Effect of YM529 on a Model of Mandibular Invasion by Oral Squamous Cell Carcinoma in Mice

Abstract

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 Ag per mouse per day of the bisphosphonate YM529; and group 2, given 10 Ag 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-a (TNF-a), receptor activator of nuclear factor-nB (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-a, 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 osteoclastmediated bone invasion by OSCC. The mechanism of this effect might involve inhibition of cytokines such as IL-6, PTHrP,TNF-a, and RANK byYM529.

Establishment of a murine model of bone invasion by oral squamous cell carcinoma

“…10 We, for our part, have carried out immunohistochemical analyses on various osteoclast related cytokines, and have been able to demonstrate the possibility that IL-6, TNF-α, and PTHrP may be involved at least in bone invasion by human gingival cancer. 3,5 In much the same manner it has also been possible, in our present study with the SCCVII cell strain, to substantiate the production of these cytokines and their involvement in bone invasion and in causing the formation of osteoclasts in large numbers.…”

“…It has been confirmed that the transplantation of SCCVII cells into the masseter region of C3H/HeN mice resulted in significant tumor proliferation after three weeks. 3 This tumor is characterized by its bone invasion potential, and marked bone resorption was detected in the mandible and the facial bones. The histopathologic findings showed evidence of funicular invasion of the tumor cells into the mandible with a serrated bone resorption pattern in all specimens of the SCCVII transplanted group.…”

“…2,3,8 In our animal models, it was possible to confirm the expression of these cytokines from the SCCVII cultured cells at the mRNA level. Roughly the same results (i.e., enhanced expression of all cytokines at the mRNA level) were also obtained with neoplastic tumor tissues that had been transplanted.…”

“…In recent years, it has been reported that osteoclast associated with bone invasion and metastasis to the bone by cancer cells is mediated by osteoclasts rather than being directly caused by cancer cells (i.e., osteoclastic bone resorption). 3 We have carried out immunohistological analysis using specimens obtained from oral squamous cell carcinoma patients following mandibulectomy. 4 The results of these analytical studies have demonstrated in particular, that the presence of the osteoclast activation factors interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and parathyroid hormone-related protein (PTHrP) have a strong involvement in this process.…”

Functional Biomarkers of Oral Cancer

“…To test the aforementioned hypothesis, several OSCC cell lines were inoculated into the masseter muscles of mice, one of the most established sites for an oral cancer orthotopic model (Cui et al, 2005;Nomura et al, 2007;Suda et al, 1997). As expected, RANKL expression was dramatically augmented at both mRNA and protein levels compared to those in cultured cells ( Figure 1B).…”