[摘要]：The ribosomal protein S27 (metallopanstimulin-1, MPS-1) has been reported to be a multifunctional protein, with increased expression in a number of cancers. We reported previously that MPS-1 was highly expressed in human gastric cancer. Knockdown of MPS-1 led to spontaneous apoptosis and repressed proliferation of human gastric cancer cells in vitro and in vivo. However, how does MPS-1 regulate these processes is unclear. Here we performed microarray and pathway analyses to investigate possible pathways involved in MPS-1 knockdown-induced apoptosis in gastric cancer cells. Our results showed that knockdown of MPS-1 inhibited NF-?B activity by reducing phosphorylation of p65 at Ser536 and I?Ba at Ser32, inhibiting NF-?B nuclear translocation, and down-regulating its DNA binding activity. Furthermore, data-mining the Gene-Regulatory-Network revealed that growth arrest DNA damage inducible gene 45 beta (Gadd45 beta), a direct NF-?B target gene, played a critical role in MPS-1 knockdown-induced apoptosis. Over-expression of Gadd45 beta inhibited MPS-1 knockdown-induced apoptosis via inhibition of JNK phosphorylation. Taken together, these data revealed a novel pathway, the MPS-1/NF-?B/Gadd45 beta signal pathway, played an important role in MPS-1 knockdown-induced apoptosis of gastric cancer cells. This study sheds new light on the role of MPS-1/NF-?B in apoptosis and the possible use of MPS-1 targeting strategy in the treatment of gastric cancer.
