Mechanism Of Lapatinib Combined With Luteolin Inhibiting HER2+ Breast Cancer Via Keap1/Nrf2 Pathway

Breast cancer is a kind of deadly tumor disease which seriously endangers women’s health.The causes of its formation are complicated and closely related to people’s living habits.Lapatinib,used as a tyrosine-kinase inhibitor,blocks the activation of the HER1 and HER2 tyrosine kinase to inhibit the activation of downstream signaling pathways and thus inhibit tumor survival and proliferation.According to the data of cell research in vitro and animal tumor model,luteolin has the effect of anti-breast cancer in different ways,and the effect of combination of luteolin on chemical sensitization and reversal of drug resistance is obvious.In the first part of the experiment,we used lapatinib and luteolin to analyze their inhibition of proliferation of HER2+human breast cancer cells SKBR-3,BT-474 and ZR-75-1.We found that although lapatinib inhibited the proliferation of HER2+human breast cancer cells to some extent,BT-474 and ZR-75-1 were less sensitive to lapatnib inhibition than SKBR-3.The sensitivity of these cells to luteolin is similar.We then treated with lapatinib and luteolin,and found that the combination of lapatinib and luteolin could enhance the inhibitory effect of lapatinib on HER2+human breast cancer cells from different sources.In the second part of the experiment,WB(Western blot),qPCR(real-time quantitative PCR),IHC(immunohistochemistry)results showed that compared with normal tissues,FOXO3a and Keap1 were all low expression in breast cancer tissues,Nrf2 and NQO1 were both high expression in breast cancer tissues.Then we verified FOXO3a/Keap1/Nrf2/NQO1 signal pathway by inhibiting Nrf2,overexpression of Keapl and FOXO3a at cell level.The rescue experiment proved that the combination of lapatinib and luteolin could inhibit the proliferation,migration,invasion and promote apoptosis of HER2+ human breast cancer cells by affecting this pathway.In the third part of the experiment,Subcutaneous tumorigenesis of two human breast cancer cell lines was performed in nude mice,lapatinib and luteolin was used for treatment.Then we detected the weight of nude mice,tumor size,and the expression of FOXO3a/Keap1/Nrf2/NQO1 signaling pathway in tumor tissues after tumor formation.The results showed that the tumor volume and growth rate of the combined treatment group were significantly lower than those of the single treatment group,and the subcutaneous tumor volume and growth rate of the combined treatment group were significantly lower than those of the single treatment group.The protein expression of FOXO3a and Keapl in lapatinib + luteolin group was significantly higher than that in single drug group,while the protein expression of Nrf2 and NQO1 were significantly decreased.These data show that lapatinib combined with luteolin can significantly enhance the inhibition of breast cancer growth,which may be realized by affecting the protein expression of FOXO3a/Keap1/Nrf2/NQO1 signaling pathway in breast tissue.