[Osteoclastic bone destruction and its regulating factors in oral squamous cell carcinoma]

To investigate the osteoclastic activity in oral squamous cell carcinoma (OSCC) invading the jaws and to observe the expression of RANKL and OPG, the two bone resorption related cytokines, in these cases.

Twelve cases of OSCC invading the mandible were studied. After pathological diagnosis, operations were done to remove part of the mandible depending upon the X-ray findings. Fresh soft tissue specimens were frozen-sectioned and other specimens with the bone tissue were fixed and decalcified to make paraffin sections. Tartrate-resistant acid phosphatase(TRAP) staining and immunohistochemical staining were then applied to observe the location of osteoclasts and the expression of RANKL and OPG.

TRAP positive multinuclear cells were detected near the interface between the bone and tumor. RANKL positive cells were commonly seen on the endothelium of blood vessel and basement membrane of the epithelium. But OPG reactivities were not seen in these sections.

The bone destruction caused by OSCC is mediated by osteoclasts but not by cancer cell itself. It appears that the differentiation and activation of osteoclasts were induced by OSCC through cytokines like RANKL.