Summary of: Apoptosis in Human Hepatoma HepG2 Cells Induced by Corn Peptides and Its Anti-tumor Efficacy in H22 Tumor Bearing Mice

Li Jiangtao, Zhang Jiuliang, He Hui, Ma Zhili, Nie Zhikui, Wang Zhenzhen, Xu Xiaogen have partnered with the Department of Food Science and Technology and the Key Laboratory of Huazhong Agricultural University. Their research on the effect of corn peptides on mouse liver tumors was funded by the China National Science Foundation and the National 863 program. They conducted research to investigate the effects of plant-derived chemicals on cancer.

Curcumin content was tested. 100 Amol / L curcumin was toxic to all three tumor cell lines MDAMB, MCF-7, and HepG 2 and the cells necrosed within 1 h after treatment. However, at 50 Amol / L curcumin, the cells were mainly killed by apoptosis, so this concentration was used in subsequent experiments (FIG. 1A). On the other hand, primary rat hepatocytes did not show cell death. We also tested the effect of GSH on curcumin-induced cell death. GSH has a protective effect against all three tumor cell lines (FIG. 1B).

To confirm that curcumin-induced cell death is due to apoptosis, we examined oligonucleosomal DNA fragmentation in all cell lines. Curcumin treatment induced cellular DNA fragmentation in all three tumor cell lines; however, no DNA fragmentation was observed in normal hepatocytes (FIG. 2A). We also confirmed apoptosis in MCF-7, MDAMB and HepG2 cells by Annexin V staining (FIG. 2B). Similarly, normal hepatocytes are not stained with Annexin V. Increase in GSH levels and related activities at GSH levels of different cell types

Apoptosis of HeLa cells is inhibited by proteins produced by the cells and these inhibitory proteins target retinoblastoma tumor suppressor proteins. These tumor suppressor proteins regulate the cell cycle, but become inactive upon binding to inhibitory proteins. HPV E6 and E7 are inhibitory proteins expressed by human papillomavirus and HPV is involved in the formation of cervical tumors from HeLa cells. HPV E6 inactivates the cell cycle regulating p53. HPV E7 binds to tumor suppressor proteins of retinoblastoma and limits the ability to control cell division. These two inhibitory proteins are partly involved in the immortalization of HeLa cells by inhibiting apoptosis. Despite the presence of these inhibitory proteins, CDV (canine distemper virus) can induce apoptosis. This is an important tumor destruction characteristic of CDV. The virus kills canine lymphoma cells