The Role Of Aurora Kinase In Breast Cancer And Drug-resistant Breast Cancer And Its Inhibitors

Cancer is a major refractory disease which threatens human's health and lives severely.Malignant tumor is the first leading causes of fatal disease in mankind.Currently,chemotherapy continues to be an important therapeutic method.With the deepening development of technology and research,molecular-targeted drugs have become the most popular field of study.It bases on the specific molecular cell biology of tumor,and acts on the cell-signaling pathway and kinases related to the development of tumor,so as to inhibit cancer growth,invasionand metastasis.These molecular-targeted agents receive extensive attention because of its high specificity and low toxicity.Aurora kinases are a family of conserved mitotic regulators,consisting of Aurora kinase A,B and C in humans.Aurora kinase A and B have been well characterized to be important players in mitosis.They are overexpressed in tumors such as colon cancer,breast cancer,ovarian cancer,gastric cancer and pancreatic cancer,and are shown to be positively correlated with chromosomal instability and clinical aggressiveness in the malignancies.This suggests the possibility that they can serve as new anticancer targets for tumor treatment.In this study,we compared the activity of Aurora kinases in MX-1 and MX-1/Taxol,the ability of proliferation and metastasis,and inducing apoptosis and cell cycle arrest in vitro and in vivo.Then we assessed the important role of Aurora A in resistant to Taxol in breast cancer.Downregulation the expression of the Aurora kinases with miRNAs was used to explore the mechanisms by which Aurora kinases exerted its effects on MX-1 and MX-1/Taxol,and the sensitivity to Taxol.We found that Aurora A was highly expression with the high level of p-gp in Taxol resistant breast cancer cells and xenograft model.Using the MX-1/Taxol sublines silencing of Aurora kinases,it was proved that the inhibition of Aurora kinases induced a significant accumulation of cells in the G2/M phase and apoptosis,Silencing of Aurora kinases resulted in the growth inhibition of MX-1/Taxol cell and invasion in vitro and in vivo,and decreaed the function of p-gp of MX-1/Taxol cells The activity of pathway of Akt,ERK and p-gp was downregulated accompanied with the silencing of Aurora kinases in MX-l/Taxol cells.We also found that inhibition of Aurora kinases could partially reverse the resistance to Taxol,and increase its apoptosis in MX-1/Taxol cells,indicating a potential role of Aurora kinase activity in Taxol resistance.For the purpose of screening and research the anti-tumor activity and mechanism of the Aurora A inhibitor in vitro and in vivo,the anti-p-Aurora A monoclonal antibody(mAbs)was produced by immunization with purified polypeptide,and the ELISA assay was established successfully.ZLJ213 was selected from the 150 targeting synthesized compounds by MTT assay.Various methods(such as,MTT assay,colony formation assay),were carried out to determine the anti-proliferative activity of Aurora A inhibitor.Antitumor activities were observed by MX-1 and MX-1/Taxol xenograft model in vivo.Flow cytometry analysis and transwell invasion assay were carried out to determine the performance of Aurora A inhibitor on cell cycle arrest and the intervention on cell invasion in vitro.And the angiogenesis effect of Aurora A inhibitor was measured by HUVEC tube formation assay.Furthermore,ELISA and Western Blot assay were performed to confirm the targets and investigate the expression level of related proteins in tumors and in cancer cells,which were treated with Aurora A inhibitor.ZLJ213 exhibited highly inhibition on cancer cells including breast cancer and colon cancer.Moreover,ZLJ213 had significant antitumor activity against MX-1,MX-1/Taxol,and HCT116 xenografts in nude mice.The antitumor activity was also observed by inhibition rate based on tumor weight and tumor size.The groups treated with ZLJ213 100 mg·kg-1 had an inhibition rate of 70%.ZLJ213 was able to reduce half of the regular protein level of p-aurora A at 0.258 ?mol·L-1 analyzed by ELISA.ZLJ213 could inhibit the activities of Aurora A,Aurora B,Histone H3,and VEGFR in breast cancer cells.Simultaneously,ZLJ213 induced activation of caspase 3,PARP cleavage and inhibited the expression of cyclinB.To conclude,our study suggested that ZLJ213 has the potential to inhibit cell proliferation in breast cancer and taxol resistant breast cancers with the definite mechanism and low toxicity.It's related analogues may be developed into a novel anticancer drug for breast cancer,colon cancer or other cancers.