Expression of peptide transporter 1 in gastric cancer and its clinical significance
10.3760/cma.j.cn121382-20250402-00024
- VernacularTitle:寡肽转运蛋白1在胃癌中的表达及其临床意义
- Author:
Xu JIAN
1
;
Xi WANG
;
Jie ZHANG
Author Information
1. 天津医科大学总医院中心实验室，天津 300052
- Keywords:
Gastric cancer;
Peptide transporter 1;
Tumor marker
- From:
International Journal of Biomedical Engineering
2025;48(3):254-263
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To investigate the expression of peptide transporter 1 (PEPT1) in gastric cancer and its clinical significance.Methods:PEPT1 protein expression and localization in human gastric cancer BGC-823, SGC-7901, MKN-45 cells were evaluated using cellular immunofluorescence staining. The expression of PEPT1 protein and mRNA in normal mucosal epithelial GES-1 cells, BGC-823, SGC-7901 and MKN-45 cells was detected by Western blot and quantitative real-time PCR (qPCR). Bioinformatics was used to analyze the expression of the slc15a1 gene, which encodes PEPT1, in gastric cancer and adjacent normal tissues. The PEPT1 expression in different pathological types of gastric cancer and adjacent normal tissues was detected by immunohistochemical staining. The serum samples of peripheral blood from 18 gastric cancer patients admitted to the Tianjin Medical University General Hospital from June to December 2019 were collected for the gastric cancer group, and the serum samples of peripheral blood from 21 gastric polyps patients were collected for the gastric polyp group. The expression level of PEPT1 in the two groups′ serum samples was detected by enzyme-linked immunosorbent assay. The diagnostic efficacy of PEPT1 was evaluated using a receiver operator characteristic curve method. The correlation between PEPT1 and gastric cancer markers was evaluated by the Pearson correlation analysis. The slc15a1 RNA interference lentivirus was constructed and transfected into MKN-45 cells, which were divided into a CON313 negative control group and a knockdown group. The effect of slc15a1 gene knockdown on MKN-45 cells proliferation was detected using cell counting kit-8 (CCK-8), Western blotting and qPCR assays. The slc15a1 RNA overexpression lentivirus was constructed and transfected into colon cancer Caco-2 cells, which were divided into a CON335 negative control group and an overexpression group. The effect of overexpression of slc15a1 gene on Caco-2 cells proliferation was detected using CCK-8, Western blotting, qPCR, and cell clone formation assays. Results:Different intensities of red fluorescence representing the PEPT1 protein were observed on the membranes of BGC-823, SGC-7901, and MKN-45 cells. PEPT1 protein expression was higher in BGC-823 (0.603±0.030), SGC-7901 (0.743±0.029), MKN-45 (0.835±0.029) cells than that in GES-1 cells (0.486±0.020) ( P<0.05, 0.01). The relative PEPT1 mRNA expression level in SGC-7901 cells (22.540±0.150) was higher than that in GES-1 cells (18.530±0.137) ( P<0.01). However, the relative PEPT1 mRNA expression level in BGC-823 (17.800±0.057) and MKN-45 (8.050±0.053) cells was lower than that in GES-1 cells (both P<0.01). Slc15a1 expression in gastric cancer tissues was significantly higher than that in adjacent normal gastric tissues ( P<0.05). PEPT1 was expressed in papillary adenocarcinoma, mucinous adenocarcinoma, signet ring cell carcinoma and squamous cell carcinoma, and the expression level was higher than that in adjacent normal gastric tissues. The PEPT1 expression in serum samples of gastric cancer patients [(3.002 8±0.689 4) ng/ml] was higher than that in gastric polyps patients [(2.575 7±0.468 1) ng/ml] ( P<0.05). The detection sensitivity and specificity of PEPT1 were 0.714 and 0.684, respectively, and the area under the curve was 0.659. A significant positive correlation was observed between PEPT1 and carcinoembryonic antigen ( R=0.459, P<0.05). The relative expression level of PEPT1 mRNA in the knockdown group (0.484±0.003) was significantly lower than that in the CON313 negative control group (1.000±0.029) ( P<0.01). There was no significant difference in the relative expression of PEPT1 protein between the knockdown group (0.954±0.007) and the CON313 negative control group (0.949±0.020) ( P>0.05). As culture time increased, the absorbance ( A) values in the knockdown group at 24, 48, 72, 96, and 120 h (0.227±0.001, 0.642±0.007, 0.773±0.006, 0.938±0.038, 1.263±0.017) were gradually decreased from 48 h compared with those in the CON313 negative control group (0.217±0.006, 0.644±0.001, 0.802±0.020, 1.053±0.002, 1.507±0.002), and the A values of the knockdown group at 96 and 120 h were significantly lower than those of the CON313 negative control group (both P<0.01). The relative expression level of PEPT1 mRNA in the overexpression group (6.696±0.071) was significantly higher than that in the CON335 negative control group (1.001±0.048) ( P<0.01). However, there was no significant difference in the relative expression of PEPT1 protein between the overexpression group (0.899±0.007) and the CON335 negative control group (0.808±0.011) ( P>0.05). As culture time increased, the A values of the overexpression group at 24, 48, 72, 96, and 120 h (0.212±0.009, 0.347±0.005, 0.639±0.003, 1.092±0.007, 1.39±0.010) were gradually increased compared with those in the CON335 negative control group (0.199±0.002, 0.323±0.003, 0.483±0.003, 0.787±0.007, 0.926±0.003) (all P<0.05). The results of cell clone formation assay showed that the number of clonal cells in the overexpression group [(371±8) cells] was significantly higher than that in the CON335 negative control group [(227±7) cells] ( P<0.05). Conclusions:PEPT1 is specifically overexpressed in gastric cancer. It affects the proliferation of gastric cancer cells by regulating slc15a1 gene expression. As a tumor marker, PEPT1 has a certain potential value in the clinical diagnosis and treatment of gastric cancer.
