Epigenetic silencing of the WNT antagonist Dickkopf 3 disrupts normal Wnt/β‐catenin signalling and apoptosis regulation in breast cancer cells

Dickkopf‐related protein 3 (DKK3) is an antagonist of Wnt ligand activity. Reduced DKK3 expression has been reported in various types of cancers, but its functions and related molecular mechanisms in breast tumorigenesis remain unclear. We examined the expression and promoter methylation of DKK3 in 10 breast cancer cell lines, 96 primary breast tumours, 43 paired surgical margin tissues and 16 normal breast tissues. DKK3 was frequently silenced in breast cell lines (5/10) by promoter methylation, compared with human normal mammary epithelial cells and tissues. DKK3 methylation was detected in 78% of breast tumour samples, whereas only rarely methylated in normal breast and surgical margin tissues, suggesting tumour‐specific methylation of DKK3 in breast cancer. Ectopic expression of DKK3 suppressed cell colony formation through inducing G0/G1 cell cycle arrest and apoptosis of breast tumour cells. DKK3 also induced changes of cell morphology, and inhibited breast tumour cell migration through reversing epithelial‐mesenchymal transition (EMT) and down‐regulating stem cell markers. DKK3 inhibited canonical Wnt/β‐catenin signalling through mediating β‐catenin translocation from nucleus to cytoplasm and membrane, along with reduced active‐β‐catenin, further activating non‐canonical JNK signalling. Thus, our findings demonstrate that DKK3 could function as a tumour suppressor through inducing apoptosis and regulating Wnt signalling during breast tumorigenesis.     

Epigenetic silencing of DACH1 induces the invasion and metastasis of gastric cancer by activating TGF‐β signalling

Gastric cancer (GC) is the fourth most common malignancy in males and the fifth most common malignancy in females worldwide. DACH1 is frequently methylated in hepatic and colorectal cancer. To further understand the regulation and mechanism of DACH1 in GC, eight GC cell lines, eight cases of normal gastric mucosa, 98 cases of primary GC and 50 cases of adjacent non‐tumour tissues were examined. Methylation‐specific PCR, western blot, transwell assay and xenograft mice were used in this study. Loss of DACH1 expression correlated with promoter region methylation in GC cells, and re‐expression was induced by 5‐Aza‐2′‐deoxyazacytidine. DACH1 is methylated in 63.3% (62/98) of primary GC and 38% (19/50) of adjacent non‐tumour tissues, while no methylation was found in normal gastric mucosa. Methylation of DACH1 correlated with reduced expression of DACH1 (P < 0.01), late tumour stage (stage III/IV) (P < 0.01) and lymph node metastasis (P < 0.05). DACH1 expression inhibited epithelial–mesenchymal transition and metastasis by inhibiting transforming growth factor (TGF)‐β signalling and suppressed GC cell proliferation through inducing G2/M phase arrest. The tumour size is smaller in DACH1‐expressed BGC823 cell xenograft mice than in unexpressed group (P < 0.01). Restoration of DACH1 expression also sensitized GC cells to docetaxel. These studies suggest that DACH1 is frequently methylated in human GC and expression of DACH1 was controlled by promoter region methylation. DACH1 suppresses GC proliferation, invasion and metastasis by inhibiting TGF‐β signalling pathways both in vitro and in vivo. Epigenetic silencing DACH1 may induce GC cells' resistance to docetaxel.     

Human ribosomal protein S13 promotes gastric cancer growth through down‐regulating p27Kip1

Our previous works revealed that human ribosomal protein S13 (RPS13) was up‐regulated in multidrug‐resistant gastric cancer cells and overexpression of RPS13 could protect gastric cancer cells from drug‐induced apoptosis. The present study was designed to explore the role of RPS13 in tumorigenesis and development of gastric cancer. The expression of RPS13 in gastric cancer tissues and normal gastric mucosa was evaluated by immunohistochemical staining and Western blot analysis. It was found RPS13 was expressed at a higher level in gastric cancer tissues than that in normal gastric mucosa. RPS13 was then genetically overexpressed in gastric cancer cells or knocked down by RNA interference. It was demonstrated that up‐regulation of RPS13 accelerated the growth, enhanced in vitro colony forming and soft agar cologenic ability and promoted in vivo tumour formation potential of gastric cancer cells. Meanwhile, down‐regulation of RPS13 in gastric cancer cells resulted in complete opposite effects. Moreover, overexpression of RPS13 could promote G1 to S phase transition whereas knocking down of RPS13 led to G1 arrest of gastric cancer cells. It was further demonstrated that RPS13 down‐regulated p27^kip1 expression and CDK2 kinase activity but did not change the expression of cyclin D, cyclin E, CDK2, CDK4 and p16^INK4A. Taken together, these data indicate that RPS13 could promote the growth and cell cycle progression of gastric cancer cells at least through inhibiting p27^kip1 expression.     

Changes in serum markers indicative of health effects in vineyard workers following exposure to the fungicide mancozeb: an Italian study

Gastric cancer is the second most common cancer worldwide. The involvement of reactive oxygen species (ROS) in the pathogenesis of gastric malignancies is well known. Many human tumours have shown significant changes in the activity and expression of superoxide dismutase (SOD), which might be correlated with clinical–pathological parameters for the prognosis of human carcinoma. The aim of this study is the detection of MnSOD and CuZnSOD activity and their expression in gastric adenocarcinoma and healthy tissues. Gastric samples (adenocarcinoma and healthy tissues) harvested during endoscopy or resected during surgery were used to determine MnSOD and CuZnSOD activity and expression by spectrophotometric and Western blotting assays. The total SOD activity was significantly higher (p<0.05) in healthy mucosa with respect to gastric adenocarcinomas. No differences were found in MnSOD activity and, on the contrary, CuZnSOD activity was significantly lower (p<0.001) in cancer samples with respect to normal mucosa. The rate of MnSOD/CuZnSOD activity in adenocarcinoma was over ninefold higher than that registered in healthy tissues (p<0.05). Moreover, in adenocarcinoma MnSOD activity represented the 83% of total SOD with respect to healthy tissues where the ratio was 52% (p<0.001). On the contrary, in cancer tissues, CuZnSOD activity accounted for only 17% of the total SOD (p<0.001 if compared with the values recorded in normal mucosa). After immunoblotting, MnSOD was more expressed in adenocarcinoma with respect to normal mucosa (p<0.001), while CuZnSOD was similarly expressed in adenocarcinoma and healthy tissues. The SOD activity assay might provide a specific and sensitive method of analysis that allows the differentiation of healthy tissue from tumour tissue. The MnSOD to CuZnSOD activity ratio, and the ratio between these two isoforms and total SOD, presented in this preliminary study might be considered in the identification of cancerous from healthy control tissue.     

CTNNBIP1 downregulation is associated with tumor grade and viral infections in gastric adenocarcinoma

Gastric cancer is a life-threatening disease; resulting from interaction among genetic, epigenetic, and environmental factors. Aberrant dysregulation and methylation changes in Wnt/β-catenin signaling downstream elements are a prevalent phenomenon encountered in gastric tumorigenesis. Also, viral infections play a role in gastric cancer development. CTNNBIP1 (β-catenin interacting protein 1) gene is an antagonist of Wnt signaling which binds to the β-catenin molecules. The CTNNBIP1 function as tumor suppressor gene or oncogene in different types of cancer is controversial. Moreover, its function and regulatory mechanisms in gastric cancer progression is unknown. In the present study, we examined CTNNBIP1 gene expression, the methylation status of the regulatory region of the gene, and their association with Epstein–Barr virus (EBV), and cytomegalovirus (CMV) and Helicobacter pylori infections in human gastric adenocarcinoma tissues in comparison with their adjacent nontumoral tissues. Our data revealed a significant downregulation of CTNNBIP1 in gastric tumors. Female patients showed lower level of CTNNBIP1 than males (p < 0.05). Also, decreased expression of CTNNBIP1 was markedly associated with well-differentiated tumor grades (p < 0.05). No methylation change was observed between tumoral and nontumoral tissues. Additionally, CTNNBIP1 down regulation was significantly associated with CMV infection (p < 0.05). In the absence of EBV infection, lower expression of CTNNBIP1 was observed. There was no association between H. pylori infection and CTNNBIP1 expression. Our findings revealed the tumor suppressor role for CTNNBIP1 in gastric adenocarcinoma. Interestingly, EBV and CMV infections modulate CTNNBIP1 expression.     

TIPE1 suppresses invasion and migration through down‐regulating Wnt/β‐catenin pathway in gastric cancer

Epithelial–mesenchymal transition (EMT) plays an important role in the invasiveness and metastasis of gastric cancer. Therefore, identifying key molecules involved in EMT will provide new therapeutic strategy for treating patients with gastric cancer. TIPE1 is a newly identified member of the TIPE (TNFAIP8) family, and its contributions to progression and metastasis have not been evaluated. In this study, we found that the levels of TIPE1 were significantly reduced and inversely correlated with differentiation status and distant metastasis in primary gastric cancer tissues. We further observed overexpression of TIPE1 in aggressive gastric cancer cell lines decreased their metastatic properties both in vitro and in vivo as demonstrated by markedly inhibiting EMT and metastasis of gastric cancer cells in nude mice. Consistently, gene silencing of TIPE1 in well‐differentiated gastric cancer cell line (AGS) inhibited these processes. Mechanistically, we found that TIPE1‐medicated Wnt/β‐catenin signalling was one of the critical signal transduction pathways that link TIPE1 to EMT inhibition. Importantly, TIPE1 dramatically restrained the expression and activities of MMP2 and MMP9 which are demonstrated to promote tumour progression and are implicated in EMT. Collectively, these findings provide new evidence for a better understanding of the biological activities of TIPE1 in progression and metastasis of gastric cancer and suggest that TIPE1 may be an innovative diagnostic and therapeutic target of gastric cancer.     

Intra-Tumour Signalling Entropy Determines Clinical Outcome in Breast and Lung Cancer

The cancer stem cell hypothesis, that a small population of tumour cells are responsible for tumorigenesis and cancer progression, is becoming widely accepted and recent evidence has suggested a prognostic and predictive role for such cells. Intra-tumour heterogeneity, the diversity of the cancer cell population within the tumour of an individual patient, is related to cancer stem cells and is also considered a potential prognostic indicator in oncology. The measurement of cancer stem cell abundance and intra-tumour heterogeneity in a clinically relevant manner however, currently presents a challenge. Here we propose signalling entropy, a measure of signalling pathway promiscuity derived from a sample’s genome-wide gene expression profile, as an estimate of the stemness of a tumour sample. By considering over 500 mixtures of diverse cellular expression profiles, we reveal that signalling entropy also associates with intra-tumour heterogeneity. By analysing 3668 breast cancer and 1692 lung adenocarcinoma samples, we further demonstrate that signalling entropy correlates negatively with survival, outperforming leading clinical gene expression based prognostic tools. Signalling entropy is found to be a general prognostic measure, valid in different breast cancer clinical subgroups, as well as within stage I lung adenocarcinoma. We find that its prognostic power is driven by genes involved in cancer stem cells and treatment resistance. In summary, by approximating both stemness and intra-tumour heterogeneity, signalling entropy provides a powerful prognostic measure across different epithelial cancers.     

Transmembrane protein 106A is silenced by promoter region hypermethylation and suppresses gastric cancer growth by inducing apoptosis

Inactivation of tumour suppressor genes by promoter methylation plays an important role in the initiation and progression of gastric cancer (GC). Transmembrane 106A gene (TMEM106A) encodes a novel protein of previously unknown function. This study analysed the biological functions, epigenetic changes and the clinical significance of TMEM106A in GC. Data from experiments indicate that TMEM106A is a type II membrane protein, which is localized to mitochondria and the plasma membrane. TMEM106A was down‐regulated or silenced by promoter region hypermethylation in GC cell lines, but expressed in normal gastric tissues. Overexpression of TMEM106A suppressed cell growth and induced apoptosis in GC cell lines, and retarded the growth of xenografts in nude mice. These effects were associated with the activation of caspase‐2, caspase‐9, and caspase‐3, cleavage of BID and inactivation of poly (ADP‐ribose) polymerase (PARP). In primary GC samples, loss or reduction of TMEM106A expression was associated with promoter region hypermethylation. TMEM106A was methylated in 88.6% (93/105) of primary GC and 18.1% (2/11) in cancer adjacent normal tissue samples. Further analysis suggested that TMEM106A methylation in primary GCs was significantly correlated with smoking and tumour metastasis. In conclusion, TMEM106A is frequently methylated in human GC. The expression of TMEM106A is regulated by promoter hypermethylation. TMEM106A is a novel functional tumour suppressor in gastric carcinogenesis.     

Gastrokine 1 regulates NF‐κB signaling pathway and cytokine expression in gastric cancers

Gastrokine 1 (GKN1) plays an important role in the gastric mucosal defense mechanism and also acts as a functional gastric tumor suppressor. In this study, we examined the effect of GKN1 on the expression of inflammatory mediators, including NF‐κB, COX‐2, and cytokines in GKN1‐transfected AGS cells and shGKN1‐transfected HFE‐145 cells. Lymphocyte migration and cell viability were also analyzed after treatment with GKN1 and inflammatory cytokines in AGS cells by transwell chemotaxis and an MTT assay, respectively. In GKN1‐transfected AGS cells, we observed inactivation and reduced expression of NF‐κB and COX‐2, whereas shGKN1‐transfected HFE‐145 cells showed activation and increased expression of NF‐κB and COX‐2. GKN1 expression induced production of inflammatory cytokines including IL‐8 and ‐17A, but decreased expression of IL‐6 and ‐10. We also found IL‐17A expression in 9 (13.6%) out of 166 gastric cancer tissues and its expression was closely associated with GKN1 expression. GKN1 also acted as a chemoattractant for the migration of Jurkat T cells and peripheral B lymphocytes in the transwell assay. In addition, GKN1 significantly reduced cell viability in both AGS and HFE‐145 cells. These data suggest that the GKN1 gene may inhibit progression of gastric epithelial cells to cancer cells by regulating NF‐κB signaling pathway and cytokine expression. J. Cell. Biochem. 114: 1800–1809, 2013. © 2013 Wiley Periodicals, Inc.     

Long noncoding RNA LINC00978 promotes cancer growth and acts as a diagnostic biomarker in gastric cancer

Objectives

Long noncoding RNAs (lncRNAs) play important roles in cancer development and progression. The deregulated expression of LINC00978 has been reported in human cancers. However, the expression pattern and biological roles of LINC00978 in gastric cancer (GC) remain unclear. In this study, we investigated the potential roles and clinical value of LINC00978 in gastric cancer.

Materials and methods

QRT‐PCR was performed to investigate the expression of LINC00978 in gastric cancer cell lines, tissues and serum samples. Cell counting, colony formation, transwell migration and matrigel invasion assays were performed to determine the effects of shRNA‐mediated knockdown of LINC00978 on gastric cancer cell functions. In vivo tumour growth assay was also conducted. Flow cytometry, immunohistochemistry, western blot and qRT‐PCR were used for potential mechanism study.

Results

LINC00978 expression level was elevated in GC tumour tissues, serum samples and cell lines. The expression level of LINC00978 was significantly correlated with tumour size (P = 0.02), lymphatic metastasis (P = 0.009) and TNM stage (P = 0.009). LINC00978 knockdown inhibited the proliferation of GC cells by suppressing cell cycle progression and inducing apoptosis. LINC00978 knockdown also inhibited the migration and invasion of GC cells. In addition, LINC00978 knockdown inhibited the activation of TGF‐β/SMAD signalling pathway and the process of epithelial‐mesenchymal transition (EMT) in GC cells. Moreover, the in vivo tumorigenicity of LINC00978 knockdown GC cells in mice was significantly decreased.

Conclusions

LINC00978 promotes gastric cancer progression and may serve as a potential biomarker for GC.     

Disabled‐1 is down‐regulated in clinical breast cancer and regulates cell apoptosis through NF‐κB/Bcl‐2/caspase‐9

Disabled‐1 (Dab1) is best known as an adaptor protein regulating neuron migration and lamination during development. However, the exact function of Dab1 in breast cancer is unknown. In this study, we examined the expression of Dab1 in 38 breast cancer paraffin sections, as well as 60 paired frozen breast cancer and their adjacent tissues. Our results showed that Dab1 was reduced in breast cancer, and its compromised expression correlated with triple negative breast cancer phenotype, poor differentiation, as well as lymph node metastasis. Functional analysis in breast cancer cell lines demonstrated that Dab1 promoted cell apoptosis, which, at least partially, depended on its regulation of NF‐κB/Bcl‐2/caspase‐9 pathway. Our study strongly suggests that Dab1 may be a potential tumour suppressor gene in breast cancer.     

AFAP1‐AS1: A novel oncogenic long non‐coding RNA in human cancers

Long non‐coding RNAs (lncRNAs), a group of non‐protein‐coding RNAs with more than 200 nucleotides in length, are involved in multiple biological processes, such as the proliferation, apoptosis, migration and invasion. Moreover, numerous studies have shown that lncRNAs play important roles as oncogenes or tumour suppressor genes in human cancers. In this paper, we concentrate on actin filament‐associated protein 1‐antisense RNA 1 (AFAP1‐AS1), a well‐known long non‐coding RNA that is overexpressed in various tumour tissues and cell lines, including oesophageal cancer, pancreatic ductal adenocarcinoma, nasopharyngeal carcinoma, lung cancer, hepatocellular carcinoma, ovarian cancer, colorectal cancer, biliary tract cancer and gastric cancer. Moreover, high expression of AFAP1‐AS1 was associated with the clinicopathological features and cancer progression. In this review, we sum up the current studies on the characteristics of AFAP1‐AS1 in the biological function and mechanism of human cancers.     

miR-125b靶向MCL1抑制胃癌 MGC-803细胞增殖

探讨mi R-125b对胃癌MGC-803细胞增殖的影响及机制,为阐明胃癌发病的分子机制提供实验依据.采用q RT-PCR和原位杂交,检测mi R-125b在正常胃黏膜(NGM)和胃癌(GAC)组织中的表达.将mi R-125b导入胃癌MGC-803细胞,观察mi R-125b高表达对MGC-803细胞增殖的影响.利用Targetscan 6.2软件及荧光素酶报告基因检测,分析mi R-125b对MCL1基因的靶向性作用.构建MCL1干扰载体,观察干扰MCL1基因表达对MGC-803细胞增殖的影响.结果发现,mi R-125b在胃癌组织中低表达,其表达与胃癌的分化程度及患者预后呈正相关,与TNM分期、淋巴结转移呈负相关(P0.01).mi R-125b高表达后MGC-803细胞的增殖降低、凋亡率增加、裂解caspase-3与裂解PARP表达增加(P0.01);mi R-125b与MCL1基因的3′UTR(2 613~2 620)结合,抑制MCL1的m RNA及蛋白质表达(P0.01);沉默MCL1基因表达后MGC-803细胞的增殖降低、凋亡率增加、裂解caspase-3与裂解PARP表达增加(P0.01).从而得出结论,mi R-125b在胃癌组织中低表达,其表达与胃癌组织分化程度、TNM分期、淋巴结转移及患者预后密切相关;mi R-125b靶向抑制MCL1基因表达,活化caspase-3信号通路,抑制MGC-803细胞增殖.     

ZIC1 is downregulated through promoter hypermethylation in gastric cancer

As one of major epigenetic changes responsible for tumor suppressor gene inactivation in the development of cancer, promoter hypermethylation was proposed as a marker to define novel tumor suppressor genes. In the current study we identified ZIC1 (Zic family member 1, odd-paired Drosophila homolog) as a novel tumor suppressor gene silenced through promoter hypermethylation in gastric cancer, the second leading cause of cancer death worldwide. In all of gastric cancer cells lines examined, ZIC1 expression was downregulated and such downregulation was accompanied with the hypermethylation of ZIC1 promoter. Demethylation treatment with 5-aza-2′-deoxycytidine (Aza) reversed ZIC1 downregulation, highlighting the importance of promoter methylation to ZIC1 downregulation in gastric cancer cells. Notably, ZIC1 expression was significantly downregulated in primary gastric carcinoma tissues in comparison with non-tumor adjacent gastric tissues (p < 0.01). Accordingly, promoter methylation of ZIC1 was frequently detected in primary gastric carcinoma tissues (94.6%, 35/37) but not normal gastric tissues, indicating that promoter hypermethylation mediated ZIC1 downregulation may play an important role in gastric carcinogenesis. Indeed, ectopic expression of ZIC1 led to the growth inhibition of gastric cancer cells through the induction of S-phase cell cycle arrest (p < 0.01). Our results revealed ZIC1 as a novel candidate tumor suppressor gene downregulated through promoter hypermethylation in gastric cancer.     

HOXB7在胃癌组织中的表达及其临床意义

目的:分析同源异型盒基因B7(Homeobox B7,HOXB7)在人胃癌组织中的表达情况,并探讨HOXB7的表达与胃癌患者临床病理特征和预后的关系。方法:收集行手术切除的胃癌组织及对应癌旁组织共120例,采用实时定量PCR(q RT-PCR)技术、蛋白印迹(Western blot)和免疫组化染色分别检测HOXB7m RNA水平及蛋白水平在胃癌及对应癌旁组织中的表达,通过卡方检验分析HOXB7表达水平与胃癌患者临床病理因素间的相关性,采用单因素及多因素Cox回归模型评估HOXB7在胃癌风险评估中的作用,Kaplan-Meier生存曲线分析HOXB7表达水平与胃癌患者无瘤生存期和总生存期的关系。结果:胃癌组织中HOXB7 m RNA和蛋白表达水平均显著高于对应癌旁组织(P0.05);HOXB7蛋白表达与肿瘤临床分期、浸润深度及淋巴结转移均具有显著相关性(P0.05),而与患者性别、年龄、分化程度及远处转移均无显著相关性(P0.05)。单因素和多因素Cox分析提示HOXB7可以作为评估胃癌患者预后的独立风险因素。Kaplan-Meier生存分析结果显示高表达HOXB7的胃癌患者无瘤生存时间和总生存时间均显著低于HOXB7低表达患者组(P0.01)。结论:HOXB7蛋白在胃癌组织中高表达,并与胃癌的恶性表型有关,可能参与胃癌发生及恶性进展过程,可作为判断胃癌患预后的重要参考指标。     

Epigenetic silenced miR‐125a‐5p could be self‐activated through targeting Suv39H1 in gastric cancer

Emerging evidence suggests that microRNAs (miRNAs) serve an important role in tumorigenesis and development. Although the low expression of miR‐125a‐5p in gastric cancer has been reported, the underlying mechanism remains unknown. In the current study, the low expression of miR‐125a‐5p in gastric cancer was verified in paired cancer tissues and adjacent non‐tumour tissues. Furthermore, the GC islands in the miR‐125a‐5p region were hypermethylated in the tumour tissues. And the hypermethylation was negatively correlated with the miR‐125a‐5p expression. Target gene screening showed that the histone methyltransferase Suv39H1 was one of the potential target genes. In vitro studies showed that miR‐125a‐5p could directly suppress the Suv39H1 expression and decrease the H3K9me3 levels. On the other hand, the Suv39H1 could induce demethylation of miR‐125a‐5p, resulting in re‐activation of miR‐125a‐5p. What is more, overexpessing miR‐125a‐5p could also self‐activate the silenced miR‐125a‐5p in gastric cancer cells, which suppressed cell migration, invasion and proliferation in vitro and inhibited cancer progression in vivo. Thus, we uncovered here that the epigenetic silenced miR‐125a‐5p could be self‐activated through targeting Suv39H1 in gastric cancer, suggesting that miR‐125a‐5p might be not only the potential prognostic value as a tumour biomarker but also potential therapeutic targets in gastric cancer.     

Aberrant expression of Arpin in human breast cancer and its clinical significance

Arpin (Arp2/3 complex inhibitor), a novel protein found in 2013, plays a pivotal role in cell motility and migration. However, the precise role of Arpin in cancer is unclear. This study investigated the expression of Arpin in breast cancer and evaluated its correlation with the characteristics of clinical pathology and prognosis of breast cancer patients. Immunohistochemistry (IHC) for Arpin protein was performed on formalin‐fixed, paraffin‐embedded 176 breast cancer tissues and 43 normal breast tissues while qRT‐PCR for Arpin mRNA with 104 paired tumour and paratumoural tissues from breast cancer patients respectively. The association of Arpin expression with clinical pathological features and survival was assessed in a retrospective cohort analysis of patients. The results showed that the expression of Arpin protein in cancer tissues was lower compared to that in normal breast and the expression of Arpin mRNA was also lower in cancer tissues than that in the matched paratumoural tissues. Among the 176 breast cancer patients, the lower expression of Arpin was significantly associated with advanced tumour, nodes and metastasis system stage, and the reduced Arpin expression was strongly associated with axillary lymph node metastasis using univariate and multivariate logistic regression analysis [odds ratio: 3.242; 95% confidence interval (CI): 1.526, 6.888; P < 0.05]. Furthermore, Arpin expression was an independent risk factor for recurrence‐free survival (HR: 0.373; 95% CI: 0.171, 0.813; P < 0.05). As Arpin expression was first examined in human breast cancer tissues with qRT‐PCR and IHC, our results suggest that Arpin downregulation may contribute to the initiation and development of breast cancer metastasis. Therefore, as a potential predictive marker, Arpin deserves future studies.