A naturally occurring MTA1 variant sequesters oestrogen receptor-alpha in the cytoplasm

Oestrogen receptor (ER) is a good prognostic marker for the treatment of breast cancers. Upregulation of metastatic tumour antigen 1 (MTA1) is associated with the invasiveness and metastatic potential of several human cancers and acts as a co-repressor of nuclear ER-alpha. Here we identify a naturally occurring short form of MTA1 (MTA1s) that contains a previously unknown sequence of 33 amino acids with an ER-binding motif, Leu-Arg-Ile-Leu-Leu (LRILL). MTA1s localizes in the cytoplasm, sequesters ER in the cytoplasm, and enhances non-genomic responses of ER. Deleting the LRILL motif in MTA1s abolishes its co-repressor function and its interaction with ER, and restores nuclear localization of ER. Dysregulation of human epidermal growth factor receptor-2 in breast cancer cells enhances the expression of MTA1s and the cytoplasmic sequestration of ER. Expression of MTA1s in breast cancer cells prevents ligand-induced nuclear translocation of ER and stimulates malignant phenotypes. MTA1s expression is increased in human breast tumours with no or low nuclear ER. The regulation of the cellular localization of ER by MTA1s represents a mechanism for redirecting nuclear receptor signalling by nuclear exclusion.     

Gene expression profiling predicts clinical outcome of breast cancer

Breast cancer patients with the same stage of disease can have markedly different treatment responses and overall outcome. The strongest predictors for metastases (for example, lymph node status and histological grade) fail to classify accurately breast tumours according to their clinical behaviour. Chemotherapy or hormonal therapy reduces the risk of distant metastases by approximately one-third; however, 70-80% of patients receiving this treatment would have survived without it. None of the signatures of breast cancer gene expression reported to date allow for patient-tailored therapy strategies. Here we used DNA microarray analysis on primary breast tumours of 117 young patients, and applied supervised classification to identify a gene expression signature strongly predictive of a short interval to distant metastases ('poor prognosis' signature) in patients without tumour cells in local lymph nodes at diagnosis (lymph node negative). In addition, we established a signature that identifies tumours of BRCA1 carriers. The poor prognosis signature consists of genes regulating cell cycle, invasion, metastasis and angiogenesis. This gene expression profile will outperform all currently used clinical parameters in predicting disease outcome. Our findings provide a strategy to select patients who would benefit from adjuvant therapy.     

NUMB controls p53 tumour suppressor activity

NUMB is a cell fate determinant, which, by asymmetrically partitioning at mitosis, controls cell fate choices by antagonising the activity of the plasma membrane receptor of the NOTCH family. NUMB is also an endocytic protein, and the NOTCH-NUMB counteraction has been linked to this function. There might be, however, additional functions of NUMB, as witnessed by its proposed role as a tumour suppressor in breast cancer. Here we describe a previously unknown function for human NUMB as a regulator of tumour protein p53 (also known as TP53). NUMB enters in a tricomplex with p53 and the E3 ubiquitin ligase HDM2 (also known as MDM2), thereby preventing ubiquitination and degradation of p53. This results in increased p53 protein levels and activity, and in regulation of p53-dependent phenotypes. In breast cancers there is frequent loss of NUMB expression. We show that, in primary breast tumour cells, this event causes decreased p53 levels and increased chemoresistance. In breast cancers, loss of NUMB expression causes increased activity of the receptor NOTCH. Thus, in these cancers, a single event-loss of NUMB expression-determines activation of an oncogene (NOTCH) and attenuation of the p53 tumour suppressor pathway. Biologically, this results in an aggressive tumour phenotype, as witnessed by findings that NUMB-defective breast tumours display poor prognosis. Our results uncover a previously unknown tumour suppressor circuitry.     

新基因BP1抗体制备及其在乳腺癌表达的初步观察

为了探讨新同源盒基因BP 1在乳腺癌的表达,运用生物信息学方法设计19肽,合成并偶联到大分子载体KLH上制成人工免疫原,制备兔抗BP 1多克隆抗体IgG.蛋白印迹方法检测BP 1在乳腺癌细胞系M CF 7、M DA-M B-231细胞均有表达:免疫组织化学结果显示,BP 1蛋白在乳腺癌的表达率显著高于癌旁组织,在雌激素受体阴性肿瘤的表达率高于雌激素受体阳性组。BP 1基因的异常表达参与了乳腺癌的发生,是一种新的乳腺癌分子标志物.     

Lysyl oxidase is essential for hypoxia-induced metastasis

Metastasis is a multistep process responsible for most cancer deaths, and it can be influenced by both the immediate microenvironment (cell-cell or cell-matrix interactions) and the extended tumour microenvironment (for example vascularization). Hypoxia (low oxygen) is clinically associated with metastasis and poor patient outcome, although the underlying processes remain unclear. Microarray studies have shown the expression of lysyl oxidase (LOX) to be elevated in hypoxic human tumour cells. Paradoxically, LOX expression is associated with both tumour suppression and tumour progression, and its role in tumorigenesis seems dependent on cellular location, cell type and transformation status. Here we show that LOX expression is regulated by hypoxia-inducible factor (HIF) and is associated with hypoxia in human breast and head and neck tumours. Patients with high LOX-expressing tumours have poor distant metastasis-free and overall survivals. Inhibition of LOX eliminates metastasis in mice with orthotopically grown breast cancer tumours. Mechanistically, secreted LOX is responsible for the invasive properties of hypoxic human cancer cells through focal adhesion kinase activity and cell to matrix adhesion. Furthermore, LOX may be required to create a niche permissive for metastatic growth. Our findings indicate that LOX is essential for hypoxia-induced metastasis and is a good therapeutic target for preventing and treating metastases.     

Efp targets 14-3-3 sigma for proteolysis and promotes breast tumour growth

Oestrogen exerts its influence on target organs through activating oestrogen receptors (ERs) and regulating downstream genes by means of their oestrogen-responsive elements. Efp, a target gene product of ER alpha, is a member of the RING-finger B-box coiled-coil (RBCC) motif family. Efp is predominantly expressed in various female organs as well as in breast cancers, and is thought to be essential for oestrogen-dependent cell proliferation and organ development Efp-disrupted mice display underdeveloped uteri and reduced oestrogen responsiveness. Here we show that Efp is a RING-finger-dependent ubiquitin ligase (E3) that targets proteolysis of 14-3-3 sigma, a negative cell cycle regulator that causes G2 arrest. We demonstrate that tumour growth of breast cancer MCF7 cells implanted in female athymic mice is reduced by treatment with antisense Efp oligonucleotide. Efp-overexpressing MCF7 cells in ovariectomized athymic mice generate tumours in the absence of oestrogen. Loss of Efp function in mouse embryonic fibroblasts results in an accumulation of 14-3-3 sigma, which is responsible for reduced cell growth. These data provide an insight into the cell-cycle machinery and tumorigenesis of breast cancer by identifying 14-3-3 sigma as a target for proteolysis by Efp, leading to cell proliferation.     

The deubiquitinase USP9X suppresses pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDA) remains a lethal malignancy despite much progress concerning its molecular characterization. PDA tumours harbour four signature somatic mutations in addition to numerous lower frequency genetic events of uncertain significance. Here we use Sleeping Beauty (SB) transposon-mediated insertional mutagenesis in a mouse model of pancreatic ductal preneoplasia to identify genes that cooperate with oncogenic Kras(G12D) to accelerate tumorigenesis and promote progression. Our screen revealed new candidate genes for PDA and confirmed the importance of many genes and pathways previously implicated in human PDA. The most commonly mutated gene was the X-linked deubiquitinase Usp9x, which was inactivated in over 50% of the tumours. Although previous work had attributed a pro-survival role to USP9X in human neoplasia, we found instead that loss of Usp9x enhances transformation and protects pancreatic cancer cells from anoikis. Clinically, low USP9X protein and messenger RNA expression in PDA correlates with poor survival after surgery, and USP9X levels are inversely associated with metastatic burden in advanced disease. Furthermore, chromatin modulation with trichostatin A or 5-aza-2'-deoxycytidine elevates USP9X expression in human PDA cell lines, indicating a clinical approach for certain patients. The conditional deletion of Usp9x cooperated with Kras(G12D) to accelerate pancreatic tumorigenesis in mice, validating their genetic interaction. We propose that USP9X is a major tumour suppressor gene with prognostic and therapeutic relevance in PDA.     

乳腺癌中CyclinB1表达及临床病理意义

目的:研究细胞周期蛋白B1、癌基因C-erbB-2和雌激素受体(ER)、孕激素受体(PR)在乳腺癌中的表达情况及临床意义.方法:采用S-P免疫组化方法对65例乳腺癌组织和15例乳腺纤维瘤组织进行cy-clinB1、C-erbB-2和ER、PR表达的联合检测.结果:乳腺癌组织中CyclinB1过阳性表达率为84.62%(55/65);乳腺纤维瘤组织CyclinB1表达率为13.3%(2/15);淋巴结转移患者CyclinB1蛋白的过阳性表达率明显高于淋巴结阴性患者;CyclinB1的表达与C-erbB-2表达具有相对的一致性,CyclinB1的阳性高表达伴随ER表达降低,但与PR的表达无显著相关性.结论:CyclinB1的过表达与乳腺癌的发生、发展相关,过表达cy-clinB1可为乳腺癌早期诊断和生物学行为的判断提供帮助.CyclinB1与C-erbB-2和ER、PR的联合检测有利于指导乳腺癌的化疗和判断预后.     

Oncogenic pathway signatures in human cancers as a guide to targeted therapies

The development of an oncogenic state is a complex process involving the accumulation of multiple independent mutations that lead to deregulation of cell signalling pathways central to the control of cell growth and cell fate. The ability to define cancer subtypes, recurrence of disease and response to specific therapies using DNA microarray-based gene expression signatures has been demonstrated in multiple studies. Various studies have also demonstrated the potential for using gene expression profiles for the analysis of oncogenic pathways. Here we show that gene expression signatures can be identified that reflect the activation status of several oncogenic pathways. When evaluated in several large collections of human cancers, these gene expression signatures identify patterns of pathway deregulation in tumours and clinically relevant associations with disease outcomes. Combining signature-based predictions across several pathways identifies coordinated patterns of pathway deregulation that distinguish between specific cancers and tumour subtypes. Clustering tumours based on pathway signatures further defines prognosis in respective patient subsets, demonstrating that patterns of oncogenic pathway deregulation underlie the development of the oncogenic phenotype and reflect the biology and outcome of specific cancers. Predictions of pathway deregulation in cancer cell lines are also shown to predict the sensitivity to therapeutic agents that target components of the pathway. Linking pathway deregulation with sensitivity to therapeutics that target components of the pathway provides an opportunity to make use of these oncogenic pathway signatures to guide the use of targeted therapeutics.     

Regulation of cancer cell migration and bone metastasis by RANKL

Bone metastases are a frequent complication of many cancers that result in severe disease burden and pain. Since the late nineteenth century, it has been thought that the microenvironment of the local host tissue actively participates in the propensity of certain cancers to metastasize to specific organs, and that bone provides an especially fertile 'soil'. In the case of breast cancers, the local chemokine milieu is now emerging as an explanation for why these tumours preferentially metastasize to certain organs. However, as the inhibition of chemokine receptors in vivo only partially blocks metastatic behaviour, other factors must exist that regulate the preferential metastasis of breast cancer cells. Here we show that the cytokine RANKL (receptor activator of NF-kappaB ligand) triggers migration of human epithelial cancer cells and melanoma cells that express the receptor RANK. RANK is expressed on cancer cell lines and breast cancer cells in patients. In a mouse model of melanoma metastasis, in vivo neutralization of RANKL by osteoprotegerin results in complete protection from paralysis and a marked reduction in tumour burden in bones but not in other organs. Our data show that local differentiation factors such as RANKL have an important role in cell migration and the tissue-specific metastatic behaviour of cancer cells.     

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.     

Global histone modification patterns predict risk of prostate cancer recurrence

Aberrations in post-translational modifications of histones have been shown to occur in cancer cells but only at individual promoters; they have not been related to clinical outcome. Other than being targeted to promoters, modifications of histones, such as acetylation and methylation of lysine and arginine residues, also occur over large regions of chromatin including coding regions and non-promoter sequences, which are referred to as global histone modifications. Here we show that changes in global levels of individual histone modifications are also associated with cancer and that these changes are predictive of clinical outcome. Through immunohistochemical staining of primary prostatectomy tissue samples, we determined the percentage of cells that stained for the histone acetylation and dimethylation of five residues in histones H3 and H4. Grouping of samples with similar patterns of modifications identified two disease subtypes with distinct risks of tumour recurrence in patients with low-grade prostate cancer. These histone modification patterns were predictors of outcome independently of tumour stage, preoperative prostate-specific antigen levels, and capsule invasion. Thus, widespread changes in specific histone modifications indicate previously undescribed molecular heterogeneity in prostate cancer and might underlie the broad range of clinical behaviour in cancer patients.