Over expression of NQO1 in CCA cells induces drug resistance towards chemotherapeutic agents Considering the fact that KKU M214 cells naturally express somewhat minimal level of NQO1, effects of NQO1 above expression by transient transfection with NQO1 expression vector on the suscepti bility of cells to chemotherapeutic agents was evaluated. Following transfection, the NQO1 enzyme action from the transfected cells was elevated approximately 2. 5 fold as well as NQO1 protein level was two. 25 fold increased than the management vector, indicating that NQO1 construct was efficiently expressed in KKU M214 cells. Then, NQO1 over expressed KKU M214 cells were exposed to five FU and Gem for 48 hr, and to Doxo for 24 hr. The results showed that the cytotoxicity of five FU, Doxo, and Gem had been markedly decreased for NQO1 in excess of expressed KKU M214 cells, indicat ing the protective impact of NQO1.

In excess of expression selelck kinase inhibitor of NQO1 suppresses chemotherapeutic agents induced p53 and protein expression from the cell death pathway Preceding experiment showed that NQO1 knockdown greater p53 and apoptogenic protein expression. The results of this experiment showed that more than expression of NQO1 in KKU M214 cells strongly suppressed the chemotherapeutic agents induced greater expression of p53, p21, and Bax. Then again, in excess of expression of NQO1 enhanced Doxo and Gem induced cyclin D1 expression. Knockdown of p53 abolishes the chemosensitizing effect of NQO1 silencing Since the effects provided above showed the knockdown and in excess of expression of NQO1 enhanced and suppressed, respectively, the chemotherapeutic agent mediated cytotox icity in association with the altered expression of p53, p53 apparently perform a part while in the expression on the cytotoxic ef fect of individuals anti cancer agents.

To validate the position of p53, we prepared the double knockdown of NQO1 and p53 in KKU 100 cells. The efficiency of NQO1 and p53 knock down was a lot more than 80%. As is proven above, NQO1 knockdown elevated the susceptibility of KKU one hundred cells to chemotherapeutic agents. Conversely, p53 knockdown markedly lowered cytotoxic impact of all tested chemotherapeutic agents in contrast with chemotherapeu selleck GSK2118436 tic agents alone. Interestingly, within the double knockdown experiment, the cytotoxic potentiation effect of NQO1 gene silencing was fully diminished from the sim ultaneous knockdown of p53. The cytotoxic results of chemotherapeutic agents on double knockdown cells have been equivalent to individuals on p53 knockdown cells.

These effects strongly propose that the cytotoxic results of all 3 chemo therapeutic agents on CCA cells were dependent on p53 expression and NQO1 is in all probability the upstream modula tor of p53. Discussion We previously showed the survival time of CCA pa tients with high NQO1 mRNA expression was shorter than individuals having CCA with lower NQO1 expression, suggesting the possible part of NQO1 in CCA professional gression.