Angiopoietin‐2 mediates blood–brain barrier impairment and colonization of triple‐negative breast cancer cells in brain

Although the incidence of breast cancer metastasis (BCM) in brain has increased significantly in triple‐negative breast cancer (TNBC), the mechanisms remain elusive. Using in vivo mouse models for BCM in brain, we observed that TNBC cells crossed the blood–brain barrier (BBB), lodged in the brain microvasculature and remained adjacent to brain microvascular endothelial cells (BMECs). Breaching of the BBB in vivo by TNBCs resulted in increased BBB permeability and changes in ZO‐1 and claudin‐5 tight junction (TJ) protein structures. Angiopoietin‐2 expression was elevated in BMECs and was correlated with BBB disruption. Secreted Ang‐2 impaired TJ structures and increased BBB permeability. Treatment of mice with the neutralizing Ang‐2 peptibody trebananib prevented changes in the BBB integrity and BMEC destabilization, resulting in inhibition of TNBC colonization in brain. Thus, Ang‐2 is involved in initial steps of brain metastasis cascade, and inhibitors for Ang‐2 may serve as potential therapeutics for brain metastasis. Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Functional and prognostic significance of the genomic amplification of frizzled 6 (FZD6) in breast cancer

Frizzled receptors mediate Wnt ligand signalling, which is crucially involved in regulating tissue development and differentiation, and is often deregulated in cancer. In this study, we found that the gene encoding the Wnt receptor frizzled 6 (FZD6) is frequently amplified in breast cancer, with an increased incidence in the triple‐negative breast cancer (TNBC) subtype. Ablation of FZD6 expression in mammary cancer cell lines: (1) inhibited motility and invasion; (2) induced a more symmetrical shape of organoid three‐dimensional cultures; and (3) inhibited bone and liver metastasis in vivo. Mechanistically, FZD6 signalling is required for the assembly of the fibronectin matrix, interfering with the organization of the actin cytoskeleton. Ectopic delivery of fibronectin in FZD6‐depleted, triple‐negative MDA‐MB‐231 cells rearranged the actin cytoskeleton and restored epidermal growth factor‐mediated invasion. In patients with localized, lymph node‐negative (early) breast cancer, positivity of tumour cells for FZD6 protein identified patients with reduced distant relapse‐free survival. Multivariate analysis indicated an independent prognostic significance of FZD6 expression in TNBC tumours, predicting distant, but not local, relapse. We conclude that the FZD6–fibronectin actin axis identified in our study could be exploited for drug development in highly metastatic forms of breast cancer, such as TNBC. © 2016 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.     

Insulin growth factor receptor‐1 expression and loss of PTEN protein predict early recurrence in triple‐negative breast cancer

Iqbal J, Thike A A, Cheok P Y, Tse G M‐K & Tan P H
(2012) Histopathology  61, 652–659 Insulin growth factor receptor‐1 expression and loss of PTEN protein predict early recurrence in triple‐negative breast cancer Aims: Insulin‐like growth factor receptor‐1 (IGFR‐1) and its signalling axis promote tumorigenesis, metastasis, and resistance to existing forms of cancer therapy, and have become a major focus for the development of anticancer drugs. As oncological management options for triple‐negative breast cancers (TNBCs) are limited, there is potential for the rapid development of novel selective anticancer agents specifically targeting components of the PTEN–phosphoinositide 3‐kinase–AKT pathway, including the phosphorylated form of AKT (pAKT) and the tumour suppressor molecule PTEN. The aim of this study was to conduct immunohistochemical analyses to examine the levels of PTEN, IGFR‐1 and pAKT expression in TNBCs, and determine whether these levels correlated with poor prognosis in this subset of aggressive breast cancers. Methods and results: Immunohistochemistry was performed on paraffin‐embedded tumour tissues from a consecutive cohort of 144 female patients diagnosed with TNBC. Associations of IGFR‐1, PTEN and pAKT expression with clinicopathological parameters, disease‐free survival (DFS) and overall survival (OS) were evaluated. There were significant increases in IGFR‐1 expression (99%) and pAKT expression (92%) with concomitant loss of PTEN expression in the majority of cases (63%). Increased IGFR‐1 expression and loss of PTEN expression were associated with reduced OS and DFS, respectively. pAKT expression showed a strong correlation with basal‐like expression. Combinatorial immunophenotypic analyses showed that loss of PTEN expression with concomitant IGFR‐1 expression correlated with poor DFS. Conclusions: A high percentage of PTEN loss with overexpression of IGFR‐1 and pAKT in TNBC indicates the potential of these molecules for predicting early recurrence and/or as targets in the formulation of effective alternative therapy regimens.     

Frequent incidence of BARD1‐truncating mutations in germline DNA from triple‐negative breast cancer patients

Triple‐negative breast cancer (TNBC) accounts for 10–20% of all breast cancers (BCs), and conventional chemotherapy is the only effective systemic treatment. Germline BRCA1/2 mutations are found in approximately 15% of TNBC patients. In the past, we have documented pathogenic mutations in BARD1, a BRCA1 interacting protein, in families at high risk for BC. In this study, we have analyzed germline DNA from 61 estrogen receptor negative patients (of which 42 were TNBC) for the presence of mutations in the BRCA1, BRCA2 and BARD1 gene. BRCA1/2 mutations were found in 8 out of 42 (19%) TNBC patients, but not in the ER?/HER2+ cohort. We also found four good candidate pathogenic BARD1 mutations in the TNBC cohort, including two protein‐truncating mutations (p.Gln564Ter and p.Arg641Ter). Our data suggest that TNBC patients are enriched for pathogenic BARD1 germline mutations as compared to control samples and high BC risk families. Ten of the 42 investigated TNBC patients carry a BRCA pathway mutation (in BRCA1, BRCA2 or BARD1) rendering them susceptible to homologous recombination deficiency. These patients should become eligible for exploring the efficacy of poly (ADP‐ribose) polymerase (PARP) inhibitors.     

Tumour stroma‐derived lipocalin‐2 promotes breast cancer metastasis

Tumour cell‐secreted factors skew infiltrating immune cells towards a tumour‐supporting phenotype, expressing pro‐tumourigenic mediators. However, the influence of lipocalin‐2 (Lcn2) on the metastatic cascade in the tumour micro‐environment is still not clearly defined. Here, we explored the role of stroma‐derived, especially macrophage‐released, Lcn2 in breast cancer progression. Knockdown studies and neutralizing antibody approaches showed that Lcn2 contributes to the early events of metastasis in vitro. The release of Lcn2 from macrophages induced an epithelial–mesenchymal transition programme in MCF‐7 breast cancer cells and enhanced local migration as well as invasion into the extracellular matrix, using a three‐dimensioanl (3D) spheroid model. Moreover, a global Lcn2 deficiency attenuated breast cancer metastasis in both the MMTV–PyMT breast cancer model and a xenograft model inoculating MCF‐7 cells pretreated with supernatants from wild‐type and Lcn2‐knockdown macrophages. To dissect the role of stroma‐derived Lcn2, we employed an orthotopic mammary tumour mouse model. Implantation of wild‐type PyMT tumour cells into Lcn2‐deficient mice left primary mammary tumour formation unaltered, but specifically reduced tumour cell dissemination into the lung. We conclude that stroma‐secreted Lcn2 promotes metastasis in vitro and in vivo, thereby contributing to tumour progression. Our study highlights the tumourigenic potential of stroma‐released Lcn2 and suggests Lcn2 as a putative therapeutic target. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Expression of autophagy‐related markers beclin‐1, light chain 3A,light chain 3B and p62 according to the molecular subtype of breast cancer

Aims: To investigate the relationship between the expression of autophagy‐related proteins, including beclin‐1, light chain (LC) 3A, LC3B, and p62, and prognosis in invasive breast cancer. Methods and results: We constructed tissue microarrays from the breast cancer cells of 489 patients, and classified molecular subtypes using surrogate immunohistochemical stains. The tumoral expression levels of LC3A and LC3B were highest in triple‐negative breast cancer (TNBC) (P < 0.001), whereas these types of tumour had the lowest expression levels of these markers in the stroma (P = 0.005 and P < 0.001, respectively). Cytoplasmic beclin‐1 expression was highest in TNBC, but nuclear expression was lowest (P < 0.001). p62 cytoplasmic and nuclear expression were highest in HER2‐type tumours (P = 0.001 and P < 0.001, respectively). Tumoral LC3A and LC3B expression were associated with high histological grade (P < 0.001, and P < 0.028, respectively), but nuclear p62 expression was associated with lower histological grade (P = 0.004). Conclusions: Autophagy‐related markers are differentially expressed according to the molecular subtype of breast cancer. In particular, expression of LC3A, LC3B and beclin‐1 was highest in TNBC tumour cells, whereas that of LC3A and LC3B in the tumour stroma was lowest in TNBC.     

Microglandular adenosis associated with triple‐negative breast cancer is a neoplastic lesion of triple‐negative phenotype harbouring TP53 somatic mutations

Microglandular adenosis (MGA) is a rare proliferative lesion of the breast composed of small glands lacking myoepithelial cells and lined by S100‐positive, oestrogen receptor (ER)‐negative, progesterone receptor (PR)‐negative, and HER2‐negative epithelial cells. There is evidence to suggest that MGA may constitute a non‐obligate precursor of triple‐negative breast cancer (TNBC). We sought to define the genomic landscape of pure MGA and of MGA, atypical MGA (AMGA) and associated TNBCs, and to determine whether synchronous MGA, AMGA, and TNBCs would be clonally related. Two pure MGAs and eight cases of MGA and/or AMGA associated with in situ or invasive TNBC were collected, microdissected, and subjected to massively parallel sequencing targeting all coding regions of 236 genes recurrently mutated in breast cancer or related to DNA repair. Pure MGAs lacked clonal non‐synonymous somatic mutations and displayed limited copy number alterations (CNAs); conversely, all MGAs (n = 7) and AMGAs (n = 3) associated with TNBC harboured at least one somatic non‐synonymous mutation (range 3–14 and 1–10, respectively). In all cases where TNBCs were analyzed, identical TP53 mutations and similar patterns of gene CNAs were found in the MGA and/or AMGA and in the associated TNBC. In the MGA/AMGA associated with TNBC lacking TP53 mutations, somatic mutations affecting PI3K pathway‐related genes (eg PTEN, PIK3CA, and INPP4B) and tyrosine kinase receptor signalling‐related genes (eg ERBB3 and FGFR2) were identified. At diagnosis, MGAs associated with TNBC were found to display subclonal populations, and clonal shifts in the progression from MGA to AMGA and/or to TNBC were observed. Our results demonstrate the heterogeneity of MGAs, and that MGAs associated with TNBC, but not necessarily pure MGAs, are genetically advanced, clonal, and neoplastic lesions harbouring recurrent mutations in TP53 and/or other cancer genes, supporting the notion that a subset of MGAs and AMGAs may constitute non‐obligate precursors of TNBCs. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Suppression of SPIN1‐mediated PI3K–Akt pathway by miR‐489 increases chemosensitivity in breast cancer

Drug resistance is one of the major obstacles for improving the prognosis of breast cancer patients. Increasing evidence has linked the association of aberrantly expressed microRNAs (miRNAs) with tumour development and progression as well as chemoresistance. Despite recent advances, there is still little known about the potential role and mechanism of miRNAs in breast cancer chemoresistance. Here we describe that 16 miRNAs were found to be significantly down‐regulated and 11 up‐regulated in drug‐resistant breast cancer tissues compared with drug‐sensitive tissues, using a miRNA microarray. The results also showed miR‐489 to be one of the most down‐regulated miRNAs in drug‐resistant tissues and cell lines, as confirmed by miRNA microarray screening and real‐time quantitative PCR. A decrease in miR‐489 expression was associated with chemoresistance as well as lymph node metastasis, increased tumour size, advanced pTNM stage and poor prognosis in breast cancer. Functional analysis revealed that miR‐489 increased breast cancer chemosensitivity and inhibited cell proliferation, migration and invasion, both in vitro and in vivo. Furthermore, SPIN1, VAV3, BCL2 and AKT3 were found to be direct targets of miR‐489. SPIN1 was significantly elevated in drug‐resistant and metastatic breast cancer tissues and inversely correlated with miR‐489 expression. High expression of SPIN1 was associated with higher histological grade, lymph node metastasis, advanced pTNM stage and positive progesterone receptor (PR) status. Increased SPIN1 expression enhanced cell migration and invasion, inhibited apoptosis and partially antagonized the effects of miR‐489 in breast cancer. PIK3CA, AKT, CREB1 and BCL2 in the PI3K–Akt signalling pathway, demonstrated to be elevated in drug‐resistant breast cancer tissues, were identified as downstream effectors of SPIN1. It was further found that either inhibition of SPIN1 or overexpression of miR‐489 suppressed the PI3K–Akt signalling pathway. These data indicate that miR‐489 could reverse the chemoresistance of breast cancer via the PI3K–Akt pathway by targeting SPIN1. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

SEMA3F prevents metastasis of colorectal cancer by PI3K–AKT‐dependent down‐regulation of the ASCL2–CXCR4 axis

Semaphorin‐3F (SEMA3F), an axonal repulsant in nerve development, has been shown to inhibit the progression of human colorectal cancer (CRC); however, the underlying mechanism remains elusive. In this study we found a negative correlation between the levels of SEMA3F and CXCR4 in CRC specimens from 85 patients, confirmed by bioinformatics analysis of gene expression in 229 CRC samples from the Cancer Genome Atlas. SEMA3F^high/CXCR4^low patients showed the lowest frequency of lymph node and distant metastasis and the longest survival. Mechanistically, SEMA3F inhibited the invasion and metastasis of CRC cells through PI3K–AKT‐dependent down‐regulation of the ASCL2–CXCR4 axis. Specifically, ASCL2 enhanced the invasion and metastasis of CRC cells in vitro and expression of ASCL2 correlated with distant metastasis, tumour size and poor overall survival in CRC patients. Treatment of CRC cells with the CXCR4 antagonist AMD3100 attenuated SEMA3F knockdown‐induced invasion and metastasis of CRC cells in vitro and in vivo. Our study thus demonstrates that SEMA3F functions as a suppressor of CRC metastasis via down‐regulating the ASCL2–CXCR4 axis. Copyright © 2015 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

RNA-seq analysis identified hormone-related genes associated with prognosis of triple negative breast cancer

Triple negative breast cancer (TNBC) is an aggressive subtype of breast cancer that currently lacks effective biomarkers and therapeutic targets required to investigate the diagnosis and treatment of TNBC. Here we performed a comprehensive differential analysis of 165 TNBC samples by integrating RNA-seq data of breast tumor tissues and adjacent normal tissues from both our cohort and The Cancer Genome Atlas (TCGA). Pathway enrichment analysis was conducted to evaluate the biological function of TNBC-specific expressed genes. Further multivariate Cox proportional hazard regression was performed to evaluate the effect of these genes on TNBC prognosis. In this report, we identified a total of 148 TNBC-specific expressed genes that were primarily enriched in mammary gland morphogenesis and hormone levels related pathways, suggesting that mammary gland morphogenesis might play a unique role in TNBC patients differing from other breast cancer types. Further survival analysis revealed that nine genes (FSIP1, ADCY5, FSD1, HMSD, CMTM5, AFF3, CYP2A7, ATP1A2, and C11orf86) were significantly associated with the prognosis of TNBC patients, while three of them (ADCY5, CYP2A7, and ATP1A2) were involved in the hormone-related pathways. These findings indicated the vital role of the hormone-related genes in TNBC tumorigenesis and may provide some independent prognostic markers as well as novel therapeutic targets for TNBC.     

Microglandular adenosis: a prime suspect in triple‐negative breast cancer development

Microglandular adenosis (MGA) and atypical MGA (AMGA) are unusual lesions of the breast. They were once regarded as benign proliferative lesions and innocent bystanders. Several lines of evidence suggested that they could be neoplastic, clonal lesions and a non‐obligate precursor for triple‐negative breast cancers (TNBC). Recent work published in The Journal of Pathology by Guerini‐Rocco and colleagues provided further evidence regarding the precursor–product relationship between MGA/AMGA and TNBC. Using a massively parallel sequencing approach, they demonstrated that MGA/AMGA, particularly those associated with TNBC, could be clonal neoplastic lesions showing clonal non‐synonymous mutations, but none in pure MGA. Importantly, those alterations were observed in the associated TNBC. They were also able to identify recurrent alterations in TP53 in those MGA/AMGA cases as well as their associated TNBC. The findings, in conjunction with others, underscore the significance for MGA in clinical diagnosis. The potential of a benign lesion to progress into an aggressive malignant tumour implies that modification of the current management approach may be necessary. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Expression patterns of stromal MMP‐2 and tumoural MMP‐2 and ‐9 are significant prognostic factors in invasive ductal carcinoma of the breast

Matrix metalloproteinases (MMPs) are matrix‐degrading enzymes that play a pivotal role in aggressive behaviours, such as rapid tumour growth, invasion, and metastasis, of several types of solid tumours. In particular, stromal MMP‐2 plays important roles in the progression of malignant tumours, but most clinical studies have focused on tumoural MMP‐2 and ‐9 expression, and not stromal MMP‐2 expression. One hundred and seventy‐seven cases diagnosed as invasive ductal carcinoma of the breast between 2000 and 2005 were included in this study. Expressions of tumoural MMP‐2 and ‐9 and stromal MMP‐2 were analysed by immunostaining on a tissue microarray. Subsequently, the associations between those results and various clinicopathological parameters were evaluated. Stromal MMP‐2 expression correlated significantly with clinicopathological parameters such as advanced T category, larger tumour size, high histological grade, tumour necrosis, ER‐ and PR‐negative, and HER‐2‐positive (all p < 0.05). In univariate and multivariate analyses, overall survival was linked with stromal MMP‐2 expression as well as dual expression of stromal MMP‐2 and tumoural MMP‐2 and ‐9 (all p < 0.05). Stromal MMP‐2 expression may play a crucial role in predicting aggressive clinical behaviour in breast cancer patients.     

Prevalence of BRCA1/2 large genomic rearrangements in Chinese women with sporadic triple‐negative or familial breast cancer

The prevalence of BRCA1/2 large genomic rearrangements (LGRs) and their underlying mechanisms have not been fully evaluated in Chinese women with breast cancer. In this study, we determined the prevalence of BRCA1/2 LGRs in 834 patients with familial breast cancer (FBC) and 660 patients with sporadic triple‐negative breast cancer (TNBC) who were negative for BRCA1/2 small‐range mutations using the multiplex ligation‐dependent probe amplification method. We found that 20 index patients (2.4%) in the FBC group carried a BRCA1 or BRCA2 LGR, and the frequencies of BRCA1 and BRCA2 LGRs were 1.6% and 0.8%, respectively. Seven index patients (1.1%) carried a BRCA1 LGR in 660 sporadic TNBC patients, whereas no BRCA2 LGRs were found in these patients. Among the BRCA1/2 LGRs, 48.1% (13/27) were novel, and the breakpoints of the majority of the LGRs were identified. ΨBRCA1‐mediated homologous recombination (HR) and Alu‐mediated HR/non‐homologous end‐joining (NHEJ) accounted for 40% and 30% of the BRCA1 LGRs, respectively. Alu‐mediated HR accounted for 71.4% of the BRCA2 LGRs, and the remaining one‐third was generated through Long interspersed nuclear elements (LINE)‐mediated NHEJ. Our findings suggest that both FBC patients and sporadic TNBC patients should be tested for BRCA1/2 LGRs.     

The expression and clinical significance of ribophorin II (RPN2) in human breast cancer

Ribophorin II (RPN2), part of the N‐oligosaccharyltransferase complex, is highly expressed in breast cancer stem cells and is associated with tumor metastasis through interaction with mutant p53. The clinicopathological implication of RPN2 expression is undetermined. We examined immunohistochemically the expression levels of RPN2 and p53 in primary breast cancer tissues surgically resected from 218 patients. The correlations of RPN2 expression with the intrinsic subtype defined by hormone receptors (HRs) and HER2, clinicopathological parameters, p53 expression, and patients’ clinical outcomes were examined. RPN2 was positive in 139 (64%), and the incidence of RPN2 expression was higher in the triple‐negative breast cancer (TNBC) (HR‐/HER2‐) (65%) and HER2‐enriched (HR‐/HER2+) subtype (95%) than in the luminal A‐like (HR+/HER2‐) subtype (58%) (P = 0.0009). RPN2 expression was also correlated with p53 nuclear accumulation (P = 0.04). The RPN2‐positive/p53‐positive patient group showed significantly poorer prognosis than the RPN2‐negative group for disease‐free survival (P = 0.05) and for overall survival (P = 0.02). By multivariate analyses, the combination of RPN2 and p53 was not an independent prognostic factor. RPN2 expression was correlated with clinically aggressive features of breast cancer. These data support the further clinical application of anti‐RPN2 therapy and the development of personalized medicine.     

三阴性乳腺癌干细胞微球体的治疗

三阴性乳腺癌(TNBC)是指雌激素受体(ER)、孕激素受体(PR)及人类表皮生长因子受体2 (HER-2)均为阴性的乳腺癌。TNBC恶性程度高,
侵袭性强,易远处转移,预后差,对内分泌治疗及靶向治疗的效果均欠佳,是临床治疗的难点。近几年研究发现,三阴性乳腺癌的发生、发展
很可能与其中的乳腺癌干细胞有关,乳腺癌干细胞微球体培养是一种收集干细胞的方法,被广泛用于三阴性乳腺癌的干细胞研究。     

Prognostic relevance of tumour cell‐associated uPAR expression in invasive ductal breast carcinoma

Kotzsch M, Bernt K, Friedrich K, Luther E, Albrecht S, Gatzweiler A, Magdolen V, Baretton G, Zietz C & Luther T
(2010) Histopathology 57 , 461–471
Prognostic relevance of tumour cell‐associated uPAR expression in invasive ductal breast carcinoma Aims: The urokinase‐type plasminogen activator receptor (uPAR) is a key molecule for pericellular proteolysis in tumour cell invasion and metastasis. The aim was to evaluate the prognostic impact of uPAR in invasive breast cancer dependent on which cell types within the tumour express uPAR. Methods and results: uPAR expression was analysed by immunohistochemistry in 270 tumour tissue specimens of invasive ductal breast carcinomas using tissue microarrays. For evaluation of uPAR immunoexpression we used the epitope‐mapped, uPAR domain II‐specific monoclonal antibody IID7. High uPAR score values in both tumour cells (uPAR‐Tc) and stromal cells were significantly related to high tumour grade (G3), and inversely correlated with oestrogen receptor status. On multivariate analysis, high uPAR‐Tc values contributed independent prognostic information for disease‐free survival (hazard ratio 1.93, P = 0.007) when adjusted for prognostically relevant clinicopathological parameters, whereas uPAR expression in stromal cells was not related to prognosis. In addition, elevated uPAR‐Tc values were found to be prognostic indicators in clinically relevant subgroups of patients with invasive breast cancer. Conclusions: In invasive breast cancer uPAR expression in invasive carcinoma cells, but not in stromal cells, has a significant impact on patients’ prognosis, and contributes to a more aggressive tumour phenotype.