SNHG14 facilitates cell proliferation in colorectal cancer through targeting KRAS via Hippo-YAP signaling.

Accumulating evidence indicates the significant role of lncRNAs in multiple biological processes and cancer progression. However, most lncRNAs in CRC remain to be excavated. In this study, we investigated SNHG14 in CRC. SNHG14 which was generally under-expressed in normal colon specimens revealed by UCSC was uncovered as markedly highly expressed in CRC cell lines. Besides, SNHG14 was a contributor to CRC cell proliferation. Additionally, we demonstrated that SNHG14 facilitated CRC cell proliferation in a KRAS-dependent manner. Moreover, the mechanistic investigations indicated that SNHG14 interacted with YAP and therefore inactivated the Hippo pathway, so as to enhance YAP-targeted KRAS expression in CRC. Furthermore, SNHG14 was explained as transcriptionally activated by FOS, a previously identified common effector molecule of KRAS and YAP. All in all, our findings elucidated a feedback loop of SNHG14/YAP/KRAS/FOS in facilitating CRC tumorigenesis, which may help develop novel effective targets for CRC patients.

Circ_0022340 promotes colorectal cancer progression via HNRNPC/EBF1/SYT7 or miR-382-5p/ELK1 axis.

Circular RNAs (circRNAs) are characterized as a class of new noncoding RNAs and function in tumorigenesis of colorectal cancer (CRC). In our study, the molecule mechanism of circ_0022340 in CRC was investigated. For this aim, quantitative real-time polymerase chain reaction (RT-qPCR) was used to test gene expression in CRC cells. Cell function assays including 5-ethynyl-20-deoxyuridine (EdU), colony formation and transwell investigated the proliferation and migration capacity in CRC cells. Luciferase reporter and RNA immunoprecipitation (RIP)assays determined the interaction between circRNA, miRNA and mRNA. Western blot was used to test protein expression. An immunohistochemistry assay was used to assess the tumor growth in vivo. Results showed that Circ_0022340 was highly expressed in CRC cells. Circ_0022340 was formed from exon 5 to 6 of the synaptotagmin 7 (SYT7). Silencing of circ_0022340 suppressed CRC cell proliferation and migration. Functionally, circ_0022340 recruited heterogeneous nuclear ribonucleoprotein C (HNRNPC) to stabilize EBF1 mRNA and thereby activated SYT7. Moreover, circ_0022340 targeted miR-382-5p to up-regulate ETS transcription factor ELK1 (ELK1). It is concluded that Circ_0022340 promoted colorectal cancer progression via recruiting HNRNPC to stabilize EBF1 mRNA and thereby activated SYT7 or miR-382-5p/ELK1 axis, which might provide a novel target for CRC treatment.

MYC-activated CERS6-AS1 sponges miR-6838-5p and regulates the expression of RUBCNL in colorectal cancer.

As a leading gastrointestinal malignancy, colorectal cancer (CRC) is a serious threat to people's health. A great amount of researches have elaborated that long non-coding RNAs (lncRNAs) play a key role in all kinds of tumors. In the current study, we mainly probed into the mechanisms of CERS6 antisense RNA 1 (CERS6-AS1) underlying CRC. For this purpose, the CERS6-AS1 expression level in CRC cells was disclosed by quantitative real-time PCR (qRT-PCR). In vitro and in vivo assays have validated the functional role of CERS6-AS1 in CRC. Mechanism assays were carried out to confirm the potential mechanism of CERS6-AS1 in CRC. Results showed that through experiments, we identified that the CERS6-AS1 expression level was up-regulated in CRC and the depletion of CERS6-AS1 hindered cell proliferative and migratory abilities and stimulated cell apoptotic levels in CRC. In addition, silencing of CERS6-AS1 repressed tumor growth. Moreover, CERS6-AS1 activated by MYC could sequestermiR-6838-5p, and then regulate rubicon-like autophagy enhancer (RUBCNL) expression level to influence the CRC cell proliferation, migration and apoptosis. In conclusion, The study focused on the MYC/CERS6-AS1/miR-6838-5p/RUBCNL axis was helpful for the potential diagnosis and standardized treatment of CRC.

Preactivation of ß-catenin in osteoblasts improves the osteoanabolic effect of PTH in type 1 diabetic mice.

Type 1 diabetes (T1D) is correlated with osteopenia primarily due to low bone formation. Parathyroid hormone (PTH) is a known anabolic agent for bone, the anabolic effects of which are partially mediated through the Wnt/ß-catenin signaling pathway. In the present study, we first determined the utility of intermittent PTH treatment in a streptozotocin-induced T1D mouse model. It was shown that the PTH-induced anabolic effects on bone mass and bone formation were attenuated in T1D mice compared with nondiabetic mice. Further, PTH treatment failed to activate ß-catenin signaling in osteoblasts of T1D mice and was unable to improve osteoblast proliferation and differentiation. Next, the Col1-3.2 kb-CreERTM; ß-cateninfx(ex3) mice were used to conditionally activate ß-catenin in osteoblasts by injecting tamoxifen, and we addressed whether or not preactivation of ß-catenin boosted the anabolic action of PTH on T1D-related bone loss. The results demonstrated that pretreatment with activation of osteoblastic ß-catenin followed by PTH treatment outperformed PTH or ß-catenin activation monotherapy and led to greatly improved bone structure, bone mass, and bone strength in this preclinical model of T1DM. Further analysis demonstrated that osteoblast proliferation and differentiation, as well as osteoprogenitors in the marrow, were all improved in the combination treatment group. These findings indicated a clear advantage of developing ß-catenin as a target to improve the efficacy of PTH in the treatment of T1D-related osteopenia.

The increase in bone resorption in early-stage type I diabetic mice is induced by RANKL secreted by increased bone marrow adipocytes.

Bone marrow adipose tissue (BMAT) has recently been found to induce osteoclastogenesis by secreting RANKL. Although Type 1 diabetes mellitus (T1DM) has been reported to be associated with increased BMAT and bone loss, little is known about the relationship between BMAT and osteoclasts in T1DM. We studied the role of BMAT in the alterations of osteoclast activities in early-stage T1DM, by using a streptozotocin-induced T1DM mouse model. Our results showed that osteoclast activity was enhanced in the long bones of T1DM mice, accompanied by increased protein expression of RANKL. However, RANKL mRNA levels in bone tissues of T1DM mice remained unchanged. Meanwhile, we found that BMAT was significantly increased in the long bones of T1DM mice, and both mRNA and protein levels of RANKL were elevated in the diabetic BMAT. More importantly, RANKL protein was mainly expressed on the cell membranes of the increased adipocytes, most of which were located next to the metaphyseal region. These results suggest that the enhanced bone resorption in early-stage diabetic mice is induced by RANKL derived from BMAT rather than the bone tissue itself.

Different effects of Wnt/ß-catenin activation and PTH activation in adult and aged male mice metaphyseal fracture healing.

BACKGROUND: Fractures in older men are not uncommon and need to be healed as soon as possible to avoid related complications. Anti-osteoporotic drugs targeting Wnt/ß-catenin and PTH (parathyroid hormone) to promote fracture healing have become an important direction in recent years. The study is to observe whether there is a difference in adult and aged situations by activating two signal paths. METHODS: A single cortical hole with a diameter of 0.6 mm was made in the femoral metaphysis of Catnblox(ex3) mice and wild-type mice. The fracture healing effects of CA (Wnt/ß-catenin activation) and PTH (activated by PTH (1-34) injections) were assessed by X-ray and CT imaging on days 7, 14, and 21 after fracture. The mRNA levels of ß-catenin, PTH1R(Parathyroid hormone 1 receptor), and RUNX2(Runt-related transcription factor 2) in the fracture defect area were detected using RT-PCR. Angiogenesis and osteoblasts were observed by immunohistochemistry and osteoclasts were observed by TRAP (Tartrate-resistant Acid Phosphatase). RESULT: Adult CA mice and adult PTH mice showed slightly better fracture healing than adult wild-type (WT) mice, but there was no statistical difference. Aged CA mice showed better promotion of angiogenesis and osteoblasts and better fracture healing than aged PTH mice. CONCLUSION: The application of Wnt/ß-catenin signaling pathway drugs for fracture healing in elderly patients may bring better early effects than PTH signaling pathway drugs, but the long-term effects need to be observed.

Different effects of Wnt/ß-catenin activation and parathyroid hormone on diaphyseal and metaphyseal in the early phase of femur bone healing of mice.

Parathyroid hormone (PTH) and agents related to the manipulation of Wnt/ß-catenin signalling are two promising anabolic anti-osteoporotic therapies that have been shown to promote the healing of bone fractures. Now, it is widely accepted that cortical bone and trabecular bone are two different compartments, and should be treated as separate compartments in pathological processes, such as fracture healing. It is currently unknown whether PTH and the activation of ß-catenin signalling would demonstrate different effects on cortical bone and trabecular bone healing. In the current study, single 0.6-mm cortex holes were made in the femur metaphysis and diaphysis of mice, and then, PTH application and ß-catenin activation were used to observe the promoting effect on bone healing. The effects of ß-catenin and PTH signalling on fracture healing were observed by X-ray and CT at 3, 6, and 14 days after fracture, and the levels of ß-catenin were detected by RT-PCR assay, and the number of specific antigen-positive cells of BRDU, OCN, RUNX2 was counted by immunohistochemical staining. While ß-catenin activation and PTH were found to demonstrate similar effects on accelerating metaphyseal bone healing, activation of ß-catenin showed a more striking effect than PTH on promoting diaphyseal bone healing. These findings might be helpful for selecting proper medication to accelerate fracture healing of different bone compartments.

Disruption of bone morphogenetic protein type IA receptor in osteoblasts impairs bone quality and bone strength in mice.

In recent years, several studies have found that the disruption of type IA receptor of bone morphogenetic proteins (BMPR1A) could increase bone mass. However, whether disruption of BMPR1A could have an effect on bone quality and bone strength is currently unknown. Osteoblast-targeted conditional knockout (cKO) of BMPRIA by crossing 3.2-kb Col1-CreER™ mice with BMPR1A fx +/+ mice was conducted. Then, in vitro and in vivo studies were employed to examine the effect of BMPR1A knockout on bone quality and bone strength. It was found that the ultimate force and stiffness of the femora decreased significantly in cKO mice when compared to control mice. The content of collagen and mineralization level decreased as the structure of the collagen became disorganized. The morphology of osteocytes in cKO mice was abnormal as well. The expression level of osteocalcin, a marker for the terminal differentiation of osteoblasts, decreased in cKO mice. This data indicated that the differentiation of osteoblasts in cKO mice was impaired. Immunohistochemistry examination revealed deregulated expression of dickkopf 1(DKK1) in osteocytes in cKO mice. Adding DKK1 to the culture medium reversed these effects. In conclusion, even though disruption of BMPR1A could increase bone mass, it also impairs bone quality and bone strength.

Constitutive ß-catenin activation in osteoblasts impairs terminal osteoblast differentiation and bone quality.

Accumulating evidence suggests that Wnt/ß-catenin signaling plays a central role in controlling bone mass. We previously reported that constitutive activation of ß-catenin (CA-ß-catenin) in osteoblasts potentially has side effects on the bone growth and bone remodeling process, although it could increase bone mass. The present study aimed to observe the effects of osteoblastic CA-ß-catenin on bone quality and to investigate possible mechanisms of these effects. It was found that CA-ß-catenin mice exhibited lower mineralization levels and disorganized collagen in long bones as confirmed by von Kossa staining and sirius red staining, respectively. Also, bone strength decreased significantly in CA-ß-catenin mice. Then the effect of CA-ß-catenin on biological functions of osteoblasts were investigated and it was found that the expression levels of osteocalcin, a marker for the late differentiation of osteoblasts, decreased in CA-ß-catenin mice, while the expression levels of osterix and alkaline phosphatase, two markers for the early differentiation of osteoblasts, increased in CA-ß-catenin mice. Furthermore, higher proliferation rate were revealed in osteoblasts that were isolated from CA-ß-catenin mice. The Real-time PCR and western blot examination found that the expression level of c-myc and cyclin D1, two G1 progression-related molecules, increased in osteoblasts that were isolated from the CA-ß-catenin mice, and the expression levels of CDK14 and cyclin Y, two mitotic-related molecules that can accelerate cells entering into S and G2/M phases, increased in osteoblasts that were isolated from the CA-ß-catenin mice. In summary, osteoblastic CA-ß-catenin kept osteoblasts in high proliferative state and impaired the terminal osteoblast differentiation, and this led to changed bone structure and decreased bone strength.

SP1-induced circ_0017552 modulates colon cancer cell proliferation and apoptosis via up-regulation of NET1.

Colon cancer (CC) is a common malignancy over the world and its morbidity and mortality significantly went up in China in recent years. Molecular functions in cancers have gradually been the pivot subject in cancer research. Neuroepithelial cell transforming 1 (NET1) was reported to contribute to prostate cancer and gastric cancer. Our study figured out that NET1 was overexpressed in CC cells. Then, loss-of-function assays revealed that NET1 facilitated CC cell proliferation and repressed CC cell apoptosis. Next, miR-338-3p was confirmed to target NET1. After that, we verified that circ_0017552 which originates from NET1 could positively modulate NET1 expression. Besides, circ_0017552 was a sponge of miR-338-3p. Rescue assays' results demonstrated that circ_0017552 could regulate CC cell proliferation and apoptosis through up-regulation of NET1. A transcription factor named Sp1 (SP1) was found to be present in circ_0017552. SP1 induced transcription of circ_0017552 to facilitate CC cell proliferation and inhibit CC cell apoptosis. In a word, SP1-induced circ_0017552 regulated CC cell proliferation and apoptosis through miR-338-3p/NET1 axis.

Synthesis of Ni/NiAlOx Catalysts for Hydrogenation Saturation of Phenanthrene.

The saturation of octahydrophenanthrene was the rate-determining step in the hydrogenation process from phenanthrene to perhydrophenanthrene, which was due to the steric hindrance and competitive adsorption of octahydrophenanthrene. In this work, a series of Ni/NiAlOx catalysts with a uniform electron-deficient state of Ni derived from the nickel aluminate structure was synthesized to overcome the disadvantage of noble catalyst and the traditional sulfided catalysts in the saturation hydrogenation process of phenanthrene. Results showed that the catalyst calcinated at 650°C possessed more Ni2+ (∼98%) occupying octahedral sites and exhibited the highest robs (1.53 × 10-3 mol kg-1 s-1) and TOF (14.64 × 10-3 s-1) for phenanthrene hydrogenation. Furthermore, its ability to overcome steric hindrance and promote the rate-determining step was proven by octahydrophenanthrene hydrogenation. Comparing the evolution of hydrogenation activity with the change in the electronic structure of surface Ni sites, it was shown that the increase of metallic electron deficiency hindered the π-back bonding between surface Ni and aromatic rings, which was unfavorable for aromatic adsorption. As a result, the phenanthrene hydrogenation saturation performance can be enhanced by stabilizing the electron-deficient state of surface Ni on an optimal degree.

Wnt/ß-catenin signalling promotes more effective fracture healing in aged mice than in adult mice by inducing angiogenesis and cell differentiation.

To investigate whether activating the Wnt/ß-catenin signalling pathway differentially promotes fracture healing in aged and adult individuals. CatnbTM2Kem, Catnblox(ex3) and wild-type adult and aged mice were used in this study. The femur was electroporated through a hole with a diameter of 0.6 mm. On the 7th, 14th and 21st days after fracture establishment, repair of the femoral diaphyseal bone was examined using X-ray and CT, the levels of mRNAs related to Wnt/ß-catenin signalling were detected using real-time polymerase chain reaction (RT-PCR), and angiogenesis and cell differentiation were observed using immunohistochemistry. The numbers of osteoclasts were determined by TRAP staining. Wnt/ß-catenin activation accelerated fracture healing in adult mice, with more pronounced effects on aged mice. Compared with wild-type mice at the corresponding ages, Wnt/ß-catenin signalling activation induced higher levels of angiogenesis and cell differentiation in aged mice than in adult mice and promoted fracture healing. The administration of medications targeting Wnt/ß-catenin signalling to aged patients may accelerate fracture healing to a greater extent.

First-aid Training for Combatants Without Systematic Medical Education Experience on the Battlefield: Establishment and Evaluation of the Curriculum in China.

INTRODUCTION: For combatants without systematic medical education experience (CSMEE), it is necessary to participate in first-aid on the battlefield, but currently there is no effective training curriculum for CSMEE in Chinese military. MATERIALS AND METHODS: A list of first-aid techniques based on expert consensus was formed, and then a curriculum was established according to the list. The effectiveness of the curriculum was further evaluated by comparing the scores among group A (the reserve officers trained by this curriculum), group B (the reserve officers in the military medical college trained by professional medic training system), and group C (the fresh officers trained by the Outline of Military Training and Assessment of Chinese military), through a 5-station assessment in a simulated battlefield environment, which included the following 5 techniques: tourniquet for massive extremities hemorrhage, thyrocricocentesis, thoracentesis, fixation of long bone fractures, and wound dressing with hemostatic bandage. RESULTS: The training curriculum entitled "Implementation and Assessment Standards of First-aid Training for Combatants on the Battlefield" was established. The comparison of average scores in the 5-station assessment showed that group A had better scores than group C in tourniquet for massive extremity hemorrhage, thyrocricocentesis, and thoracentesis, with no significant differences compared with group B. Also, no significant difference between groups A and B in overall completion time and overall scores was observed, whereas an excellent candidate rate in overall score of group B was better than that of group A (87.4% vs. 80.9%, χ2 = 4.40, p = 0.036), and group A was better than group C (80.9% vs. 37.5%, χ2 = 62.01, p < 0.001). CONCLUSION: The established training curriculum is indeed effective, which improved the CSMEE's first-aid capacity on the battlefield, and is equivalent to the level of medics.

Naphthalene Hydrogenation Saturation over Ni2P/Al2O3 Catalysts Synthesized by Thermal Decomposition of Hypophosphite.

A series of Ni2P/Al2O3 catalysts with different Ni2P loadings were synthesized via thermal decomposition of hypophosphite and employed for naphthalene hydrogenation saturation. Results showed that Ni2P loading greatly affected Ni2P particle size and the number of active sites of the as-synthesized catalysts, which was derived from the variable interaction between POx and Al2O3. When the hydrogenation saturation reaction was performed at 300 °C, 4 MPa, a H2/oil volume ratio of 600, and a liquid hourly space velocity (LHSV) of 3 h-1, 98% naphthalene conversion and 98% selectivity to decalin were achieved over Ni2P/Al2O3 catalysts with 10 wt % Ni2P. The superior naphthalene hydrogenation saturation performance was ascribed to the large specific surface area (169 m2·g-1), small Ni2P particle size (3.8 nm), and the high number of exposed active sites (CO sorption 30 µmol·g-1), which were beneficial to the adsorption and diffusion of the reactant molecules on the catalyst.

Efficacy of a Temporary Hemostatic Device in a Swine Model of Closed, Lethal Liver Injury.

INTRODUCTION: Solid abdominal organ hemorrhage remains one of the leading causes of death both on the battlefield of modern warfare and in the civilian setting. A novel, temporary hemostatic device combining CELOX and direct intra-abdominal physical compression was invented to control closed SAOH during transport to a medical treatment facility. MATERIALS AND METHODS: A swine model of closed, lethal liver injury was established to determine hemostasis. The animals were randomly divided into group A (extra-abdominal compression), group B (gauze packing), group C (intra-abdominal compression), group D (CELOX coverage), and group E (intra-abdominal compression and CELOX coverage) with six swines per group. Survival time (ST), blood loss (BL), vital signs, pathologic examination, and CT-scan were monitored to further observe the effectiveness of the device. RESULTS: Group E had an average 30-minute extension in ST (74.3 ± 15.4 minutes versus 44.0 ± 13.8 minutes, p = 0.026) with less BL (46.0 ± 13.0 versus 70.8 ± 8.2 g/kg, p = 0.018), and maintained mean arterial pressure≥70 mmHg and cardiac output ≥ 3.5 L/minute for a longer time. No significant differences were observed in ST and BL of groups B and E, and there were no marked differences in ST and BL of groups A, C, and D. No CELOX clots were noted in the spleen, pancreas, lungs, heart, kidneys, or the adjacent large vessels in groups D and E. Compared to group A, the CT-scan showed better hepatic hemorrhage control in group E. CONCLUSIONS: The device, which combined 20 g of CELOX particles and 20 pieces of CELOX (8 g) sponge tablets with 50-mmHg intra-abdominal compression for 10 minutes, prolonged the ST by an average of 30 minutes with less BL. It was not markedly different from the full four quadrants gauze packing of liver in hemostatic effect, with no CELOX clot formation in other organs.

Progress on combat damage control resuscitation/surgery and its application in the Chinese People's Liberation Army.

Damage control resuscitation (DCR) and damage control surgery (DCS) has now been developed as a well-established standard of care for severely injured civilian patients worldwide. On the other hand, the application of combat DCR/DCS has saved the lives of thousands of severely injured casualties in several wars during the last two decades. This article describes the great progress on DCR/DCS in the last two decades and its application in the Chinese People's Liberation Army (PLA). The main development of the advanced theories of combat DCR/DCS including the global integration of DCR/DCS, application of remote battlefield DCR, balanced hemostatic resuscitation in combat hospitals and enhancement of en route DCR. There are two key factors that determine the feasibility of combat DCR: one is the availability of resources and supplies to implement the advanced theories of combat DCR/DCS, the other is the availability of qualified personnel who master the skills needed for the implementation of DCR/DCS. In the PLA, the advanced theories of combat DCR/DCS have now been widely accepted, and some of related advanced products, such as fresh-frozen plasma, packed red blood cells, and platelets, have been available in Level III medical facilities. In conclusion, great progress in combat DCR/DCS has been achieved in recent years, and the Chinese PLA is keeping good pace with this development, although there is still room for improvement.

Differential effects of type 1 diabetes mellitus and subsequent osteoblastic ß-catenin activation on trabecular and cortical bone in a mouse model.

Type 1 diabetes mellitus (T1DM) is a pathological condition associated with osteopenia. WNT/ß-catenin signaling is implicated in this process. Trabecular and cortical bone respond differently to WNT/ß-catenin signaling in healthy mice. We investigated whether this signaling has different effects on trabecular and cortical bone in T1DM. We first established a streptozotocin-induced T1DM mouse model and then constitutively activated ß-catenin in osteoblasts in the setting of T1DM (T1-CA). The extent of bone loss was greater in trabecular bone than that in cortical bone in T1DM mice, and this difference was consistent with the reduction in the expression of ß-catenin signaling in the two bone compartments. Further experiments demonstrated that in T1DM mice, trabecular bone showed lower levels of insulin-like growth factor-1 receptor (IGF-1R) than the levels in cortical bone, leading to lower WNT/ß-catenin signaling activity through the inhibition of the IGF-1R/Akt/glycogen synthase kinase 3ß (GSK3ß) pathway. After ß-catenin was activated in T1-CA mice, the bone mass and bone strength increased to substantially greater extents in trabecular bone than those in cortical bone. In addition, the cortical bone of the T1-CA mice displayed an unexpected increase in bone porosity, with increased bone resorption. The downregulated expression of WNT16 might be responsible for these cortical bone changes. In conclusion, we found that although the activation of WNT/ß-catenin signaling increased the trabecular bone mass and bone strength in T1DM mice, it also increased the cortical bone porosity, impairing the bone strength. These findings should be considered in the future treatment of T1DM-related osteopenia.

Expert consensus on the evaluation and diagnosis of combat injuries of the Chinese People's Liberation Army.

The accurate assessment and diagnosis of combat injuries are the basis for triage and treatment of combat casualties. A consensus on the assessment and diagnosis of combat injuries was made and discussed at the second annual meeting of the Professional Committee on Disaster Medicine of the Chinese People's Liberation Army (PLA). In this consensus agreement, the massive hemorrhage, airway, respiration, circulation and hypothermia (MARCH) algorithm, which is a simple triage and rapid treatment and field triage score, was recommended to assess combat casualties during the first-aid stage, whereas the abbreviated scoring method for combat casualty and the MARCH algorithm were recommended to assess combat casualties in level II facilities. In level III facilities, combined measures, including a history inquiry, thorough physical examination, laboratory examination, X-ray, and ultrasound examination, were recommended for the diagnosis of combat casualties. In addition, corresponding methods were recommended for the recognition of casualties needing massive transfusions, assessment of firearm wounds, evaluation of mangled extremities, and assessment of injury severity in this consensus.

An appropriate Wnt/ß-catenin expression level during the remodeling phase is required for improved bone fracture healing in mice.

Accumulating evidence demonstrates that the Wnt/ß-catenin signaling pathway plays a dominant role in bone repair. However, the role of Wnt/ß-catenin signaling in the remodeling phase during bone fracture healing is currently unknown. In the present study, ß-catenin was activated at different levels or deleted in mice at the late stage of fracture healing, and the effects on healing quality were investigated. Deletion of ß-catenin disturbed bone remodeling, as confirmed by increased bone resorption and decreased bone formation, and significantly decreased bone strength compared with wildtype mice. In addition, the constitutive activation of ß-catenin significantly increased the bone mass and delayed the bone remodeling process, resulting in slightly impaired bone strength. In contrast, a slight activation of ß-catenin significantly increased bone formation and slightly hindered bone resorption. These effects lead to improved bone fracture healing quality compared with wildtype mice. In summary, the present study provides the first demonstration showing that Wnt/ß-catenin signaling should be maintained at a slightly activated level during the late stage of fracture healing to ensure better bone fracture repair.

Different bone remodeling levels of trabecular and cortical bone in response to changes in Wnt/ß-catenin signaling in mice.

Trabecular bone and cortical bone have different bone remodeling levels, and the underlying mechanisms are not fully understood. In the present study, the expression of Wnt/ß-catenin signaling and its downstream molecules along with bone mass in trabecular and cortical bone were compared in wild-type mice, constitutive activation of ß-catenin (CA-ß-catenin) mice and ß-catenin deletion mice. It was found that the expression level of most of the examined genes such as Wnt3a, ß-catenin, osteocalcin and RANKL/OPG ratio were significantly higher in trabecular bone than in cortical bone in wild-type mice. CA-ß-catenin resulted in up-regulated expression of the above-mentioned genes except for RANKL/OPG ratio, which were down-regulated. Also, CA-ß-catenin led to increased number of osteoblasts, decreased number of osteoclasts and increased bone mass in both the trabecular bone and cortical bone compared with wild-type mice; however, the extent of changes was much greater in the trabecular bone than in the cortical bone. By contrast, null ß-catenin led to down-regulated expression of the above-mentioned genes except for RANKL/OPG ratio. Furthermore, ß-catenin deletion led to decreased number of osteoblasts, increased number of osteoclasts and decreased bone mass when compared with wild-type mice. Again, the extent of these changes was more significant in trabecular bone than cortical bone. Taken together, we found that the expression level of Wnt/ß-catenin signaling and bone remodeling-related molecules were different in cortical bone and trabecular bone, and the trabecular bone was more readily affected by changes in the Wnt/ß-catenin signaling pathway. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:812-819, 2017.