Clinical Significance Of CD44 And CXCR4 In Gastric Cancer

Background and significance:Gastric Cancer（GC）is generally considered to be highly heterogeneous and lack of specific and sensitive markers.With the deepening of research,the molecular mechanism of gastric cancer has been explored in detail.Under the background of precision medicine,this study attempts to start with the dry markers of gastric cancer.To explore the clinical significance of differentiation antigen cluster 44（Cluster of differentiation 44,CD44）and chemokine receptor 4（CXC motif chemokine receptor 4,CXCR4）in gastric cancer.As a transmembrane glycoprotein,CD44 participates in the signal transduction between cells and between cells and extracellular matrix,regulates the operation of lymphocytes,and participates in the occurrence,development,invasion,metastasis and drug resistance of tumors.CXCR4 directly or indirectly affects Cancer stem cells（CSCs）through the CXCL12-CXCR4 axis,and participates in activating or enhancing the function of CSCs.We did not find the clinical significance of CD44 combined with CXCR4 in gastric cancer,so we intend to explore the relationship between CD44 and CXCR4 expression and lymph node metastasis,survival and prognosis of patients by analyzing the differential expression of CD44 and CXCR4 in gastric cancer,paracancerous tissues and normal gastric tissues.And provide a research basis for early diagnosis and drug target therapy of that gastric cancer.Methods:1.Some gastric cancer stem molecules CD44 and CXCR4,THY1,NT5E,TFRC,ALDH1A1,PROM1,LGR5,ABCG2,POU5F1,NANOG,SALL4 were found by consulting the literature,and the correlation between CD44 and these molecules was analyzed by downloading data from TCGA database.Then the expression of CD44 and CXCR4 in pan carcinoma was analyzed based on the GEPIA2 database.2.Complete data of clinicopathological information and clinical prognosis of 407patients with gastric cancer were downloaded from TCGA database,including 32 cases of gastric cancer paracancerous tissue and 179 cases of normal gastric tissues in the control group.The expression levels of CD44 and CXCR4 in gastric cancer tissues,paracancerous tissues and normal tissues were analyzed after cleaning the data,and the relationship between CD44 and CXCR4 and lymph node metastasis,survival and prognosis of patients was explored.3.From May 2018 to March 2021,30 pairs of primary gastric cancer tissues and paracancerous tissues without preoperative radiotherapy and chemotherapy were collected.The m RNA levels of CD44 and CXCR4 were detected by RT-q PCR,and the relationship between them and p TNM was analyzed Staging,lymph node metastasis,survival and prognosis of patients.In addition,the m RNA levels of CD44 and CXCR4 in gastric cancer cell lines MKN-45,SUN-1,HGC-27 and normal gastric epithelial cell line GES-1 were detected.4.Quantitative data were expressed as Mean±SD,and t-test,analysis of variance and nonparametric test were used for statistical analysis.Qualitative data were expressed as frequency or rate,andχ²test was used for statistical analysis.Survival analysis was performed by KM analysis,and correlation analysis was performed by Spearman rank correlation,and Med Calc 20.0.14 software was used for ROC curve drawing and comparison.SPSS 25.0 and Graphpad prism 9 were used for data statistical analysis,and the test level wasα=0.05.Results:1.There was a positive correlation between the expression of CD44 and CXCR4（rs=0.328）,THY1（rs=0.234）,NT5E（rs=0.279）,TFRC（rs=0.162）（P<0.05）.There was no significant correlation between the expression of CD44 and ALDH1A1,PROM1,LGR5,ABCG2,POU5F1,NANOG,SALL4（all P>0.05）.CD44 m RNA and CXCR4m RNA were up-regulated in STAD,CHOL,GBM,KIRC,LAML,LGG,OV and TGCT;In addition,CD44 m RNA levels were up-regulated in COAD,KICH,PCPG,READ and THCA,and down-regulated in THYM,UCEC and UCS;CXCR4 m RNA levels were up-regulated in BRCA,KIRP,PAAD,SKCM,UCEC and UCS,and down-regulated in PCPG（all P<0.05）.2.Cell line detection results:Compared with GES-1 cell line,CD44 m RNA expression was down-regulated in SNU-1 cell line（P<0.05）,and CXCR4 m RNA expression was up-regulated in MKN-45 cell line（P<0.05）.3.TCGA database analysis results:CD44 m RNA level in gastric cancer tissues was higher than that in paracancerous tissue,but there was no significant difference（P>0.05）.CXCR4 m RNA level was up-regulated in cancer paracancerous tissue（P<0.05）.The levels of CD44 and CXCR4 m RNA in G₃（Ⅲ）group were higher than those in G₂（Ⅱ）group（P<0.001）.CD44 m RNA level was up-regulated in T₄compared with T_1-3（P=0.008）,and CXCR4 m RNA level was up-regulated in T₂,T₃,T₄compared with T₁,respectively（all P<0.001）.CD44 m RNA level was upregulated in N₃versus N_0-2（P=0.023）.CXCR4 m RNA level was up-regulated in stage N₃compared with stage N_0-2,but there was no significant difference（P=0.288）.CD44 m RNA level was upregulated in M₁versus M₀（P=0.016）.CXCR4 m RNA level was upregulated in M₁versus M₀,but there was no significant difference（P=0.056）.At the same follow-up time,the survival probability of the low level group of CD44 m RNA was higher than that of the high level group of CXCR4 m RNA（P<0.05）.Analysis of OS and PFI events:CD44 m RNA level in the death group was higher than that in the survival group,but there was no significant difference（P>0.05）.The level of CXCR4 m RNA in the death group was higher than that in the survival group（P<0.05）.DSS event analysis:CD44 and CXCR4 m RNA levels were up-regulated in the death group compared with the survival group（P<0.05）.4.Test results of clinical tissue samples:CD44 and CXCR4 m RNA levels were up-regulated in gastric cancer tissues（P<0.05）.There was no significant difference between the m RNA levels of CD44 and CXCR4 in different T stages（P>0.05）.CD44m RNA level was up-regulated in N_1-3versus N₀（P=0.048）and in M₁versus M₀（P=0.037）.CXCR4 m RNA level was up-regulated in N_1-3stage compared with N₀stage and M₁stage compared with M₀stage,but the difference was not statistically significant（P>0.05）.CD44 m RNA level was higher in clinical stageⅢ-Ⅳthan that in clinical stageⅠ-Ⅱ（P=0.041）.CXCR4 m RNA level was higher in stageⅢ-Ⅳthan in stageⅠ-Ⅱ,but there was no significant difference（P=0.487）.CD44 m RNA level in the moderate and low differentiation group was higher than that in the middle and high differentiation group（P=0.041）,similarly,CXCR4 m RNA level was up-regulated in moderate and low differentiation group,but there was no significant difference（P=0.527）.CD44 and CXCR4 m RNA levels were not significantly associated with lymph node metastasis,vascular nerve invasion and survival status of patients（all P>0.05）.5.The ROC curve of CD44 and CXCR4 expression showed that the area under the curve（AUC）of CD44,CXCR4 and their combination were 0.844（95%CI:0.814-0.872）,0.822（95%CI:0.790-0.851）and 0.905（95%CI:0.879-0.927）,respectively（all P<0.05）.The AUC of the combination of CD44 and CXCR4 was larger than that of the CD44 or CXCR4 alone（all P<0.05）.Conclusion:1.There was a strong positive correlation between the expression of CD44 and CXCR4 in gastric cancer.In addition,CD44 and CXCR4 are highly expressed in a variety of cancers.2.CD44 and CXCR4 were correlated with histological grade,depth of tumor invasion and lymph node metastasis of gastric cancer.Low expression of CD44 and CXCR4 was associated with good prognosis.3.CD44,CXCR4 and their combination have certain reference value for the diagnosis of gastric cancer,and the combination of the two has a higher diagnostic value than CD44 or CXCR4 alone.