The Effect Of B7-H3 And IDH1 On The Prognosis Of CRC And The Mechanism Of Their Action

Colorectal cancer?CRC?is one of the most common malignant tumors of the digestive tract worldwide.Recent studies have shown that the development of CRC is closely related to tumor immunity and metabolic reprogramming.In our previous study on the immune escape mechanism of CRC,it was found by TCGA database that B7-H3 may affect the expression of isocitrate dehydrogenase?IDH1?in the glutathione metabolic pathway.B7-H3 is a member of the B7/CD28 immunoglobulin superfamily and IDH1 is involved in a variety of metabolic pathways.Currently,it is believed that intestinal inflammation leads to gut microbiota disorders in the occurrence and development of colorectal cancer,and then tumor immune and metabolic disorders,affecting the malignant progression and poor prognosis of colorectal cancer.So we plan to explore the value of B7-H3 and IDH1 for the prognosis of CRC patients and study the mechanism of action of B7-H3 and IDH1.Further analysis of the differential gut microbiota abundance between CRC patients with different expression of B7-H3 and IDH1 was used as an auxiliary index to judge the prognosis of patients.In clinical studies,tissue microarrays were prepared from Formalin fixed paraffin-embedded?FFPE?patients with CRC from 2006 to 2012.According to immunohistochemical staining,the survival curves were drawn by Kaplan-Meier method and the multivariate survival analysis was carried out by Cox proportional risk regression.Investigated the relationship between B7-H3,IDH1 and clinicopathological parameters and their prognostic value of patients with CRC.The expression of B7-H3,IDH1,the upstream transcription factors of IDH1?SREBP1?,and related genes in PI3K/Akt pathway were detected by real-time PCR and western blot in stably transformed cells of B7-H3 and IDH1?SW480-NC,SW480-B7-H3;Caco-2-NC,Caco-2-sh B7-H3 and SW480-NC,SW480-IDH1;HCT116-NC,HCT116-sh IDH1?.The rescue experiments verified the effect of B7-H3 on the m RNA level of IDH1.The effects of IDH1 on tumor cell proliferation and migration were verified by cell clone formation assay and wound healing assay in IDH1 stable transformed cells.To further analyze the differential abundance of gut microbiota,we collected FFPE from CRC patients after surgery in 2018 and divided patients into B7-H3+IDH1-and B7-H3+IDH1+ expression groups according to immunohistochemistry.And then collected 10 samples of fresh faeces from patients before postoperative adjuvant chemotherapy.The gut microbiota were measured and the differences in the composition abundance of the flora were analyzed as an auxiliary index to judge the prognosis of CRC patients.Clinical data showed that the correlation between high expression of IDH1 and lymphatic metastasis and TNM staging was statistically significant?P=0.043,P=0.008?.In the subgroup with positive b7-h3 expression,the median survival time of patients with high IDH1 expression was 71.4 months,and the median survival time of patients with low IDH1 expression was 87.3 months.The high expression of IDH1 affected the poor prognosis of patients?log-rank ?2=6.411,P=0.036?.The expression of B7-H3 and IDH1 in CRC tissues was correlated?P=0.044?.Multivariate Cox regression analysis showed that CRC patients with B7-H3+IDH1+ expression had a higher risk of death?HR=1.760,95% CI=1.105-2.934,P=0.043?.At the cellular level,the expression levels of IDH1,SREBP1,and p-Akt were consistent with the expression of B7-H3 in the B7-H3 stable transformed cells.In the IDH1 stable transformed cells,the expression level of IDH1 was only consistent with p-Akt?P=0.038?and affected the proliferation and migration of tumor cells.The expression of m RNA of B7-H3 was disturbed in the rescue experiment,then the m RNA expression level of IDH1 decreased accordingly?P<0.001?.In the gut microbiota of B7H3+IDH1-and B7-H3+IDH1+ patients,the difference in expression abundance between Bacteroidetes?36.96% vs 56.50%,P<0.05?,Proteobacteria?17.66% vs 6.87%,P<0.05?,Prevotella₉?1.33% vs 35.65%,P=0.008?and Bacteroides(25.31% vs 10.31%,P=0.016 was statistically significant.The combined expression of B7-H3 and IDH1 in the clinical tissue specimens of patients with CRC suggests poor prognosis.B7-H3 acts on IDH1 via SREBP1 and affects the proliferation and migration of CRC cells by PI3K/Akt.Among the patients with high expression of B7-H3,the high abundance expression of Prevotella₉ and the low abundance expression of Bacteroides can be used as an auxiliary index to judge the poor prognosis of CRC patients.