Research On The Relation Between Expression GRP78 In Gastric Cancer Cell Lines And Its Sensitivity To Chemotherapeutic Drugs

Objective: To evaluate the expression of GRP78 in different gastric cancer cell lines and research their sensitivity to chemotherapeutic drugs, in order to analyze the relation between them and explore the initial mechanisms.Methods: MKN45, SGC7901 and NCI-N87 were cultured in vitro. The expression of GRP78 was analyzed by RT-PCR and Western blot, sensitivities of those gastric cancer cells to chemotherapeutic drugs ADM, VCR and 5-Fu, were analyzed by MTT assay, then researched the relation between expression of GRP78 and sensitivity to chemotherapeutic drugs. SGC7901 was treated by the Ca²⁺ carrier A23187 and the Ca²⁺ chelator BAPTA-AM. The expression of GRP78 and AKT/PKB in SGC7901, A23187-SGC7901 and BAPTA-AM-SGC7901 were also analyzed by RT-PCR and Western blot. The MTT assay and flow cytometry were used for evaluating sensitivities of those gastric cancer cells to chemotherapeutic drugs. Then explore the initial mechanisms.Results: GRP78 was expressed in all the different gastric cancer cell lines, the highest expression in MKN45, followed by SGC7901, the lowest in NCI-N87, ratios of gray values of GRP78 mRNA andβ-actin mRNA were 1.450±0.055,0.694±0.067,0.462±0.061(p<0.05), ratios of gray values of GRP78 protein andβ-actin were 0.838±0.079,0.559±0.030,0.478±0.016(p<0.05). Inhibition of chemotherapeutic drugs to MKN45 was the lowest one, the highest one was NCI-N87, Inhibitions of ADM were 53.2%,69.8%,82.1%(p<0.05),Inhibitions of VCR were 38.0%,50.7%,75.0%(p<0.05), Inhibitions of 5-Fu were 26.1%,41.5%,57.1%(p<0.05). GRP78mRNA and protein and AKT/PKB protein expression were significantly increased in SGC7901 cells treated by A23187 compared with the control group, which were decreased in SGC7901 cells treated by BAPTA-AM, ratios of gray values of GRP78 mRNA andβ-actin mRNA were 2.794±0.104,1.300±0.074,0.838±0.072(p<0.05),ratios of gray values of GRP78 protein andβ-actin were 1.133±0.068,0.905±0.020,0.601±0.041(p<0.05),ratios of gray values of AKT/PKB protein andβ-actin were 1.446±0.053, 0.857±0.034 , 0.703±0.018 ( p<0.05 ) . Inhibitions of VCR to those cell were 38.8%,56.1%,77.0%,Apoptotic rates were 2.26%,8.12%,19.74%(p<0.05).Conclusion: (1) GRP78 expression in different differentiated gastric cancer cell lines were diverse, those sensitivity to chemotherapeutic drugs were significant different , the sensitivity to chemotherapeutic drugs associated with expression of GRP78; (2) The expression of GRP78 could be increased and decreased by A23187 and BAPTA-AM, which also affected expression of AKT / PKB, thereby affected sensitivity of those cancer cells to chemotherapeutic drug.