Molecular Mechanism Study Of PP2A Activator Combined With Docetaxel In Treatment Of Lung Adenocarcinoma

Objective: Lung cancer is the leading cause of cancer-related death.Non-small cell lung cancer accounts for about 85% of lung cancer patients,of which lung adenocarcinoma is the main type of lung cancer.The therapeutic effect and prognosis of non-small cell lung cancer were poor,and the 5-year survival rate was only 23%.Chemotherapy,immunotherapy,and small molecule targeted therapy had made some progress in the treatment of lung adenocarcinoma,but some patients didn’t respond to treatment,and some patients were prone to drug resistance and recurrence.The purpose of this study was to explore the effect and mechanism of natural medicine PP2A activator arctigenin in the treatment of bone metastasis of lung adenocarcinoma,and to verify the efficacy and mechanism of arctigenin combined with chemotherapeutic drug docetaxel in the treatment of lung adenocarcinoma,to provide a new scheme for the treatment of lung adenocarcinoma.Methods: Firstly,this study analyzed the transcriptional expression level of PPP2 CB gene in LUAD and its prognostic relationship with LUAD based on the C subunit of PP2A protein phosphatase.IF and WB experiments were performed to detect the effect of arctigenin on the expression level of PP2A catalytic C subunit.Molecular docking technique was used to predict the binding site of arctigenin and PP2A,and DARTS combined with WB experiments to verify the binding.The effects of arctigenin on proliferation and migration of lung adenocarcinoma cells were examined by CCK8,Transwell,and wound healing assays.Immunofluorescence assay was performed to observe the nuclear morphology and WB to detect the expression level of shear caspase3 to explore the effect of arctigenin on apoptosis.Then,a lung adenocarcinoma bone metastasis model was constructed to verify the effect of arctigenin treatment on lung adenocarcinoma.The expression of PP2AC protein and the phosphorylation level of STAT3 in tumor cells after arctigenin treatment were further examined.Co-IP assay was performed to verify whether PP2A could bind to STAT3.ChIP and qPCR were combined to detect the expression of apoptosis-related gene Timp1 to verify whether Timp1 gene was regulated by STAT3.Finally,arctigenin was combined with docetaxel to treat lung adenocarcinoma.CCK8,IF,WB and qPCR experiments were performed to detect the effects of combined treatment on proliferation and apoptosis of lung adenocarcinoma cells.A mouse model of lung adenocarcinoma bone metastasis was constructed to verify the effect of the combination treatment.Results: This study found that the transcriptional expression of PPP2 CB was downregulated in LUAD,and the low expression of PPP2 CB was significantly correlated with the poor prognosis of lung adenocarcinoma.Results of IFA,WB,and DARTS experiments showed that arctigenin could bind to the junction of A and C subunits of PP2A,increase the stable expression of PP2AC subunit,and promote PP2A activation.The results of Co-IP and other experiments confirmed that PP2A binds to STAT3,downregulates STAT3 phosphorylation status,and inhibits the transcriptional expression of the downstream STAT3 target gene Timp1.Arctigenin inhibits the proliferation and migration of lung adenocarcinoma cells and promotes apoptosis by promoting PP2A activation and regulating the downstream STAT3 signaling pathway.Validated in a mouse model of lung cancer bone metastasis,arctigenin inhibited the progression of lung adenocarcinoma bone metastasis in vivo,attenuated osteolytic destruction,and prolonged the life cycle of mice.Arctigenin combined with docetaxel treatment inhibited lung adenocarcinoma proliferation and increased apoptosis by decreasing the phosphorylation level of STAT3 in lung adenocarcinoma cells.Combination drugs can significantly inhibit the growth of bone metastases of lung adenocarcinoma in mice,and the anticancer effect is better than that of single drugs.Conclusion: Arctigenin promotes PP2A activation,and inhibits the proliferation and migration of lung adenocarcinoma cells in vitro.In vivo,Arctigenin promotes apoptosis,inhibits bone metastasis of lung adenocarcinoma and lytic bone destruction,and prolongs the survival of mice.Arctigenin combined with docetaxel is more efficacy than single drug in the treatment of lung adenocarcinoma.This effect may be achieved by promoting the activation of PP2A and inhibiting the activation of STAT3 signaling pathways,thereby regulating the expression of downstream gene of Timp1.