Analysis Of Factors Related To Endocrine Therapy Resistance In Stage Ⅰ-Ⅲ Hormone Receptor Positive Breast Cancer

Objective:To explore the clinicopathological characteristics and genetic information related to endocrine therapy(ET)resistance of stage I-III hormone receptor(HR)positive breast cancer,verify the relationship between the expression of relevant genes and ET resistance,and provide reference for the diagnosis and treatment of clinical HR-positive breast cancer.Methods:1.Data of histopathologically confirmed stage I-III HR-positive breast cancer patients from Suining Central Hospital and Affiliated Hospital of North Sichuan Medical College from 2014 to 2020 were retrospectively collected,including sociodemography,pathological information and treatment measures,and follow-up data were obtained through follow-up surveys.The cases were divided into ET resistance group and ET sensitive group according to whether the patient has progressed during ET period or within one year after the auxiliary ET period.2.Differently expressed genes of ET resistance in breast cancer were screened by Gene Expression Omnibus(GEO)database and Venn diagram,and these genes were analyzed by protein interaction network(PPI)analysis using STRING database and Cytoscape 3.8.2 software.The relationship between genes and prognosis was analyzed by Kaplan-Meier Plotter,so genes that may be associated with ET resistance in breast cancer were screened.3.In order to analyze the relationship between protein expression and drug resistance,21 paraffin specimens were randomly selected from the drug-resistant group and the sensitive group respectively.The expression of the corresponding protein of the related gene was detected by immunohistochemistry(IHC).4.Statistical method: Independent sample T test was used for inter-group comparison of data conforming to normal distribution,and Wilcoxon rank sum test was used for nonconforming data.The chi-square test or Fisher’s exact probability method was used for comparison between groups of categorical variables.Univariate binary Logistic regression was used to analyze the factors that might be related to drug resistance of ET,and the variables with P<0.05 in univariate analysis were entered into multivariate binary Logistic regression to analyze independent correlation factors of drug resistance.All tests were double-tailed,the test level was α=0.05.Results:1.Analysis of clinicopathological factors related to ET drug resistanceA total of 535 HR-positive patients were included,including 360 cases in the ET sensitive group(67.29%)and 175 cases in the ET resistance group(32.71%).The median age was 49 years old and the median follow-up is 78 months old.Logistic regression analysis of single-factor two classification showed that menstrual state,tumor size,lymph node staging,PR expression level,HER-2 state,Ki-67 index,histological classification and molecular classification might be related to ET resistance(all P<0.05).The results of Logistic regression analysis in the multi-factor two-category showed that menopausal,lymph node positive,PR low expression,Luminal B type and HER2 positive were independent risk factors for ET resistance to HR-positive breast cancer(all P<0.05).2.Analysis of ET resistance-related genesBioassay revealed 184 differentially expressed genes between the endocrine therapy resistance and sensitive groups.Among the top 20 genes in the PPI network,11 genes were associated with prognosis,including PTPN11,SDC1,CD24,ITPR1,GATA3,PLCG2,ESR1,PGR,ERBB4,TP53 and FGFR2.3.Differential gene protein verificationThe protein expression of 7 differential genes was detected in paraffin samples from42 patients,and the results showed that: The protein expression level of SDC1(t=-2.689,P=0.010)in drug-resistant group was significantly higher than that in sensitive group,while PGR(t=2.198,P=0.033)and PLCG2(t=2.754,P=0.008)were significantly lower than that in sensitive group.Conclusion:1.Menstrual status,lymph node stage,PR expression rate,HER2 status and molecular typing might be independent correlation factors for ET resistance in stage I-III HR-positive breast cancer.2.PGR,PLCG2 and SDC1 might be related genes of ET resistance in stage Ⅰ-Ⅲ HRpositive breast cancer.