients (54/90) was classified as stage-1, and were not receiving systemic-treatment (76/90). The incidence of osteoporosis/osteopenia was threefold higher in the patients' cohort, compared to controls (OR: 3.17 95% CI 1.16-7.8, p < 0.001). Among NEN patients, gastric-NET had the lowest bone mass, especially in LS. In addition, GEPNET patients demonstrated significantly lower TFM and RSMI, compared to controls (TFM: 31.6 ± 9.6 kg vs. 38.6 ± 6.4 kg, respectively, p = 0.03; RSMI: 6.4 ± 1.1 vs. 8.2 ± 0.6, respectively, p < 0.001). Within our patients' cohort, RSMI was significantly associated with LS-BMD (rho = 0.49, p < 0.001) and TH-BMD (rho = 0.58, p < 0.001), and TFM was associated with TH-BMD (rho = 0.31, p = 0.004).

CONCLUSIONS

Patients with GEPNET even at an early stage exhibit significantly lower bone, muscle and fat mass compared to the non-NET population, highlighting the importance of continuous monitoring of the musculoskeletal system in these patients.

Analysis of Bone Phenotype Differences in MEN1-Related and Sporadic Primary Hyperparathyroidism Using 3D-DXA

Background: The rarity and variability of MEN1-related primary hyperparathyroidism (mPHPT) has led to contradictory data regarding the bone phenotype in this patient population. Methods: A single-center retrospective study was conducted among young age- and sex-matched patients with mPHPT and sporadic hyperparathyroidism (sPHPT). The main parameters of calcium-phosphorus metabolism, bone remodeling markers, and bone mineral density (BMD) measurements were obtained during the active phase of hyperparathyroidism before parathyroidectomy (PTE) and 1 year after. Trabecular Bone Score (TBS) and 3D-DXA analysis of the proximal femur were used to evaluate the differences in bone architecture disruption between groups. Results: Patients with mPHPT had significant lower preoperative BMD compared to sPHPT at lumbar spine-LS (p = 0.002); femur neck-FN (p = 0.001); and total hip-TH (p = 0.002). 3D-DXA analysis showed the prevalence of cortical rather than trabecular bone damage in mPHPT compared to sPHPT: cortical thickness (p < 0.001); cortical surface BMD (p = 0.001); cortical volumetric BMD (p = 0.007); and trabecular volumetric BMD (p = 0.029). One year after, PTE DXA and 3D-DXA parameters were similar between groups, while 3D-visualisation showed more extensive regeneration in cortical sBMD and cortical thickness in mPHPT. Conclusions: mPHPT is associated with lower preoperative BMD values with predominant architecture disruption in the cortical bone. The absence of differences in DXA and 3D-DXA parameters 1 year after PTE between mPHPT/sPHPT combined with significantly lower BMD in mPHPT at the initial stage may indicate faster bone recovery after surgery in mPHPT than in sPHPT.

Relationship between urinary tract infections and serum vitamin D level in adults and children- a literature review

Over time, researchers have accumulated significant evidence indicating that vitamin D deficiency not only impacts skeletal health but also contributes to the development and progression of various diseases, including cancer, diabetes, and cardiovascular conditions. The risk of low serum 1, 25(OH)2D3 level ultimately directs the way to morbidity, the beginning of new diseases, and numerous infections. Infections are the first entity that affects those with vitamin D deficiency. The common infection is urinary tract infection (UTI), and its relationship with vitamin D deficiency or insufficiency remains controversial. This infection affects both men and women, but comparatively, women are more prone to this infection because of the short length of the urethra, which makes an easy entry for the bacteria. The low level of serum vitamin D increases the risk of UTIs in children. Recurrent UTIs are one of the major weaknesses in women; if left untreated, they progress to appallingly serious conditions like kidney dysfunction, liver damage, etc. Hence improving the vitamin D status may help to improve the immune system, thus making it more resistant to infections. In this review, we have focused on examining whether vitamin D deficiency and insufficiency are the causes of UTIs and the association between them in women and children. We have also described the connection between vitamin D deficiency and insufficiency with UTIs and additional nanotechnology- based treatment strategies.

Role of Bone Metastases in Lung Neuroendocrine Neoplasms: Clinical Presentation, Treatment and Impact on Prognosis

Lung neuroendocrine neoplasms (L-NEN) are heterogeneous tumors. While bone metastases (BM) have been associated with worse prognosis in other NEN, their role in L-NEN deserves in-depth analysis. This study analyzes the clinical presentation, treatment and survival outcomes of L-NEN, focusing on patients with BM compared with patients without metastases or with metastases in other sites (OtherMtx). The clinicopathological and survival data of L-NEN admitted to the Federico II University were retrospectively evaluated. Fifty L-NEN were included. Among 27 metastatic patients (54%), 13 (26%) had BM, more commonly occurring in males than females and in primary bilateral L-NEN or L-NEN > 26 mm, with higher Ki67. Atypical carcinoid and hypovitaminosis D were associated with BM. The number of metastatic sites was higher in patients with BM than OtherMtx. Synchronous metastases were associated with shorter overall survival (OS). The median progression-free survival (PFS) and OS in patients with BM were similar to OtherMtx, but a two-times increased risk of shorter OS was detected. BM do not impact PFS or OS more than OtherMtx, but the increased risk of shorter OS in patients with BM should be considered. Periodic bone evaluation in L-NEN should be recommended.

Survival Outcomes in Malignancy-related Hypercalcemia: A Tertiary Care Single-center Experience

Introduction

Malignancy-related hypercalcemia is commonly observed in patients with advanced stages of cancer. It is intricately linked with an unfavorable prognosis among oncology patients. This study aimed to evaluate survival outcomes among individuals diagnosed with hypercalcemia associated with malignancy.

Materials and Methods

This retrospective analysis of 173 cancer patients with hypercalcemia who sought treatment at Shaukat Khanum Memorial Cancer Hospital and Research Centre, Lahore, Pakistan, between July 2019 and June 2020. This cohort of patients underwent a longitudinal follow-up for 2.5 years. To assess survival outcomes, the Kaplan-Meier tool was used to construct survival curves and estimate the survival probability over time. The significance of potential survival factors was evaluated using the log-rank test.

Results

All patients exhibited elevated levels of calcium. At admission, the cohort demonstrated varying degrees of hypercalcemia severity attributable to malignancy: Mild hypercalcemia was observed in approximately 61.3% of patients, moderate hypercalcemia in 23.7%, and severe hypercalcemia in 15% of cases. Among the total sample, most patients were female (54.9%), with a median age of 54. The primary tumor site most frequently observed was in cases of breast cancer (35.3%), wherein the prevalent histological subtype was lobular/ductal invasive carcinoma (34.1%). Most of the patients (93.6%) had an Eastern Cooperative Oncology Group (ECOG) performance status (ECOG) >1. In addition, the median overall survival for patients diagnosed with hypercalcemia was 51 days. Notably, there was a significant association between survival factors, including the primary site of malignancy (P = 0.001), bone metastasis (P = 0.04), severity and symptoms of hypercalcemia (P = 0.001), altered mental state (P = 0.001), albumin levels (P = 0.001), and ECOG (P = 0.001).

Conclusion

Malignancy-related hypercalcemia in patients with cancer is a significant predictor of an unfavorable prognosis. The aforementioned survival factors may have the potential to influence patient survival outcomes. Further studies on larger cohorts are warranted.

The Application of 68Ga-Somatostatin Analog and 18F-FDG PET/CT for Bone Metastasis from Neuroendocrine Tumors

INTRODUCTION

Aims of the study were to assess the differences in the diagnostic efficacy of 68Ga-somatostatin receptor analogs (68Ga-SSAs) and 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) for detecting bone metastases in neuroendocrine neoplasm (NEN) and to analyze the correlation between imaging features and clinical features of BMs.

METHODS

We retrospectively analyzed the clinical and imaging data of 213 NEN patients who underwent 68Ga-SSA PET/CT and were finally diagnosed as BMs by pathology or follow-up. Of those, 103 patients underwent 18F-FDG PET/CT within 7 days after 68Ga-SSA PET/CT.

RESULT

The BM detection rate of 68Ga-SSA PET/CT was higher than 18F-FDG PET/CT (86.4% vs. 66.0%, p = 0.02) in 103 patients with dual scanning. Meanwhile, the number of positive lesions in 68Ga-SSA PET/CT was significantly more than in 18F-FDG PET/CT (3.37 ± 1.95 vs. 2.23 ± 2.16, t = 4.137, p < 0.001). Most bone metastasis lesions presented as osteogenic change in CT (55.4%, 118/213). Concerning the primary tumor, the most frequent were of pancreatic origin (26.3%, 56/213), followed by rectal origin (22.5%, 48/213), thymic origin in 33 cases (15.5%), pulmonary origin in 29 cases (13.6%), paraganglioma in 20 cases (9.4%). The efficiency of 68Ga-SSA PET/CT to detect BMs was significantly correlated with the primary site (p = 0.02), with thymic carcinoid BMs being the most difficult to detect, and the positive rate was only 60.6% (20/33). However, 18F-FDG PET/CT positive rate was 76.92% (10/13) in thymic carcinoid BMs. In addition, the BMs of 7 patients in this study were detected by 68Ga-SSA PET earlier than CT for 4.57 months (range: 2-10 months).

CONCLUSION

68Ga-SSA PET/CT has higher sensitivity for detecting the BMs of NEN than 18F-FDG and detects the BM earlier than CT. Moreover, 18F-FDG PET/CT should be a complement for diagnosing the BMs of thymic carcinoids.

[Comparative analysis of bone complications/manifestations in sporadic and MEN1-related primary hyperparathyroidism]

BACKGROUND

Multiple endocrine neoplasia type 1 (MEN1) - is a rare syndrome with an autosomal dominant inheritance pattern caused by a mutation in the tumor suppressor gene (MEN1). Parathyroid involvement is the most common MEN1 manifestation resulting in primary hyperparathyroidism (mPHPT). Data on the prevalence and structure of bone disease in mPHPT compared to sporadic one (sPHPT) are often incomplete and contradictory.

AIM

The purpose of this study was to compare the severity of bone involvement between mPHPT and sPHPT.

MATERIALS AND METHODS

A single-center retrospective study was conducted among young patients in the active phase of PHPT and without prior parathyroidectomy in anamnesis. The analysis included the main parameters of calcium-phosphorus metabolism, bone remodeling markers, as well as an assessment of disease complications. Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry (DXA) at sites of lumbar spine, femur and radius. Trabecular bone score (TBS) was applied to estimate trabecular microarchitecture. All patients included in the study underwent genetic testing.

RESULTS

Group 1 (mPHPT) included 26 patients, and group 2 (sSHPT) included 30 age-matched patients: the median age in group 1 was 34.5 years [25; 39], in group 2 - 30.5 years [28; 36], (p=0.439, U-test). Within group 1, the subgroup 1A (n=21) was formed with patients without other hormone-produced neuroendocrine neoplasms (NEN) in the gastrointestinal tract (GI) and the anterior pituitary gland. The duration of PHPT was comparable in both groups: mPHPT - 1 year [0; 3] versus sPHPT - 1 year [0; 1], (p=0.533, U-test). There were no differences in the main parameters of calcium-phosphorus metabolism, as well as in the prevalence of kidney complications. In the mPHPT group, bone abnormalities were observed significantly more often compared to sPHPT: 54 vs 10% (p=<0.001; F-test). Statistically significant differences were revealed both in BMD and in Z-score values of the femoral neck and total hip, which were lower in the mPHPT group. These differences remained significant when comparing subgroup 1A with sPHPT.

CONCLUSION

MEN1-associated PHPT may be accompanied by a more severe decrease in BMD in the femoral neck and total hip compared to sPHPT regardless of the other hormone-producing NEN. Clarifying the role of mutation in the MEN1 gene in these processes requires further study.

Current understanding of pathogenetic mechanisms in neuroendocrine neoplasms

INTRODUCTION

Despite the fact that important advances in research on neuroendocrine neoplasms (NENs) have been made, consistent data about their pathogenetic mechanism are still lacking. Furthermore, different primary sites may recognize different pathogenetic mechanisms.

AREAS COVERED

This review analyzes the possible biological and molecular mechanisms that may lead to NEN onset and progression in different organs. Through extensive research of the literature, risk factors including hypercholesterolemia, inflammatory bowel disease, chronic atrophic gastritis are evaluated as potential pathogenetic mechanisms. Consistent evidence is available regarding sporadic gastric NENs and MEN1 related duodenopancreatic NENs precursor lesions, and genetic-epigenetic mutations may play a pivotal role in tumor development and bone metastases onset. In lung neuroendocrine tumors (NETs), diffuse proliferation of neuroendocrine cells on the bronchial wall (DIPNECH) has been proposed as a premalignant lesion, while in lung neuroendocrine carcinoma nicotine and smoke could be responsible for carcinogenic processes. Also, rare primary NENs such as thymic (T-NENs) and Merkel cell carcinoma (MCC) have been analyzed, finding different possible pathogenetic mechanisms.

EXPERT OPINION

New technologies in genomics and epigenomics are bringing new light to the pathogenetic landscape of NENs, but further studies are needed to improve both prevention and treatment in these heterogeneous neoplasms.

Impact of Vitamin D Deficiency on Tumor Aggressiveness in Neuroendocrine Neoplasms

Background: The role of vitamin D (25(OH)D) in the pathogenesis and outcome of several conditions, including autoimmune diseases, diabetes and cancers is largely described in the literature. The aims of this study were to evaluate the prevalence of 25(OH)D deficit in a cohort of patients with neuroendocrine neoplasms (NENs) in comparison to a matched healthy control group and to analyze the possible role of 25(OH)D as a prognostic factor for NENs in terms of biological aggressiveness, tumor progression and survival. Methods: From 2009 to 2023, 172 patients with NENs (99 females; median age, 63 years) were included in the study. Serum 25(OH)D levels were defined as deficient if ≤20 ng/mL. The possible associations between 25(OH)D levels and disease grading, staging, ki67%, overall survival (OS), and progression-free survival (PFS) were considered. Results: NEN patients had significantly lower 25(OH)D levels compared to controls (p < 0.001) regardless of the primary origin. Patients with 25(OH)D < 20 ng/mL had a significantly higher ki67 index (p = 0.02) compared to the ones with 25(OH)D levels above 20 ng/mL. Patients with disease progression were found to have a significantly lower 25(OH)D at baseline (p = 0.02), whereas PFS and OS were not significantly influenced by 25(OH)D. Conclusions: Vitamin D deficiency is highly prevalent among NENs and is associated with higher ki67 and disease progression. Our study highlights the importance of monitoring 25(OH)D levels in patients with NENs, as its deficiency appeared to be linked to the worst biological tumor aggressiveness.

Selected Parameters of Bone Turnover in Neuroendocrine Tumors-A Potential Clinical Use?

BACKGROUND

Currently, there are no effective markers to diagnose and monitor patients with neuroendocrine tumors (NETs). The aim of this study was to assess bone metabolism based on selected markers of bone turnover: OST, OPG, and IGFBP-3, in both the group of patients with NETs and the control group. Associations with selected sociodemographic, biochemical, and clinicopathological characteristics were examined. We also evaluated any potential associations between these markers and selected biochemical markers of NETs commonly used in clinical practice.

METHODS

The study group included 60 patients with GEP-NETs and BP-NETs, while the control group comprised 62 healthy individuals. The serum concentrations of OST, OPG and IGFBP-3 were assessed using ELISA.

RESULTS

OST and OPG levels were significantly higher in the study group compared to the control group. In the study group, we observed a significant correlation between OPG and the clinical stage and chromogranin A. Additionally, an association was found between OPG and histological grade, Ki-67, and metastasis in GEP-NET cases.

CONCLUSIONS

Markers of bone turnover cannot be used in the routine diagnostics of neuroendocrine tumors. Nonetheless, these markers may help evaluate the skeletal system in patients with NETs. Further research is needed to determine the utility of osteocalcin (OST) and osteoprotegerin (OPG) as potential biomarkers for neuroendocrine tumors.

Vitamin D and Bone Metabolism in Adult Patients with Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1) is a genetic multisystemic autosomal dominant disorder determining reduced life expectancy due to higher risk of developing benign and malignant tumors. Low levels of vitamin D and reduced bone mineral density (BMD) have been reported in young patients with NF1. However, correlation between vitamin D and NF1 phenotype needs to be elucidated. Aim of this study was to assess vitamin D levels and bone metabolism in NF1 patients, analyzing potential correlations with clinical phenotype. A cross-sectional study was carried out in a monocentric series of NF1 patients, evaluating genotype, clinical phenotype, BMD, biochemical evaluation with focus on serum 25OH-vitamin D, parathyroid hormone (PTH), calcium and phosphate levels. Correlations between clinical manifestations, neurofibromas, and vitamin D status have been studied in comparison with healthy controls. 31 NF1 adult patients were matched for sex, age and body mass index with 31 healthy controls. A significantly difference in vitamin D level emerged in NF1 patients compared to controls. Interestingly low vitamin D levels correlated with a more aggressive phenotype and with a bigger size of neurofibromas. These data underline that vitamin D deficiency/insufficiency may play a role in clinical severity of neurofibromas in patients with NF1, suggesting the need to check bone status and replace vitamin D in these patients.

Bone Loss in Patients with Pancreatic Neuroendocrine Tumors

Background: Pancreatic diseases may affect nutritional status, which is one of the important associated factors of bone health. High prevalence of osteoporosis or osteopenia has been reported in patients with pancreatitis. The bone loss in pancreatic neuroendocrine tumors (PNETs) has not been reported. In this study, we showed the prevalence of bone loss and possible associated factors in PNET patients. Methods: A total of 91 PNET patients were included. Bone status was evaluated based on computed tomography (CT) attenuation (Housfield units, HU): >160 HU, normal bone mineral density; osteopenia, 135 HU ≤ CT value ≤ 160 HU; osteoporosis, <135 HU. Associated factors for bone loss were identified by logistic regression analyses. Results: The average age was 55.76 years old in PNET patients. The prevalence of osteoporosis and low bone mass was 37.4% and 60.4%, respectively. Higher prevalence of osteoporosis was observed in patients older than 50 years (64.0%). Multivariate logistic analysis showed that age was an associated factor for low bone mass (odds ratio (OR) = 1.13, 95% confidence interval (CI): 1.04−1.22) and osteoporosis (OR = 1.14, 95% CI: 1.03−1.20). Diabetes was also associated with bone loss in PNET patients after adjusting with confounders (OR = 13.56, 95% CI: 1.02−132.4). Conclusions: Our data show that bone loss is common in patients with PNETs. Age and diabetes are associated with bone loss in PNET patients.

Vitamin D deficiency and tumor aggressiveness in gastroenteropancreatic neuroendocrine tumors

PURPOSE

Data regarding vitamin D status in patients affected by gastroenteropancreatic (GEP) neuroendocrine tumor (NET) are limited and often showing contrasting results. The aim of the study was to evaluate the incidence of vitamin D deficiency (<20 ng/mL) in GEP-NET patients and compare the 25-hydroxyvitamin D (25(OH)D) levels with clinicopathological parameters and clinical outcome.

METHODS

A retrospective cross-sectional study including 75 low grade (G1-G2) GEP-NETs and 123 healthy controls matched for age, sex, and body mass index, was performed.

RESULTS

GEP-NET patients had significantly lower 25(OH)D levels compared to controls (17.9 ± 7.8 vs 24.2 ± 7.7 ng/mL, p < 0.0001). Ileal NETs were associated to lower 25(OH)D levels compared to other primary tumor sites (p = 0.049) and small bowel resection posed a significant increased risk of severe vitamin D deficiency (OR = 2.81, 95% CI = 1.25-3.37, p = 0.018). No correlation with somatostatin analogs treatment was found. 25(OH)D levels were significantly lower in G2 compared to G1 GEP-NETs (15.6 ± 7.8 vs 19.9 ± 7.4 ng/mL, p = 0.016) and in patients with progressive disease (12.6 ± 5.7 ng/mL) compared to those with stable disease (mean 21.5 ± 8.2 ng/mL, p = 0.001) or tumor free after surgery (19.6 ± 7.3 ng/mL, p = 0.002). Patients with vitamin D deficiency and insufficiency had shorter progression-free survival compared to those with sufficiency (p = 0.014), whereas no correlation was found with disease-specific survival.

CONCLUSIONS

Vitamin D deficiency is highly prevalent among GEP-NETs and could be associated with high tumor grade and disease progression. Therefore, the monitoring of 25(OH)D levels is relevant in these patients and vitamin D supplementation should be considered in the management of GEP-NET patients with vitamin D deficiency or insufficiency.

Novel serological biomarker models composed of bone turnover markers, vitamin D, and estradiol and their auxiliary diagnostic value in girls with idiopathic central precocious puberty

OBJECTIVE

To establish serological biomarker models composed of bone turnover markers (BTMs), vitamin D (Vit D), and estradiol (E2) and to explore their auxiliary diagnostic value in girls with idiopathic central precocious puberty (ICPP).

METHODS

Ninety-three girls with ICPP and 93 healthy girls were included in the ICPP group and the control group, respectively. The serum levels of total procollagen type 1 N-terminal propeptide (P1NP), N-terminal midfragment of osteocalcin (N-MID), β-C-terminal telopeptide of type 1 collagen (β-CTX), Vit D, E2, and other biochemical parameters were detected in all participants. Serological biomarker models for assistance with ICPP diagnosis were established by logistic regression analyses.

RESULTS

Serum P1NP, β-CTX, Vit D, and E2 levels differed significantly between the two groups (p < 0.05). Three models were established. Model 1 consisted of P1NP and β-CTX, and had an area under curve (AUC) of 0.764, sensitivity of 74.19%, and specificity of 72.04%. Model 2 consisted of P1NP, β-CTX, and Vit D, and had an AUC of 0.840, sensitivity of 83.87%, and specificity of 72.04%. Model 3 consisted of P1NP, β-CTX, Vit D, and E2, and had an AUC of 0.917, sensitivity of 82.80%, and specificity of 86.02%.

CONCLUSIONS

Serum P1NP, β-CTX, Vit D, and E2 levels may be effective indicators for auxiliary diagnosis of ICPP. Serological biomarker models composed of P1NP, β-CTX, Vit D, and E2 (models 1, 2, and 3) may have auxiliary diagnostic value for ICPP.

Neuroendocrine neoplasia and bone (Review)

This is a narrative review focusing on neuroendocrine neoplasia (NEN) and bone status, in terms of metastases and osteoporosis/fractures. One fifth of NEN have skeletal dissemination, this affinity being regulated by intrinsic tumor factors such as the C-X-C chemokine receptor 4 (CXCR4). Bone colonization impairs the patient quality of life, representing a surrogate of reduced survival. Patients with NEN without bone metastases may exhibit low bone mineral density, perhaps carcinoid-related osteoporosis, yet not a standardized cause of osteoporosis. Case-finding strategies to address bone health in NEN with a good prognosis are lacking. Contributors to fractures in NEN subjects may include: menopausal status and advanced age, different drugs, induced hypogonadism, malnutrition, malabsorption (due to intestinal resection, carcinoid syndrome), hypovitaminosis D, impaired glucose profile (due to excessive hormones such as glucagon, somatostatinoma or use of somatostatin analogues), various corticoid regimes, and high risk of fall due to sarcopenia. Pheocromocytoma/paraganglioma involve bone through malignant forms (bone is an elective site) and potential secondary osteoporosis due to excessive hormonal content and increased sympathetic activity which is a key player of bone microarchitecture/quality as reflected by low Trabecular Bone Score. Glucocorticoid osteoporosis is related to NEN-associated ectopic Cushing syndrome. Currently, there are a lack of studies to emphasis that excessive gut-derivate serotonin in NENs with carcinoid syndrome is a specific activator of bone loss thus a contributor to carcinoid-related osteoporosis.

Cinnamtannin B-1 Prevents Ovariectomy-Induced Osteoporosis via Attenuating Osteoclastogenesis and ROS Generation

Osteoporosis (OP) is one of the common bone metabolic diseases that endangers postmenopausal women and the elders. Both excessive bone resorption caused by osteoclast over-activation and increased oxidative stress are associated with osteoporosis. Cinnamtannin B-1 (CB-1) is considered as a high-valued plant extract monomer due to its antioxidant properties. However, the mechanism of CB-1 impacts on reducing oxidative stress, inhibiting the production of reactive oxygen species (ROS) and osteoclast differentiation and preventing ovariectomy-induced osteoporosis are still unclear. In this study, the effects of CB-1 on nuclear factor κB (RANKL)-induced osteoclasts formation and differentiation in vitro and the potential therapeutic effect on ovariectomy (OVX)-induced osteoporosis in vivo are investigated. CB-1 was found to inhibit osteoclast formation and bone resorption function in a dose-dependent manner, and it inhibited specific genes related to osteoclast as well. Micro-CT and histopathological staining showed that CB-1 can effectively prevent OVX-induced osteoporosis. In addition, CB-1 treatment can effectively inhibit the production of reactive oxygen species (ROS) in vivo and in vitro. Mechanistically, CB-1 inhibits the activation of osteoclasts by inhibiting the activation of the NF-κB signaling pathway. In conclusion, CB-1 would be able to be used as a promising new drug strategy to inhibit RANKL-induced osteoclastogenesis and prevent ovariectomy-induced osteoporosis.