| Background and aim Colorectal cancer(CRC)is a common malignant tumor of digestive tract with high morbidity and mortality.The pathogenesis of CRC is complex and diverse,so it is particularly important to understand the pathogenesis of CRC and grasp the effective opportunity of treatment.High-fat diet(HFD)can promote the transformation of normal cells into mild to severe dysplasia,and then develop into cancer.The specific mechanism is not clear.Oxidized low density lipoprotein(ox-LDL)is a predictor of cancer in patients with dyslipidemia and is abnormally elevated in patients with CRC.Ox-LDL can directly promote the progression of many kinds of malignant tumors and regulate macrophages to a certain extent.Based on the background,we explore the role and related mechanism of ox-LDL in CRC.Methods In vivo experiment,we collected CRC tissues without radiotherapy,chemotherapy or operation,and normal colorectal tissues to perform ox-LDL immunohistochemical staining to detect the expression of ox-LDL in CRC.The mice fed with HFD were divided into three groups: control group,4W-HFD group and 12W-HFD group.Colorectal samples were taken for ox-LDL immunofluorescence staining to confirm the high expression of ox-LDL in colorectal tissue of hyperlipidemic mice.HE staining was used to evaluate the morphological changes of colorectal tissue.CD144 and CD133 immunohistochemical staining were used to evaluate the expression level of tumor stem cell markers.In the in vitro experiment,we used ox-LDL to stimulate Lo Vo cells and NCM460 cells to detect the expression of apoptosis marker factor p53,proliferation marker factor PCNA and tumor stem cell marker factor CD44 and CD133.CCK8 test and scratch test were performed to detect the ability of cell proliferation and migration.Besides,F4/80 was co-located with i NOS or CD206 immunofluorescence staining in human colorectal tissue specimens and hyperlipidemic mouse colorectal specimens to identify the polarization phenotype of macrophages.At the same time,CD206 and ox-LDL or its receptor LOX-1 were colocated to detect the correlation between ox-LDL and CD206.THP-1 cells were stimulated with ox-LDL for 24 hours and 72 hours.The expression levels of i NOS and CD206 were detected by q PCR,and the polarization effect of ox-LDL on THP-1cells was detected by transfection with LOX-1si RNA.RAW264.7 cells were stimulated with ox-LDL for 72 hours and CD206 fluorescence staining was performed.Finally,Lo Vo cells were co-cultured with THP-1 cells in the transwell culture plate with ox-LDL added for 72 hours.Lo Vo cell proteins were extracted and the expression levels of p53,PCNA,CD44 and CD133 were detected by WB.Results Compared with normal colorectal tissues,the level of ox-LDL was significantly upregulated in CRC tissues.In HFD mice,with the extension of the time of HFD,the expression of ox-LDL in colorectal tissue of mice was high.After HFD,the expression of tumor stem cell marker factors CD133 and CD44 was up-regulated.In the cell experiment,we found that ox-LDL could down-regulate the apoptosis factor p53,increase the levels of proliferation factor PCNA and tumor stem cell markers CD44 and CD133 in normal colorectal cells and CRC cells,and promote the proliferation and migration of CRC cells in vitro.In addition,we also found that the expression of CD206 in CRC tissue and colorectal tissue of hyperlipidemic mice increased.By stimulating macrophages with ox-LDL,it was found that continuous stimulation could induce the increase of CD206 expression in macrophages,which in turn promoted the down-regulation of p53 and the increase of PCNA,CD44 and CD133 levels in CRC cells.Conclusion1.The level of ox-LDL in cancer tissues of patients with CRC is increased.2.ox-LDL can directly increase the tendency of colorectal carcinogenesis in vivo and in vitro.3.ox-LDL can promote colorectal progression indirectly through macrophages acting on CRC cells. |
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