The Study On Relation Between Cancer And Environment Factors Via The MDM4 Rs4245739 And Anti-cancer Mechanism Of TRAIL Pathway

According to the GLOBOCAN data,the incidence and mortality of cancer are increasing rapidly worldwide.At the same time,the study of genetics and epidemiology found that the occurrence of cancer is related to genetic variations and living environment.For example,ultraviolet radiation and smoke can induce gene variants such as TP53,CDKN2 A and RAC1,thus increasing the risk index of melanoma and lung cancer.Therefore,it is necessary to research the occurrence and development of cancer from the perspective of heredity and environment for the prevention and treatment of caner in the future.It was found that the regulatory network of TP53 and its negative regulator MDM2 was significantly correlated with cancer risk index.In east Asian population,the grequency of TP53 SNP rs 1042522 G is negatively correlated with the lowest temperature in winter,and the frequency of MDM2 SNP rs2279744 G is negatively correlated with the intensity of UV radiation.These results suggests the susceptibility to lung cancer,breat cancer and retinoblastoma in this region is closely related to environmental factors,providing population genetic evidence to explain the occurrence of cancer in these populations.Similar to MDM2,another negative regulator,MDM4,is rarely mutated in cancer and is highly expressed in a variety of cancers,of which rs4245739 A is significantly associated with the increased risk of lung cancer,breast cancer and other cnacers in the east Asian population.But few studies of it on the correlation with environmental factors.Therefore,this study investigated the genotype of rs4245739 in a total of 3,694 individuals from 64 populations in Eastern Asia and found that the frequency of rs4245739 A,a susceptilbility site,was closely related to ultraviolet radiation and winter temperature.For the expression of MDM4 is up-regulated by rs4245739 A,the distribution of rs424539 A is lower in areas with higher UV intensity to provide higher activity of TP53 against UV damage and cancer.Higher activity of TP53 is required to produce more ATP to maintain body temperature and fight against cancer in colder winter regions.MDM4,TP53 and MDM2 may have coevolutionary effects in the face of environmental stress.The correlation between the frequency of rs4245739 A and the intensity of UV radiation was the strongest and most significant,suggesting that UV radiation may be the main selection pressure for the adaptive evolution of this site.UV radiation could induce DNA damage which causes genetic toxicity.Intermittent UV irradiation causes melanoma,while long-term UV exposure increases the risk of non-melanoma skin cancer.Although melanoma accounts for a low proportion of skin cancer(about 4%),it has a high mortality rate(79%)and its incidence is increasing year by year.At present,malignant melanoma is not sensitive to most commonly used anticancer drugs,so new treatments need to be found.Tumor necrosis factor-associated apoptosis-inducing ligand(TRAIL)apoptosis pathway specifically induces apoptosis of cancer cells and hardly affects the survival of normal cells.So drugs targeting TRAIL and its receptors(DR4/5)have broad application prospects in the field of anti-cancer.Although recombinant human TRAIL(rhTRAIL)and DR4 or DR5 monoclonal antibodies have better activity and have entered clinical trails,there are still some disadvantages such as poor stability,short half-life and high cost.Therefore,it is urgent to find compounds that are easy to be synthesized,stable and cheap to target DR4/5 in order to obtain specific anticancer effects.1,8-naphthyridine derivatives are compounds with anticancer activity and can inhibit the growth of cancer cells via a variety of mechanisms.In this study,25 1,8-naphthyridine compounds were evaluated for their anticancer activity,so as to obtain anticancer lead compounds with good anticancer activity and high specificity.After preliminary screening and rescreening,it was found that compound 3u selectively inhibited the growth of human malignant melanoma A375 cell line and had little impact on normal cell line pulp and HSF.After death,the cell showed typical apoptosis charaterisitics such as the intact cell membrane.So 3u is a potential apoptosis-inducing compound.By the help of HSC,real-time PCR and western blot,we found that compound 3u could up-regulate the expression of death receptor and FADD,suppress the expression of XIAP,cleave caspase-8 and caspase-3 at a high concentration in A375 cells,and induce apoptosis via exogenous pathway.In order to improve its specific activation to DR4/5 and further reduce impact on the survival of normal cells,the structure of 3u should be modified.Cancer cells mainly resist TRAIL induced apoptosis by high expression of anti-apoptoic proteins such as c-FLIP and XIAP,it is necessary to specifically target DR4/5 with compound and increase the sensitivity of cancer cells to TRAIL treatement.Then a better therapy effect will be obtained.At present,there are no studies on simultaneously activating TRAIL apoptosis pathway and inhibiting the activity of c-FLIP and XIAP to improve the anticancer effect.Therefore,Rocaglamide,an inhibitor of c-FLIP,and At406,an inhibitor of XIAP,were used in combination with rhTRAIL to study the anti-caner effects of the three-drug combination treatment on 20 kinds of cancer cell lines.It was found that the combination of the three drugs could induce apoptosis in most cancer cell lines via the death receptor-mediated exogeous apoptosis pathway.But there were 4 cancer cell lines insensitive to the treatment.Meanwhile,normal cell lines pulp and MRC-5 were also insensitive to the treatment.By detecting the expression level of key proteins in TRAIL pathway in these cells,it was found that pulp,MRC-5,U373,U87 and U251 escaped apoptosis via low expression of caspase-8,while MCF7 was caspase-3 deficient.Then we used the deacetylase inhibitor valproic acid to up-regulate the expression of caspase-8 in U373,U87 and U251,and restored their sensitivity to three drugs combination treatment.This study provides new ideas for revealing the apoptosis mechanism of cancer cells escaping TRAIL induced apoptosis and optimizing the scheme of three drug combination.In summary,our foundings in this study is that the relation between MDM4 cancer-related SNP site rs4245739 and the environmental factors in east Asian populations has been discovered.The most significant environment factor is ultraviolet.These results suggest the possiblitiy of the coevolution of p53,MDM2 and MDM4 in this region.In malignat melanoma cell line A375,the anticancer mechanism of a 1,8-naphthyridine derivative 3u upregulating of death receptor of TRAIL and FADD and downregulating of FADD was elucidated,which provided a possibility for the treatment of malignant melanoma and other cancers.It was found that the reason of cancer cells escaping TRAIL induced apoptosis was the low expression of caspase-8 or 3 through the combination of three drugs,providing ideas for the optimization of the combination of three drugs.