Study On Pharmacological Effects And Mechanism Of Dihydroartemisinin On Non-small Cell Lung Cancer

Lung cancer is the most common malignant tumors with the highest morbidity and mortality in China,which is a serious threat to citizens' health.Non-small cell lung cancer(NSCLC),which accounts for 85%of lung cancers,is often diagnosed at an advanced stage and has a low 5-year survival rate.In addition to surgery,radio-therapy and chemotherapy,molecular targeted drugs developed for the characteristics of multiple oncogenic driver gene mutations in NSCLC can significantly improve patients'progression-free survival and objective response rate,pioneer a new approach to precision therapy.Tyrosine kinase inhibitor(TKI),a small molecule targeting EGFR mutations,is a typical NSCLC targeting agent.However,as with other targeting agents,its use is limited by the inevitable development of resistance in patients after about a year of use.Therefore,new treatments need to be developed.Previous studies have suggested that tumor metabolism is characterized by enhanced glycolysis and impaired oxidative phosphorylation.However,recent studies have found that in addition to enhanced glycolysis,there are also enhanced oxidative phosphorylation and tricarboxylic acid cycle in NSCLC patients.The normal function of oxidative phosphorylation requires a variety of heme-assisted proteins.At the same time,multiple studies have shown that excessive heme intake is closely related to the occurrence of colorectal cancer,lung cancer and other cancers.In view of this,the exploration of new therapeutic regiments targeting heme is worthy of further study.In this study,the heme level in NSCLC cells was first detected.The results showed that NSCLC cells had higher heme levels compared with normal lung cells,and heme in NSCLC cells were hyper-metabolized.Meanwhile,high expression of heme metabolism-related genes was associated with shorter disease-free survival of NSCLC.The high heme level in NSCLC cells was further investigated,and it was found that it might be caused by high oxidative stress in the cells.Antimalarial drug artemisinin uses heme as the activator and target.In view of the characteristics of high heme level in NSCLC cells,Dihydroartemisinin(DHA),the main active metabolic component of artemisinin in vivo,was selected for further pharmacodynamic study and mechanism exploration.The results showed that DHA inhibited the growth of a variety of NSCLC cells,and its efficacy was positively correlated with the heme level in the cells,while it had no significant cytotoxicity on normal cells with low heme level.After activation by heme,DHA can induce the production of a mass of ROS and inhibit the activity of antioxidant enzymes HO-1,GSTP-1 and Cox2.At the same time,DHA can inhibit the activity of various protein kinases and play a role in inhibiting the growth of NSCLC cells.Since the IC50 of DHA in NSCLC cells is micromolar level,which is much higher than the nanomolar level in heme-rich plasmodium,this study attempted to improve the inhibitory effect of DHA on NSCLC growth by combining it with 5-aminolevulinic acid(ALA),the precursor of heme synthesis.Pharmacodynamic experiments confirmed that ALA combined with DHA can induce the generation of more ROS,promote cell apoptosis,inhibit the activity of EGFR and its downstream signaling pathway,and thus inhibit the growth of NSCLC cells.Then addition of Succinylacetone(SA),which inhibits heme production,can reverse the inhibitory effect of DHA on NSCLC.On the other hand,considering that EGFR-resistant cells have higher heme levels than their parental cells,this study investigated whether DHA combined with EGFR-TKI can enhance the sensitivity of targeted EGFR-TKI-sensitive and EGFR-TKI-resistant cells.The pharmacodynamic experiments results showed that DHA combined with EGFR-TKI could enhance the sensitivity of EGFR-TKI-sensitive cells to EGFR-TKI by inhibiting the downstream signal STAT3 activated by EGFR-TKI.Similarly,DHA in combination with EGFR-TKI inhibits activated bypasses signaling pathway in EGFR-TKI-resistant cells,rendering the cells re-sensitive to EGFR-TKI.In summary,this study confirmed the characteristics of high-heme-level in NSCLC cells,and explored the inhibitory effect of DHA on NSCLC,providing a new idea and experimental basis for clinical treatment of NSCLC.