CD44 Correlates With Clinicopathological Features And Is Upregulated By EGFR In Lung Adenocarcinoma

Background: The epidermal growth factor receptor EGFR is a member of the Erb B family of receptors,and EGFR signal pathway plays an important role in lots of physiological processes such as tumor growth,cell proliferation and cell differentiation,Studies have shown that EGFR gene mutations and aberrant overexpression of EGFR protein are present in a variety of solid tumors,EGFR is closely related to tumor cell invasion and metastasis,and its mechanism has not been fully elucidated,Adhesion molecule CD44 is an important member of the adhesion family,which can mediate the adhesion between cell to cell and cell to extracellular matrix,CD44 is highly expressed in many malignant tumors,CD44 plays a important role in the migration,invasion,metastasis and chemoresistance of tumor cells,Previous studies in head and neck tumors found that EGFR signal pathway and CD44 is closely related and synergistic effect on tumor progression,However,the role of EGFR and CD44 in patients with lung adenocarcinoma is not completely clear,This study will investigate the relationship between CD44 and EGFR,the clinical significance,and whether CD44 is upregulated by EGFR signaling pathway,Methods:1 Transient transfection technique was used to downregulate or upregulate EGFR in A549 and H1975 cell lines,The expression of CD44 was detected by RT-PCR and Western blot,2 NCBI was used to analyze the difference of EGFR mRNA level between lung adenocarcinoma tissues;Immunohistochemistry staining and Western blot analysis of the consecutive sections of paraffin-fixed lung adenocarcinoma tissues was used to detect the EGFR protein level,3 EGFR mutations were detected by amplified refractory mutationsystem(ARMS),4 TCGA database was used to analyze the paired adjacent normal tissues and The correlation between EGFR and CD44 mRNA,Reverse TranscriptionPCR and Western Blot assays were used to detect the expression levels of EGFR and CD44 in lung adenocarcinoma tissues and paired adjacent normal tissues as well as in the non-mutated and mutated lung adenocarcinoma tissues,5 The clinical data was gathered,The correlation between the expression levels of EGFR and CD44 with the clinicopathological parameters was analyzed,Result:1 EGFR signaling pathway can regulate CD44 expression,In A549 and H1975 cell lines,the expression of CD44 was downregulated by siEGFR,while the expression of CD44 was up-regulated after overexpression of EGFR,2 EGFR mRNA and protein were highly expressed in lung adenocarcinoma,The mRNA level of EGFR in 60 matched lung adenocarcinoma tissues was significantly higher than that in adjacent normal tissues(P<0,0001)by analyzing NCBI database(GSE19804),Meanwhile,we selected 8 cases of paired lung adenocarcinoma tissues and adjacent normal tissue,and using Western blot method to detect the expression of EGFR expression,EGFR protein expression in tumor tissue was significantly higher than the adjacent normal tissue,Immunohistochemical staining showed that the expression of EGFR was positive in the tumor tissues,but no expression or weak expression of the corresponding normal tissues,3 EGFR gene mutations are present in lung adenocarcinoma,EGFR mutations were detected by amplified refractory mutation system(ARMS)in82 cases of lung adenocarcinoma,EGFR mutation was found in 54 cases,The positive rate of EGFR mutation was 65,9%,of which 28 cases were exon 19 mutations and 25 cases were exon 21 mutation,1 case of exon 18 mutation,4 The EGFR protein expression in EGFR mutate tissues was significantly higher than that in non-mutant tissue,Four paired EGFR mutated and non-mutated tissues were selected to compare the expression level of EGFR mRNA and protein were compared by RT-PCR and Western blot,EGFR mRNA and protein expression levels were higher in mutant tissues than nonmutant tissues,Immunohistochemical staining of 82 lung adenocarcinoma tissues show that EGFR protein level in mutant tissues was higher than that in non-mutated tissues(=10,108,P<0,01),5 The expression level of EGFR and CD44 was positively correlated in lung adenocarcinoma tissues,The expression of EGFR and CD44 mRNA in522 cases of lung adenocarcinoma tissues were analyzed in TCGA database,The correlation coefficient was 0,27(P<0,05),Immunohistochemical staining of 82 cases of lung adenocarcinoma tissues show that EGFR and CD44 was positively correlated,the correlation coefficient was 0,31(P<0,05),The expression of CD44 protein in EGFR mutant group was significantly higher than that in non-mutated group,and the correlation coefficient was 0,31(=8,732,P<0,05),6 The relationship between CD44 protein expression and clinicopathological parameters,The expression of CD44 was positively correlated with lymph node metastasis,tumor stage and tumor differentiation,but not with age,sex,smoking history,Conclusion:1 In lung adenocarcinoma cell lines,EGFR signaling pathway regulates the expression of CD442 The expression of EGFR gene and protein in lung adenocarcinoma tissues was significantly higher than that in adjacent normal tissues,About 2/3of lung adenocarcinoma exist EGFR mutations,and the mutation leads to EGFR gene and protein over expression,3 The mRNA and protein level of EGFR and CD44 in lung adenocarcinoma was positively correlated,EGFR gene mutation was associated with high expression of CD44,4 The expression of CD44 in lung adenocarcinoma tissue level was relate to tumor differentiation,TNM stage,lymph node involvement,...