Study On Expression And Mechanism Of Syk In Human B Lymphoma Cell Lines

Backgroud: Spleen Tyrosine Kinase (Syk) is a non-receptor type of protein–tyrosine kinase that is widely expressed in humatopoietic cells, lymphocyte, fibroblast and vascular endothelial cells. Syk plays an essential role in lymphocyte development and activation. Syk gene is a candidate anti-oncogene, plays a significant role in suppressing the growth and metastasis of malignant tumor cells. In this study, expression of Syk gene and protein in human B lymphomas and methylation status of the 5'CpG island locating in the promoter region of Syk gene were investigated.Methods:1 Immunohistochemical (S-P method) and Western-blot were used to detect the expression of Syk in B lymphoma cell lines Raji, Ramos and Namalwa cell.2 RT-PCR was used to measure the expression of Syk gene.3 Proliferation, cell cycle and apoptosis in Raji and Ramos cells were analyzed by MTT method, flow cytometry, agarose gel electrophoresis and electronmicroscope after treatment with 5-aza-CDR.4 The methylation status of the 5'CpG island locating in the promoter region of Syk gene in B lymphoma cell lines was detected by methylation specific PCR.Results:1 By immunohistochemical staining with anti-Syk antibody, Syk was expressed in cytoplasm which is as positive reaction; whereas is as negative reaction if Syk was not expressed in cytoplasm. It is showed that Syk is expressed in Raji and Namalwa cell, Ramos cell did not express Syk protein. The results of Western-blot analysis showed Syk is expressed in Raji and Namalwa cell, Ramos cell did not express Syk protein.2 By analysis of RT-PCR, it is show that Syk mRNA express in Raji and Namalwa cells, but did not express in Ramos cells.3 The proliferation of Raji and Ramos were markedly inhibited by methylation inhibitor 5-aza-CdR. After treatment with 5-aza-CdR for 96h, the cell cycle of Raji and Ramos cells were not obviously altered (P>0.05). At the same time, the apoptosis rate of Raji and Ramos cells were obviously increased than the group treat with 0μΜ5-aza-CDR(P<0.05).4 By analysis of methylation-specific PCR, it is shown that Syk is not hypermethylated in Ramos and Raji cells.Conclusions:1 Both Raji and Namalwa of B lymphoma cell lines express syk protein and syk gene, but another B lymphoma cell line Ramos cell were not express syk in gene level and protein level. 2 5-aza-CDR, a methylation inhibitor, can inhibit the proliferation and augment apoptosis of Raji and Ramos cells, but not alter cell cycle.3 There was no significant correlation between the silencing of Syk gene and gene methylation in Raji and Ramos cells.