The Effect Of Hypoxia Environment And PSiNPs On Anticancer Drugs-mediated Tumor Apoptosis

Cancer,also known as malignant tumor,has become a major disease threatening human life and health.The essence is the uncontrolled growth and division of normal cells,resulting in infinite proliferation.The biological characteristics have abnormal cell differentiation,proliferation and uncontrolled growth,etc.The growth advantage of cancer cells has been attributed to a unique glucose metabolism pathway that produces energy through accelerated glycolysis rather than oxidative phosphorylation of mitochondria under normoxic and hypoxic conditions known as the Warburg effect.Highly proliferating cancer cells are exposed to a hypoxic microenvironment due to increased oxygen consumption,which results in a reprogramming of cellular metabolism.The hypoxia-induced transcription factor(HIF-1)plays a fundamental role in this reprogramming,and it expression has been detected in many human cancer.HIF-1 also associated with resistance to treatment.Another important cell death regulator is the transcription factor P53.This gene and its product regulate the expression of various pro-apoptotic members of the Bcl-2 family proteins,which is a key event in triggering the mitochondrial apoptotic pathway.In many tumors,P53 is either mutated or its expression is suppressed.Chemotherapy is one of the most important methods in the treatment of malignant tumors.Whereas,the resistance of tumor cells often leads to treatment failure.Crosstalk between HIF-1 and P53 family proteins can be a determinant of cancer progression;however,the relationship between hypoxia and P53 is still controversial.Although hypoxic conditions have frequently been described to be a P53 inducer,hypoxia,alone or in combination with other stresses,might not stimulate or even decrease p53 protein levels.It is urgent to improve the efficacy of chemotherapy drugs in the treatment of malignant tumors through effective ways.In this study,colon carcinoma cells HCT116 and adenocarcinoma cells A549 were taken as the main research objects.Chemotherapy drugs DOX(Doxorubicin)and cisplatin(CIS,cisplatin)were used to induce apoptosis of tumor cells under hypoxic environment.Here we show that hypoxia attenuates p53 expression,leading to a decrease in the level of pro-apoptotic proteins Bax,Bid,and Puma.As a result,OMM permeabilization is suppressed and cell death is attenuated.Secondly,the effect of DOX loaded with porous silicon nanoparticle carriers(PSiNPs)on the apoptosis of a variety of tumor cells was studied,and the drug release process and biodegradation cycle of the carriers were discussed.The purpose of this study is to provide theoretical basis for the cause of chemotherapeutic drug resistance in tumor cells and provide an effective method for improving the therapeutic effect of chemotherapeutic drugs.The main research results are as follows:(1)The expression levels of HIF-1 and HKII in tumor cells induced by chemotherapeutic drugs in the hypoxia induced by deferamine(DFO,deferoxamine)were increased compared with those in the normoxia induced by chemotherapeutic drugs.Decreased oxygen consumption of cell mitochondria;The number of apoptosis decreased;The expression levels of Bax,Bid and Puma were significantly decreased,the expression levels of Bcl-2 were not significantly changed,and the expression levels of P53 were significantly decreased.(2)Compared with the detection results under normoxia environment,the expression level of Cl-PARP,the characteristic parameter of cell apoptosis,and the expression level of pro-apoptotic protein Puma and transcription factor P53 were significantly decreased under hypoxia environment.The results of A549 test with human alveolar basal epithelial cells from lung cancer were consistent with those of HCT116 test.(3)PCR analysis showed that the expression of TP53 mRNA in cells induced by chemotherapy drugs in hypoxic environment did not change,and the decreased expression level of P53 protein was a post-translational modification.These results indicated that HIF-1 did not affect the stability of TP53 mRNA and did not promote the decomposition of P53.(4)The deletion of P53 had no significant effect on the expression level of HIF-1,and the expression levels of pro-apoptotic proteins Bax and Puma were inhibited.The analysis of phosphatidylserine externalization showed that the loss of P53 led to the decrease of apoptosis level.The possibility of P21 affecting apoptosis in the absence of P53 was excluded.These results indicate that P53 plays a major role in regulating apoptosis in the hypoxia environment.(5)HCT116 cells was treated with PSiNPs carrier loaded with chemotherapy drugs,which significantly enhanced the occurrence of apoptosis of cancer cells.Similar results were further verified by RKO cells,MCF-7 cells and SH-SY5 Y cells.HCT116 cells was treated with DOX-PSiNPs,and the apoptosis of cancer cells was significantly enhanced by the detection of cell morphology,nuclear and mitochondrial changes,and cell ultrastructure changes.(6)The release time and degradation process of DOX-PSiNPs in MCF-7 cells were analyzed: the maximum release of DOX was reached at the 12 th h;the carrier was completely degraded at the 13 th d.Conclusion,hypoxia attenuates p53 expression,leading to a decrease in the level of pro-apoptotic proteins Bax,Bid,and Puma.As a result,OMM permeabilization is suppressed and cell death is attenuated.In vitro studies have shown that biodegradable and nontoxic porous silicon nanocontainers can be used as an effffective drug carrier for regulating tumor cell death pathways.For the first time,in vitro studies have shown the possibility of targeted activation of apoptosis or necrosis in cancer cells of difffferent etiology.