Role Of Sodium Bicarbonate Cotransporter,Member 4(SLC4A4) In Suppressing Proliferation And Invasion Of Colon Cancer Cells

Objective Colon cancer is a digestive tumor with poor prognosis,and ranks second in the cause of malignant tumor death.Patients who reach locally advanced stage of colon cancer,or have developed distant metastases,have a 5-year survival rate of only 7%,which is much lower than that of patients with early colon cancer.Difficulty in early diagnosis and lack of effective treatment are important causes of death.Therefore,an in-depth exploration of the molecular mechanisms associated with the invasion and metastasis of colon cancer can help in the early diagnosis of colon cancer and the search for effective gene therapy targets.Nowadays,abnormal tumor metabolism has been found to be an important feature throughout the whole process of tumor development,but the specific function and molecular mechanism of pyruvate metabolism-related gene SLC4A4 in colon cancer have not been fully elucidated.This study aims to explore the mechanism and significance of SLC4A4 in colon cancer cells through clinical specimen detection,bioinformatics analysis and vitro experiments.Methods Analysis and screening of pyruvate metabolism-related genes in the database;clinical specimen detection and database analysis are used to explore the expression of SLC4A4 in colon cancer and its correlation with clinicopathological factors;database analysis of the correlation between the expression of SLC4A4 and immune cell infiltration;analysis of differential genes and related genes to study the regulatory network of SLC4A4;pan-cancer analysis of SLC4A4 expression in multiple tumors and prognosis;bioinformatic analysis of the correlation between SLC4A4 in pan-cancer and immune checkpoints,TMB and MIS;construction of colon cancer cell lines overexpressing SLC4A4;EDU proliferation assay,CCK8 proliferation assay and migration assay are selected to detect the proliferation and migration of over expression cell lines;bioinformatics predictions,Western blot assay are performed to verify the related molecules and pathways that SLC4A4 may affect.Results Database analysis screened SLC4A4,a gene related to pyruvate metabolism,as a study target.Clinical specimen detection and database analysis identified that the expression of SLC4A4 was lower in colon cancer,and the expression of SLC4A4 was proportional to the prognosis:correlation analysis revealed that SLC4A4 expression levels were significantly correlated with lymph node staging and clinical staging;in addition,we found that SLC4A4 extensively affected immune cell infiltration;the regulatory network analysis found that SLC4A4 involved in the network regulation of steroid dehydrogenase activity,ion channel activity,steroid metabolic process,intracellular calcium activated chloride channel activity,glycoprotein metabolism process,passive transmembrane transport protein activity,anion transmembrane transporter protein activity;pan-cancer analysis showed that SLC4A4 was differentially expressed in multiple tumors and had prognostic value for tumors;The analysis of immune checkpoints showed that the expression of SLC4A4 was correlated with 60 immune checkpoint genes in multiple tumors.At the same time,the expression of SLC4A4 was positively correlated with the expression of TMB and MSI.Vitro experiments showed that SLC4A4 not only promoted the proliferation of colon cancer cells,but also significantly enhanced its migration ability,The bioinformatics prediction results found that SLC4A4 may be related to the process of EMT.western blot assay further confirmed that SLC4A4 promoted elevation of E-cadherin protein and down-regulated Twistl protein expression in colon cancer cells,but did not affect the expression of N-cadherin protein,and SLC4A4 inhibited part of EMT process,thus inhibited the development of colon cancer.Conclusion(1)SLC4A4 was lowly expressed in colon cancer tissues,and its expression was positively correlated with prognosis;the expression level of SLC4A4 is correlated with lymph node stage and clinical stage.(2)SLC4A4 is involved in a variety of tumor biological regulation processes,such as steroid metabolic process,glycoprotein metabolic process,passive transmembrane transporter protein activity and cell cycle regulation in colon cancer.(3)The expression of SLC4A4 in colon cancer is positively correlated with B cells,dendritic cells and CD8+T cells.(4)Vitro experiments showed that SLC4A4 inhibited the migration and proliferation ability of colon cancer cells.(5)SLC4A4 can promote the expression of E-cadherin,while inhibited the expression of Twist1,which suppressed the invasion and proliferation ability of colon cancer cells by inhibiting part of the EMT process.