The Study Of P62-KEAP1-Nrf2Pathway In VK3Resistance In Cisplatin-resistant Human Ovairan Cancer Cells

Disbalance of redox homeostasis may be responsible for chemotherapyresistance of cancer. Muti-functional protein p62/SQSTM1is involved in the processof clearing ubiquitinated proteins and regulation of antioxidative signal. Our previousstudies found that the expression of p62was highly expressed in cisplatin-resistanthuman ovarian cancer cells. Therefore, VK3was used to observe its effect onSKOV3/DDP cells and the change of redox homeostasis was observed in order toreveal some mechanisms in cisplatin resistance.In order to study the relationship between redox homeostasis and drug resistance,in this study vitamin K3(a reported oxidants) was used to induce oxidative stress inSKOV3cells and SKOV3/DDP cells. The apoptosis was tested in these two cell linesby MTT assay, Hoechst stain and flow cytometry. The change of proteins and genes inNrf2signal pathway were examined by western blot, PCR and immunofluorescence.Moreover, in order to observe the change of Nrf2signaling, the expression of p62wasknockdown in SKOV3/DDP cells by siRNA. We found that SKOV3/DDP cellsshowed a strong ability to resistant the pro-apoptotic effect of VK3when treated withVK3. In SKOV3/DDP cells, Keap1was combined by over-expressed p62, and therewere more nuclear Nrf2in SKOV3/DDP cells than in SKOV3cells. At the same timehigher level of antioxidant genes HO-1and NQO1were observed in SKOV3/DDPcells compared with SKOV3cells. We found that the nuclear Nrf2was decreased andthe expression of HO-1and NQO1were reduced after knocking down the expressionof p62in SKOV3/DDP cells, and more apoptotic chromatin condensation wasobserved when treated with VK3.In conclusion, our results showed that SKOV3/DDP cells can resist both cisplatinand VK3. And we supposed that high-pressed p62could combine Keap1then promotethe nuclear translocation of Nrf2which could active the transcript of antioxidantgenes such as HO-1and NQO-1in SKOV3/DDP cells. These genes could effectively release the damage role of VK3and confer the drug resistance of SKOV3/DDP cells.Therefore, we suppose that the regulation of Keap1/Nrf2by p62is a potentialmechanism of drug resistance in cancer, and these results might provide newperspective to overcome drug resistance in ovarian cancer.