The Expression Of Grp78 In Tumor And Induced By Tunicamycin

Background and objectiveIt has been well-documented that GRP78 is highly elevated in a variety of solid tumors, and human cancer biopsies, associating with malignancy and metastasis. So that GRP78 as a new target for cancer therapy. At present,there is no report on the relationship between GRP78 expression and gastric carcinoma. In this study, we explore the expression of GRP78 in human gastric cancer and tumor cell lines, as well as the expression of GRP78 under the induction of tunicamycin in A375 cell line.Methods1.We applied SYBR Green I real-time PCR to detect the mRNA level of GRP78,and immunohistochemistry to measure the GRP78 expression in carcinoma and normal gastric tissues,and used statistical software SPSS 15.0 to analyze the difference between the GRP78 expression in carcinoma and normal gastric tissues。2. We applied SYBR Green I real-time PCR to detect the mRNA level of GRP78 in normal live cell line L02 and eight tumor cell lines: HepG2,7721,A375,Raji,K562, MCF-7, AGS and HeLa. We detect GRP78 protein in cell surface and cytoplasm by FCM.3. A375 cells were expanded in 24-well tissue culture plates in dulbecco's modified eagale's medium, containing tunicamycin(4μg/m1) and 10% fetal calf serum . Harvested TM- treated A375 cells at different time points of 2h, 6h,12h and 24h respectively, DMSO-treated A375 cells were used as control. SYBR Green I real-time PCR and FCM were used in analyzing the expression of GRP78 at mRNA and protein levels.Results:1. The mRNA level of GRP78 gene in gastric carcinoma tissue was significantly higher than the normal mucosa(P<0.05). The proportion of GRP78 positive cells in gastric carcinoma tissue were significantly higher than normal gastric mucosa (P <0.05) in the cytoplasmic type staining.2. mRNA of GRP78 was not different between L02and HepG2,Raji,K562. GRP78 mRNA shows low expression in A375 compared with L02. In 7721,MCF-7,AGS and HeLa GRP78 mRNA shows high expression compared with L02. GRP78 were found high expression in the membrane of MCF-7, but little or no in other cell lines. In AGS GRP78 is highly expressed at mRNA and cytoplasmic protein level.3. GRP78 at mRNA level and protein both significantly increased in early phase but decreased in later phase of A375 cell line treated with tunicamycin.Conclusion1. GRP78 is over expressed in gastric carcinoma tissue, mainly located in the cytoplasm.2. GRP78 is highly expressed in gastric cancer cell line AGS, mainly located in the cytoplasm.3. The expression of GRP78 both at mRNA and protein levels were increased obviously in A375 cell line induced by tunicamycin.