ABSTRACT
Recent studies have demonstrated that a caspase-activated deoxyribonuclease (CAD) causes DNA degradation in nuclei after treatment of cells with caspase-3. In this study, we evaluated the effect of CAD overexpression on tumor cells treated with a chemotherapeutic agent in vitro and in vivo. In an in vitro study, we transfected mouse fibroblast L cells with a vector encoding mouse CAD and evaluated the therapeutic potential of CAD gene transfer to L cells treated with cisplatin (CDDP). In an in vivo study, percutaneous transfer of the mouse CAD gene by particle-mediated (gene gun) delivery caused overexpression of CAD in mouse squamous cell carcinoma (SCC). Our results showed that a combined treatment of CDDP and exogenous introduction of the CAD gene into tumor cells in vitro and in vivo arrested tumor growth and induced apoptosis. These results suggest that combined treatment of CDDP and exogenous CAD expression might be a useful strategy for cancer therapy.
Subject(s)
Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Carcinoma, Squamous Cell/therapy , Cisplatin/pharmacology , Deoxyribonucleases/genetics , Genetic Therapy/methods , Head and Neck Neoplasms/therapy , Animals , Apoptosis/genetics , Biolistics , Carcinoma, Squamous Cell/pathology , Cells, Cultured , Combined Modality Therapy , Deoxyribonucleases/metabolism , Fibroblasts/enzymology , Fibroblasts/ultrastructure , Genetic Vectors , Head and Neck Neoplasms/pathology , Mice , Mice, Inbred C3H , Neoplasm Transplantation , TransfectionABSTRACT
Platelet-derived endothelial cell growth factor (PD-ECGF) was isolated as an endothelial mitogen from platelets and demonstrated to have angiogenic activity and thymidine phosphorylase (TP) activity. It was reported that the overexpression of PD-ECGF occurred with the rapid tumor growth in vivo. In this study, we transfected PD-ECGF into the head and neck squamous cell carcinoma cell line IMC-3 and investigated the property of transfectants in vitro. Highly overexpressed PD-ECGF transfectants rapidly grew compared with parental cells and control vector (CV) transfectants (p<0.05). The expression of cyclin D1 and cyclin E were more enhanced in PD-ECGF transfectants than parental cells and CV transfectants, while the p27kip1 was inhibited in PD-ECGF transfectants. In PD-ECGF transfectants, S and G2/M-phase cells rapidly increased compared with parental cells and CV transfectants. These results showed that the cancer cell line with high expression of PD-ECGF had a rapid cell cycle and consequently facilitated rapid cell growth not only in vivo but also in vitro. Furthermore, the inhibitor of thymidine phosphorylase (TPI) suppressed the cell cycle and rapid cell growth that were acquired by PD-ECGF transfection. Since PD-ECGF was reported to be an independent, poor prognosis factor for head and neck cancer, TPI might be useful for the inhibition of cancer cell growth.
Subject(s)
Carcinoma, Squamous Cell/pathology , Cell Cycle/physiology , Gene Expression Regulation, Enzymologic/physiology , Head and Neck Neoplasms/pathology , Thymidine Phosphorylase/metabolism , Carcinoma, Squamous Cell/enzymology , Cell Cycle Proteins/metabolism , Cyclin D1/metabolism , Cyclin E/metabolism , Cyclin-Dependent Kinase Inhibitor p27 , Cyclin-Dependent Kinases/antagonists & inhibitors , Enzyme Inhibitors/pharmacology , Head and Neck Neoplasms/enzymology , Humans , In Vitro Techniques , Thymidine Phosphorylase/genetics , Transfection , Tumor Cells, Cultured , Tumor Suppressor Proteins/metabolismABSTRACT
We retrospectively reviewed 52 patients who underwent middle ear surgery during which the chorda tympani nerves were severed and who then underwent secondary surgery 1 to 5 years later. In 22 patients (42.3%), regenerated chorda tympani nerves (entire length of the tympanic segment) were detected in the submucosal layer of the reconstructed eardrum during the secondary surgery. Before the secondary surgery, 16 patients (30.8%) showed threshold recovery on electrogustometry. When 5 regenerated nerves were observed by transmission electron microscopy, myelinated nerve fibers were detected in a small fascicle or connective tissue, but the number of myelinated axons was significantly decreased (7.4% to 84.6%; p = .01) compared with that in normal subjects (1,911 +/- 324; n = 4). There was a significant difference in the incidence of regeneration between the group with end-to-end anastomosis (5/5 or 100%) and that with nerve gap defects (17/47 or 36.2%; p <.05); this finding suggests that repair of the sectioned nerve produces a better incidence of regeneration than leaving the nerve unrepaired.
