Regulation of angiogenesis via Notch signaling in breast cancer and cancer stem cells

Breast cancer angiogenesis is elicited and regulated by a number of factors including the Notch signaling. Notch receptors and ligands are expressed in breast cancer cells as well as in the stromal compartment and have been implicated in carcinogenesis. Signals exchanged between neighboring cells through the Notch pathway can amplify and consolidate molecular differences, which eventually dictate cell fates. Notch signaling and its crosstalk with many signaling pathways play an important role in breast cancer cell growth, migration, invasion, metastasis and angiogenesis, as well as cancer stem cell (CSC) self-renewal. Therefore, significant attention has been paid in recent years toward the development of clinically useful antagonists of Notch signaling. Better understanding of the structure, function and regulation of Notch intracellular signaling pathways, as well as its complex crosstalk with other oncogenic signals in breast cancer cells will be essential to ensure rational design and application of new combinatory therapeutic strategies. Novel opportunities have emerged from the discovery of Notch crosstalk with inflammatory and angiogenic cytokines and their links to CSCs. Combinatory treatments with drugs designed to prevent Notch oncogenic signal crosstalk may be advantageous over λ secretase inhibitors (GSIs) alone. In this review, we focus on the more recent advancements in our knowledge of aberrant Notch signaling contributing to breast cancer angiogenesis, as well as its crosstalk with other factors contributing to angiogenesis and CSCs.     

Interaction between Ras and Src clones causes interdependent tumor malignancy via Notch signaling in Drosophila

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Ectopic expression of CC chemokine receptor 7 promotes prostate cancer cells metastasis via Notch1 signaling

There currently exists no satisfactory treatment for patients with prostate cancer with local evolution and distant metastasis. Previous studies have confirmed the importance of CC chemokine receptor 7 (CCR7) in the invasion and metastasis of prostate cancer. And increasing evidence prove that Notch1 can play diametrically opposite roles in the development and progression of different tumors. To demonstrate the correlation between CCR7 and Notch1, PC-3 cells were transfected with pcDNA3.1-CCR7 or CCR7 si-RNA, respectively. Then Western blot analysis was used to detect the expressions of Notch1, ERK, P38, JNK, NF-κB, MMP-9, and epithelial-mesenchymal transition (EMT)-related proteins. Moreover, matrigel invasion assays were performed to assess the migratory and invasive activities of PC-3 cells. PcDNA3.1-CCR7 increased the expression of Notch1, phospho-MAPK, phospho-P65, MMP-9, N-cadherin, and Snail in PC-3 cells, but decreased the expression of E-cadherin. PcDNA3.1-CCR7 also promoted the migration and invasion of PC-3 cells. However, CCR7 si-RNA reversed the effect of pcDNA3.1-CCR7 in PC-3 cells. And MAPK and NF-κB pathway inhibitors were used to testify that activation of Notch1 induces EMT through MAPK and NF-κB pathway. All these results indicate that upregulation of Notch1 by CCR7 can accelerate the evolution of EMT and develop the invasion and metastasis in prostate cancer cells by activating MAPK and NF-κB signaling pathways in prostate cancer cells, which provides a new molecular evidence for targeted therapy in metastatic prostate cancer.     

Pro-metastatic functions of Notch signaling is mediated by CYR61 in breast cells

Metastasis is the main cause of cancer related deaths, and unfolding the molecular mechanisms underlying metastatic progression is critical for the development of novel therapeutic approaches. Notch is one of the key signaling pathways involved in breast tumorigenesis and metastasis. Notch activation induces pro-metastatic processes such as migration, invasion and epithelial to mesenchymal transition (EMT). However, molecular mediators working downstream of Notch in these processes are not fully elucidated. CYR61 is a secreted protein implicated in metastasis, and its inhibition by a monoclonal antibody suppresses metastasis in xenograft breast tumors, indicating the clinical importance of CYR61 targeting. Here, we aimed to investigate whether CYR61 works downstream of Notch in inducing pro-metastatic phenotypes in breast cells. We showed that CYR61 expression is positively regulated by Notch activity in breast cells. Notch1-induced migration, invasion and anchorage independent growth of a normal breast cell line, MCF10A, were abrogated by CYR61 silencing. Furthermore, upregulation of core EMT markers upon Notch1-activation was impaired in the absence of CYR61. However, reduced migration and invasion of highly metastatic cell line, MDA MB 231, cells upon Notch inhibition was not dependent on CYR61 downregulation. In conclusion, we showed that in normal breast cell line MCF10A, CYR61 is a mediator of Notch1-induced pro-metastatic phenotypes partly via induction of EMT. Our results imply CYR61 as a prominent therapeutic candidate for a subpopulation of breast tumors with high Notch activity.     

CREB5在大肠癌转移中的调控机制

大肠癌转移过程中所涉及的细胞信号调控网络非常复杂, 寻找调控网络中的关键调控点对阐明大肠癌转移机制以及寻找药物治疗靶点均具有重要意义。研究表明, CREB5 (cAMP responsive element binding protein 5)可能为大肠癌转移相关信号调控网络中的关键基因。文章基于大肠癌表达谱数据, 根据CREB5基因表达值的大小对大肠癌的相关分子事件进行了富集分析, 发现这些分子事件与肿瘤转移密切相关。根据CREB5能够和c-Jun结合成为异二聚体的特点, 联合分析转录因子AP-1结合位点的富集情况, 筛选出在CREB5基因高表达组中表达上调、具有AP-1结合位点、且属于癌症通路的基因16个, 这些基因所构成的分子网络与细胞迁移功能类相关度最高。细胞迁移功能类主要由5个基因——CSF1R、MMP9、PDGFRB、FIGF和IL6所构成, 因此CREB5可能是通过调控这5个关键基因进而促进大肠癌的转移。     

TNF inhibitor suppresses bone metastasis in a breast cancer cell line

In the evolution of cancer, tumor necrosis factor-alpha (TNF-α) plays a paradoxical role. High doses induce significant anticancer effects, but conversely, physiologic and pathologic levels of TNF-α may be involved in cancer promotion, tumor growth, and metastasis.Infliximab is a chimeric murine monoclonal antibody that binds with high affinity to soluble and membrane TNF-α and inhibits binding of TNF-α to its receptors. In the present study, we investigated the effect of infliximab, a TNF-α antagonist, on breast cancer aggressiveness and bone metastases.Infliximab greatly reduced cell motility and bone metastases in a metastatic breast cancer cell line, MDA-MB-231. The mechanism of bone metastasis inhibition involved decreased expression of CXC chemokine receptor 4 (CXCR4) and increased expression of decorin, which is the prototype of an expanding family of small leucine-rich proteoglycans. These results suggest a novel role for TNF-α inhibition in the reduction or prevention of bone metastases in this breast cancer model. Our study suggests that inhibition of TNF-α using infliximab may become a preventive therapeutic option for breast cancer.     

Notch信号通路与肺纤维化

Notch信号通路是在进化上非常保守的单次跨膜信号受体蛋白家族,广泛表达于脊椎动物与无脊椎动物中,主要由Notch受体、Notch配体及细胞内效应分子CSL蛋白组成。Notch信号通路是多种组织和器官早期发育所必需的细胞间调节信号,参与对细胞增殖、分化、凋亡的调控。近年的研究表明,Notch信号通路参与肺纤维化的发生发展,阻断或激活这一途径可以影响肺纤维化的进展,本文就Notch信号通路与肺纤维化的关系的研究进展做一综述。     

Denbinobin suppresses breast cancer metastasis through the inhibition of Src-mediated signaling pathways

Denbinobin (5-hydroxy-3,7-dimethoxy- 1,4-phenanthraquinone), a biologically active chemical isolated from Ephemerantha lonchophylla, has been demonstrated to display anti-cancer activity. Breast cancer is the leading cause of female mortality, and the high mortality is mainly attributable to metastasis. Src kinase activity is elevated in many human cancers, including breast cancer, and is often associated with aggressive disease. In the present study, we examined the anti-metastatic effects of denbinobin through decreasing Src kinase activity in human and mouse breast cancer cells. Denbinobin caused significant block of Src kinase activity in both human and mouse breast cancer cells. Moreover, phosphorylation of the signaling molecules focal adhesion kinase, Crk-associated substrate and paxillin downstream of Src was also inhibited by denbinobin. Furthermore, denbinobin inhibited the in vitro migration, invasion and in vivo metastasis of breast cancers in a mouse metastatic model. The denbinobin-treated group showed a significant reduction in tumor metastasis, orthrotopic tumor volume, and spleen enlargement compared to the control group. In addition, transfection of breast cancer cells with a plasmid coding for a constitutively active Src prevented the denbinobin-mediated phosphorylation of Src and downstream molecules and cell migration. Our findings provide evidences that denbinobin inhibits Src-mediated signaling pathways involved in controlling breast cancer migration and metastasis, suggesting that it has therapeutic potential in breast cancer treatment.     

Epiregulin promotes growth and metastasis of gastric cancer via the ERK/JNK/p38 signaling pathway

Epiregulin (EREG) is a ligand of the epidermal growth factor receptor. It belongs to the ErbB family of ligands found overexpressed in various cancers such as colon cancer and lung carcinoma and is likely to play diverse oncogenic roles in several other cancer types. However, little is known about the mechanisms of EREG in the pathogenesis of gastric cancer (GC). The present study was undertaken to investigate whether EREG influences the development and progression in GC. The results revealed that EREG was found to be overexpressed in human GC cells lines. Moreover, EREG induced cell migration, invasion, and proliferation, and inhibited apoptosis in vitro. The study also found that EREG depletion inhibited tumor growth in vivo. Our findings indicated that EREG activated the ERK/JNK/p38 signaling pathway and PI3K/Akt signaling pathways to promote GC malignant progression. Overall, this study suggests that EREG may promote GC development and progression through the ERK/JNK/p38 and PI3K/Akt signaling pathways, which may improve our understanding of the molecular mechanism of EREG in GC. Thus, EREG may be a potential target for GC treatment.     

Tartrate-resistant acid phosphatase 5b as a serum marker of bone metastasis in breast cancer patients

Diagnosis and follow-up of bone metastases in breast cancer patients usually rely on symptoms and imaging studies. Tartrate-resistant acid phosphatase 5b (TRACP 5b) is a specific marker of osteoclasts and is herein proposed as a marker of bone metastasis in breast cancer patients. An immunoassay using a monoclonal antibody, 14G6, was used to measure the activity of serum TRACP 5b at pH 6.1 in 30 early breast cancer patients without bone metastasis and in 30 aged-matched breast cancer patients with bone metastasis. Another 60 normal volunteers were recruited as controls. Bone alkaline phosphatase (BAP), a traditional marker of bone turnover, was also measured in selected cases. The overall mean TRACP 5b activity in normal women was 2.83 ± 1.1 U/I, and it increased with age. The mean TRACP 5b activity in early breast cancer patients did not differ from that of the normal group (2.93 ± 0.64 vs. 2.83 ± 1.1 U/I; p=0.66), whereas it was significantly higher in breast cancer patients with bone metastasis (5.42 ± 2.5 vs. 2.83 ± 1.1 U/I; p<0.0001). BAP activity was significantly higher in breast cancer patients with bone metastasis than in early breast cancer patients (p=0.004). Serum TRACP 5b activity correlated well with BAP activity in breast cancer patients with bone metastasis (p<0.0001), but not in normal individuals or in patients without bone metastasis. TRACP 5b activity can be considered a surrogate indicator of bone metastasis in breast cancer patients.     

Centchroman suppresses breast cancer metastasis by reversing epithelial–mesenchymal transition via downregulation of HER2/ERK1/2/MMP-9 signaling

Metastatic spread during carcinogenesis worsens disease prognosis and accelerates the cancer progression. Therefore, newer therapeutic options with higher specificity toward metastatic cancer are required. Centchroman (CC), a female oral contraceptive, has previously been reported to possess antiproliferative and proapoptotic activities in human breast cancer cells. Here, we investigated the effect of CC-treatment against breast cancer metastasis and associated molecular mechanism using in vitro and in vivo models. CC significantly inhibited the proliferation of human and mouse mammary cancer cells. CC-treatment also inhibited migration and invasion capacities of highly metastatic MDA-MB-231 and 4T1 cells, at sub-IC₅₀ concentrations. Inhibition of cell migration and invasion was found to be associated with the reversal of epithelial-to-mesenchymal transition (EMT) as observed by the upregulation of epithelial markers and downregulation of mesenchymal markers as well as decreased activities of matrix metalloproteinases. Experimental EMT induced by exposure to TGFβ/TNFα in nontumorigenic human mammary epithelial MCF10A cells was also reversed by CC as evidenced by morphological changes and modulation in the expression levels of EMT-markers. CC-mediated inhibition of cellular migration was, at least partially, mediated through inhibition of ERK1/2 signaling, which was further validated by using MEK1/2 inhibitor (PD0325901). Furthermore, CC-treatment resulted in suppression of tumor growth and lung metastasis in 4T1-syngeneic mouse model. Collectively, our findings suggest that CC-treatment at higher doses specifically induces cellular apoptosis and inhibits cellular proliferation; whereas at lower doses, it inhibits cellular migration and invasion. Therefore, CC could further be developed as an effective drug candidate against metastatic breast cancer.     

Upregulation of lncRNA GAS5 inhibits the growth and metastasis of cervical cancer cells

This study aims to figure out the methylation of long non-coding RNA GAS5 promoter in cervical cancer and the mechanism of GAS5 on the progression of cervical cancer cells. The expression of GAS5 and methylation state of GAS5 in cervical cancer tissues and cells were determined. With the aim to to explore the ability of GAS5 in the proliferation, cell cycle progression, apoptosis, invasion, migration as well as the tumor growth, and metastasis in nude mice were determined. The expression of GAS5 was decreased and methylation state of GAS5 was elevated in cervical cancer. Overexpression of GAS5 inhibited proliferation, cell cycle progression, invasion, migration while inducing apoptosis of cervical cancer cells as well as suppressed tumor growth and metastasis in nude mice. Our study demonstrates that abnormal methylation of GAS5 contributes to poor expression of GAS5 in cervical cancer. In addition, upregulation of GAS5 inhibits the cervical cancer development.     

Identification of novel metastasis suppressor signaling pathways for breast cancer

Cancer lethality is mainly caused by metastasis. Therefore, understanding the nature of the genes involved in this process has become a priority. Given the heterogeneity of mutations in cancer cells, considerable focus has been directed toward characterizing metastasis genes in the context of relevant signaling pathways rather than treating genes as independent and equal entities. One signaling cascade implicated in the regulation of cell growth, invasion and metastasis is the MAP kinase pathway. Raf kinase inhibitory protein (RKIP) functions as an inhibitor of the MAP kinase pathway and is a metastasis suppressor in different cancer models. By utilizing statistical analysis of clinical data integrated with experimental validation, we recently identified components of the RKIP signaling pathway relevant to breast cancer metastasis. Using the RKIP pathway as an example, we show how prior biological knowledge can be efficiently combined with genome-wide patient data to identify gene regulatory mechanisms that control metastasis.     

Identification of novel metastasis suppressor signaling pathways for breast cancer

Cancer lethality is mainly caused by metastasis. Therefore, understanding the nature of the genes involved in this process has become a priority. Given the heterogeneity of mutations in cancer cells, considerable focus has been directed toward characterizing metastasis genes in the context of relevant signaling pathways rather than treating genes as independent and equal entities. One signaling cascade implicated in the regulation of cell growth, invasion and metastasis is the MAP kinase pathway. Raf kinase inhibitory protein (RKIP) functions as an inhibitor of the MAP kinase pathway and is a metastasis suppressor in different cancer models. By utilizing statistical analysis of clinical data integrated with experimental validation, we recently identified components of the RKIP signaling pathway relevant to breast cancer metastasis. Using the RKIP pathway as an example, we show how prior biological knowledge can be efficiently combined with genome-wide patient data to identify gene regulatory mechanisms that control metastasis.