[Short-term preoperative treatment of celecoxib, a selective cyclooxygenase-2 inhibitor, on E-cadherin expression in gastric carcinoma tissues].

BACKGROUND AND OBJECTIVE: Cyclooxygenase-2 (COX-2) inhibitors have been shown to exert chemopreventive effects against gastrointestinal carcinomas. This study was to investigate the effect of celecoxib, a selective COX-2 inhibitor, on the expression of E-cadherin and serum levels of soluble E-cadherin in gastric carcinomas. METHODS: Fifty-nine gastric carcinoma patients were randomly divided into two groups: surgery group (n=22) and celecoxib plus surgery group (n=37). Patients in the surgery group underwent surgical resection after diagnosis, while patients in the celecoxib plus surgery group received oral celecoxib, 200 mg twice daily for six days before curative resection. Twenty healthy subjects were recruited as normal controls. COX-2 and E-cadherin expressions were detected by immunohistochemistry. Serum levels of soluble E-cadherin were quantitatively measured using a commercially available enzyme-linked immunosorbent assay (ELISA) kit. RESULTS: Compared to the surgery group, the expression of COX-2 was significantly lower while that of E-cadherin was significantly higher in celecoxib plus surgery group. The concentrations of serum soluble E-cadherin before treatment were significantly higher in the surgery [(53.47+/-9.62) ng/mL] and the celecoxib plus surgery [(51.57+/-9.79) ng/mL] groups than in the control group [(37.17+/-5.38) ng/ml] (P<0.01). The soluble E-cadherin levels after surgery in both groups [(39.29+/-7.72) ng/mL and (29.29+/-8.28) ng/mL] were significantly lower than those before surgery (P<0.01). The soluble E-cadherin level on the sixth day [(44.11+/-8.36) ng/mL] was significantly lower than that before treatment in the celecoxib plus surgery group (P<0.01). CONCLUSION: Short-term preoperative treatment of celecoxib up-regulates the expression of E-cadherin in gastric carcinomas.

[A preliminary study on role of acid sphingomyelinase in receptor clustering induced by 50-Hz magnetic fields].

OBJECTIVE: To investigate the relationship among a 50-Hz MF-induced epidermal growth factor receptor (EGFR) clustering, acid sphingomyelinase (A-SMase) and ceramide (CER), and to explore the possible mechanism of receptor clustering. METHODS: Human amnion (FL) cells were exposed to a 50-Hz sinusoidal magnetic field at 0.4 mT for 15 min with or without imipramine, a specific inhibitor of A-SMase and ceramide pretreatment. EGF treatment served as the positive control and DMSO treatment served as the solvent control. The EGFR was labeled with polyclonal anti-EGFR antibody and the clustering of EGFR was analyzed using immunofluorescence and confocal microscopy. The percentage of cells with EGFR clustering was counted and compared. RESULTS: Both EGF treatment and 50-Hz MF exposure could induce EGFR clustering. However, the effect could be eliminated by imipramine pretreatment for 4 hours. When FL cells were incubated with ceramide following the imipramine pretreatment for 30 min, EGFR clustering induced by 50-Hz MF exposure could be recovered. CONCLUSION: EGFR clustering induced by 50-Hz MF depends on A-SMase activity, and ceramide, as the hydrolyzate from A-SMase might participate in the process of EGFR clustering.

[CK20 mRNA expression in peripheral blood of patients with gastrointestinal carcinoma and its clinical significance].

BACKGROUND & OBJECTIVE: Detecting expression levels of cytokeratin 19 (CK19), CK20, MUC1, and carcinoembryonic antigen (CEA) in peripheral blood,lymph node,and bone marrow is a major method for diagnosing micro-metastasis in patients with gastrointestinal carcinoma of early stages. This study was to examine the expression, before and after operation, of CK20 mRNA in peripheral blood of patients with gastrointestinal carcinoma, to further explore hematogenous-spread micro-metastasis status of these patients, and significance of CK20 mRNA detection in treatment during perioperation period. METHODS: Peripheral blood samples were collected before, and 2 weeks after operation from 62 patients with gastrointestinal carcinoma,and 22 controls (12 patients with benign gastrointestinal disease, and 10 healthy volunteers). CK20 mRNA expression in the blood samples was specifically detected by nested reverse transcriptase-polymerase chain reaction (RT-PCR). Pathologic examination of all cases was done by conventional methods. RESULTS: Of 62 patients with gastrointestinal carcinoma, 34 (54.3%) have positive CK20 mRNA expression before operation,and so did 31 (50.0%) postoperatively, but no CK20 mRNA expressed in 22 controls. In patients of stageI-IV, CK20 mRNA positive rates were 37.5% (3/8), 36.3% (8/22), 66.7% (18/27), and 100% (5/5), respectively, difference between stage I+II (36.9%) and stage III+IV (83.3%) was significant (P< 0.05). Among 35 patients with local lymph node metastasis, 27 (77.1%) were positive for CK20 mRNA; among 27 patients without lymph node metastasis, 7 (25.9%) have positive CK20 mRNA expression (P< 0.01). CK20 mRNA expression was not correlated with tumor cell differentiation,and cancer embolus existance. There was no significant difference in CK20 mRNA expression before and after operation (P >0.05). CONCLUSIONS: CK20 mRNA may be a sensitive marker for detecting micro-metastasis,and recurrence of patients with gastrointestinal carcinoma. It may be helpful for the correct clinical staging,and reasonable treatment for patients.