Effects of Helicobacter pylori infection on expression of heat shock protein 70 in human gastric mucosa and gastric cancer cells

  Background  Heat shock protein 70 (HSP70) is a protective protein produced by cells under adverse stress, and its expression in gastric mucosa cells can be affected by Helicobacter pylori (Hp) infection.

  Objective  To investigate the effect of H.pylori infection on the expression of HSP70 in human gastric mucosa and gastric cancer cells, and explore the expression characteristics of HSP70 in human gastric mucosa.

  Methods  Human gastric mucosa cells (Ges-1) and gastric cancer cells (BGC-823) were co-cultured with Hp ATCC 26695 respectively. The expression of HSP70 protein and mRNA were detected by Western-blot and RT-PCR/qPCR. Immunohistochemical staining (IHC) was used to detect Hp infection and HSP70 expression in gastric mucosa, and the distribution patterns of HSP70 protein in gastric cancer and normal gastric gland tissues were also analyzed.

  Results  HSP70 mRNA levels in both Ges-1 and BGC-823 cells co-cultured with Hp were downregulated transiently. The downregulation was most significant at 12 h in Ges-1, and at 24 h in BGC-823 cells. However, their mRNA expression levels increased at 48 h, while the expression level of HSP70 protein in Ges-1 cells and BGC-823 cells decreased gradually within 48 h. IHC showed no significant decrease in HSP70 protein expression in long-term Hp infected human gastric mucosa glands in tissue sections. Compared with normal gastric glands, HSP70 protein was highly expressed in gastric cancer tissues. HSP70 expression was also found in the oxyntic glands and proliferative cells in the normal gastric mucosa, but not in the mature gastric pit epithelial cells.

  Conclusion  The downregulation of HSP70 expression in normal gastric mucosa cells and gastric cancer cells caused by Hp infection exhibits a time dependent rhythm. The HSP70 mRNA levels of Ges-1 and BGC-823 cells decrease to the lowest point at 12 h and 24 h in vitro, and then begin to rise gradually. The expression of HSP70 protein is down-regulated gradually within 48 h, but there is no down-regulation trend in gastric mucosa tissue with long-term infection in vivo. Therefore, the down-regulation of HSP70 expression caused by Hp infection shows transient characteristics.