Jagged1促进乳腺癌发生发展及远处转移的研究进展

乳腺癌是一种严重危害女性身心健康的疾病。晚期乳腺癌患者的死亡在很大程度上归因于重要脏器的远处转移而非原发肿瘤。Jagged1(JAG1)作为Notch信号通路的重要配体之一,不仅表达于肿瘤细胞,亦可表达于肿瘤微环境中的间质细胞,通过激活Notch信号通路,促进乳腺癌的侵袭性进展与远处转移。本文就JAG1基因位置与JAG1蛋白的结构、JAG1促进乳腺癌远处转移相关机制、JAG1与乳腺癌脑转移、JAG1与乳腺癌骨转移及JAG1的靶向治疗等方面进行综合论述。     

Tumor-derived JAGGED1 promotes osteolytic bone metastasis of breast cancer by engaging notch signaling in bone cells

Despite evidence supporting an oncogenic role in breast cancer, the Notch pathway's contribution to metastasis remains unknown. Here, we report that the Notch ligand Jagged1 is a clinically and functionally important mediator of bone metastasis by activating the Notch pathway in bone cells. Jagged1 promotes tumor growth by stimulating IL-6 release from osteoblasts and directly activates osteoclast differentiation. Furthermore, Jagged1 is a potent downstream mediator of the bone metastasis cytokine TGFβ that is released during bone destruction. Importantly, γ-secretase inhibitor treatment reduces Jagged1-mediated bone metastasis by disrupting the Notch pathway in stromal bone cells. These findings elucidate a stroma-dependent mechanism for Notch signaling in breast cancer and provide rationale for using γ-secretase inhibitors for the treatment of bone metastasis.     

Notch signaling drives multiple myeloma induced osteoclastogenesis

Multiple myeloma (MM) is closely associated with bone destruction. Once migrated to the bone marrow, MM cells unbalance bone formation and resorption via the recruitment and maturation of osteoclast precursors.The Notch pathway plays a key role in different types of cancer and drives several biological processes relevant in MM, including cell localization within the bone marrow, proliferation, survival and pharmacological resistance.Here we present evidences that MM can efficiently drive osteoclastogenesis by contemporaneously activating Notch signaling on tumor cells and osteoclasts through the aberrant expression of Notch ligands belonging to the Jagged family. Active Notch signaling in MM cells induces the secretion of the key osteoclastogenic factor, RANKL, which can be boosted in the presence of stromal cells. In turn, MM cells-derived RANKL causes the upregulation of its receptor, RANK, and Notch2 in pre-osteoclasts. Notch2 stimulates osteoclast differentiation by promoting autocrine RANKL signaling. Finally, MM cells through Jagged ligands expression can also activate Notch signaling in pre-osteoclast by direct contact.Such synergism between tumor cells and pre-osteoclasts in MM-induced osteoclastogenesis can be disrupted by silencing tumor-derived Jagged1 and 2. These results make the Jagged ligands new promising therapeutic targets in MM to contrast bone disease and the associated co-morbidities.     

Notch1 signaling regulates the epithelial–mesenchymal transition and invasion of breast cancer in a Slug-dependent manner

Background

The epithelial–mesenchymal transition (EMT) is crucial for the invasion and metastasis of breast cancer. However, how Notch signaling regulates the EMT process and invasion in breast cancer remains largely unknown.

Methods

The impact of Notch1 silencing by specific shRNAs on the EMT and invasion of human breast cancer MCF-7 and MDA-MB-231 cells as well as xenografts was tested by western blot, real-time polymerase chain reaction (RT-PCR), immunofluorescence, transwell, and immunohistochemistry assays. The effect of Slug silencing or upregulation on the EMT and invasion of breast cancer cells was analyzed, and the effect of Notch1 signaling on Slug expression was determined by the luciferase reporter assay.

Results

The Notch1 intracellular domain (N1ICD) and Jagged1 were expressed in breast cancer cells. Notch1 silencing reversed the spontaneous EMT process and inhibited the migration and invasion of breast cancer cells and the growth of xenograft breast cancers. The expression of N1ICD was upregulated significantly by Jagged1-mediated Notch signaling activation. Moreover, Jagged1-mediated Notch signaling promoted the EMT process, migration, and invasion of breast cancer cells, which were abrogated by Notch silencing. Furthermore, the N1ICD positively regulated the Slug expression by inducing Slug promoter activation. Importantly, the knockdown of Slug weakened the invasion ability of breast cancer cells and reversed the Jagged1-induced EMT process with significantly decreased expression of vimentin and increased expression of E-cadherin. In addition, Slug overexpression restored the Notch1 knockdown-suppressed EMT process.

Conclusions

Our novel data indicate that Notch signaling positively regulates the EMT, invasion, and growth of breast cancer cells by inducing Slug expression. The Notch1–Slug signaling axis may represent a potential therapeutic target for breast cancer therapy.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0295-3) contains supplementary material, which is available to authorized users.     

Maspin regulates hypoxia-mediated stimulation of uPA/uPAR complex in invasive breast cancer cells

Maspin, a unique serine proteinase inhibitor (serpin), plays a key role in mammary gland development and is silenced during breast cancer progression. Maspin has been shown to inhibit tumor cell motility and invasion in cell culture, as well as growth and metastasis in animal models. In this study, we investigated the effect of maspin on the regulation of hypoxia-induced expression of urokinase-type plasminogen activator (uPA) and its receptor (uPAR), with respect to invasive potential in metastatic breast cells MDA-MB-231. We hypothesized that maspin can neutralize or mitigate hypoxia-induced expression of uPA/uPAR in metastatic breast cancer cells, resulting in suppression of their invasive potential. To test our hypothesis, we employed the highly invasive MDA-MB-231 breast cancer cells that are devoid of maspin, and transfected them with the maspin gene, and then determined the effect of hypoxia on uPA/uPAR expression. Normal mammary epithelial cells 1436N1 were used as a control. Our findings demonstrate that maspin downregulated the basal and hypoxia-induced uPA/uPAR expression and reduced the stimulatory effect of hypoxia on the in vitro invasive ability of MDA-MB-231-cells. In addition, maspin also inhibited the enzymatic activity of secreted and cell associated uPA in MDA-MB-231 cells. These results indicate that maspin inhibits hypoxia-induced invasion of metastatic breast cancer cells by blocking the uPA system, thus illuminating an important molecular pathway for therapeutic consideration.     

Prognostic significance of Notch 3 gene expression in ovarian serous carcinoma

The Notch signaling pathway is an important cell signaling system, which regulates cell differentiation, proliferation, and apoptosis, and is aberrantly activated in a wide range of cancer, including ovarian cancers. However, it remains unclear as to whether Notch signaling plays a role in the progression and prognosis of ovarian cancer. We examined the mRNA and protein expression of Notch 3, Jagged 1, and Jagged 2 in 98 ovarian epithelial tumors via real‐time PCR and in 175 tumors with immunohistochemical analysis, and then correlated their expression levels with clinicopathological parameters and patient survival. In this study, we detected high levels of Notch3 mRNA and protein expression especially in serous ovarian carcinomas compared to their benign counterparts, accompanied by a positive correlation with the expressions of Jagged 1 and Jagged 2. High levels of Notch 3 mRNA expression (>2‐fold than that of benign tumor) were noted in 63% of the serous carcinomas (mean level: 17‐fold, P = 0.032). Additionally, Notch 3 protein overexpression was significantly associated with advanced stage (P = 0.0008), lymph node (P = 0.001), and distant metastasis (P = 0.003). Notably, high Notch 3 mRNA and protein expressions were correlated with chemoresistance (P = 0.033) and poor overall survival (P = 0.027, P = 0.042) in these patients. Our results indicate that the Notch 3 signaling pathway is involved in the tumor progression of ovarian serous carcinoma, and higher Notch 3 expression may be an independent poor prognostic factor in this subset of tumors. (Cancer Sci 2010)     

Manic fringe inhibits tumor growth by suppressing Notch3 degradation in lung cancer

Notch signaling plays an essential role in development as well as cancer. We have previously shown that Notch3 is important for lung cancer growth and survival. Notch receptors are activated through the interaction with their ligands, resulting in proteolytic cleavage of the receptors. This interaction is modulated by Fringe, a family of fucose-specific β1,3 N-acetylglucosaminyltransferases that modify the extracellular subunit of Notch receptors. Studies in developmental models showed that Fringe enhances Notch’s response to Delta ligands at the expense of Jagged ligands. We observed that Manic Fringe expression is down-regulated in lung cancer. Since Jagged1, a known ligand for Notch3, is often over-expressed in lung cancer, we hypothesized that Fringe negatively regulates Notch3 activation. In this study, we show that re-expression of Manic Fringe down-regulates Notch3 target genes HES1 and HeyL and reduces tumor phenotype in vitro and in vivo. The mechanism for this phenomenon appears to be related to modulation of Notch3 protein stability. Proteasome inhibition reverses Manic Fringe-induced protein turnover. Taken together, our data provide the first evidence that Manic Fringe functions as a tumor suppressor in the lung and that the mechanism of its anti-tumor activity is mediated by inhibition of Notch3 activation.     

Jagged1/Notch3信号通路蛋白在人三阴乳腺癌中的表达及临床意义

目的：研究Jagged1/Notch3在TNBC患者中的表达水平及临床意义,阐明Jagged1和Notch3异常表达对TNBC患者的预后影响。方法：Ventana免疫组化法检测Jagged1、Notch3在石蜡标本的蛋白表达,分析其与临床病理及复发转移的关系。结果：共纳入患者70例,Jagged1和Notch3在TNBC组织中的阳性表达率分别为35.7%（25/70）和40.0%（28/70）。Jagged1在无淋巴结转移患者中表达高,Notch3则在4个以上淋巴结转移和Ⅲ期患者中的表达更高。结论：TNBC患者中Jagged1/Notch3蛋白的异常表达与淋巴结转移和分期相关。     

Quantitative DNA hypomethylation of ligand Jagged1 and receptor Notch1 signifies occurrence and progression of breast carcinoma

Methylation alterations of Jagged1 and Notch1 genes have been reported in non-tumor lesions and a few cancers. However, methylation profiles of Jagged1 promoter and Notch1 exon25 in breast cancer and matched normal tissue and the association of methylation with clinicopathological characteristics still remain unclear. To explore the potential effects of aberrant DNA methylation of Jagged1 and Notch1 on occurrence and progression of breast cancer, we detected the quantitative DNA methylation of Jagged1 and Notch1 in 73 breast cancer (BC) and 20 adjacent normal breast tissues (ANBT) by using MassARRAY spectrometry. The methylation level of overall and majority individual CpG sites of the two genes were synergistically significantly lower in BC than in ANBT. The overall hypomethylation of the two genes, particularly of Jagged1 CpG_8.9.10 and Notch1 CpG_14.15.16 in primary tumors, were markedly associated with lymph node metastasis, advanced stage and high grade. The protein expressions of the both genes were examined by immunohistochemical staining in same cohorts. The expression was significantly inverse correlation with methylation. The two proteins in primary tumor were synergistically up-regulated and dramatically related to lymph node metastasis, advanced stage and high grade. Our findings suggest that the synergetic hypomethylation of Jagged1 and Notch1 genes, especially of Jagged1 CpG_8.9.10 and Notch1 CpG_14.15.16, may involve tumorigenesis and development of breast cancer. The negative relationship between methylation and expression indicates methylation role for expression regulation. The synergetic overexpression of the two proteins further indicates the effects on occurrence and progression of breast cancer.     

Quantitative DNA hypomethylation of ligand Jagged1 and receptor Notch1 signifies occurrence and progression of breast carcinoma

Methylation alterations of Jagged1 and Notch1 genes have been reported in non-tumor lesions and a few cancers. However, methylation profiles of Jagged1 promoter and Notch1 exon25 in breast cancer and matched normal tissue and the association of methylation with clinicopathological characteristics still remain unclear. To explore the potential effects of aberrant DNA methylation of Jagged1 and Notch1 on occurrence and progression of breast cancer, we detected the quantitative DNA methylation of Jagged1 and Notch1 in 73 breast cancer (BC) and 20 adjacent normal breast tissues (ANBT) by using MassARRAY spectrometry. The methylation level of overall and majority individual CpG sites of the two genes were synergistically significantly lower in BC than in ANBT. The overall hypomethylation of the two genes, particularly of Jagged1 CpG_8.9.10 and Notch1 CpG_14.15.16 in primary tumors, were markedly associated with lymph node metastasis, advanced stage and high grade. The protein expressions of the both genes were examined by immunohistochemical staining in same cohorts. The expression was significantly inverse correlation with methylation. The two proteins in primary tumor were synergistically up-regulated and dramatically related to lymph node metastasis, advanced stage and high grade. Our findings suggest that the synergetic hypomethylation of Jagged1 and Notch1 genes, especially of Jagged1 CpG_8.9.10 and Notch1 CpG_14.15.16, may involve tumorigenesis and development of breast cancer. The negative relationship between methylation and expression indicates methylation role for expression regulation. The synergetic overexpression of the two proteins further indicates the effects on occurrence and progression of breast cancer.     

Pericyte depletion results in hypoxia-associated epithelial-to-mesenchymal transition and metastasis mediated by met signaling pathway

The functional role of pericytes in cancer progression remains unknown. Clinical studies suggest that low numbers of vessel-associated pericytes correlated with a drop in overall survival of patients with invasive breast cancer. Using genetic mouse models or pharmacological inhibitors, pericyte depletion suppressed tumor growth but enhanced metastasis. Pericyte depletion was further associated with increased hypoxia, epithelial-to-mesenchymal transition (EMT), and Met receptor activation. Silencing of Twist or use of a Met inhibitor suppressed hypoxia and EMT/Met-driven metastasis. In addition, poor pericyte coverage coupled with high Met expression in cancer cells speculates the worst prognosis for patients with invasive breast cancer. Collectively, our study suggests that pericytes within the primary tumor microenvironment likely serve as important gatekeepers against cancer progression and metastasis.     

DEK is highly expressed in breast cancer and is associated with malignant phenotype and progression

DEK proto-oncogene (DEK) has been demonstrated as an oncogene and is associated with the development of many types of tumor; however, the expression and role of DEK in breast cancer remain unknown. The present study aimed to determine the role of DEK in the progression of breast cancer. The expression of DEK in 110 breast cancer tissues and 50 adjacent normal breast tissues was examined using immunohistochemistry. Furthermore, DEK expression was upregulated by DEK transfection or downregulated by DEK shRNA interference in MCF7 cells. Proliferative and invasive abilities were examined in MCF7 cells using MTT assay, colony-formation assay and transwell invasion assays. The results demonstrated that DEK expression level was significantly increased in breast cancer tissues compared with normal breast tissues. Furthermore, high DEK expression was associated with high histological grade, lymph node metastasis, advanced Tumor-Node-Metastasis stage and high Ki-67 index; however, DEK expression was not associated with the expression level of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2. High DEK expression indicated poor prognosis in patients with breast cancer. DEK overexpression upregulated the protein expression of β-catenin and Wnt and increased the proliferative and invasive abilities of breast cancer cells. DEK downregulation had the opposite effect. Taken together, the results from the present study demonstrated that high expression of DEK was common in patients with breast cancer and was associated with progression of the disease and poor prognosis, and that DEK overexpression promoted the proliferative and invasive abilities of breast cancer cells.     

ADAM-17 predicts adverse outcome in patients with breast cancer

ADAM-17 is a matrix metalloproteinase-like enzyme involved in the release of several ligands that have been shown to promote both cancer formation and progression. These ligands include transforming growth factor-α, amphiregulin, heparin-binding epidermal growth factor, epiregulin and tumor necrosis factor-α. In this investigation, we measured the expression of total ADAM-17 by enzyme-linked immunosorbent assay in 153 invasive breast cancers. We also measured the precursor and active forms by western blotting in 140 invasive breast cancers. Expression of ADAM-17 was significantly increased in high-grade compared with low-grade tumors and was independent of tumor size, lymph node metastasis and estrogen receptor status. Patients with high expression of ADAM-17 had a significantly shorter overall survival compared with those with low expression. Significantly, the prognostic impact of ADAM-17 was independent of conventional prognostic factors for breast cancer. Our results are further evidence that ADAM-17 is involved in breast cancer progression and thus provides further impetus for exploiting ADAM-17 as new target for cancer treatment.     

Hedgehog overexpression is associated with stromal interactions and predicts for poor outcome in breast cancer

Hedgehog (Hh) signaling plays an important role in several malignancies but its clinical significance in breast cancer is unclear. In a cohort of 279 patients with invasive ductal carcinoma of the breast, expression of Hh ligand was significantly associated with increased risk of metastasis, breast cancer-specific death, and a basal-like phenotype. A paracrine signature, encompassing high epithelial Hh ligand and high stromal Gli1, was an independent predictor for overall survival in multivariate analysis. In 2 independent histological progression series (n = 301), Hh expression increased with atypia. Hh ligand overexpression in a mouse model of basal breast cancer increased growth, induced a poorly differentiated phenotype, accelerated metastasis, and reduced survival. A stromal requirement for these effects was supported by the lack of similar Hh-mediated changes in vitro, and by stromal-specific expression of Hh target genes in vivo. Furthermore, inhibition of Hh ligand with a monoclonal antibody (5E1) inhibited tumor growth and metastasis. These data suggest that epithelial-stromal Hh signaling, driven by ligand expression in carcinoma cells, promotes breast cancer growth and metastasis. Blockade of Hh signaling to peritumoral stromal cells may represent a novel therapeutic approach in some basal-like breast cancers.