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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.
Key words : RNAi Transfection, uPAR, uPA, Salivary Gland Tumor Cell Line