Effects of bisphosphonate on experimental jaw metastasis model in nude mice

Validating of the pre-clinical mouse model for metastatic breast cancer to the mandible

Metastatic breast carcinoma has a great tendency to spread to the mandible. It is concomitantly associated with bone destruction, food intake disorder, and a poorer prognosis. Appropriate animal models need to be developed for a better understanding of the mechanisms underlying the metastatic process of breast cancer cells to mandible and to test the effects of potential lead compounds. Here, we assessed the metastasis model of intracardiac injection using luciferase-transfected metastatic breast cancer cells (MDA-MB-231^Luc+) by determining the incidences of metastasis, mCT images, and histopathological results. A high bioluminescence signal mainly detected mandibular lesions with less frequent distal femora and proximal tibiae lesions. Extensive mandibular bone destruction occurred in nude mice grafted with metastatic breast cancer cells. This type of animal model might be a useful tool in assessing therapeutic implications and the efficacy of anti-cancer drugs for osteolytic cancers.

Bisphosphonate-related osteonecrosis of the jaw and its associated risk factors: a Belgian case series

OBJECTIVES

Bisphosphonate-related osteonecrosis of the jaw (BROJ) is a serious oral complication of bisphosphonate (BP) treatment involving the exposure of necrotic maxillary or mandibular bone. Our purpose is to describe the clinical presentation of 34 cases of BROJ and to identify potential risk factors.

STUDY DESIGN

A retrospective study was performed in four Belgian institutions.

METHODS

Complete medical histories were recorded and analyzed. These data include age, gender, initial disease requiring BP, type and duration of BP treatment, symptomatology and location of BROJ, prior dental procedures, treatment of the BROJ and treatment outcome, and radiographic, histological, and microbiological data.

RESULTS

Bisphosphonates (BP) were used in the management of disseminated cancers in 30 patients (88.5% of total studied), while four patients received BP due to osteoporosis (11.5%). The most frequently used BP was zoledronic acid in 29 patients (83%). Microbiological data obtained in 25 patients demonstrated that 72% of these patients were infected or colonized by an actinomyces. Eight of the 14 patients (57%) who received only medical treatment were cured. Of the 20 patients who underwent surgical treatments, only four were completely cured (20%). BROJ lesions smaller than 1 cm are associated with better prognosis in terms of treatment outcomes (P = .0009). Local treatments combined with long-term antibiotics are also correlated with better prognosis (P = .02).

CONCLUSIONS

Lesions smaller than 1 cm and lesions that were subject to medical treatments are associated with a better outcome. Surgical treatments appear to be non-beneficial for BROJ.

Radiographic and histological evaluation of bisphosphonate alendronate and metotrexate effects on rat mandibles inoculated with Walker 256 carcinosarcoma

PURPOSE

To investigate the effects of bisphosphosnate alendronate (ALD) and metotrexate (MTX) on an experimental model of Walker 256 carcinosarcoma developed in the oral cavity of rats. METHODS Walker 256 carcinosarcoma cell suspension (0,1 mL) containing 10(6) cell/mL was implanted in the alveoli of the first and second molars. The animals were divided and treated with saline, MTX, ALD, and MTX plus ALD. Later, the animals were sacrificed, the tumors were measured and the mandibles were removed for radiographic and histological analysis.

RESULTS

In the control group, the radiographic images demonstrated radioluscency with poorly defined borders, and the microscopic examination revealed tumor infiltration into the peripheral and central regions of the bone. Areas of necrosis were commonly seen. In the treated groups with ALD, associated or not with MTX, the radiographic analysis revealed circumscribed tumor-induced osteolysis and various degrees of radiotransparence; while, histologically, preserved bone trabeculae with osteoid formation was observed among malignant cells.

CONCLUSION

The bisphosphonate alendronate exherted an osteoprotective effect and induced bone neoformation on the Walker 256 carcinosarcoma inoculated in rat mandibles. The combination of metotrexate with bisphosphonate alendronate is more successful than treatment with the agents alone in controlling the growth of neoplastic cells and in stimulating reactive new bone. Therefore, this may be an alternative treatment to malignant lesions of maxillaries with osteolysis.

Effect of YM529 on a model of mandibular invasion by oral squamous cell carcinoma in mice

PURPOSE

This study examined the mechanisms of osteoclast-mediated bone invasion in a model of oral squamous cell carcinoma (OSCC). C3H/HeN mice were inoculated with SCC VII cells into the masseter region to establish an animal model of mandibular invasion by OSCC.

EXPERIMENTAL DESIGN

The mice were divided into three groups: a control group, given daily s.c. injections of saline; group 1, given 2 microg per mouse per day of the bisphosphonate YM529; and group 2, given 10 microg per mouse per day of YM529. After 3 weeks of treatment, the lesions were studied by micro-computed tomography. After tartrate-resistant acid phosphatase (TRAP) staining, the osteoclasts were easily identified, and the percentages of the area occupied by osteoclasts were calculated by computer for each sample. The tumors were analyzed by RT-PCR to determine the mRNA expression of interleukin-6 (IL-6), parathyroid hormone-related protein (PTHrP), tumor necrosis factor-alpha (TNF-alpha), receptor activator of nuclear factor-kappaB (RANK), RANK ligand (RANKL), and osteoprotegerin.

RESULTS

SCC VII cells rapidly multiplied in the masseter muscle of the mice. Bone invasion was evident only in the control group on micro-computed tomography. On TRAP-stained slices, the percentages of osteoclasts in groups 1 and 2 were significantly lower than that in the control group. The mRNA expressions of IL-6, PTHrP, THF-alpha, and RANK decreased as the concentration of YM529 increased.

CONCLUSIONS

We conclude that various cancer-derived cytokines play important roles in the invasion of bone by OSCC. YM529, a third-generation bisphosphonate, can suppress osteoclast-mediated bone invasion by OSCC. The mechanism of this effect might involve inhibition of cytokines such as IL-6, PTHrP, TNF-alpha, and RANK by YM529.

Modelo experimental de tumor na cavidade oral de ratos com carcinossarcoma de Walker 256

OBJETIVO: Estabelecer um modelo experimental de desenvolvimento tumoral na cavidade oral de ratos, permitindo, assim, o estudo da osteólise induzida pelo tumor nos ossos do complexo maxilomandibular como também nas estruturas dentais, através da caracterização histomorfológica da reabsorção óssea e dentária. MÉTODOS: Uma suspensão de células tumorais (0,1mL) do Carcinossarcoma de Walker 256, na concentração de 10(6) células/mL foi implantado na cavidade alveolar de ratos previamente aberta por exodontia. Os animais foram observados durante 12 (doze) dias consecutivos para determinação da curva de peso corpóreo, sendo posteriormente sacrificados e as mandíbulas removidas para exames radiográfico e histológico. RESULTADOS: No exame radiográfico foi verificada área lítica, sem evidência de reparo, na região dos alvéolos. No exame microscópico foi identificada infiltração óssea, periférica e central, de pequenas células hipercromáticas e pleomórficas, com leve infiltrado inflamatório mononuclear associado e áreas de necrose. O índice de pega foi de 100%. CONCLUSÃO: O modelo animal de invasão óssea, do tumor de Walker na cavidade oral, possibilita a avaliação in vivo de drogas antitumorais e esquemas terapêuticos no tratamento do câncer bucal.

MDA-MB-435 human breast carcinoma metastasis to bone

Breast cancer metastasizes to bone with high frequency and incidence. However, studies of breast cancer metastasis to bone have been limited by two factors. First, the number of models that colonize bone are limited. Second, detection of bone metastases is too insensitive or too laborious for routine, large-scale studies or for studying the earliest steps in bone colonization. To partially alleviate these problems, the highly metastatic MDA-MB-435 (435) human breast carcinoma cell line was engineered to constitutively express enhanced green fluorescent protein (GFP). While 435GFP cells did not form femoral metastases following orthotopic or intravenous injections, they produced widespread osteolytic skeletal metastases following injection into the left ventricle of the heart. All mice developed at least one femur metastasis as well as a mandibular metastasis. As in humans, osseous metastases localized predominantly to trabecular regions, especially proximal and distal femur, proximal tibia, proximal humerus and lumbar vertebrae. 435GFP cells also developed metastases in adrenal glands, brain and ovary following intracardiac injection, suggesting that this model may also be useful for studying organotropism to other tissues as well. Additionally, GFP-tagging permitted detection of single cells and microscopic metastases in bone at early time points following arrival and at stages of proliferation prior to coalescence of individual metastases.

Antitumor effects of bisphosphonates

BACKGROUND

Bisphosphonates are widely used to treat skeletal complications of malignancy. These drugs accumulate in bone where they inhibit osteoclastic bone resorption and reduce the local release of factors that stimulate tumor growth. The mechanism of action of bisphosphonates is dependent on chemical structure: Nonnitrogen-containing compounds (e.g., etidronate, clodronate) are metabolized into cytotoxic analogues of ATP, whereas the more potent nitrogen-containing compounds (N-BPs; e.g., pamidronate, ibandronate, zoledronic acid) inhibit protein prenylation, thus affecting cell function and survival. Because protein prenylation is required by all cells, not just osteoclasts, the possibility arises that N-BPs could also affect the viability of tumor cells.

METHODS

Several groups have investigated the in vitro effects of bisphosphonates, either alone or in combination with other antineoplastic agents, on the viability and metastatic properties of many tumor cell types. Similarly, the effect of bisphosphonate treatment on osteolysis and tumor burden has been studied in a variety of animal tumor models.

RESULTS

In vitro, submicromolar concentrations of N-BPs inhibited tumor cell adhesion and reduced invasion through extracellular matrix. At higher concentrations, antiproliferative and proapoptotic effects have been reported. In animal models of bone metastases, bisphosphonate treatment markedly reduced osteolytic lesions. There is also evidence of a reduction in tumor burden in bone and occasionally in other organs. Survival may be prolonged, but bisphosphonates do not appear to inhibit the growth of primary soft tissue tumors or orthotopic xenografts.

CONCLUSIONS

The cell culture data clearly demonstrated that N-BPs exert antitumor properties and interact synergistically with other antineoplastic agents. As bisphosphonates accumulate in bone, they can also exert cytostatic effects on tumor cells in bone metastases, either directly or indirectly via osteoclast inhibition and alterations in the bone microenvironment. Further in vivo research is now required to optimize the dosing regimen of N-BPs to exploit fully their antitumor potential.