The Role And Mechanism Of Fusobacterium Nucleatum In The Development Of Colorectal Cancer

Background Fusobacterium nucleatum(F.nucleatum)is a Gram-negative bacillus that survives under anaerobic conditions.Early studies have found that it colonizes the oral cavity and is associated with inflammation and even carcinogenesis in the oral cavity,and a few studies have also found associations with intrauterine infections and lung disease.Recently,it has been reported in the literature that F.nucleatum adheres to colorectal adenocarcinoma and even promotes the progression of colorectal cancer(CRC),which provides a theoretical basis for the study of CRC,but the specific mechanism of action of F.nucleatum affecting the progression of CRC is still unclear and needs to be further investigated.However,the specific mechanism of F.nucleatum affecting CRC progression is still unclear and further studies are needed.Objective CRC was investigated and further validated in cellular and animal experiments by dividing F.nucleatum into blank control group,F.nucleatum-infected group and Escherichia coli(E.coli)infected group.In addition,the effect of F.nucleatum on epithelial-mesenchymal transition(EMT)was investigated to elucidate the mechanisms involved and provide some experimental basis for the clinical aspects of cancer treatment.Research methods CRC cell lines HCT116 and SW480 cells were selected for the study,F.nucleatum was identified by mass spectrometry and cultured at 37 ℃ in anaerobic environment,E.coli was cultured in 37 ℃ warm box broth medium;the experiment was divided into blank control group,F.nucleatum infection group and E.coli infection group,in the scratch experiment,the appropriate number of cells were selected The proliferation of cells was observed at 0h and 24 h in 6-well plates;OD450values were measured and recorded at 1,2,3 and 4 days in CCK8 experiments;in transwell migration invasion,serum-free medium was added to the small chamber,and the appropriate number of cells and serum-containing medium were added to the well plates;in invasion experiments,100 μL of matrix gel was spread in the lower chamber and air-dried overnight.After 48 hours of cell migration and invasion,the chambers were removed and the number of migrating and invading cells was counted in images taken under a randomly selected field of view under a microscope;the expression of EMT-related proteins E-cadherin,N-cadherin and Vimentin was detected by protein immunoblotting(Western blotting,WB);4-6 weeks were taken balb/c female nude mice were divided into 10 nude cells as control group and 5 F.nucleatum-infected colorectal cancer cells as experimental group,and the two groups of tumor cells were injected subcutaneously in the left and right abdomen,respectively.The mice were routinely kept for 20 days and then executed,the subcutaneous tumor cells were removed,and the volume of tumor cells was measured and calculated;the subcutaneous tumors of nude mice were embedded,and the sections were stained for immunohistochemistry to detect the expression of EMT-related proteins E-cadherin,N-cadherin and Vimentin.ResultsIn cell scratch experiments,a concentration of F.nucleatum in HC116 and SW480 cancer cells promoted Cell proliferation assays using CCK8-promoted cell proliferation capacity confirmed the healing of the scratch site.Cell migration and invasion of the transplanted site were also promoted.The performance of EMT-related markers was also examined by western blotting,which showed a decrease in the performance of E-cadherin and an increase in the performance of N-cadherin and vimentin.To clarify the relationship between inflammation and colon cancer,we also developed an animal model of inflammation and showed that subcutaneous administration of colon cancer cells to nude mice infected with F.nucleatum promoted tumor growth and increased tumor volume compared to controls.Immunohistochemical detection of EMT-related protein expression after subcutaneous tumor formation in nude mice revealed decreased E-cadherin expression and increased N-cadherin and vimentin expression,with statistically significant differences.conclusion1.F.nucleatum promotes the proliferative capacity of CRC cells by promoting wound healing.2.F.nucleatum promotes the migratory and invasive capabilities of CRC cells,thereby promoting the progression of related diseases.3.F.nucleatum promotes EMT progression by promoting the expression of EMT-related proteins,probably by increasing autophagy,associated with decreased expression of E-cadherin,increased expression of N-cadherin,and increased expression of vimentin,which promotes CRC progression.