[Small interfering RNA in silencing cox-2 expression enhances radiosensitivity of esophageal cancer EC9706 cell].

OBJECTIVE: To explore the effects of small interfering RNA (siRNA) specific to cox-2 gene on the radiosensitivity of esophageal cancer cell EC9706. METHODS: The siRNA vector was established for cox-2 gene and then induced into esophageal cancer cell EC9706 by lipofectamine. G418 screening yielded stably transfected cells. After the irradiation of 0, 2 and 4 Gy, the cellular expression levels of cox-2, matrix metalloproteinase-2 (MMP2), Bax and Bcl-2 were detected by reverse transcriptase-polymerase chain reaction (RT-PCR) and those of cox-2 protein, AKT protein and phosphorylation AKT protein (pAKT) by Western blot. Cell apoptosis was examined by flow cytometer. Invasion of cells was detected by invasive assay in vitro. The invasive and metastatic capacities of cancer cells were assessed by invasion assay in vitro. Proliferative potential was quantified by clone-forming assay. RESULTS: The sequencing result confirmed that siRNA vector pRNA-U6 for cox-2 gene was established. The results of 1-sinCox214, RT-PCR and Western blot showed that cox-2 gene expression of transfected EC9706 cell was silenced efficiently. After the irradiation of 0, 2 and 4 Gy, the expressions of MMP2, Bcl-2 mRNA, AKT protein and pAKT in silencing cox-2 gene expression significantly decreased. There was an inverse correlation with irradiation dose. The Bax mRNA expression evidently increased directly with irradiation dose; the apoptotic rate in cox-2 silencing groups was evidently higher than the control groups. And the difference was significant (P < 0.01); invasion cells in vitro in Cox-2 silencing groups evidently decreased with significant difference (P < 0.01). The colony formation rate of cells decreased obviously in cox-2 silencing groups after the irradiation of 0, 1, 2, 4, 6, 8 and 10 Gy (P < 0.01). CONCLUSIONS: Small interference RNA in silencing cox-2 gene expression can enhance significantly the radiosensitivity of esophageal cancer EC9706 cells. And the mechanism may be related with MMP2, Bax, Bcl-2, AKT protein and pAKT protein.

[Role of adenosine diphosphate in the course of thrombin signal transmission].

OBJECTIVE: To study the effects adenosine diphosphate (ADP) on platelet aggregation and expression of glycoprotein (GP) on the surface of platelet membrane after activation of thrombin receptors, so as to investigate its role in thrombin signal transmission. METHODS: Peripheral blood samples were collected from from 10 healthy volunteers. Platelets were extracted. The thrombin receptor activating peptides (TRAP), protease-activated receptor 1 activated peptide (PAR1-AP, SFLLRN, 25 micromol/L) and PAR4-AP (AYPGKF, 250 micromol/L) were added into the suspension of platelets respectively to induce platelet aggregation. In apyrase inhibition test apyrase II was added into the suspension of platelets for 2 hours and then PAR1-AP or PAR4-AP was added respectively to observe the the expression of GPIb and P-selectin with flow cytometry. RESULTS: Either PAR1 and PAR4 induced platelet aggregation. After apyrase II stimulation the PAR4-AP induced platelet aggregation was not influenced and PAR1-AP induced platelet aggregation was partially inhibited with a reversible aggregation curve. Stimulated by PAR1-AP and PAR4-AP the GPIb decreased firstly and then gradually returned to normal. Apyrase VII have not significant influence on the GPIb expression, but accelerated the return of GPIb to the platelet surface after PAR1 stimulation so that the lowest point was accelerated to 2 min, compared to that of the control group (5 min) and there were significantly differences 10 and 30 min later between these 2 groups (all P < 0.05). The P-selectin expression was remarkably increased 2 min after the PAR1-AP and PAR4-AP induction and peaked 2 min later. Apyrase VII did not significantly influence the P-selectin expression in these 2 activation ways. CONCLUSION: ADP plays an important role in the thrombin signal transmission, especially in the PAR1 pathway.

[Clinical significance of plasminogen activator inhibitor-1 (PAI-1) in the early development of HSCT-associated thrombotic complications.].

OBJECTIVE: To illustrate the early alteration of plasminogen activator inhibitor-1 (PAI-1) in the recipients of hematopoietic stem cell transplantation (HSCT) and explore its clinical significance in transplantation-associated thrombotic complications. METHODS: Ninety-five patients undergoing HSCT were enrolled in this study. PAI-1 level and other hemostatic parameters were measured by enzyme linked immunosorbent assay (ELISA) in platelet poor plasma samples from patients on conditioning therapy and then weekly until four weeks after HSCT. RESULTS: Significant increase in PAI-1 was detected after conditioning treatment, followed by a diminution in the very week on transplantation (week 0), then increased with in time after transplantation. According to the occurrence of transplant-associated complications, patients were classified into four groups: thrombus group \[veno-occlusive disease (VOD) (n = 5), thrombotic microangiopathy (TMA) n = 1\], aGVHD group (n = 29), infection group (n = 19) and non-complication group (n = 41). One of 30 patients (3.3%) was diagnosed as thrombus in the auto-HSCT group, while five of 65 patients (7.7%) did in the allo-HSCT group. PAI-1 level of thrombotic patients was significantly increased compared with non-thrombotic subjects, and the patients without thrombotic complications have higher PAI-1 level in the allo-HSCT group than in auto-HSCT group. All the patients with complications presented with significantly increased PAI-1 compared with those with no complications (P < 0.05). The six patients with thrombotic complications showed extremely elevated PAI-1 \[(62.8 +/- 7.5) microg/L\] compared with that of aGVHD patients \[(45.1 +/- 9.1) microg/L\] or infection patients \[(50.0 +/- 11.2) microg/L\] post-HSCT (P < 0.05). CONCLUSION: The increase in plasma PAI-1 may be a specific mark for transplantation-associated thrombotic complications. Increased PAI-1 reflects the development of thrombotic complications. Extreme elevation of PAI-1 contributes to the early diagonsis of VOD and TMA after HSCT.