The Effects And Mechanisms Of Oridonin On Proliferation And Cisplatin Resistance Of Non-small Cell Lung Cancer

The lungs are the respiratory organs of the human body,which are composed of the trachea,bronchus and alveoli.Epithelial malignant tumors from the lungs are called lung cancer.It is one of the malignant tumors with the fastest increase in morbidity and mortality and the greatest impact on human health.The biological characteristics of malignant tumors include proliferation,invasion and metastasis,which together determine the degree of malignancy of the tumor.Therefore,the principles of lung cancer treatment are to inhibit the proliferation of lung cancer cells.In the treatment of advanced lung cancer,cisplatin is the first-line chemotherapy drug,however,about 63% of lung cancer patients show resistance to cisplatin during treatment,which severely affects the prognosis and median survival of lung cancer patients.Therefore,to elucidate the mechanisms of tumor proliferation and cisplatin resistance and to develop drugs with inhibitory effects are the focus of lung cancer research.Studies have shown that the proliferation of tumor cells is closely related to the disorder of cell cycle,cell autophagy and apoptosis can regulate cell cycle processes and affect tumor cell proliferation.In addition,chemotherapeutic drug cisplatin works by combining with DNA in cells to form compounds,inhibiting the transcription and replication of cells,and inducing apoptosis of tumor cells.Therefore,DNA is the main target of cisplatin,and cispatin resistance can be induced by influencing the binding of cisplatin to DNA or subsequent apoptosis.Studies have shown that the related molecular pathways include oxidative stress,apoptosis,autophagy and ferroptosis.Monomers with specific chemical structures can be extracted by natural drugs and have a wide range of biological activities,such as antioxidant,anti-inflammatory and anti-tumor.Compared with the conventional treatment of modern medicine,the advantage of natural compounds in treating tumors lies in that they can regulate the occurrence and progression of tumors through multiple ways.Oridonin(Ori),a diterpenoid compound from ruthenium ruthenicum,has anti-inflammatory,antioxidant and anti-tumor activities.Therefore,it is very important to explore the inhibitory effects of Ori on proliferation and cisplatin resistance and the relevant mechanisms.This paper is divided into two parts.In the first part,A549 cells were selected.First,the inhibitory effects of Ori on the proliferation of lung cancer cells and its related mechanisms were investigated.Then the sensitization to cisplatin and its related mechanisms were discussed.In the second part,A549/DDP cells were selected.Firstly,the differences in protein expression levels induced by cisplatin in A549 and A549/DDP cells were compared to discuss the mechanisms of cisplatin resistance.Then,the inhibitory effects of Ori on cisplatin resistance and the regulating effects of related mechanisms were discussed.This experiment mainly involved CCK8 method,colony formation assay,immunofluorescence,western blot and Annexin ?/PI double staining techniques.The results showed that Ori could significantly inhibit the proliferation of A549 cells and induce the production of autophagosomes and the activation of autophagy-related proteins(LC3B,P62 and ATG3);the phosphorylation of Akt/mTOR was inhibited while the expression of P-AMPK was enhanced;activation of pro-apoptotic proteins(PARP,Bax and caspase3)and inhibition of anti-apoptotic protein Bcl2.Further studies showed that after adding AMPK inhibitor CC,the activation of autophagy and apoptosis induced by Ori was reversed.The induction effects of Ori on apoptosis were reversed after the addition of autophagy inhibitor 3-MA.Subsequent studies have shown that Ori can enhance the sensitivity of cells to cisplatin.And when combined with cisplatin,the regulatory effects of Ori on AMPK/Akt/mTOR,autophagy,and apoptotic pathways were enhanced.These results suggested that the role of Ori in anti-tumor and chemotherapeutic sensitization may be related to activation of AMPK/Akt/mTOR-mediated autophagy and apoptosis pathways.In A549/DDP cells,cisplatin inhibited the expression of some ferroptosis-related proteins(GPX4 and FTH1)and autophagy-related proteins(P62 and LC3B);caused the degradation of Keap-1 and activation of Nrf2 and HO-1.After adding Ori,ferroptosis inducer,autophagy inducer and Nrf2 inhibitor,cell survival rate decreased significantly.Further studies have shown that Ori induced the activation of ferrous ions and lipid peroxidation and the inhibition of ferroptosis-related proteins(GPX4,xCT and FTH1);caused the conversion of LC3B-? to LC3B-? and the expression of P62 and P-mTOR was inhibited;Keap-1 expression was activated while Nrf2/HO-1 expression was inhibited.Thus,we hypothesized that Ori could reverse cisplatin resistance of A549/DDP cells by regulating autophagy,ferroptosis and Keap-1/Nrf2.To sum up,this research has proved the anti-tumor effects and chemosensitization of Ori.For the first time,the relationship between the anti-tumor effects of Ori and autophagosomes,as well as the relationship between the sensitization of cisplatin and autophagy,ferroptosis,oxidative stress and apoptosis have been clarified,which provides a theoretical basis for the clinical application of Ori and cisplatin in the treatment of lung cancer.