Despite existing chemotherapy and surgical resection strategies, salivary gland adenocarcinoma(AdCa NOS) is one of the major causes of mortality among malignant salivary gland tumors. New therapeutic measure are needed to improve the outcome for patients with AdCa. Overexpression of urokinase-type plasminogen activator receptor/urokinase-type plasminogen activator(uPAR-uPA) has been implicated in progression and metastasis of oral cancer. RNA interference(RNAi) which has emerged as an effective method to target specific genes for silencing has provided new opportunities for cancer therapy. But there has been rarely reported using RNAi-uPAR/uPA transfection in salivary gland AdCa. The purpose of this study were to examine the specific inhibition of uPAR/uPA mRNA and protein expression by RNAi transfection of uPAR/uPA through RT-PCR and Immunoslot blot, and to study tumor cell proliferation activity, adhesion, invasion and migration of SGT cell line in vitro compared to the controls. In adhesion assay, cells transfected with RNAi-uPAR/uPA inhibited markedly adhesion to vitronectin compared to parental cells. Angiogenic assays revealed a significant decrease in the angiogenic potential of SGT cells downregulated by both uPAR and uPA. In migration assay, suppressing uPAR and uPA inhibited the capacity of the cells to migrate compared to parental cells. In invasion assay, cells transfected with RNAi-uPAR/uPA showed the maximum decrease in invasion when compared to all other treatment conditions. RNAi expressing plasmids efficiently downregulated mRNA and protein expression of uPAR and uPA. Cell cycle analysis showed that the simultaneous downregulation of uPAR and uPA caused the accumulation of cells in the sub-G0/G1 phase in SGT cells. Immunoslot blot analysis revealed that downregulation of uPAR and uPA caused the prominent activation of caspase 8. It suggested that the RNAi targeting of the uPAR/uPA system could have a therapeutic potentiality for malignant salivary gland tumors.

• 오민구(단국대학교 치과대학 구강병리학교실) | Min Koo Oh (Department of Oral Pathology, College of Dentistry, Dankook University)
• 이종헌(단국대학교 치과대학 구강노화연구소) | Chong Heon Lee (Department of Oral Pathology, College of Dentistry, Oral Aging Research Center, Dankook University) Correspondence