CCL2 recruits inflammatory monocytes to facilitate breast-tumour metastasis

Macrophages, which are abundant in the tumour microenvironment, enhance malignancy. At metastatic sites, a distinct population of metastasis-associated macrophages promotes the extravasation, seeding and persistent growth of tumour cells. Here we define the origin of these macrophages by showing that Gr1-positive inflammatory monocytes are preferentially recruited to pulmonary metastases but not to primary mammary tumours in mice. This process also occurs for human inflammatory monocytes in pulmonary metastases of human breast cancer cells. The recruitment of these inflammatory monocytes, which express CCR2 (the receptor for chemokine CCL2), as well as the subsequent recruitment of metastasis-associated macrophages and their interaction with metastasizing tumour cells, is dependent on CCL2 synthesized by both the tumour and the stroma. Inhibition of CCL2-CCR2 signalling blocks the recruitment of inflammatory monocytes, inhibits metastasis in vivo and prolongs the survival of tumour-bearing mice. Depletion of tumour-cell-derived CCL2 also inhibits metastatic seeding. Inflammatory monocytes promote the extravasation of tumour cells in a process that requires monocyte-derived vascular endothelial growth factor. CCL2 expression and macrophage infiltration are correlated with poor prognosis and metastatic disease in human breast cancer. Our data provide the mechanistic link between these two clinical associations and indicate new therapeutic targets for treating metastatic breast cancer.     

Clinical and pathological features of miR-10b and RHOC gene expression in hepatocellular carcinoma

Aberrant expression of microRNAs （miRNAs） was reported frequently in different human cancers. The major role of miRNA is targeting 31-UTR of coding gene and causing translational repression or mRNA degradation. miR-10b overexpression was reported to promote breast cancer metastasis by up-regulating RHOC expression. But its expression in hepatocellular carcinoma （HCC） remains unclear. Our study indicated that the expression of miR-10b was different in HCC and adjacent tissue samples, and reduced expression of miR-10b in HCC was related tovein invasion. High-level expression of RHOC was also related to vein invasion in HCC. But no correlation was found between miR-10b and RHOC expression. These results suggest that miR-10b and RHOC are independent predictors of HCC invasion and metastasis.     

血清miR-25、miR-223和miR-373作为食管鳞癌生物标志物的评价

为了探讨血清miRNA作为诊断标志物的可行性,利用茎环引物进行qRT-PCR,检测了miR-25、miR-223和miR-373在正常人血清、食管鳞癌患者术前和术后第7 d血清、癌组织和癌旁组织的相对表达量.实验结果表明:术前食管鳞癌病人的3种血清miRNA相对表达量高于正常人和手术后第7 d病人,AUC分别为0.794、0.839和0.873,癌组织的这3种miRNA相对表达量高于癌旁组织.这3种miRNA在食管癌患者癌组织的高表达导致血清的这3种miRNA含量增高,因此这3种血清miRNA可以作为候选诊断标志物.     

Involvement of chemokine receptors in breast cancer metastasis

Breast cancer is characterized by a distinct metastatic pattern involving the regional lymph nodes, bone marrow, lung and liver. Tumour cell migration and metastasis share many similarities with leukocyte trafficking, which is critically regulated by chemokines and their receptors. Here we report that the chemokine receptors CXCR4 and CCR7 are highly expressed in human breast cancer cells, malignant breast tumours and metastases. Their respective ligands CXCL12/SDF-1alpha and CCL21/6Ckine exhibit peak levels of expression in organs representing the first destinations of breast cancer metastasis. In breast cancer cells, signalling through CXCR4 or CCR7 mediates actin polymerization and pseudopodia formation, and subsequently induces chemotactic and invasive responses. In vivo, neutralizing the interactions of CXCL12/CXCR4 significantly impairs metastasis of breast cancer cells to regional lymph nodes and lung. Malignant melanoma, which has a similar metastatic pattern as breast cancer but also a high incidence of skin metastases, shows high expression levels of CCR10 in addition to CXCR4 and CCR7. Our findings indicate that chemokines and their receptors have a critical role in determining the metastatic destination of tumour cells.     

藻蓝色素蛋白通过调控miR-642a-5p抑制LTEP-a2细胞的增殖和迁移

研究藻蓝色素蛋白抑制非小细胞肺癌LTEP-a2体外增殖迁移的机制.以LTEP-a2细胞为模型,采用高通量miRNA转录组学对藻蓝蛋白处理后细胞中差异表达的miRNA进行了筛选;对筛选出的差异miRNA,利用体外转染mimics的方法对细胞的增殖、迁移能力进行验证.研究结果显示,藻蓝蛋白处理LTEP-a2细胞后能够显著增加细胞内miR-642a-5p的表达水平;过表达miR-642a-5p能够显著抑制细胞的体外增殖、迁移能力;此外,藻蓝蛋白可以通过上调miR-642a-5p表达抑制核受体NF-κB信号通路,降低蛋白磷酸化水平,进而抑制LTEP-a2细胞的增殖迁移能力.研究能够为藻蓝色素蛋白的应用以及非小细胞肺癌的治疗提供一定的理论基础.      

Correlation of microRNAs responding to high dose γ-irradiation with predicted target mRNAs in HeLa cells using microarray analyses

An increasing data indicates that altered microRNAs （miRNAs） participate in the radiation-induced DNA damage response. However, a correlation of mRNA and miRNA profiles across the entire genome and in response to irradiation has not been thor- oughly assessed. We analyzed miRNA microarray data collected from HeLa cells after ionizing radiation （IR）, quantified the ex- pression profiles of mRNAs and performed comparative analysis of the data sets using target prediction algorithms, Gene Ontol- ogy （GO） analysis, pathway analysis, and gene network construction. The results showed that the altered miRNAs were involved in regulation of various cellular functions, miRNA-gene network analyses revealed that miR- 186, miR- 106b, miR- 15 a/b, CCND 1 and CDK6 played vital role in the cellular radiation response. Using qRT-PCR, we confirmed that twenty-two miRNAs showed differential expression in HeLa cells treated with IR and some of these miRNAs affected cell cycle progression. This study demonstrated that miRNAs influence gene expression in the entire genome during the cellular radiation response and suggested vital pathways for further research.     

A viral microRNA functions as an orthologue of cellular miR-155

All metazoan eukaryotes express microRNAs (miRNAs), roughly 22-nucleotide regulatory RNAs that can repress the expression of messenger RNAs bearing complementary sequences. Several DNA viruses also express miRNAs in infected cells, suggesting a role in viral replication and pathogenesis. Although specific viral miRNAs have been shown to autoregulate viral mRNAs or downregulate cellular mRNAs, the function of most viral miRNAs remains unknown. Here we report that the miR-K12-11 miRNA encoded by Kaposi's-sarcoma-associated herpes virus (KSHV) shows significant homology to cellular miR-155, including the entire miRNA 'seed' region. Using a range of assays, we show that expression of physiological levels of miR-K12-11 or miR-155 results in the downregulation of an extensive set of common mRNA targets, including genes with known roles in cell growth regulation. Our findings indicate that viral miR-K12-11 functions as an orthologue of cellular miR-155 and probably evolved to exploit a pre-existing gene regulatory pathway in B cells. Moreover, the known aetiological role of miR-155 in B-cell transformation suggests that miR-K12-11 may contribute to the induction of KSHV-positive B-cell tumours in infected patients.     

Mesenchymal stem cells within tumour stroma promote breast cancer metastasis

Mesenchymal stem cells have been recently described to localize to breast carcinomas, where they integrate into the tumour-associated stroma. However, the involvement of mesenchymal stem cells (or their derivatives) in tumour pathophysiology has not been addressed. Here, we demonstrate that bone-marrow-derived human mesenchymal stem cells, when mixed with otherwise weakly metastatic human breast carcinoma cells, cause the cancer cells to increase their metastatic potency greatly when this cell mixture is introduced into a subcutaneous site and allowed to form a tumour xenograft. The breast cancer cells stimulate de novo secretion of the chemokine CCL5 (also called RANTES) from mesenchymal stem cells, which then acts in a paracrine fashion on the cancer cells to enhance their motility, invasion and metastasis. This enhanced metastatic ability is reversible and is dependent on CCL5 signalling through the chemokine receptor CCR5. Collectively, these data demonstrate that the tumour microenvironment facilitates metastatic spread by eliciting reversible changes in the phenotype of cancer cells.     

Aberrant microRNA expression in the development of breast carcinoma

microRNAs, a class of small non-coding regulatory RNAs, are involved in oncogenesis and cancer development. Studies have shown that aberrant miRNA expression occurs in breast cancer and is associated with specific clinicopathological features. Some miRNAs might act as suppressor genes or oncogenes, which can be considered as novel markers for breast cancer diagnosis and as prognostic factors. Here we present a review of recent discoveries on miRNAs involved in breast cancer tumorigenesis, invasion, and metastasis.     

Dynamic analysis of DNA damage induced miRNAs in colon cancer cells

It is known that microRNAs （miRNAs） expression profile shows substantial changes in cells under DNA damage. Here, we did miRNA microarray and quantitative real-time PCR to comprehensively identify the differentially expressed miRNAs in colon cancer cell lines HCT116 p53＋/＋ and HCT116 p53-/-. Cluster analysis revealed a panel of differentially expressed miRNAs which are regulated by p53 and/or UV-C induced DNA damage. These altered miRNAs tend to be located in chromosomes 13, X and 17. Moreover, pathways enrichment analysis estimated that MAPK pathway, focal adheren pathway, p53 pathway and Wnt pathway were mediated by these miRNAs to exert their functions in DNA damage response. Additionally, we found that miR- 320a, one of the UV-C induced miRNAs, play a role in protecting cells from DNA damage. Taken together, our results show that miRNAs are dynamic regulated in p53- dependent or -independent manners in different cell contexts and different situations following DNA damage.     

Suppression of murine breast cancer metastasis by selective inhibition of CXCR4 by synthetic polypeptide derived from viral macrophage inflammatory protein II

Stromal cell-derived factor-1 and its receptor CXC chemokine receptor-4 (CXCR4) have been implicated in breast cancer metastasis. A significant association between HER2 and CXCR4 expression has been observed in human breast tumor tissues, and overexpression of CXCR4 is essential for HER2-mediated tumor metastasis. Moreover, CXCR4 expression is low in normal breast tissues and high in malignant tumors, suggesting that a blockade of CXCR4 may limit tumor metastasis. The present study investigated the action of a synthetic antagonist 21-mer peptide derived from viral macrophage inflammatory protein II against CXCR4 (NT21MP) in inhibiting metastasis in vitro and in vivo. The results showed that chemotaxis of SKBR3 cells toward SDF-1α was reduced by NT21MP in a dose-dependent manner (P < 0.05). NT21MP inhibited tumor growth at 500 μg/kg and in combination with Herceptin, the anti-HER2 antibody. The in vivo metastatic assay showed that NT21MP significantly inhibited pulmonary metastasis, and the number of metastatic tumor nodes on the surface of the lung was greatly decreased. Compared with the saline-treated control group, PCNA expression was dose-dependently decreased by NT21MP, the percentage of apoptotic cells was increased, and CXCR4 mRNA and protein expression were downregulated. In conclusion, NT21MP inhibits cellular prolifer-ation, promotes apoptosis by downregulating CXCR4 expression, and suppresses the progression of primary and metastatic tumors. CXCR4 may be a useful therapeutic target for breast cancer, and NT21MP may serve as a potential target drug for the treatment of breast cancer metastasis.     

Interactions between cancer stem cells and their niche govern metastatic colonization

Metastatic growth in distant organs is the major cause of cancer mortality. The development of metastasis is a multistage process with several rate-limiting steps. Although dissemination of tumour cells seems to be an early and frequent event, the successful initiation of metastatic growth, a process termed 'metastatic colonization', is inefficient for many cancer types and is accomplished only by a minority of cancer cells that reach distant sites. Prevalent target sites are characteristic of many tumour entities, suggesting that inadequate support by distant tissues contributes to the inefficiency of the metastatic process. Here we show that a small population of cancer stem cells is critical for metastatic colonization, that is, the initial expansion of cancer cells at the secondary site, and that stromal niche signals are crucial to this expansion process. We find that periostin (POSTN), a component of the extracellular matrix, is expressed by fibroblasts in the normal tissue and in the stroma of the primary tumour. Infiltrating tumour cells need to induce stromal POSTN expression in the secondary target organ (in this case lung) to initiate colonization. POSTN is required to allow cancer stem cell maintenance, and blocking its function prevents metastasis. POSTN recruits Wnt ligands and thereby increases Wnt signalling in cancer stem cells. We suggest that the education of stromal cells by infiltrating tumour cells is an important step in metastatic colonization and that preventing de novo niche formation may be a novel strategy for the treatment of metastatic disease.