The Mechanism Of Enolase Secreted By Candida Albicans Regulates The Metabolic Reprogramming Of Macrophages And Promotes The Progression Of Colorectal Cancer

Part one: Abundance of Candida albicans in colorectal cancer and its effect on colorectal cancerObjective: The aim of this study was to investigate the abundance of Candida albicans(C.albicans)in colorectal cancer and its impact on colorectal cancer.Methods: A total of three groups of stool samples were collected from patients with colorectal cancer,patients with colon polyps and healthy individuals for preliminary analysis of 18 S r RNA gene and internal transcribed spacer(ITS)region.C.albicans,the fungus with the highest abundance and obvious difference in colorectal cancer,was screened out.DSS+AOM-induced mouse colorectal cancer and mouse colorectal cancer subcutaneous tumor models were established,and C.albicans was administered by gavage,and the tumor growth rate and tumor volume were counted in each group.Results:(1)The level of C.albicans in the intestine of patients with colorectal cancer was significantly increased.(2)C.albicans promotes the progression of colorectal cancer.Conclusions: C.albicans is increased in the intestines of colorectal cancer patients and can promote the progression of colorectal cancer.Part two: The mechanism of Enolase secreted by Candida albicans regulates macrophages to promote colorectal cancer progressionObjective: The previous study of this subject showed that C.albicans increased in the gut of patients with colorectal cancer and could promote the progression of colorectal cancer,but the specific mechanism was unclear.The transition between yeast and hyphal phase is the hallmark of the virulence change of C.albicans,and the release of enolase is the core of C.albicans virulence.Macrophages are the main immune cells against fungal infection,and thus they also become the main target cells for the action of C.albicans in the tumor microenvironment.This study aimed to further investigate the mechanism by which Enolase secreted by C.albicans regulates macrophages to promote colorectal cancer progression.Methods:(1)The proportion of hyphae of C.albicans in normal intestinal tissue and colorectal cancer tissue was detected by in situ hybridization.(2)To detect the effects of Enolase on the proliferation,cytokine secretion,proteomics and organic acid metabolism of colorectal cancer cells and macrophages.The effects of knockdown of ACOD1 and ATF3 on macrophage function and metabolism were examined.Ch IP-q PCR was used to further explore the downstream target genes of transcription factor ATF3.(3)To study the therapeutic effect of Enolase neutralizing antibody on Candida albicans on colorectal cancer and its effect on T cells in the tumor microenvironment.Results:(1)Enolase secreted by C.albicans is enriched in colorectal cancer tissues from colorectal cancer patients.(2)Polyamines secreted by tumor cells promote the transformation of Candida albicans from yeast state to hyphal state,and induce C.albicans to secrete more Enolase.(3)Enolase specifically affects macrophages but not colorectal cancer cells.(4)Enolase affects the changes of metabolism-related protein levels in macrophages.(5)Enolase activates ACOD1 expression in macrophages through the Dectin-1/SYK cascade.(6)ATF3 regulates the transcription of PGE2 in macrophages as a downstream target of the Dectin-1/SYK/ACOD1 axis.(7)The proportion and function of CD8+ CTLs inhibited by PGE2 produced by macrophage in vitro.(8)In vivo experiments,Enolase neutralizing antibody has a therapeutic effect on C.albicans on colorectal cancer,and can increase the proportion and function of CD8+ CTLs in the microenvironment of colorectal cancer.(9)The results of tissue microarray showed that the expression of ATF3 was negatively correlated with the survival of colorectal cancer.Conclusions:(1)Intestinal C.albicans increased in colorectal cancer patients,and polyamines secreted by tumor cells induced C.albicans to secrete more Enolase.(2)Enolase stimulates the expression of aconitate decarboxylase 1(ACOD1)in tumor-associated macrophages in the colorectal cancer microenvironment to increase,thereby promoting the production of itaconic acid,which affects the macrophage tricarboxylic acid cycle and affects ACOD1/ATF3 signaling pathway.(3)The downstream factor PEG2 of transcription factor ATF3 promotes the progression of colorectal cancer by affecting CD8~+ cytotoxic T cells in the tumor microenvironment.