| Objective: Lymphoma is one of the common cancers in hematological system with an increasing incidence. At present, treatment is still the primary means of traditional chemotherapy and radiotherapy, but there are some important factors which will induce secondary tumor and drugs resistance to influence long term survival. Therefore, it is urgently needed that exploring more safe, economic, effective methods and treatments to improve the patient's prognosis and quality of life. Studies in recent years have founded that COX-2 is high expression in a lot of tumors, and COX played a key role in tumorigenesis and development. Nonsteroidal anti-inflammatory drugs (NSAIDs) especially the selective inhibitor of COX-2 have a wide range of tumor inhibition may reduce the incidence of tumors and prevent tumor formation, tumor recurrence and the transfer of the body. Celecoxib, is one of the selective inhibitor of COX-2 and it has been widely used in bone and joint diseases. In recent years, many reports show that it can induce anti-neoplastic activity on many human tumor cell lines. Bcl-2 in human follicular lymphoma t(14;18)(q32; q21) translocation breakpoints found on a proto-oncogene, located in human chromosome 18q21. Bcl-2 protein is to inhibit the function of apoptosis, to extend the life of cells, the cells increased apoptosis incentives for all kinds of resistance, but does not affect cell division and proliferation. At present, little has been elucidated on the relationship between expression of Bcl-2 and apoptosis induced by Celecoxib in lymphoma cells. In this study, in order to investigate the possible antitumor mechanism of Celecoxib in COX-2 independent pathway, we observed the effect of selective COX-2 inhibitor Celecoxib on proliferation, apoptosis, cell cycle distribution and Bcl-2 mRNA expression in human malignant lymphoma cell line Namalwa. Thus, theory evidence of Celecoxib in clinical application will be provided.Materials and method:Human lymphoma cells Namalwa were cultivated in vitro and then treated with various concentrations of Celecoxib. Cell inhibitory growth rate was investigated by MTT assay. Apoptosis rate, cell cycle distribution were detected by Flow cytometry (FCM). Expression of Bcl-2 mRNA in Namalwa cells was detected by RT-PCR. The results were analyzed by SPSS13.0, and we established the standard of statistic significance asα=0.05.Results:1. Celecoxib on Namalwa cell growth inhibition: Cell inhibitory growth rate of Namalwa after treated with various concentrations of Celecoxib ( 20, 40, 80, 120, 160μmol/L) for 24 hours were 4.11%, 5.74%, 9.30%, 15.43%, 16.68% respectively. Cell inhibitory growth rate of Namalwa after treated with various concentrations of Celecoxib for 48 hours were 10.31%, 11.04%, 21.01%, 28.48%, 29.47% respectively. Cell inhibitory growth rate of Namalwa after treated with various concentrations of Celecoxib for 72 hours were 11.30%, 11.87%, 28.82%, 44.39%, 43.33% respectively. Cell inhibitory growth rate in experiment groups after treated Namalwa cells for 24h, 48h, 72h were significantly different (P<0.05) , at the same time, there was a significant difference between concentration groups and time groups (P<0.05).2. Celecoxib on cell cycle of Namalwa: After Namalwa cells treated with various concentrations of Celecoxib (0, 40, 80, 120μmol/L) for 48 hours, the cell percentage in G0/G1 phase of test groups were (27.76±1.89)%, (42.85±0.25)%, (48.45±0.6)%, (51.63±1.97)% respectively; the cell percentage in S phase were (52.86±4.60)%, (43.65±2.12)%, (38.18±1.29)%, (34.47±0.71)% respectively; the cell percentage in G2/M phase were (18.87±0.49)%, (15.98±1.15)%, (13.60±0.55)%, (11.07±0.23)% respectively. By one-way ANOVA, cell cycle distribution were significantly different among concentration groups, with the concentration of Celecoxib increased, cells in G0/G1 phase increased obviously and cells in S, G2/M phase decreased (P<0.05), the cells were blockaged on G0/G1 phase.3. Celecoxib on apoptosis of Namalwa: Apoptosis cells increased significantly after Namalwa cells treated with Celecoxib (40, 80, 120μmol/L) for 48 hours. Apoptosis percentage (AP) were (14.48±2.18)%, (24.74±3.19)%, (31.60±4.83)% respectively; and AP in control (Celecoxib is 0μmol/L) was (4.82±0.58)%. By one-way ANOVA, AP were significantly different among concentration groups (P<0.05).4. RT-PCR showed: The correspondent expression of Bcl-2 mRNA in Namalwa cells after treated with Celecoxib for 48 hours at the concentrations of 0μmol/L, 40μmol/L, 80μmol/L, 120μmol/L were (0.92±0.031), (0.81±0.04), (0.71±0.042), (0.57±0.051) respectively. The correspondent expression of Bcl-2 mRNA were significantly decreased. The decreasing expression of Bcl-2 mRNA existed significant difference among concentration groups (P<0.05).Conclusions:1 The survival of Namalwa cells was inhibited by Celecoxib in vitro with a concentration and time dependent manners.2 The number of Namalwa cells in G0/G1 phase was increased, while those in S and G2 phase was decreased by the effect of Celecoxib. Celecoxib induced cell cycle arrest in G0/G1 phase and inhibited the growth of Namalwa Cells.3 Celecoxib can induce apoptosis on Namalwa. With the Celecoxib concentration increased, apoptotic percentage of Namalwa cells increased in a concentration-dependent.4 The expression of Bcl-2 mRNA in Namalwa cells can be downregulated by Celecoxib in vitro with a concentration dependent manner. So think that apoptosis in Namalwa cells can be induced by Celecoxib through the downregulation of Bcl-2 mRNA expression.
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