[Effect of hypoglycosylated E-cadherins on proliferation and invasiveness of tongue squamous cell carcinoma].

PURPOSE: To investigate the effect of N-glycosylated E-cadherins on proliferation and invasiveness of tongue squamous cell carcinoma CAL 27 cells, and to study the effect of hypoglycosylation of E-cadherins on the stability of adherens junctions (AJs) mediated by E-cadherins. METHODS: Human tongue squamous cell carcinoma CAL 27 cells were respectively transfected with the plasmids encoding either hypoglycosylated or wild-type E-cadherins with FLAG as tags. Western blot of FLAG was used to detect the expression of exogenous E-cadherins in the transfected cells after 48 hours. The cell proliferation counting, monolayer cell scratch wound healing and in vitro cell invasiveness assays were performed to evaluate the proliferation and invasiveness of cells. Immunoprecipitation experiments were used to assay the quantity of α-catenins, ß-catenins, γ-catenins and vinculins linked with the cytosolic tails of E-cadherins. All statistical analysis were performed using SPSS 17.0 software package. RESULTS: The expression of exogenous E-cadherins was detected in transfected CAL 27 cells by Western blot. Cell proliferation counting assay revealed that hypoglycosylated E-cadherins significantly inhibited proliferation of CAL 27 cells, compared with wild-type E-cadherins. The monolayer cell scratch wound healing and in vitro cell invasiveness assays indicated that hypoglycosylated E-cadherins also significantly restrained both invasiveness of CAL 27 cells, compared with wild-type E-cadherins. The immunoprecipitation experiments demonstrated that hypoglycosylated E-cadherins exhibited an increased association with α-catenins, ß-catenins, and γ-catenins and vinculins. CONCLUSIONS: Compared with wild-type E-cadherins, hypoglycosylated E-cadherins can significantly suppress proliferation and invasiveness of tongue squamous cell carcinoma CAL 27 cells, and the mechanism was that hypoglycosylated E-cadherins can induce more stable AJs than wild-type E-cadherin. Supported by Scientific Research Foundation for the Returned Oversea Chinese Scholars, State Ministry of Education of China and Shandong Provincial Award Foundation for Excellent Middle- and Young-Aged Scientists (BS2010YY021).

Aberrant amplification of the crosstalk between canonical Wnt signaling and N-glycosylation gene DPAGT1 promotes oral cancer.

Oral cancer is one of the most aggressive epithelial malignancies, whose incidence is on the rise. Previous studies have shown that in a subset of human oral squamous cell carcinoma (OSCC) tumor specimens, overexpression of the DPAGT1 gene, encoding the dolichol-P-dependent N-acetylglucoseamine-1-phosphate transferase, a key regulator of the metabolic pathway of protein N-glycosylation, drives tumor cell discohesion by inhibiting E-cadherin adhesive function. Recently, we reported that DPAGT1 was a target of the canonical Wnt signaling pathway. Here, we link overexpression of DPAGT1 in human OSCC tumor specimens to aberrant activation of canonical Wnt signaling. We report dramatic increases in ß- and γ-catenins at the DPAGT1 promoter and correlate them with reduced expression of a Wnt inhibitor, Dickkopf-1 (Dkk-1). Using human squamous carcinoma cell lines of the head and neck, we show that partial inhibition of DPAGT1 reduces canonical Wnt signaling, indicating that DPAGT1 and canonical Wnt signaling function in a positive feedback loop. We provide evidence that E-cadherin inhibits DPAGT1, canonical Wnt signaling and the OSCC cancer phenotype by depleting nuclear ß- and γ-catenins, with hypoglycosylated E-cadherin being the most effective. This suggests that in human OSCC, extensive N-glycosylation of E-cadherin compromises its ability to inhibit canonical Wnt signaling and DPAGT1 expression. Our studies reveal a novel interplay between DPAGT1/N-glycosylation and canonical Wnt signaling and suggest that dysregulation of this crosstalk is a key mechanism underlying OSCC. They also suggest that partial inhibition of DPAGT1 may represent an effective way to restore normal interactions among these essential pathways in oral cancer.

Combined effects of soluble vascular endothelial growth factor receptor FLT-1 gene therapy and cisplatin chemotherapy in human tongue carcinoma xenografts.

The aim of the present study was to assess the anti-tumor effect of a defective adenovirus that expresses soluble vascular endothelial growth factor (VEGF) receptor FLT-1 (AdsFLT-1) in combination with cisplatin (cis-diamminedichloroplatinum, DDP) on human tongue carcinoma Tca8113 cell xenografts that had been pre-established in nude mice. In vitro, Tca8113 cells secreted soluble FLT-1 (sFLT-1) after infection with AdsFLT-1, and the conditioned medium from AdsFLT-1-treated Tca8113 cells seemed to inhibit VEGF-induced proliferation of human umbilical vein endothelial cells. The combined effects of sFLT-1 gene therapy and DDP chemotherapy was then studied in well-established Tca8113 xenografts. The concentration of sFLT-1 in serum reached a peak 8 days after intratumoral injection of AdsFLT-1. In these tumors, AdsFLT-1 intratumoral injections had only a small effect. Interestingly, when the cells were also exposed to DDP chemotherapy, significantly higher (P<0.05), and possibly synergistic, anti-tumoral effects were observed that were highly correlated to a marked reduction in intratumoral vascularization and an increase in tumor-cell apoptosis. Together, these data emphasize the potential of combining an anti-angiogenic gene therapy strategy with a destructive approach directed against the tumor cells to fight human tongue carcinoma.

[Clinical application of maxillary sinus lifting, bone graft and simultaneous placement of implant].

PURPOSE: To evaluate the results of two kinds of sinus lifting techniques with simultaneous implant placement. METHODS: 31 maxillary sinus underwent two kinds of sinus lifting techniques and simultaneously 42 implants placement. The sinuses were observed 1, 3, 6 months after the surgery. RESULTS: There were no implants loose or lost; X ray examination showed well osseointegration and no maxillary sinusitis. All the patients finished implant prosthesis in 6 months postoperatively. Through 6-36 months' follow-up, clinical results were satisfactory. CONCLUSION: With properly handling of indication and the operation skill, the results of two kinds of maxillary sinus lifting techniques with bone grafting and simultaneously implants placement are both satisfactory.

[Expression and secretion of human tumor necrosis factor gene transfected on human embryo myoblasts].

OBJECTIVE: To observe human tumor necrosis factor-alpha (hTNF-alpha) expression and secreting level of human embryo myoblasts transfected by hTNF-alpha gene. METHODS: Human embryo myoblasts were transfected with shuttle plasmid pSV23SHTNF containing hTNF-alpha gene by cationic liposomes DOSPER. The control group was only given equivalent liposomes except plasmid. After culturing for 24, 48, 72 and 96 hours, hTNF-alpha expression level of human embryo myoblasts was observed with immunocytochemistry staining, and hTNF-alpha secreting of human embryo myoblasts was analyzed by ELISA. RESULTS: After transfected by hTNF-alpha gene for 24, 48, 72 and 96 hours, the human embryo myoblasts displayed significant secretion of hTNF-alpha in the cultural supernatant (P < 0.05), and overexpression in cytoplasma and cell membrane. CONCLUSION: Transfection of hTNF-alpha gene to human myoblasts made myoblasts secrete high concentration of hTNF-alpha, implying it is feasible that transfecting muscle cells surrounding tongue carcinoma lesion with hTNF-alpha gene can prevent tongue carcinoma from intruding into deeper muscle tissue.

Induction of apoptosis and tumor regression by vesicular stomatitis virus in the presence of gemcitabine in lung cancer.

Vesicular stomatitis virus (VSV) has been shown to replicate rapidly in vitro and kill selectively a variety of tumor cell lines. The present study was designed to determine whether gemcitabine potentiates the antitumor activity of VSV in vitro and in vivo. A549 human lung adenocarcinoma cells and LLC Lewis lung carcinoma cells were treated with VSV (0.1-10 plaque-forming units per cell) plus gemcitabine (20 nM to 20 microM). Mice bearing A549 or LLC were treated with VSV (5 x 10(4) to 1 x 10(8) plaque-forming units) daily for 5 days plus gemcitabine (5-125 mg/kg/day) once every 3 days for 4 times. Induction of apoptosis and effects on growth inhibition were assessed. The lung cancer cells treated with VSV plus gemcitabine displayed the apparently increased apoptotic cells compared with treatment with VSV or gemcitabine alone. The combined treatment with VSV plus gemcitabine induced the apparent antitumor activity with complete regression of the established lung cancer in both A549 and LLC lung cancer models and augmented the induction of apoptosis in lung cancer cells in vivo as well. This study suggests that the combined treatment with VSV plus gemcitabine may augment the induction of apoptosis in lung cancer cells in vitro and in vivo, and that the augmented antitumor activity in vivo may result from the increased induction of apoptosis in lung cancer cells. The present findings may be of importance to the further exploration of the potential application of this combined approach in the treatment of lung cancer.