Therapeutic efficacy of soluble receptor activator of nuclear factor-κB-Fc delivered by nonviral gene transfer in a mouse model of osteolytic osteosarcoma

Abstract

Osteosarcoma is the most frequent primary bone tumor that develops mainly during youth, the median age of diagnosis being 18 years. Despite improvement in osteosarcoma treatment, survival rate is only 30% after 5 years for patients with pulmonary metastases at diagnosis. This warrants exploration of new therapeutic options. The anti-bone resorption molecule receptor activator of NF-KB (RANK) is very promising, as it may block the vicious cycle between bone resorption and tumor proliferation that takes place during tumor development in bone site. The cDNA encoding murine RANK-Fc (mRANK-Fc) was administered by gene transfer using an amphiphilic polymer in a mouse model of osteolytic osteosarcoma. Clinical and bone microarchitecture variables were assessed by radiography and micro-CT analyses. In vitro experiments were designed to determine the mechanism of action of RANK-Fc on tumor cell proliferation (XTT assays), apoptosis (caspase activation), cell cycle distribution (fluorescence-activated cell sorting analysis), or gene expression (reverse transcription-PCR). RANK-Fc was effective in preventing the formation of osteolytic lesions associated with osteosarcoma development and in reducing the tumor incidence, the local tumor growth, and the lung metastases dissemination leading to a 3.9-fold augmentation of mice survival 28 days after implantation. On the contrary, mRANK-Fc did not prevent the development of nonosseous tumor nodules, suggesting that bone environment is necessary for mRANK-Fc therapeutic efficacy. Furthermore, mRANK-Fc has no direct activity on osteosarcoma cells in vitro. mRANK-Fc exerts an indirect inhibitory effect on osteosarcoma progression through inhibition of bone resorption. [Mol Cancer Ther 2008;7(10):3389 -98]

Advantages of bioluminescence imaging to follow siRNA or chemotherapeutic treatments in osteosarcoma preclinical models

“…Histological analyses of transplanted LucF-POS-1 tumors showed minor necrotic, fibrotic regions (Figure 3d), which were much smaller than those observed within LucF-OSRGA tumors (Figure 2d). Radiography and microscanner analyses revealed osteolytic lesions resulting in cortical destruction comparable with those observed for parental POS-1 tumors (Figures 3e and f), suggesting that the interaction between osteoclasts and tumor cells that has been previously described for parental POS-1 cells 14 was maintained for luciferase-expressing POS-1 cells.…”

“…In our previous preclinical studies, RANKL blockade was achieved by overexpression of decoy receptors (osteoprotegerin or RANK-Fc) by gene transfer, which resulted in a strong inhibition of osteosarcoma growth. 13,14 In this study, we demonstrate that siRNA can be successfully used to target a specific gene in osteosarcoma induced in mice. This raises the possibility that RANKL inhibition in osteosarcoma may be achieved using synthetic siRNA, which would be ideal for antitumor therapies due to its ease of manufacturing and the transient nature of its effect.…”

“…The reduction in tumor incidence and growth by RANKL inhibition has also been demonstrated in osteosarcoma models. 13,14 As blocking RANKL was proven to be effective in several in vivo models, a fully humanized monoclonal antibody directed against RANKL (Denosumab) has been developed for clinical use, and is currently being evaluated in several clinical trials for the treatment of patients with lytic bone lesions secondary to multiple myeloma, prostate or breast cancer. 15 Currently, RNA interference (RNAi) is being explored as a potential treatment for cancer.…”

Orthotopic murine model of a primary malignant bone tumor in the spine: functional, bioluminescence, and histological correlations

“…6,20 Although several animal models of primary malignant bone tumors have been described, 3,5,8,9,19,23 there are no animal models of any primary malignant bone tumor in the spine; therefore, none of them addresses the sequence of events …”

Mechanisms of Humoral Hypercalcemia of Malignancy in Leukemia/Lymphoma

“…RANK-Fc was generated by combining the carboxyl-terminus of RANK with the Fc portion of human IgG1. It has been shown to decrease tumor burden in two multiple myeloma mouse models, inhibit prostate cancer bone metastasis, and decrease the incidence of lung metastasis and bone lysis in a osteosarcoma mouse model (Lamoureux et al, 2008;Sordillo & Pearse, 2003;Zhang et al, 2003). Fc-OPG was generated by combining the Fc portion of the immunoglobulin heavy chain to the amino-terminus of OPG.…”