Oral squamous cell carcinoma (OSCC) is the most common oral malignancy and an increasing global public health problem. OSCC frequently invades the jaw bone. OSCC-induced bone invasion has a significant impact on tumor stage, treatment selection, patient outcome, and quality of life. A number of studies have shown that osteoclastmediated bone resorption is a major step in the progression of bone invasion by OSCC; however, the molecular mechanisms involved in OSCC bone invasion are not yet clear. In this review, we present the clinical types of OSCC bone invasion and summarize the role of key molecules, including proteases, cytokines, and growth factors, in the sequential process of bone invasion. A better understanding of bone invasion will facilitate the discovery of molecular targets for early detection and treatment of OSCC bone invasion.

Introduction
 Proteases
 Cytokines
 Growth Factors
 Conclusions

• Seung Hwa Son(Oral Cancer Research Institute, Yonsei University College of Dentistry)
• Won-Yoon Chung(Oral Cancer Research Institute, Yonsei University College of Dentistry/Department of Oral Biology and BK21 PLUS Project, Yonsei University College of Dentistry/Department of Applied Life Science, The Graduate School, Yonsei University) Correspondence to