The Significance Of FOXP3 Expression And Prognosis In The Breast Invasive Ductal Carcinoma Tissue

Objective:Forkhead Box Protein 3(FOXP3)is a key transcription factor and a well-known hallmark of immunosuppressive CD4+CD25+ regulatory T cells(Treg).FOXP3 plays a crucial role in the generation of Treg,which is critical for immune homeostasis maintaining.During past decades,the definition that FOXP3 expression was restricted to Treg has been gradually revised.Recent studies have provided evidences that some types of human carcinoma cells also expressed FOXP3,which may play an important role in tumor pathogenesis and development.However,there is still no consensus on the presence and function of FOXP3 in human breast cancer cells up to now.Preclinical researches have reported FOXP3 as a tumor suppressor gene.However,an agreement on the prognostic value of FOXP3 in breast cancer has not be reached.Therefore,more study data is needed to clarify the precise value of FOXP3 in breast cancer.Thus,we designed this study to evaluate the FOXP3 protein expression in breast invasive ductal carcinoma,aiming to explore the association between FOXP3 expression and clinical pathological features,especially the prognostic factors.FOXP3 may act as a potential prognostic marker for breast cancer.Methods:1 This study included 123 females who underwent primary surgery at breast cancer center of the Fourth Hospital of Hebei Medical University from January 2009 to April 2012,without any neoadjuvant therapy.Formalin-fixed,paraffin-embedded specimens from 123 patients were retrieved and reassessed by examining hematoxylin and eosin-stained histologic sections.The FOXP3 protein expression in breast invasive ductal carcinoma was detected on tumor sections by Max Vision TM immunohistochemical stain.2 FOXP3 expression of breast invasive ductal carcinoma in a cohort of123 patients was compared with clinical pathological features such as age,tumor size,axillary lymph node metastasis,pathological grade,vessel tumor embolus,molecular subtype and the level of ER,PR,HER-2 and Ki-67,and follow-up data,aiming to explore the association between FOXP3 expression and the prognosis of patients with breast cancer.3 All analyses were conducted using SPSS for Windows,version 21.0.The association between the FOXP3 expression and pathologic characteristics was examined using Chi square statistical tests and Spearman order correlated examination.The Kaplan-Meier method was used for survival analysis and the unstratified log-rank test was adopted for comparison.Cox proportional hazards model was used to estimate the hazard ratio(HR)of each clinicopathologic variables for OS and DFS.P values were two-tailed and P<0.05 was considered statistically significant.Results:1 The subcellular localization of FOXP3 in breast cancer cells was heterogeneous,including the nucleus and the cytoplasm.The expression ratio of tumor FOXP3(in nucleus and/or cytoplasm)was 68.29%(84/123).The expression ratio of nuclear FOXP3 was 47.97%(59/123).The expression ratio of cytoplasmic FOXP3 was 63.41%(78/123).2 According to the status of vessel tumor embolus,the 123 cases were divided into 2 groups,tumor embolus group with 86 cases and non-tumor embolus group with 37 cases.The difference of FOXP3 expression between above two groups was of statistical significance.FOXP3 expression was significantly associated with negative vessel tumor embolus,with ?2=9.431,P=0.002.3 According to the Ki67 index,the 123 cases were divided into 2 groups.The cut-off value of Ki67 index was 30%.84 of the patients presented with high Ki67 index,and 39 with low Ki67 index.The difference of FOXP3 expression between above two groups was of statistical significance.NuclearFOXP3 expression was significantly associated with lower Ki67 index,with?2=4.214,P=0.041.4 The molecular subtype was classified according to 13 th St.Gallen International Expert Consensus.22 of the patients presented with Luminal A breast cancer,44 with Luminal B breast cancer,32 with HER2+ breast cancer,and 25 with triple negative breast cancer(TNBC).Nuclear FOXP3 expression was also significantly correlated with the molecular subtypes of breast cancer(?2=12.983,P=0.002),displaying the highest ratio in the Luminal A subtype(68.18%).Cytoplasmic FOXP3 significantly associated with molecular subtype(?2=13.795,P=0.003),displaying the highest ratio in the TNBC(68.18%).5 The expression of FOXP3 was not associated with the age of patient,tumor size,status of lymph node metastasis,histological grade and pTNM stage,with P>0.05.6 FOXP3 expression and survival analysisIn the whole cohort of patients,Kaplan-Meier curves showed that tumor FOXP3+(expression in nucleus and/or cytoplasm)conferred a significantly improved DFS(89.29% vs.71.79%,log-rank P=0.013),but not a significantly improved OS(91.67% vs.82.05%,log-rank P=0.167).While,nuclear FOXP3+ was significantly associated with improved OS(94.92% vs.82.81%,Log-rank P=0.022)and DFS(91.53% vs.76.56%,Log-rank P=0.026).However,cytoplasmic FOXP3+ had not significant correlation with OS and DFS(Log-rank P=0.355,P=0.061).Multivariate Cox regression analysis indicated that nuclear FOXP3+ was an independent prognostic factor for OS(HR: 0.245;95%CI: 0.067-0.892;P=0.033).By contrast,neither the tumor FOXP3+,nor cytoplasmic FOXP3+was an independent prognostic factor for OS or DFS(P>0.05).In addition,the multivariate analysis showed that vessel tumor embolus appeared to be an independent risk factor(HR=2.904,P=0.047),and positive-ER was an independent protective factor for OS(HR=0.181,P=0.009).Conclusions:1 Nuclear FOXP3 expression is correlated with low Ki-67 index and negative vessel tumor embolus in breast invasive ductal carcinoma.In additon,it is expressed highest in luminal A subtype breast cancer.It indicates that nuclear FOXP3 is negatively related to the malignant degree of tumor in breast invasive ductal carcinoma.2 The prognostic significance of FOXP3 expression in breast invasive ductal carcinoma specimens is relevant to the different subcellular localizations of FOXP3.Nuclear FOXP3 is demonstrated an independent prognostic factor for improved OS,whereas cytoplasmic FOXP3 is of no prognostic significance.Nuclear FOXP3 represents as a potential prognostic marker for breast cancer.