Investigating a Causal Relationship Between Diabetes Mellitus and Oropharyngeal Cancer: A Mendelian Randomization Study

OBJECTIVE

Previous observational studies reported an association of diabetes mellitus (DM) with oropharyngeal cancer (OPC), however, the potential causality of the association between them remains unclear.

METHODS

To explore this causal relationship in individuals of European descent, a two-sample Mendelian randomization (MR) study was conducted. A genome-wide association study (GWAS) of DM was used to represent the exposure factor (T1DM: n = 24,840; T2DM: n = 215,654), and GWAS of OPC represented the outcome (n = 3,448).

RESULTS

Forty-one single nucleotide polymorphisms (SNPs) related to T1DM and fifty-four SNPs related to T2DM were identified as effective instrumental variables (IVs) in the two-sample MR analyses. In IVW estimates, neither T1DM nor T2DM significantly contributed to an increased risk of OPC [T1DM: OR 1.0322 (95% CI 0.9718, 1.0963), P = 0.3033; T2DM: OR 0.9998 (95% CI 0.9995, 1.0002), P = 0.2858]. Four other regression models produced similar results. MR-Egger regression results [Cochran's Q statistic was 47.1544 (P = 0.1466) in T1DM, and 35.5084 (P = 0.9512) in T2DM] suggested no horizontal pleiotropy between IVs and outcomes.

CONCLUSION

Our findings suggest little evidence to support the genetic role of diabetes mellitus in OPC development in the European population.

Quantitatively biomechanical response analysis of posterior musculature reconstruction in cervical single-door laminoplasty

BACKGROUND AND OBJECTIVE

The current trend of laminoplasty is developing toward the goal of muscle preservation and minimum tissue damage. Given this, muscle-preserving techniques in cervical single-door laminoplasty have been modified with protecting the spinous processes at the sites of C2 and/or C7 muscle attachment and reconstruct the posterior musculature in recent years. To date, no study has reported the effect of preserving the posterior musculature during the reconstruction. The purpose of this study is to quantitatively evaluate the biomechanical effect of multiple modified single-door laminoplasty procedures for restoring stability and reducing response level on the cervical spine.

METHODS

Different cervical laminoplasty models were established for evaluating kinematics and response simulations based on a detailed finite element (FE) head-neck active model (HNAM), including ① C3 - C7 laminoplasty (LP_C37), ② C3 - C6 laminoplasty with C7 spinous process preservation (LP_C36), ③ C3 laminectomy hybrid decompression with C4 - C6 laminoplasty (LT_C3 + LP_C46) and ④ C3 - C7 laminoplasty with unilateral musculature preservation (LP_C37 + UMP). The laminoplasty model was validated by the global range of motion (ROM) and percentage changes relative to the intact state. The C2 - T1 ROM, axial muscle tensile force, and stress/strain levels of functional spinal units were compared among the different laminoplasty groups. The obtained effects were further analysed by comparison with a review of clinical data on cervical laminoplasty scenarios.

RESULTS

Analysis of the locations of concentration of muscle load showed that the C2 muscle attachment sustained more tensile loading than the C7 muscle attachment, primarily in flexion-extension (FE) and in lateral bending (LB) and axial rotation (AR), respectively. Simulated results further quantified that LP_C36 primarily produced 10% decreases in LB and AR modes relative to LP_C37. Compared with LP_C36, LT_C3 + LP_C46 resulted in approximately 30% decreases in FE motion; LP C37 + UMP also showed a similar trend. Additionally, when compared to LP_C37, LT_C3 + LP_C46 and LP C37 + UMP reduced the peak stress level at the intervertebral disc by at most 2-fold as well as the peak strain level of the facet joint capsule by 2-3-fold. All these findings were well correlated with the result of clinical studies comparing modified laminoplasty and classic laminoplasty.

CONCLUSIONS

Modified muscle-preserving laminoplasty is superior to classic laminoplasty due to the biomechanical effect of the posterior musculature reconstruction, with a retained postoperative ROM and loading response levels of the functional spinal units. More motion-sparing is beneficial for increasing cervical stability, which probably accelerates the recovery of postoperative neck movement and reduces the risk of the complication for eventual kyphosis and axial pain. Surgeons are encouraged to make every effort to preserve the attachment of the C2 whenever feasible in laminoplasty.

High-fidelity ATP imaging via an isothermal cascade catalytic amplifier

Artificial catalytic DNA circuits that can identify, transduce and amplify the biomolecule of interest have supplemented a powerful toolkit for visualizing various biomolecules in cancer cells. However, the non-specific response in normal tissues and the low abundance of analytes hamper their extensive biosensing and biomedicine applications. Herein, by combining tumor-responsive MnO2 nanoparticles with a specific stimuli-activated cascade DNA amplifier, we propose a multiply guaranteed and amplified ATP-sensing platform via the successive cancer-selective probe exposure and stimulation procedures. Initially, the GSH-degradable MnO2 nanocarrier, acting as a tumor-activating module, ensures the accurate delivery of the cascade DNA amplifier into GSH-rich cancer cells and simultaneously provides adequate Mn2+ cofactors for facilitating the DNAzyme biocatalysis. Then, the released cascade amplifier, acting as an ATP-monitoring module, fulfills the precise and sensitive analysis of low-abundance ATP in cancer cells where the catalyzed hairpin assembly (CHA) is integrated with the DNAzyme biocatalyst for higher signal gain. Additionally, the cascade catalytic amplifier achieved tumor-specific activated photodynamic therapy (PDT) after integrating an activatable photosensitizer into the system. This homogeneous cascade catalytic aptasensing circuit can detect low-abundance endogenous ATP of cancer cells, due to its intrinsically rich recognition repertoire and avalanche-mimicking hierarchical acceleration, thus demonstrating broad prospects for analyzing clinically important biomolecules and the associated physiological processes.

P11.26.A STAT3 expression in brain metastases from breast cancer: correlations with different molecular subtypes and clinical outcome

Background

STAT3 expression in peritumoral reactive astrocytes (RA) of brain metastases (BM) may favor a pro-metastatic environment. The aim of the study was to evaluate in a retrospective cohort of surgically resected BM from breast cancer (BC) the expression of pSTAT3 in RA of peritumoral tissue of BM, identify different patterns of expression according to molecular subtypes, and correlate with intracranial progression-free survival (i-PFS).

Material and Methods

Patients with histologically proven BM diagnosis from BC were identified from the biobank of Pathology Unit of University of Turin and Spanish national BrM network (RENACER). pSTAT3 expression was evaluated and scored in RA of peritumoral tissue using GFAP and STAT3 immunohistochemistry, according to Priego et al. (Nat Med 2018). Data on histological diagnosis, molecular subtypes, and i-PFS were retrieved by chart review. Intracranial progression was defined based on MRI reports.

Results

Eighty-five BM specimens from BC of 85 female patients with a median age of 54 years (range 30-81 years) were available for analysis. Immunohistochemistry for GFAP and pSTAT3 was feasible in 68/85 (80%). Fifteen out of 68 patients (21.1%) had BM from luminal BC, 27/68 (39.7%) from HER2-positive BC, and 26/68 (39.2%) from TNBC. Fifty-six out of 68 (82.4%) showed positive staining of pSTAT3 in peritumoral RA, of which 9/68 (13.3%) scored with 3, 26/68 (38.2%) with 2, and 21/68 (30.9%%) with 1, while pSTAT3 expression was negative (score 0) in 12/68 (17.6%). High pSTAT3 expression (score 2-3) was observed in 17/27 (62.9%) BM from HER2-positive BC and in 15/26 (57.7%) BM from TNBC, while most of BM from luminal BC (12/15 - 80%) had low or absent pSTAT3 (score 0-1) (p=0.021). Overall i-PFS was 16 months (range 7-41): low pSTAT3 BM (score 0-1) had a median i-PFS of 21 months versus 12 months for high pSTAT3 BM (score 2-3). A shorter median i-PFS was observed in high pSTAT3 BM from TNBC (4 months) as compared with low pSTAT3 BM (11 months). Conversely, i-PFS of high pSTAT3 BM (7 months) was similar to low pSTAT3 BM (6 months) in HER2-positive BC.

Conclusion

pSTAT3 expression in RA of peritumoral tissue of BM from TNBC and HER2-positive BC is higher than in BM from luminal BC. Of note, patients with high pSTAT3 BM from TNBC progressed earlier in comparison with those with low pSTAT3, suggesting that pSTAT3 expression has an influence on the outcome.

OS02.6.A Lacosamide in monotherapy in brain tumour-related epilepsy (BTRE): results from an Italian multicentre retrospective study

Background

Lacosamide (LCM) is a third-generation anti-seizure medication (ASM) approved for focal onset epilepsy in patients aged ≥4 years. Previous studies have reported an efficacy of LCM as add-on treatment in brain tumour-related epilepsy (BTRE). To date, there are no studies in the literature focusing on lacosamide used in monotherapy to treat BTRE. In our retrospective study we investigated efficacy and tolerability of LCM in monotherapy in a multicentre national cohort of primary brain tumour patients.

Patients and Methods

Adult patients who were treated with LCM in monotherapy were collected from 12 Italian Centres (either mainly involved in neuro-oncology or in epileptology). Main inclusion criteria were diagnosis of primary brain tumour; at least two focal-onset seizures in the disease course; LCM used either as primary or secondary monotherapy after withdrawal of previous ASMs. For each patient, we evaluated seizure freedom at 3 and 6 months (primary endpoints), side effects and drop-out rate (secondary endpoints).

Results

We collected 132 patients. The majority of patients had a diagnosis of diffuse gliomas, being those with lower-grade glioma 66 (50.0%) and those with glioblastoma 33 (25.0%). Overall, LCM led to seizure-freedom in 64.4% of patients at 3 months and 55% at 6 months. Patients who used two or more ASMs before LCM had a worse seizure control than patients in monotherapy with LCM as first choice.In 14 patients, we observed seizure control despite tumour progression on magnetic resonance (MRI). Multivariate analysis showed that gross-total resection at diagnosis and use of steroids were significantly associated with higher seizure freedom rate at 6 months. Side effects were mainly mild (grade 1-2 according to the CTCAE classification), and the drop-out rate was low (1.5%). The main side effects were dizziness and somnolence.

Conclusion

This is the first study on the role of LCM in monotherapy in BTRE. The study has shown a good efficacy and tolerability of LCM with more than a half of patients becoming seizure-free at 6 months and with a very low rate of drop-out. Further studies are needed to confirm these preliminary data in a prospective manner, adding quality of life and neurocognitive functions as endpoints.

Prognostic implication of the neoadjuvant rectal score and other biomarkers of clinical outcome in Hong Kong Chinese patients with locally advanced rectal cancer undergoing neoadjuvant chemoradiotherapy

BACKGROUND

Neoadjuvant chemoradiotherapy is a standard treatment for locally advanced rectal cancer, for which pathological complete response is typically used as a surrogate survival endpoint. Neoadjuvant rectal score is a new biomarker that has been shown to correlate with survival. The main objectives of this study were to investigate factors contributing to pathological complete response, to validate the prognostic significance of neoadjuvant rectal score, and to investigate factors associated with a lower neoadjuvant rectal score in a cohort of Hong Kong Chinese.

METHODS

Data of patients with locally advanced rectal cancer who received neoadjuvant chemoradiotherapy from August 2006 to October 2018 were retrieved from hospital records and retrospectively analysed.

RESULTS

Of 193 patients who had optimal response to neoadjuvant chemoradiotherapy and surgery, tumour down-staging was the only independent prognostic factor that predicted pathological complete response (P<0.0001). Neoadjuvant rectal score was associated with overall survival (hazard ratio [HR]=1.042, 95% confidence interval [CI]=1.021-1.064; P<0.0001), disease-free survival (HR=1.042, 95% CI=1.022-1.062; P<0.0001), locoregional recurrence-free survival (HR=1.070, 95% CI=1.039-1.102; P<0.0001) and distant recurrence-free survival (HR=1.034, 95% CI=1.012-1.056; P=0.002). Patients who had pathological complete response were associated with a lower neoadjuvant rectal score (P<0.0001), but pathological complete response was not associated with survival. For patients with intermediate neoadjuvant rectal scores, late recurrences beyond 72 months from diagnosis were observed.

CONCLUSION

Neoadjuvant rectal score is an independent prognostic marker of survival and disease recurrence in a cohort of Hong Kong Chinese patients who received neoadjuvant chemoradiotherapy for locally advanced rectal cancer.

A dynamic DNA nanosponge for triggered amplification of gene-photodynamic modulation

Nucleic acid therapeutics has reached clinical utility through modulating gene expression. As a potential oligonucleotide drug, DNAzyme has RNA-cleaving activity for gene silencing, but faces challenges due to the lack of a safe and effective delivery vehicle and low in vivo catalytic activity. Here we describe DNAzyme-mediated gene regulation using dynamic DNA nanomaterials with intrinsic biocompatibility, stability, tumor-targeted delivery and uptake, and self-enhanced efficacy. We assemble programmable DNA nanosponges to package and deliver diverse nucleic acid drugs and therapeutic agents such as aptamer, DNAzyme and its cofactor precursor, and photosensitizer in one pot through the rolling circle amplification reaction, formulating a controllable nanomedicine using encoded instructions. Upon environmental stimuli, DNAzyme activity increases and RNA cleavage accelerates by a supplementary catalytic cofactor. In addition, this approach induces elevated O₂ and ¹O₂ generation as auxiliary treatment, achieving simultaneously self-enhanced gene-photodynamic cancer therapy. These findings may advance the clinical trial of oligonucleotide drugs as tools for gene modulation.

Oligonucleotide drug delivery approach is provided with a biomimetic, dynamic DNA nanomaterial, which enables disease gene regulation and auxiliary therapy in a controllable and self-boosting manner.

Portable and sensitive detection of non-glucose target by enzyme-encapsulated metal-organic-framework using personal glucose meter

Personal glucose meter (PGM) is one of the most commercially available POC (point-of-care) devices for monitoring the level of glucose reliably, yet its non-glucose quantification ability is limited since such strategy needs ingenious interface design and tedious enzyme conjugation. Herein, we constructed a portable and sensitive platform that can detect non-glucose target by combining enzyme-encapsulated zeolitic imidazole framework-90 (ZIF-90) with personal glucose meter. ZIF-90 is an ideal carrier and susceptor due to the extraordinary capability of packaging enzyme and stimuli-responsiveness. We selected adenosine-5'-triphosphate (ATP) as the target model of non-glucose analytes. Upon ATP-induced decomposition of MOF, the released enzyme (glucose oxidase or invertase) catalyzed substrate and gave rise to the change of the glucose concentration for PGM assay. This method determined ATP with a remarkably sensitivity of 233 nM and effective recovery in real serum samples. Our strategy provides a facile and practical approach for measuring the non-glucose target using PGM, and could potentially be applied in bimolecular detection in point-of-care diagnosis.

Visualization of Vaccine Dynamics with Quantum Dots for Immunotherapy

The direct visualization of vaccine fate is important to investigate its immunoactivation process to elucidate the detailed molecular reaction process at single-molecular level. Yet, visualization of the spatiotemporal trafficking of vaccines remains poorly explored. Here, we show that quantum dot (QD) nanomaterials allow for monitoring vaccine dynamics and for amplified immune response. Synthetic QDs enable efficient conjugation of antigen and adjuvants to target tissues and cells, and non-invasive imaging the trafficking dynamics to lymph nodes and cellular compartments. The nanoparticle vaccine elicits potent immune responses and anti-tumor efficacy alone or in combination with programmed cell death protein 1 blockade. The synthetic QDs showed high fluorescence quantum yield and superior photostability, and the reliable and long-term spatiotemporal tracking of vaccine dynamics was realized for the first time by using the synthetic QDs, providing a powerful strategy for studying immune response and evaluating vaccine efficacy.

P14.42 Neratinib for treatment of leptomeningeal metastases from HER2-positive breast cancer in extended access program: preliminary results

BACKGROUND

Leptomeningeal metastases (LM) occur in 5% of human epidermal growth factor receptor 2 (HER2) breast cancer (BC) with a poor overall survival (OS) of 3 months. Neratinib is an oral, irreversible tyrosine kinase pan-inhibitor that was approved by FDA for the treatment of HER2-enriched BC, who completed a prior adjuvant trastuzumab-based therapy. The aim of the study was to evaluate the activity of neratinib in LM from HER2-positive BC after the failure of multiple lines of treatment, including trastuzumab.

PATIENTS AND METHODS

Inclusion criteria were as follows: age ≥ 18 years; histological diagnosis of primary HER2-positive BC; newly-diagnosed LM according to LANO criteria; KPS ≥60 at the time of diagnosis of LM; coexistence of BM that have or not received WBRT or radiosurgery; systemic disease with a life expectancy of at least 3 months; concomitant drugs, including capecitabine, trastuzumab, TDM-1, pertuzumab, and hormone therapy were allowed, with the exclusion of lapatinib or other investigational agents. Neratinib was administered 240 mg daily continuously. The primary endpoint was the OS after the diagnosis of LM. Secondary endpoints were progression-free survival (PFS) following the diagnosis of LM, neurological benefit, radiological response rate, and tolerability.

RESULTS

From January 2018 to April 2021, 9 patients with LM have been enrolled. Median age at the time of diagnosis of LM was 44 years (95%CI 36–59) with a median KPS of 80 (95%CI 60–90). Median time since LM onset from the diagnosis of primary BC was 42 months (95%CI 11–166), and patients underwent a median number of adjuvant treatments before LM of 3 (95%CI 2–5). Three patients developed LM alone, and other 6 had LM associated with multiple brain metastases. Six-months and 1-year OS were 66.7% and 22.3%, respectively, with a median OS of 8 months (95%CI 3–13*). Median PFS was 3.5 months (95%CI 2–6) after the start of treatment. A neurological improvement was reported in 2/9 patients (22.2%), while in other 4/9 patients (44.5%) was achieved a neurological stabilization lasting for a median time of 5 months (95%CI 2–19). The best radiological response was a stable disease in 5/9 patients (55.6%), while no complete or partial response were achieved according to LANO and RANO criteria, respectively. A CSF clearance was observed in 1 patient only (11.1%) following two months of neratinib. Grade III-IV adverse events were not reported, and 2 patients only (22.2%) had mild diarrhea correlated with neratinib.

CONCLUSION

This is the first study that shows that neratinib might be a safe and effective treatment in LM from heavily pretreated HER2-positive BC.

Precision photothermal therapy and photoacoustic imaging by in situ activatable thermoplasmonics

Phototherapy holds great promise for disease treatment; however, traditional "always-on" photoagents have been restricted to clinical translation due to their nonspecific response and side effects on normal tissues. Here, we show a tumor microenvironment activated photothermal and photoacoustic agent as an activatable prodrug and probe that allows precise cancer diagnosis and treatment. Such an in situ revitalized therapeutic and contrast agent is achieved via controllable plasmonic heating for thermoplasmonic activation. This enables monitoring of signal molecule dynamics, real-time photothermal and photoacoustic imaging of tumors and lymph node metastasis, and targeted photothermal therapy without unwanted phototoxicity to normal tissues. Our study provides a practical solution to the non-specificity problem in phototherapy and offers precision cancer therapeutic and theranostic strategies. This work may advance the development of ultrasensitive disease diagnosis and precision medicine.

Quantum dot-pulsed dendritic cell vaccines plus macrophage polarization for amplified cancer immunotherapy

Dendritic cell (DC) vaccines hold great potential in cancer immunotherapy, but the suboptimal design of DC vaccines and the immunosuppressive tumor microenvironment largely impair their anti-tumor efficacy. Here, quantum dot (QD) pulsed-DC vaccines integrating with tumor-associated macrophage polarization are developed for amplified anti-tumor immunity. Semiconductor QDs are engineered with diverse functions to act as fluorescence nanoprobes, immunomodulatory adjuvants, and nanocarriers to load tumor antigens and Toll-like receptor 9 agonists. The QD-pulsed DC vaccines enable spatiotemporal tracking of lymphatic drainage and efficacy evaluation of DC immunotherapy, and trigger potent immunoactivation. Specifically, designer DC vaccine plus macrophage polarization elicits potent immune response to stimulate innate and adaptive antitumor immunity and ameliorate the immunosuppressive tumor microenvironment. As a new combination therapy, this strategy greatly boosts antigen-specific T-cell immunity and thus strongly inhibits local tumor growth and tumor metastasis in vivo. This study may provide an applicable treatment for cancer immunotherapy.

Biosynthesized Quantum Dot for Facile and Ultrasensitive Electrochemical and Electrochemiluminescence Immunoassay

Nanomaterials are commonly utilized for amplified immunoassay of biomarkers. However, traditional nanomaterial-based immunoassay usually requires a time-consuming and labor-intensive nanoparticle modification and conjugation process, which impedes their practical applications. Here, a new immunoassay method based on biosynthesized nanomaterials is developed with versatile functions for facile and ultrasensitive detection of cancer biomarker. In this method, the utilized biosynthesized quantum dots (BQDs) allow convenient antibody conjugation and electrode modification, and demonstrate excellent electrochemical and electrochemiluminescent responses. The differential pulse voltammetric, faradaic impedance spectroscopy, and electrochemiluminescent measurements with the BQD-modified electrode show detection limits at picomolar levels as well as good specificity toward human prostate-specific antigen detection. The inherent recognization capability as well as the inherent electrochemical and electrochemiluminescence features thus enable BQDs as good candidates for facile immunosensors with high sensitivity. Such a biosynthesized nanomaterial-based approach opens up the possibility of using innovative designs for nanoparticle-based assays, and developing reliable and practical methods for early disease diagnosis.

P04.09 Patterns of care and impact on survival of first salvage therapy in high-risk grade II gliomas following initial temozolomide

BACKGROUND

Initial chemotherapy with temozolomide (TMZ) may provide benefit in high-risk low-grade gliomas. To date, no standard treatment is validated at first progression. The aim of this retrospective study was to investigate the optimal salvage therapy after the first progression and the factors that influence the PFS and overall survival (OS).

MATERIAL AND METHODS

we evaluated 71 patients with an histological diagnosis of grade II glioma according to WHO 2016 classification, who were included in a phase II AINO (Italian Association for Neuro-Oncology) trial, and progressed following initial chemotherapy with TMZ. Molecular data were available in all patients: 32 (45.1%) patients were oligodendrogliomas IDH 1/2 mutated and 1p19q codeleted, 11 (15.5%) were diffuse astrocytomas IDH mutant, and 28 (39.4%) were diffuse astrocytomas IDH wild-type. Thirty-five (49.3%) patients were MGMT methylated. Median follow up was 144 months (range 23–180).

RESULTS

thirty-one patients (43.7%) underwent second surgery, 24 patients (33.8%) second-line chemotherapy (rechallenge with TMZ or nitrosoureas), and 16 patients (22.5%) radiotherapy with a median PFS of 58 months (IC 95% 49–116). The association between prognostic factors and type of salvage therapy revealed a prevalence of younger age (≤ 45 years), non-enhancing tumor and location in eloquent area among patients treated with second surgery or chemotherapy, while aolder age (> 45 years) and contrast-enhancing tumors prevailed among patients receiving radiotherapy. Overall, median PFS was 60 months after second surgery (IC95% 43–116) and chemotherapy (IC95% 51–69), and 38 months after radiotherapy (IC95% 15–64) (p 0.09). No significant benefit in length of PFS was achieved in oligodendrogliomas undergoing second surgery (60 months) as compared with oligodendrogliomas treated with radiation or chemotherapy (58 months, p 0.11). PFS of diffuse astrocytomas IDH wild-type following second surgery (53 months) did not differ from that of patients treated with adjuvant treatments (65 months, p 0.28). Overall, median OS from the first salvage therapy was 117 months (IC95% 93 - 123+): 120 months (IC95% 108–140+) after second surgery, 94 months (IC95% 75–117+) after chemotherapy, and 62 months (IC95% 27–112) after radiotherapy (p 0.04). Median OS (123 months, IC95% 106–154) was prolonged in oligodendrogliomas receiving second surgery as compared to those receiving radiotherapy or chemotherapy (93 months, IC 95% 61–112, p 0.07), while median OS in diffuse astrocytomas IDH wild-type did not differ between those who received second surgery or radiotherapy or chemotherapy.

CONCLUSION: W

hen feasible, reoperation as first salvage treatment following initial TMZ in grade II gliomas seems to offer a probability of a longer OS as compared with second-line chemotherapy or radiotherapy, and this could hold true especially for oligodendrogliomas.

Correction to: Rehmanniae Radix Preparata suppresses bone loss and increases bone strength through interfering with canonical Wnt/β-catenin signaling pathway in OVX rats

There was a mistake in the part of OVX rats model and RRP intervention in the original publication.

Rehmanniae Radix Preparata suppresses bone loss and increases bone strength through interfering with canonical Wnt/β-catenin signaling pathway in OVX rats

Rehmanniae Radix Preparata (RRP) improves bone quality in OVX rats through the regulation of bone homeostasis via increasing osteoblastogenesis and decreasing osteoclastogenesis, suggesting it has a potential for the development of new anti-osteoporotic drugs.

INTRODUCTION

Determine the anti-osteoporotic effect of RRP in ovariectomized (OVX) rats and identify the signaling pathway involved in this process.

METHODS

OVX rats were treated with RRP aqueous extract for 14 weeks. The serum levels of tartrate-resistant acid phosphatase (TRAP), receptor activator of nuclear factor kappa-Β ligand (RANKL), alkaline phosphatase (ALP), and osteoprotegerin (OPG) were determined by ELISA. Bone histopathological alterations were evaluated by H&E, Alizarin red S, and Safranin O staining. Bone mineral density (BMD) and bone microstructure in rat femurs and lumbar bones were determined by dual-energy X-ray absorptiometry and micro-computed tomography. Femoral bone strength was detected by a three-point bending assay. The expression of Phospho-glycogen synthase kinase 3 beta (p-GSK-3β), GSK-3β, Dickkopf-related protein 1 (DKK1), cathepsin K, OPG, RANKL, IGF-1, Runx2, β-catenin, and p-β-catenin was determined by western blot and/or immunohistochemical staining.

RESULTS

Treatment of OVX rats with RRP aqueous extract rebuilt bone homeostasis demonstrated by increasing the levels of OPG as well as decreasing the levels of TRAP, RANKL, and ALP in serum. Furthermore, RRP treatment preserved BMD and mechanical strength by increasing cortical bone thickness and epiphyseal thickness as well as improving trabecular distribution in the femurs of OVX rats. In addition, RRP downregulated the expression of DKK1, sclerostin, RANKL, cathepsin K, and the ratio of p-β-catenin to β-catenin, along with upregulating the expression of IGF-1, β-catenin, and Runx2 and the ratio of p-GSK-3β to GSK-3β in the tibias and femurs of OVX rats. Echinacoside, jionoside A1/A2, acetoside, isoacetoside, jionoside B1, and jionoside B2 were identified in the RRP aqueous extract.

CONCLUSION

RRP attenuates bone loss and improves bone quality in OVX rats partly through its regulation of the canonical Wnt/β-catenin signaling pathway, suggesting that RRP has the potential to provide a new source of anti-osteoporotic drugs.