Proteasome inhibitors can improve the efficiency of cancer treatments by inhibiting nuclear factor κB(NF-κB) activation in cancer cells. Lentils are a type of beans of which consumption of such beans is increasing. The purpose of this study was to investigate the effects of lentils extract (LE) on the proteasomal activities, NF-κB activation, and cell cycle in HepG2 human liver cancer cells. LE treatments inhibited proteasomal activities at concentrations of 10, 50, and 100 μg/mL respectively, and repressed NF-κB activation at concentrations of 1, 10, and 100 μg/mL respectively, in HepG2 cells. LE treatments at concentrations of 1, 10, and 100 μg/mL respectively, increased sub-G1 cell population in HepG2 cells, which may be the result of apoptosis. The results suggest that LE inhibited NF-κB activation partially with its proteasome inhibitory activities, and the increase of sub-G1 cell population was induced partially, by inhibition of NF-κB activation in HepG2 cells.

Inhibition of proteasome activity may reduce many types of cancer, so it's pathway is effective in cancer as well as in clinical fields. Here the author has carried out experiment targeting on the elevation of apoptosis in oral cancer cells by combination of proteasome inhibitor, lactacystin, and DNA replication inhibitor, etoposide. The growth of KB cells was measured by MTT methods and apoptosis was analyzed by DNA fragmentation and Hochest nucleus staining. The proteasome activity was analyzed by fluorescent tagged peptide and cellular protein expression was detected by Western hybridization. Though lactacystin and etoposide inhibited KB cell growth alone, but low combined doses inhibited cell growth more strongly and induced apoptosis. The proteasome activity was also seriously inhibited by the combination of both chemicals. Tumor suppressor proteins and apoptosis inducing proteins were highly increased under the combination of both chemicals. From above studies we can conclude that proteasome inhibitors may be used for the treatment of oral cancer and proteasome inhibitors with DNA replication inhibitors may be effective in clinical trials of oral cancer.