The Relationship Between TRX-binding Protein-2 And Breast Cancer

Breast cancer is one of the most common malignant tumors, the incidence accounts for 10-22.7% in various systemic malignant tumors. It is a kind of common disease endangering the human health. There are about 40,000 people die of breast cancer every year in China, which is next to uterine carcinoma. It has been showed recently that breast cancer was caused by various effects of internal and external factors, but its mechanism is still unknown. The therapeutic methods for breast cancer include surgery, radiotherapy, chemotherapy, biological therapy and so on, however, the therapeutic methods for breast cancer are limited, thus in order to prevent early and to decrease the pain and death brought by breast cancer, it is necessary to study the mechanism further.Thioredoxin is regulating redox protein, exists ubiquitous in various tissues, cells. It has the biology activities of anti-oxidantion, anti-apoptosis, promoting the growth of the cell and immune accommodation. Thioredoxin binding protein-2 is a negative modulatory protein of thioredoxin, it binds the activity site of thioredoxin and inhibits the reducing function of thioredoxin. In many tissues of cancer, expression of thioredoxin is increased and expression of thioredoxin binding protein-2 is decreased or deleted. Cyclooxygenase is a rate-limiting enzyme of arachidonic acid metabolism. It plays roles in anti-apoptosis, up regulating vascular endothelial growth factor. Its expression is also increased in cancer tissue.This study detected the expression changes of thioredoxin, thioredoxin-binding protein-2 and cyclooxygenase-2 in clinical breast cancer tissue and tissues surrounding tumors by western blot and fluorescence real-time PCR. The MCF-7 cells were treated with paclitaxel, and the inductive effect of paclitaxel on the thioredoxin binding proterin-2 was examined. The results showed that expression of thioredoxin and cyclooxygenase-2 were increased, while the expression of thioredoxin-binding protein-2 was decreased in breast cancer tissues. SB203580, the inhibitor of p38 mitogen activited protein kinase, inhibited the increased expression of tioredoxin binding protein-2 induced by paclitaxel in the MCF-7 cells. The above results are concluded that thioredoxin,thioredoxin-binding protein-2 and cyclooxygenase-2 are closely related and closely associated to breast cancer. Thioredoxin binding protein-2 played an important role in paclitaxel anti-cancer, Paclitaxel induced thioredoxin-binding protein-2 expression through the p38 mitogen-activated protein kinase in MCF-7 cells and inhited the cell growth.This study further elucidated the new mechanism on paclitaxel anti-cancer and provided the research base with thioredoxin-binding protein-2 becoming target of breast cancer.