Bisphosphonates regulate cell proliferation, apoptosis and pro-osteoclastic expression in MG-63 human osteosarcoma cells

Gadolinium-Bisphosphonate Nanoparticle-Based Low-Dose Radioimmunotherapy for Osteosarcoma

Osteosarcoma is a malignant osteogenic tumor with a high metastatic rate commonly occurring in adolescents. Although radiotherapy is applied to treat unresectable osteosarcoma with radiation resistance, a high dose of radiotherapy is required, which may weaken the immune microenvironment. Therefore, there is an urgent need to develop novel agents to maximize the radiotherapeutic effects by eliciting immune activation effects. In this study, we synthesized therapeutic gadolinium-based metal-bisphosphonate nanoparticles (NPs) for osteosarcoma treatment that can be combined with radiotherapy. The gadolinium ion (Gd) was chelated with zoledronic acid (Zol), a commonly used drug to prevent/treat osteoporosis or bone metastases from advanced cancers, and stabilized by ovalbumin (OVA) to produce OVA-GdZol NPs. OVA-GdZol NPs were internalized into K7M2 osteosarcoma cells, showing a high sensitization effect under X-ray irradiation. Cell pretreatment of OVA-GdZol NPs significantly enhanced the radiation therapeutic effect in vitro by reducing the cell colonies and increased the signal of γH2AX-positive cells. More importantly, OVA-GdZol NPs promoted the maturation of bone marrow-derived dendritic cells (BMDCs) and M1 polarization of macrophages. The inhibitory effect on K7M2 osteosarcoma of OVA-GdZol NPs and X-ray radiation was evident, indicated by a significantly reduced tumor volume, high survival rate, and decreased lung metastasis. Meanwhile, both innate and adaptive immune systems were activated to exert a strong antitumor effect. The above results highly suggest that OVA-GdZol NPs serve as both radiosensitizers and immune adjuvants, suitable for the sequential combination of vaccination and radiotherapy.

Antibacterial Effect of Some Eukaryotic Sterol Biosynthesis Inhibitors

BACKGROUND

Isoprenoids and their derivatives are building blocks for the synthesis of biomolecules with important biological functions such as cholesterol in eukaryotes and lipid carrier undecaprenol, which is involved in cell wall biosynthesis in bacteria. With the global threat of multidrug-resistant bacteria, there is a need for finding new metabolic targets for killing bacteria. In the present study, we examined the impact of eukaryotic sterol biosynthesis inhibitors on the growth of four pathogenic bacteria.

MATERIALS AND METHODS

Antibacterial effect of HMG CoA reductase inhibitor (simvastatin), farnesyl pyrophosphate synthase inhibitor (alendronate), squalene epoxidase inhibitor (terbinafine), and lanosterol demethylase inhibitor (ketoconazole) were studied against four pathogenic bacteria: two gram-positive bacteria, Staphylococcus aureus and Enterococcus faecalis and two gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa. Broth microdilution method was used for assessing the antibacterial susceptibility of the components using 96 well plats. MIC and MBC were determined visibly.

RESULTS

MIC of Ketoconazole for Staphylococcus aureus and Enterococcus faecalis were 0.166 and 1 mg/mL, respectively. Terbinafine had a weak inhibitory effect on Staphylococcus aureus (MIC: 8 mg/mL). Ketoconazole and terbinafine had no inhibitory effect on gram-negative bacteria. MBC of Simvastatin for both Staphylococcus aureus and Enterococcus faecalis was 0.5 mg/mL and of Alendronate for Pseudomonas aeruginosa was 6.6 mg/mL.

CONCLUSION

Our results show that farnesyl pyrophosphate synthase and class II HMG-CoA reductases inhibitors (ketoconazole and simvastatin) have reasonable antibacterial activity against gram-positive bacteria. These two enzymes provide suitable targets for designing new antibiotics based on modifying the chemical structure of currently used drugs to obtain maximum activity.

Therapeutic Effects of Zoledronic Acid-Loaded Hyaluronic Acid/Polyethylene Glycol/Nano-Hydroxyapatite Nanoparticles on Osteosarcoma

Zoledronic acid (ZOL) has been approved as the only bisphosphonate for the prevention and treatment of metastatic bone diseases with acceptable safety and tolerability. However, systemic or direct injection of ZOL often causes severe side effects, which limits its clinical application. Here, an innovative nano-drug delivery system, ZOL-loaded hyaluronic acid/polyethylene glycol/nano-hydroxyapatite nanoparticles (HA-PEG-nHA-ZOL NPs), has been found to effectively inhibit the proliferation of three types of human osteosarcoma cell lines (143b, HOS, and MG63) at 1–10 μmol/L, while with low cell cytotoxicity on normal cells. The NPs significantly enhanced the apoptosis-related protein expression and tumor cell apoptosis rate. The NPs could also inhibit the proliferation of osteosarcoma cells by blocking the S phase of the cell cycle. In the orthotopic osteosarcoma nude mice model, local injection of the HA-PEG-nHA-ZOL NPs stimulated tumor necrosis, apoptosis, and granulocyte infiltration in the blood vessels. Altogether, the ZOL nano-delivery system possesses great potential for local treatment to prevent local tumor recurrence and can be applied in clinical osteosarcoma therapy.

The New Role of Sirtuin1 in Human Osteoarthritis Chondrocytes by Regulating Autophagy

OBJECTIVE

The aim of this study is to investigate the role of Sirtuin1 (Sirt1) in the regulation of autophagy for human osteoarthritis (OA) chondrocytes.

DESIGN

All cartilage samples were collected from human donors, including young group, aged group, and OA group. Primary chondrocytes were isolated and cultured with Sirt1 activator or inhibitor. Sirt1 expression in cartilage tissue and chondrocytes was evaluated, and the deacetylation activity of Sirt1 was determined. The alteration of autophagy activity after upregulating or downregulating Sirt1 was detected. Chondrocytes were treated with autophagy activator and inhibitor, and then the protein level of Sirt1 was examined. The interactions between Sirt1 and autophagy-related proteins Atg7, microtubule associated protein 1 light chain 3 (LC3), and Beclin-1 were determined by using immunoprecipitation.

RESULTS

The assay of articular cartilage revealed that the expression of Sirt1 might be age-related: highly expressed in of younger people, and respectively decreased in the elderly people and OA patients. In vitro study was also validated this result. Further study confirmed that higher levels of Sirt1 significantly increased autophagy in aged chondrocytes, while the lower expression of Sirt1 reduced autophagy in young chondrocytes. Of note, the high levels of Sirt1 reduced autophagy in OA chondrocytes. When the chondrocytes were treated with autophagy activator or inhibitor, we found the expression of Sirt1 was not affected. In addition, we found that Sirt1 could interact with Atg7.

CONCLUSION

These results suggest that Sirt1 in human chondrocytes regulates autophagy by interacting with autophagy related Atg7, and Sirt1 may become a more important target in OA treatment.

Polyethylenimine-Bisphosphonate-Cyclodextrin Ternary Conjugates: Supramolecular Systems for the Delivery of Antineoplastic Drugs

Bisphosphonates (BPs) are bone-binding molecules that provide targeting capabilities to bone cancer cells when conjugated with drug-carrying polymers. This work reports the design, synthesis, and biological evaluation of polyethyleneimine-BP-cyclodextrin (PEI-BP-CD) ternary conjugates with supramolecular capabilities for the loading of antineoplastic drugs. A straightforward, modular, and versatile strategy based on the click aza-Michael addition reaction of vinyl sulfones (VSs) allows the grafting of BPs targeting ligands and βCD carrier appendages to the PEI polymeric scaffold. The in vitro evaluation (cytotoxicity, cellular uptake, internalization routes, and subcellular distribution) for the ternary conjugates and their doxorubicin inclusion complexes in different bone-related cancer cell lines (MC3T3-E1 osteoblasts, MG-63 sarcoma cells, and MDA-MB-231 breast cancer cells) confirmed specificity, mitochondrial targeting, and overall capability to mediate a targeted drug transport to those cells. The in vivo evaluation using xenografts of MG-63 and MDA-MB-231 cells on mice also confirmed the targeting of the conjugates.

Zoledronic Acid-Loaded Hybrid Hyaluronic Acid/Polyethylene Glycol/Nano-Hydroxyapatite Nanoparticle: Novel Fabrication and Safety Verification

Osteosarcoma is a malignant tumor that often occurs in adolescents and children. Zoledronic acid, a new-generation bisphosphonate, has been widely used as an antitumor drug to inhibit bone metastasis. However, the rapid renal elimination results in low effective concentrations. Meanwhile, high-dose intravenous zoledronic acid administration leads to severe side effects. The present study fabricated an organic-inorganic hybrid nanoparticle as the carrier of zoledronic acid. The rod-like nanoparticle, which had 150-nm length and 40-nm cross-sectional diameter, consisted of a hyaluronic acid/polyethylene glycol (HA-PEG) polymer shell and a nano-hydroxyapatite (nHA) core, with zoledronic acid molecules loading on the surface of nHA and clearance of HA-PEG shell. The nanoparticle was characterized by microscopic analysis, in vitro release study, cytotoxicity analysis, and in vivo immune response examination. Results showed that the compact and stable structure could achieve high drug loading efficiency, sustained drug release, and great biocompatibility. In vitro and in vivo experiments revealed the low cytotoxicity and acceptable immune response under low-dose nanoparticle treatment, indicating its potential application for future osteosarcoma therapeutic strategies.

New insights into molecular and cellular mechanisms of zoledronate in human osteosarcoma

Osteosarcoma is the most common primary malignant tumor of the skeleton in teenagers and young adults and continues to confer a generally poor prognosis in patients who do not respond to chemotherapy or who present with metastatic diseases at diagnosis. The nitrogen-containing zoledronate, the third generation bisphosphonate (BP), effectively inhibits osteoclastic bone resorption and is widely utilized in the treatment of metabolic and metastatic bone diseases nowadays. Owing to an acceptable safety profile and tolerability, zoledronate is the only BP currently approved for the prevention and treatment of skeletal relevant events in patients with metastatic bone lesions, especially bone metastases from advanced renal cell carcinoma and prostate cancer, and breast cancer, due to all solid malignancy. Moreover, zoledronate possesses diverse anti-osteosarcoma properties and may have potential to become an adjunctive treatment for high-grade osteosarcoma to enhance survival rates and to obliterate complications of the chemotherapy. Herein we highlighted the pharmacology of BPs and its underlying molecular mechanisms in osteoclasts and various cancer cells. We further provided the available literature on in vitro studies to illustrate the new insights into the intracellular molecular mechanisms of zoledronate in human osteosarcoma cell lines and in vivo animal models that led to the development and regulatory approval of zoledronate in patients with human osteosarcoma. This review also addresses clinical trials to focus on the efficacy of zoledronate on human osteosarcoma.

Bone-Bound Bisphosphonates Inhibit Proliferation of Breast Cancer Cells

Bisphosphonates are used in treating patients with breast cancer. In vitro studies have shown that bisphosphonates act directly on tumour cells, inhibiting cell proliferation and inducing apoptosis. In most such studies, drugs were added to culture media exposing cells to high bisphosphonate concentrations in solution. However, since bisphosphonates bind to bone hydroxyapatite with high affinity and remain bound for very long periods of time, these experimental systems are not an optimal model for the action of the drugs in vivo. The aim of this study was to determine whether bone-bound zoledronate has direct effects on adjacent breast cancer cells. Bone slices were pre-incubated with bisphosphonate solutions, washed, and seeded with cells of the breast cancer cell lines, MCF7 or MDA-MB-231. Proliferation was assessed by cell counts and thymidine incorporation for up to 72 h. Inhibition of the mevalonate pathway was tested by measuring the levels of unprenylated Rap1A, and apoptosis was examined by the presence of cleaved caspase-8 on western blots. The proliferation rate of breast cancer cells on zoledronate-treated bone was significantly lower compared to cells on control bone. Other bisphosphonates showed a similar inhibitory effect, with an order of potency similar to their clinical potencies. Unprenylated Rap1A accumulated in MCF7 cells on zoledronate-treated bone, suggesting zoledronate acted through the inhibition of the mevalonate pathway. Accumulation of cleaved caspase-8 in MDA-MB-231 cells on bisphosphonate-treated bone indicated increased apoptosis in the cells. In conclusion, bone-bound zoledronate inhibits breast cancer cell proliferation, an activity that may contribute to its clinical anti-tumour effects.

Which Combination Treatment Is Better for Spinal Metastasis: Percutaneous Vertebroplasty With Radiofrequency Ablation, 125I Seed, Zoledronic Acid, or Radiotherapy?

BACKGROUND

Percutaneous vertebroplasty (PVP) can not only alleviate pain but also restore mechanical stability with injection of bone cement, whereas it exhibits a poor effect on antitumor activity. But through combinations with other therapies, it may be possible to achieve the maximum effect in clinical treatment. Thus, this study is designed to assess the clinical efficacy of PVP separately combined with 4 ways for spinal metastasis (SM) treatment.

STUDY QUESTION

Which combination treatment is better for spinal metastasis, percutaneous vertebroplasty with radiofrequency ablation, I seed, zoledronic acid or radiotherapy?

STUDY DESIGN

A total of 169 patients with SM were retrospectively recruited and randomly assigned to 4 groups to receive 4 different ways separately: 49 patients (group A) received PVP plus I seed, 51 (group B) received PVP plus radiofrequency ablation (RFA), 38 (group C) underwent PVP plus zoledronic acid (ZA), and 31 (group D) underwent PVP plus radiotherapy (RT).

MEASURES AND OUTCOMES

All of them underwent routine examinations before operation. Visual analog scale (VAS), World Health Organization (WHO) Pain Relief, and ODI were applied to evaluate pain relief and motor function.

RESULTS

PVP plus RT achieved the best efficacy in relieving pains, with the highest WHO Pain Relief (P < 0.05). The PVP plus RFA exhibited lowest ODI, suggesting the best outcome after treatment (P < 0.05). The PVP plus I showed the lowest VAS score, but it was the worst to improve the routine exercise ability and relieve pains from patients. The PVP plus ZA presented higher VAS and ODI (P < 0.05).

CONCLUSIONS

PVP combined with I seed exhibited the best clinical efficacy in terms of VAS, PVP combined with RT was the best choice in terms of WHO Pain Relief, and PVP combined with RFA showed the best effect in terms of ODI for the treatment of SM.

Calcium Sulphate/Hydroxyapatite Carrier for Bone Formation in the Femoral Neck of Osteoporotic Rats

This study investigated bone regeneration in the femoral neck canal of osteoporotic rats using a novel animal model. A calcium sulphate (CS)/hydroxyapatite (HA) carrier was used to deliver a bisphosphonate, zoledronic acid (ZA), locally, with or without added recombinant human bone morphogenic protein-2 (rhBMP-2). Twenty-eight-week-old ovariectomized Sprague–Dawley rats were used. A 1 mm diameter and 8 mm long defect was created in the femoral neck by drilling from the lateral cortex in the axis of the femoral neck, leaving the surrounding cortex intact. Three treatment groups and one control group were used: (1) CS/HA alone, (2) CS/HA + ZA (10 μg) (3) CS/HA + ZA (10 μg) + rhBMP-2 (4 μg), and (4) empty defect (control). The bone formation was assessed at 4 weeks post surgery using in vivo micro computed tomography (micro-CT). At 8 weeks post surgery, the animals were sacrificed, and both defect and contralateral femurs were subjected to micro-CT, mechanical testing, and histology. Micro-CT results showed that the combination of CS/HA with ZA or ZA + rhBMP-2 increased the bone formation in the defect when compared to the other groups and to the contralateral hips. Evidence of new dense bone formation in CS/HA + ZA and CS/HA + ZA + rhBMP-2 groups was seen histologically. Mechanical testing results showed no differences in the load to fracture between the treatments in either of the treated or contralateral legs. The CS/HA biomaterial can be used as a carrier for ZA and rhBMP-2 to regenerate bone in the femoral neck canal of osteoporotic rats.

Evidence of novel miR-34a-based therapeutic approaches for multiple myeloma treatment

MiR-34a acts as tumor suppressor microRNA (miRNA) in several cancers, including multiple myeloma (MM), by controlling the expression of target proteins involved in cell cycle, differentiation and apoptosis. Here, we have investigated the combination between miR-34a and γ-secretase inhibitor (γSI), Sirtinol or zoledronic acid (ZOL) in order to enhance the inhibitory action of this miRNA on its canonical targets such as Notch1 and SIRT1, and on Ras/MAPK-dependent pathways. Our data demonstrate that miR-34a synthetic mimics significantly enhance the anti-tumor activity of all the above-mentioned anti-cancer agents in RPMI 8226 MM cells. We found that γSI enhanced miR-34a-dependent anti-tumor effects by activating the extrinsic apoptotic pathway which could overcome the cytoprotective autophagic mechanism. Moreover, the combination between miR-34a and γSI increased the cell surface calreticulin (CRT) expression, that is well known for triggering anti-tumor immunological response. The combination between miR-34a and Sirtinol induced the activation of an intrinsic apoptotic pathway along with increased surface expression of CRT. Regarding ZOL, we found a powerful growth inhibition after enforced miR-34a expression, which was not likely attributable to neither apoptosis nor autophagy modulation. Based on our data, the combination of miR-34a with other anti-cancer agents appears a promising anti-MM strategy deserving further investigation.

Can the microRNA expression profile help to identify novel targets for zoledronic acid in breast cancer?

Zoledronic acid (ZOL), belonging to third generation bisphosphonate family, is a potent inhibitor of osteoclast-mediated bone resorption, widely used to effectively prevent osteolysis in breast cancer patients who develop bone metastases. Low doses of ZOL have been shown to exhibit a direct anticancer role, by inhibiting cell adhesion, invasion, cytoskeleton remodelling and proliferation in MCF-7 breast cancer cells. In order to identify the molecular mechanisms and signaling pathways underlying the anticancer activity exerted by ZOL, we analyzed for the first time the microRNA expression profile in breast cancer cells. A large-scale microarray analysis of 377 miRNAs was performed on MCF7 cells treated with 10 μM ZOL for 24 h compared to untreated cells. Furthermore, the expression of specific ZOL-induced miRNAs was analyzed in MCF-7 and SkBr3 cells through Real-time PCR. Low-dose treatment with ZOL significantly altered expression of 54 miRNAs. Nine upregulated and twelve downregulated miRNAs have been identified after 24 h of treatment. Also, ZOL induced expression of 11 specific miRNAs and silenced expression of 22 miRNAs. MiRNA data analysis revealed the involvement of differentially expressed miRNAs in PI3K/Akt, MAPK, Wnt, TGF-β, Jak-STAT and mTOR signaling pathways, and regulation of actin cytoskeleton. Our results have been shown to be perfectly coherent with the recent findings reported in literature concerning changes in expression of some miRNAs involved in bone metastasis formation, progression, therapy resistance in breast cancer. In conclusion, this data supports the hypothesis that ZOL-induced modification of the miRNA expression profile contributes to the anticancer efficacy of this agent.

Combined Use of Zoledronic Acid Augments Ursolic Acid-Induced Apoptosis in Human Osteosarcoma Cells through Enhanced Oxidative Stress and Autophagy

Ursolic acid (UA), a naturally occurring pentacyclic triterpene acid found in many medicinal herbs and edible plants, triggers apoptosis in several tumor cell lines but not in human bone cancer cells. Most recently, we have demonstrated that UA exposure reduces the viability of human osteosarcoma MG-63 cells through enhanced oxidative stress and apoptosis. Interestingly, an inhibitor of osteoclast-mediated bone resorption, zoledronic acid (ZOL), also a third-generation nitrogen-containing bisphosphonate, is effective in the treatment of bone metastases in patients with various solid tumors. In this present study, we found that UA combined with ZOL to significantly suppress cell viability, colony formation, and induce apoptosis in two lines of human osteosarcoma cells. The pre-treatment of the antioxidant had reversed the oxidative stress and cell viability inhibition in the combined treatment, indicating that oxidative stress is important in the combined anti-tumor effects. Moreover, we demonstrated that ZOL combined with UA significantly induced autophagy and co-administration of autophagy inhibitor reduces the growth inhibitory effect of combined treatment. Collectively, these data shed light on the pathways involved in the combined effects of ZOL and UA that might serve as a potential therapy against osteosarcoma.

Zoledronic acid in metastatic osteosarcoma: encouraging progression free survival in four consecutive patients

Background

Zoledronic acid (ZA) is a third-generation bisphosphonate in widespread clinical use to reduce pain and skeletal events in patients from a variety of malignancies with bone metastases. Pre-clinical studies indicate that ZA inhibits osteosarcoma through direct anti-proliferative effects, immune activation and anti-angiogenic activity.

Methods

The purpose of this study was to evaluate the antitumor efficacy of ZA at standard dose until progression in patients with stage IV osteosarcoma lacking a standard of care treatment option proven to influence survival. Researchers retrospectively reviewed medical records of all patients at our institution with high-grade osteosarcoma presumed to be incurable due to metastases progressive after primary combination chemotherapy who received single agent ZA in an effort to delay progression.

Results

In our four-patient cohort following initiation of ZA, the median progression-free survival was 19 months, and median overall survival was 56+ months. Two of four patients have remained progression-free since starting ZA. The other two initially progressed after 18–20 months on ZA followed by metastasectomy of lung or dural metastases and further stability for over a year following resumption of ZA. After a 20-month progression-free interval on ZA alone, one patient had partial response following addition of pazopanib to ZA that likely contributed to long term disease control. The four patients experienced no significant toxicities despite protracted dosing of ZA for up to 5 years, and none have required chemotherapy since beginning ZA.

Conclusions

Single agent ZA was associated with encouraging progression-free survival in four consecutive patients with metastatic osteosarcoma. Prospective trials of single agent ZA are warranted as protracted maintenance therapy in surgically incurable osteosarcoma relapsed or refractory to first line combination chemotherapy with radiographically measurable metastases.

Zoledronic acid induces apoptosis via stimulating the expressions of ERN1, TLR2, and IRF5 genes in glioma cells

Glioblastoma multiforme (GBM) is the most common and aggressive brain tumor that affects older people. Although the current therapeutic approaches for GBM include surgical resection, radiotherapy, and chemotherapeutic agent temozolomide, the median survival of patients is 14.6 months because of its aggressiveness. Zoledronic acid (ZA) is a nitrogen-containing bisphosphonate that exhibited anticancer activity in different cancers. The purpose of this study was to assess the potential effect of ZA in distinct signal transduction pathways in U87-MG cells. In this study, experiments performed on U87-MG cell line (Human glioblastoma-astrocytoma, epithelial-like cell line) which is an in vitro model of human glioblastoma cells to examine the cytotoxic and apoptotic effects of ZA. IC50 dose of ZA, 25 μM, applied on U87-MG cells during 72 h. ApoDIRECT In Situ DNA Fragmentation Assay was used to investigate apoptosis of U87MG cells. The quantitative reverse transcription polymerase chain reaction (qRT-PCR) (LightCycler480 System) was carried out for 48 gene expression like NF-κB, Toll-like receptors, cytokines, and inteferons. Our results indicated that ZA (IC50 dose) increased apoptosis 1.27-fold in U87MG cells according to control cells. According to qRT-PCR data, expression levels of the endoplasmic reticulum-nuclei-1 (ERN1), Toll-like receptor 2 (TLR2), and human IFN regulatory factor 5 (IRF5) tumor suppressor genes elevated 2.05-, 2.08-, and 2.3-fold by ZA, respectively, in U87MG cells. Our recent results indicated that ZA have a key role in GBM progression and might be considered as a potential agent in glioma treatment.

Zoledronic acid inhibits the pentose phosphate pathway through attenuating the Ras-TAp73-G6PD axis in bladder cancer cells

Zoledronic acid (ZA) is the current standard of care for the therapy of patients with bone metastasis or osteoporosis. ZA inhibits the prenylation of small guanosine‑5'-triphosphate (GTP)‑binding proteins, such as Ras, and thus inhibit Ras signaling. The present study demonstrated that ZA inhibited cell proliferation and the pentose phosphate pathway (PPP) in bladder cancer cells. In addition, the expression of glucose‑6‑phosphate dehydrogenase (G6PD, the rate‑limiting enzyme of the PPP) was found to be inhibited by ZA. Furthermore, the stability of TAp73, which activates the expression G6PD was decreased in zoledronic acid treated cells. Decreased levels of Ras‑GTP and phosphorylated‑extracellular signal-regulated kinase 1/2 were also observed following treatment with ZA. This may be due to the fact that activated Ras was reported to stabilize TAp73 inducing its accumulation. The inhibition of Ras activity by PT inhibitor II also significantly reduced the levels of TAp73 and G6PD and the PPP flux. Moreover, knockdown of TAp73, attenuated the PPP flux and eliminated the affection of ZA on the PPP flux. In conclusion, it was proposed that ZA can inhibit stability of TAp73 and attenuate the PPP via blocking Ras signaling in bladder cancer cells.

Skeletal consequences of RANKL-blocking antibody (IK22-5) injections during growth: mouse strain disparities and synergic effect with zoledronic acid

High doses of bone resorption inhibitors are currently under evaluation in pediatric oncology. Previous works have evidenced transient arrest in long bone and skull bone growth and tooth eruption blockage when mice were treated with zoledronic acid (ZOL). The question of potential similar effects with a RANKL-blocking antibody (IK22.5) was raised. Sensitivity disparities in these inhibitors between mouse strains and synergic effects of zoledronic acid and a RANKL-blocking antibody were subsidiary questions. In order to answer these questions, newborn C57BL/6J and CD1 mice were injected every two or three days (4 injections in total so 7 or 10 days of treatment length) with high doses of a RANKL-blocking antibody. The consequences on the tibia, craniofacial bones and teeth were analyzed by μCT and histology at the end of the treatment and one, two and three months later. The results obtained showed that RANKL-blocking antibody injections induced a transient arrest of tibia and skull bone growth and an irreversible blockage of tooth eruption in C57BL/6J mice. In CD1 mice, tooth eruption defects were also present but only at much higher doses. Similar mouse strain differences were obtained with zoledronic acid. Finally, a synergic effect of the two inhibitors was evidenced. In conclusion as previously observed for bisphosphonates (ZOL), a RANKL-blocking antibody induced a transient arrest in long bone and skull bone growth and a blockage of tooth eruption with however disparities between mouse strains with regard to this last effect. A synergic effect of both bone resorption inhibitors was also demonstrated.

Reactive oxygen species and autophagy associated apoptosis and limitation of clonogenic survival induced by zoledronic acid in salivary adenoid cystic carcinoma cell line SACC-83

Salivary adenoid cystic carcinoma is an epithelial tumor in the head and neck region. Despite its slow growth, patients with salivary adenoid cystic carcinoma exhibit poor long term survival because of a high rate of distant metastasis. Lung and bone are common distant metastasis sites. Zoledronic acid, a third generation bisphosphonate, has been used for tumor-induced osteolysis due to bone metastasis and has direct antitumor activity in several human neoplasms. Here, we observed that zoledronic acid inhibited salivary adenoid cystic carcinoma cell line SACC-83 xenograft tumor growth in nude mice. In vitro, zoledronic acid induced apoptosis and reduced clonogenic survival in SACC-83. Flow cytometry and western blotting indicated that the cell cycle was arrested at G0/G1. Zoledronic acid treatment upregulated reactive oxygen species as well as the autophagy marker protein LC-3B. Reactive oxygen species scavenger N-acetylcysteine and autophagy antagonist 3-methyladenine decreased zoledronic acid-induced apoptosis and increased clonogenic survival. Silencing of the autophagy related gene Beclin-1 also decreased zoledronic acid-induced apoptosis and inhibition of clonogenic formation. In addition, isobolographic analysis revealed synergistic effects on apoptosis when zoledronic acid and paclitaxel/cisplatin were combined. Taken together, our results suggest that zoledronic acid induced apoptosis and reduced clonogenic survival via upregulation of reactive oxygen species and autophagy in the SACC-83 cell line. Thus, zoledronic acid should be considered a promising drug for the treatment of salivary adenoid cystic carcinoma.

Establishment and analysis of osteosarcoma cell sublines with different metastatic characteristics

The aim of this study is to establish human osteosarcoma MG-63 cell sublines with different metastatic characteristics and provide good experimental models for mechanism study of osteosarcoma metastasis. Six cell sublines were screened and established by using the in vitro cloning technology. In vitro invasion experiments, cellular electrophoretic mobility determinations, cellular proliferation rate determinations, and soft agar clone formation assays were used to compare, analyze, and identify the metastatic characteristics of various cell sublines. The results indicated that the invasion capacity, cellular electrophoretic mobility, cell proliferation, and soft agar clone formation capacity of A2, A3, and A16 sublines were higher than those of A1, A6, and A20 sublines. There was no significant difference in various values determined among A2, A3, and A16, and among A1, A6, and A20 (P > 0.05), but there were significant differences in various values determined between the former three and the latter three (P < 0.05). In conclusion, MG-63 cell sublines with different metastatic characteristics can be established by combining several technologies and can contribute to further research on the mechanism of osteosarcoma metastasis.

The dual role of autophagy in chondrocyte responses in the pathogenesis of articular cartilage degeneration in osteoarthritis

The present study aimed to analyze the responses to autophagy in osteoarthritis (OA) and aging chondrocytes in order to elucidate the role of autophagy in the pathogenesis of OA. We used multiple assays to confirm that autophagic activity was downregulated in chondrocytes of aged articular cartilage. Surprisingly, we found that the expression of autophagy-related proteins was not decreased in the tissues of patients with OA. We also observed that rapamycin-induced autophagy prevented the accumulation of subdiploid cells in young chondrocytes, while it induced cell death by autophagy in OA chondrocytes. Our results demonstrate that autophagic activity decreases with aging, and may be responsible for the cytoprotective effects in young cartilage. However, we found that autophagic activity in patients with OA was higher than in the aging group, and reported autophagic cell death in OA chondrocytes. These results suggest that autophagy plays both a cytoprotective and death-promoting role in the pathogenesis of OA.