Terfenadine (TFN) was a second generation histamine receptor antagonist. Although several studies have reported the regulatory effect of H1-histamine receptor antagonists in human cancer cell lines, its effect in oral cancer remains unclear. In this study, we focused on addressing the anti-cancer activity of TFN in human oral cancer cell lines. The anti-cancer activities of TFN were performed by tryphan blue exclusion assay, 4'-6-diamidino-2-phenylindole (DAPI) staining, live/dead assay and Western blot analysis. TFN induced a significant reduction of the growth in three different human oral cancer cell lines (MC3, HSC4 and Ca9.22). TFN markedly induced apoptosis through DNA damage and increase in cytotoxicity. It also accumulated cleaved PARP and caspase 3. This process was due to cleavage of caspase 8 and Bid protein. The results from this study strongly demonstrated that the cleavages of caspase 8 and Bid are required for the apoptotic activity of TFN in human oral cancer cells. Taken together, these findings suggest TFN as a potent anticancer drug candidate for the treatment of oral cancer.

Abstract
 Ⅰ. INTRODUCTION
 Ⅱ. MATERIALS AND METHODS
  1. Chemicals and antibodies
  2. Cell culture and chemical treatment
  3. Trypan blue exclusion assay
  4. DAPI staining
  5. Viability/cytotoxicity assay
  6. Western blot analysis
  7. Statistical analysis
 Ⅲ. RESULTS
  1. Terfenadine (TFN) inhibits cell viability in threedifferent human oral cancer cell lines.
  2. TFN accelerates cytotoxicity and inducesapoptosis in human oral cancer cell lines byregulating caspase 8 and Bid.
 IV. DISCUSSION
 V. REFERENCES

• Dong Hoon Won(Department of Oral Pathology, School of Dentistry, and Institute of Oral Bioscience, Chonbuk National University, Jeonju, 561-756, Republic of Korea.) | 원동훈
• Hyun Ju Yu(Department of Oral Pathology, School of Dentistry, and Institute of Oral Bioscience, Chonbuk National University, Jeonju, 561-756, Republic of Korea.) | 유현주
• Nam Pyo Cho(Department of Oral Pathology, School of Dentistry, and Institute of Oral Bioscience, Chonbuk National University, Jeonju, 561-756, Republic of Korea.) | 조남표
• Sung Dae Cho(Department of Oral Pathology, School of Dentistry, and Institute of Oral Bioscience, Chonbuk National University, Jeonju, 561-756, Republic of Korea.) | 조성대 Corresponding author