ing breast cancer, and expression is frequently lost in other human epi thelial carcinomas. Moreover, other 14 3 3��, ��, B, isoforms have also been identified in cancer. After DNA damage, 14 3 3�� down regulated cells fail to maintain a G2 M arrest and undergo a mitotic catastrophe, which re sults in apoptosis. The reduction of 14 3 3�� expression induced the G2 arrest, which leads to mitotic catastrophe and increase radio sensitivity. To verify the expressions of identified proteins, we performed an immuno blotting analysis on 14 3 3��, 14 3 3�� and 14 3 3, which have been suggested to be involved in various cancers. Quantification of the protein bands determined that the expression of 14 3 3��, 14 3 3�� and 14 3 3 were decreased in the vitamin C treated group compared to the vehicle treated control Carfilzomib group.
These data indicated that vitamin C de creased the expression of 14 3 3 isoforms in AGS cells. These data suggest that down regulation of 14 3 3 could be a useful information in therapeutic targets of human gastric cancers. Vitamin C down regulated the cytoskeleton and associated proteins, tropomyosin alpha 3 chain and tropomyosin alpha 4 chain proteins Tropomyosins are actin binding proteins that can inte grate cell mechanics and signaling essential for cellular migration and invasion. Proteomic studies showed that the expression of tropomyosin changes, which suggest an important role for tropomyosin in maintaining cell shape. In addition, tropomyosins increase filament stiffness, stabilize actin filaments by protecting them against the severing action of gelsolin and cofilin.
In our 2 D gel system, the spots corresponding to tropo myosin 3 and tropomyosin 4 showed a decreased exp ression in the response to vitamin C. These decreased changes in the tropomyosins expression might be coincidental with morphologic changes and migratory characteristics of AGS cells in response to vitamin C. Vitamin C up regulated the antioxidant proteins, peroxiredoxin 4 and thioredoxin domain containing protein 5 Generally, antioxidant proteins play a pivotal role in the antioxidant defense system and protect the cells from oxi dative stress. There are six peroxiredoxins found in mam malians, and peroxiredoxin 4 is localized in the endoplasmic reticulum. In the present study, antioxidant and detoxification proteins, like peroxiredoxin 4 and thioredoxin domain containing protein 5, were over expressed in vitamin C treated AGS cells.
Since, vitamin C is an excellent antioxidant that increased anti oxidant protein expressions in AGS cells and protects from oxidative stress. To our knowledge there has not been a reported study regarding peroxiredoxin 4 protein expres sion in human gastric cancer adenocarcinoma AGS cells response to vitamin C. Therefore, a detailed study is neces sary regarding the effects of vitamin C on peroxiredoxin 4 protein expressions and the role of peroxiredoxin 4 protein in tumorigenesis of gastric cancer. Vitamin C altered the proteins involved in