Teller Anne, Jechorek Doerthe, Hartig Roland, Adolf Daniela, Reißig Kathrin, Roessner Albert, Franke Sabine
Institute of Pathology, Otto-von-Guericke University, Leipziger Str. 44, D-39120 Magdeburg, Germany.
Institute of Molecular and Clinical Immunology, Otto-von-Guericke University, Leipziger Str. 44, D-39120 Magdeburg, Germany.
Pathol Res Pract. 2015 Jan;211(1):62-70. doi: 10.1016/j.prp.2014.09.005. Epub 2014 Sep 28.
Cathepsin X (CTSX, also called cathepsin Z/P) is a cysteine protease that still plays an unknown role in human cancer. It has been shown to bind cell surface heparin sulphate proteoglycans and integrins, indicating possible functions of CTSX in cellular adhesion, phagocytosis, and immune response. Our previous studies have shown an association between Helicobacter pylori (H. pylori) infection, a strong up-regulation of CTSX, and development of gastric cancer. In this study, yeast two-hybrid analysis revealed that RPLP0, a ribosomal protein P0, interacts with the human CTSX protein in gastric cancer. The CTSX/RPLP0 interaction was confirmed by co-immunoprecipitation assays. In addition, co-localization studies in cancer cell line N87 and gastric cancer tissue samples were performed. Laserscan microscopy revealed a shuttling of RPLP0 (and CTSX) from cytoplasm to the nucleus after CTSX knockdown. Down-regulation of RPLP0 resulted in G1 arrest of gastric cancer cells, whereas knockdown of CTSX led to G1 arrest and apoptosis after 48 h. Knockdown of both proteins caused increased apoptosis. RPLP0 deficiency could suppress cell growth and cell cycle progression by down-regulating CDK2. It was further demonstrated that RPLP0 affected p21 expression, but did not change the expression of Cyclin E. Down-regulation of both proteins at least through CDK2 suggests an anti-apoptotic effect on gastric cancer cells and opens up new possibilities for apoptotic immune modulation and gastric cancer therapy.
组织蛋白酶X（CTSX，也称为组织蛋白酶Z/P）是一种半胱氨酸蛋白酶，其在人类癌症中的作用尚不清楚。已证明它能结合细胞表面硫酸乙酰肝素蛋白聚糖和整合素，这表明CTSX在细胞黏附、吞噬作用和免疫反应中可能发挥作用。我们之前的研究表明，幽门螺杆菌（H. pylori）感染、CTSX的强烈上调与胃癌的发生之间存在关联。在本研究中，酵母双杂交分析显示，核糖体蛋白P0（RPLP0）在胃癌中与人CTSX蛋白相互作用。通过免疫共沉淀试验证实了CTSX/RPLP0的相互作用。此外，还对癌细胞系N87和胃癌组织样本进行了共定位研究。激光扫描显微镜显示，CTSX敲低后，RPLP0（和CTSX）从细胞质穿梭至细胞核。RPLP0的下调导致胃癌细胞G1期停滞，而CTSX的敲低导致48小时后G1期停滞和凋亡。两种蛋白的敲低均导致凋亡增加。RPLP0缺陷可通过下调CDK2抑制细胞生长和细胞周期进程。进一步证明，RPLP0影响p21表达，但不改变细胞周期蛋白E的表达。至少通过CDK2下调这两种蛋白表明其对胃癌细胞具有抗凋亡作用，并为凋亡免疫调节和胃癌治疗开辟了新的可能性。
