| Background: renal carcinoma is one of the most common malignant tumors in the world,and its incidence ranks 13 th among malignant tumors.And as the world ages,the incidence of kidney cancer is on the rise.However,with the improvement of medical technology and the enhancement of people’s health awareness,most(60%)patients with renal cancer can be found in the early stage of the disease,and if the tumor can be removed in time by surgery,patients can often obtain a good prognosis.Unfortunately,20%-30% of patients are found to be at an advanced stage.More important,RCC lack sensitive to radiation therapy and chemotherapy.The five-year survival rate for patients with advanced renal carcinroma is less than 10%.Therefore,renal Carcinoma,especially advanced renal cancer,has become a serious threat to people’s health.Therefore,it is urgent to explore the mechanisms of the occurrence and development of renal carcinoma and find new effective treatment schemes for renal carcinoma.The human digestive tract is inhabited by many microorganisms,including bacteria,fungi,viruses and so on.It has been reported that the total number of adult gut microbiota is about 30 trillion.The human body and its gut microbiota constitute a complex,interactive and dynamically balanced ecosystem.Intestinal flora has many functions,which not only promote the synthesis and absorption of nutrients in the host,but also help the host resist the invasion of pathogens and enhance the immune system of the host.At the same time,the interaction between host and gut microbiota can produce many metabolites,which can act as important signaling factors and energy substrates to regulate other metabolic pathways.Nowadays,it has been confirmed that human intestinal microorganisms have a critical impact on the occurrence,development and prognosis of a series of human diseases such as a variety of cancers,cardiovascular,neurological,respiratory and metabolic diseases.These effects are partly due to the imbalance of intestinal flora,which leads to the imbalance of intestinal microbial catabolites.This may be one of the important mechanisms by which gut microbiota affects the occurrence and development of many diseases.The metabolism of tryptophan is of particular interest.Trp is an essential amino acid that,in addition to being involved in protein synthesis,is also a precursor for the synthesis of many microbial and host metabolites.For example,Trp can be used as a substrate for bacteria to synthesize vitamins,biotin,melatonin and other bioactive substances.It has been well established that changes in the composition of the gut microbiota not only alter the concentration of tryptophan and its metabolites in the gut,but also in the plasma.In addition,studies have shown that the Trp metabolism disorders lead to changes in related metabolites such as Kynurenine(Kyn),indole and other products.It leads the dysfunction of immune cells,and lead an immunosuppressive microenvironment,increases the heterogeneity of cancer cells,and promotes the occurrence and development of tumors.Aryl hydrocarbon receptor(Ah R)is a ligand-dependent transcription factor,which binds to ligands and enters the nucleus,and then acts cooperatively with other transcription factors to regulate gene transcription.It can be involved in many biological processes such as signal transduction,cell differentiation and apoptosis.For example,in intestinal cancer,kyn can be acted as an agonist of Ah R.Once binding with Ah R,it can enhance the activity of indoleamine 2,3 dioxygenase(IDO),mediate the immunosuppression of tumor microenvironment,inhibit the apoptosis of intestinal cancer cells,and promote the proliferation and migration of tumor cells.However,whether Trp metabolites and Ah R have similar effects in RCC has not been confirmed.Based on the effects of Ah R receptor activation by Trp metabolites on cell proliferation,migration and anti-apoptosis,we hypothesized that Trp metabolites may play an important regulatory role in the occurrence and development of RCC.PurposeTo explore the differences in intestinal flora composition and Trp metabolism between RCC patients and healthy people,and verify the mechanism of Kyn promoting the progression of renal cell carcinoma.Method: 16 sr RNA was used to detect stool samples from kidney cancer patients and healthy people.To analyze the composition of intestinal microbiota between renal cell carcinoma patients and healthy people.Then liquid chromatography-tandem mass spectrometry(LC-MS)was used to measure the contents of nine tryptophan metabolites in stool samples of renal cancer patients and healthy people.Then Western Blot,CCK-8,Transwell,flow cytometry and immunofluorescence were used to analyze the effects of tryptophan metabolites and Ah R on the proliferation,apoptosis and migration of renal cell carcinoma cells.To provides a new idea for the study of the related mechanism of renal cell carcinoma progression.Result :1: There were differences in the composition of intestinal flora between RCC patients and healthy people.In the phylum field,the abundance of Firmicutes and Actinobacteria in the intestinal tracts of healthy people was significantly higher than that of RCC patients(p <0.001).The abundance of Bacteroidetes was significantly lower than that in renal carcinoma group(p < 0.001).In the class field,the abundance of Clostridia in the intestine of healthy people was significantly higher than that of renal cancer group(p < 0.001).The abundance of Bacteroidia was significantly lower than that of renal cancer patients(p < 0.001).In the order field,the abundance of intestinal Clostridiales in healthy people was significantly higher than that in renal cancer group(p < 0.001).The abundance of Bacteroidales in healthy people was significantly lower than that in renal cancer group(p < 0.001).Nine Trp metabolites(L-Kynurenine,Tryptamine,Indole,3-Methylindole,Indoxyl Sulfate potassium,salt,Indole-3-acetic acid,3-Indolepropionic acid,and 3-Indoleacrylicacid Kynurenic acid)in two groups were different.The data were showed that3-Indoleacrylicacid,Indoxyl Sulfate potassium salt,and 3-Methylindole were significantly reduced in RCC group.While the level of L-Kynurenine was significantly increased in RCC group.The Spearman’s rank correlation was performed to analyze the correlation between the top 20 gut microbiota and nine tryptophan metabolites.The results showed that L-Kynurenine was negatively correlated with Agathobacter.Tryptamine was negatively correlated with Escherichia-Shigella.Indole was positively correlated with Tyzzerella＿3.3-Methylindole was positively correlated with Romboutsia,Bifidobacterium,and [Ruminococcus]＿torques＿group.Indoxyl Sulfate potassium salt was positively correlated with Subdoligranulum and [Ruminococcus]＿torques＿groups.Indole-3-acetic acid was positively correlated with Romboutsia,Blautia,Bifidobacterium,and [Ruminococcus]＿torques＿group.Indole-3-acetic acid was negatively correlated with Bacteroides and Akkermansia.3-Indolepropionic acid was negatively correlated with Roseburia,Prevotella＿9,and Megamonas.3-Indoleacrylicacid was positively correlated with Blautia.3-Indoleacrylicacid was negatively correlated with Akkermansia.Kynurenic acid was negatively correlated with Prevotella＿9 and Akkermansia.Compared with the Control tissues group,the Ah R protein expression in the RCC tissues group was significantly increased.It showed that Ah R expression was abnormally increased in RCC.Compared with the Control tissues group,E-cadherin expression in the RCC tissues group was inhibited,but N-cadherin and Vimentin expressions were significantly upregulated.After being treated with Kyn,the migration,invasion,proliferation and anti-apoptosis ability of 786-O cells were increased.And it was positively correlated with Kyn concentration.At the same time,Kyn also affects the cell cycle of 786-O cell and the effect of Kyn on the cell cycle of 786-O cells is also reduced after the blocking of Ah R.However,our results suggest that the effect of Kyn on the cell cycle of 786-O cell is independent of Kyn concentration.Conclusion: The intestinal flora composition of RCC patients was different from that of healthy people.The changes of intestinal flora can affect the metabolism of Trp in the gut.and the level of Kyn in the gut of RCC patients was increased.Kyn can promote the progression of RCC by activating Ah R. |
