Efficacy of an orally active small-molecule inhibitor of RANKL in bone metastasis

Bone is one of the preferred sites for the metastasis of malignant tumours,such as breast cancer,lung cancer and malignant melanoma.Tumour cells colonizing bone have the capacity to induce the expression of receptor activator of nuclear factor-κB ligand(RANKL),which promotes osteoclast differentiation and activation.Tumour-induced osteoclastic bone resorption leads to a vicious cycle between tumours and bone cells that fuels osteolytic tumour growth,causing bone pain and hypercalcaemia.Furthermore,RANKL contributes to bone metastasis by acting as a chemoattractant to bone for tumour cells that express its receptor,RANK.Thus inhibition of the RANKL–RANK pathway is a promising treatment for bone metastasis,and a human monoclonal anti-RANKL antibody,denosumab,has been used in the clinic.However,orally available drugs targeting RANKL must be developed to increase the therapeutic benefits to patients.Here we report the efficacy of the small-molecule RANKL inhibitor AS2676293 in treating bone metastasis using mouse models.Oral administration of AS2676293 markedly inhibited bone metastasis of human breast cancer cells MDA-MB-231-5a-D-Luc2 as well as tumour-induced osteolysis.AS2676293 suppressed RANKLmediated tumour migration in the transwell assay and inhibited bone metastasis of the murine cell line B16F10,which is known not to trigger osteoclast activation.Based on the results from this study,RANKL inhibition with a small-molecule compound constitutes a promising therapeutic strategy for treating bone metastasis by inhibiting both osteoclastic bone resorption and tumour migration to bone.

Calcitonin and vitamin D3 have high therapeutic potential for improving diabetic mandibular growth

The goal of this study was to assess the effect of the intermittent combination of an antiresorptive agent （calcitonin） and an anabolic agent （vitamin D3） on treating the detrimental effects of Type 1 diabetes mellitus （DM） on mandibular bone formation and growth. Forty 3-week-old male Wistar rats were divided into four groups： the control group （normal rats）, the control C＋D group （normal rats injected with calcitonin and vitamin D3）, the diabetic C＋D group （diabetic rats injected with calcitonin and vitamin D3） and the diabetic group （uncontrolled diabetic rats）. An experimental DM condition was induced in the male Wistar rats in the diabetic and diabetic C＋ D groups using a single dose of 60 mg.kg-1 body weight of streptozotocin. Calcitonin and vitamin D3 were simultaneously injected in the rats of the control C＋D and diabetic C＋D groups. All rats were killed after 4 weeks, and the right mandibles were evaluated by micro-computed tomography and histomorphometric analysis. Diabetic rats showed a significant deterioration in bone quality and bone formation （diabetic group）. By contrast, with the injection of calcitonin and vitamin D3, both bone parameters and bone formation significantly improved （diabetic C＋ D group） （P 〈 0.05）. These findings suggest that these two hormones might potentially improve various bone properties.

A new approach to transfect NF-κB decoy oligodeoxynucleotides into the periodontal tissue using the ultrasound-microbubble method

The objective of this study is to investigate the effect of the ultrasound-microbubble technique in nuclear factor kappa B(NF-κB) decoy oligodeoxynucleotide(ODN) transfection in the gingival tissue in mice. The 6-FAM-labeled scrambled decoy ODN with microbubbles was applied to the periodontal tissue in 8-week-old male C57BL/6J mice by ultrasound radiation at low(LUM-Sc) and high(HUM-Sc) intensities to optimize the transfection condition of the ultrasound-microbubble method.Histological inspections were performed two hours after transfection to compare the expression with that in the sham-operated group without ultrasound radiation(A-Sc). Then, an NF-κB decoy was transfected into the periodontal tissue using the highintensity ultrasound-microbubble(HUM-NF) technique to examine the anti-inflammatory effects of the decoy ODN. Western blot analysis was performed to investigate the expression of interleukin(IL)-1β, IL-6 and intercellular adhesion molecule-1(ICAM-1)in the gingival tissues in the HUM-Sc, the HUM-NF and control groups. The fluorescence microscopy results showed that the fluorescent intensity in the periodontal tissues in the LUM-Sc and HUM-Sc groups was significantly higher than that in the A-Sc and the control groups. The fluorescent intensity in the HUM-Sc group, especially in the gingival connective tissue,was the highest of all groups. Western blot analysis indicated that the protein expression levels of IL-1β, IL-6 and ICAM-1 in the HUM-NF group were significantly lower than those in the HUM-Sc and the control groups. These findings suggest that the high-intensity ultrasound-microbubble technique is an effective tool for decoy transfection into the periodontal tissue.