Centromere protein-A, an essential centromere protein, is a prognostic marker for relapse in estrogen receptor-positive breast cancer

Introduction

Centromere protein A (CENP-A), an essential centromere protein, has been associated with high grade cancers. This study was undertaken to determine if CENP-A is a prognostic factor for breast cancer patients not receiving systemic therapy or predictive of response to tamoxifen or neoadjuvant chemotherapy.

Methods

mRNA levels of CENP-A and CENP-B, a centromere protein that binds independently of CENP-A, were measured in breast cancer specimens from 484 patients receiving no systemic therapy, 276 patients receiving tamoxifen, and 233 patients treated with neoadjuvant chemotherapy. Associations between CENP-A, CENP-B, Ki-67, relapse, and chemotherapy response were determined.

Results

CENP-A but not CENP-B was higher in estrogen receptor (ER)-negative tumors than ER-positive tumors and positively correlated with Ki-67 expression. Among patients with ER-positive disease who received no systemic therapy or tamoxifen, higher levels of CENP-A were associated with lower rates of 5-year distant relapse free survival (DRFS). On multivariate analyses including Ki-67, high CENP-A expression had a hazard ratio of 10.9 for relapse in patients with ER-positive disease not receiving systemic therapy (95% CI, 2.86 to 41.78; P = 0.00047) and 1.64 for patients with ER-positive disease receiving tamoxifen (95% CI, 0.99 to 2.71; P = 0.054). CENP-A was not an independent prognostic marker in ER-negative tumors. For both ER-positive and ER-negative tumors, CENP-A was not a significant independent predictor of chemotherapy response.

Conclusions

CENP-A was a significant independent prognostic marker for patients with ER-positive breast cancer not treated with systemic therapy but had limited predictive value in tamoxifen treated patients and was not predictive of response to neoadjuvant chemotherapy.     

Centromere numerical abnormality in the papillary,papillotubular type of early gastric cancer,a further characterization of a subset of gastric cancer

Papillary adenocarcinoma of the stomach is a relatively uncommon histological type, and it is often detected in the early stage. We recently characterized the papillary type of gastric cancer and found frequent microsatellite instability and associated mutations. In this study we analyzed the centromere numerical abnormality (CNA) of 18 chromosomes (chromosomes 1-4, 6-12, 15-18, 20, X, and Y) in the papillary and papillotubular types of gastric cancer by a modified fluorescence in situ hybridization technique with microwave treatment. All 3 cases (100%) of papillary adenocarcinoma had high microsatellite instability (MSI-H), and low CNA, and 41% (7 cases) of the 17 cases of papillotubular adenocarcinoma exhibited MSI-H and all 7 cases had low CNA. Further 8 cases (47%) had extensive CNA. In these 15 cases, all the MSI-H cases had lower CNA, and low microsatellite instability (MSI-L) and MSS cases had higher CNA. The remaining two cases showed low CNA and MSI-L and MSS. These profiles were different from those of tubular type gastric cancer, which always had extensive CNA and no MSI. Although the numbers of the cases in this series are limited, our data may suggest that a modest CNA may be another characteristic of gastric cancer with papillary structure.     

Centromere protein H is up-regulated in primary human colorectal cancer and its overexpression induces aneuploidy

Chromosomal instability (CIN) has been recognized as a hallmark of human cancer and is caused by continuous chromosome missegregation during mitosis. Proper chromosome segregation requires a physical connection between spindle microtubules and centromeric DNA and this attachment occurs at proteinaceous structures called kinetochore. Several centromere proteins such as CENP-A and CENP-H are the fundamental components of the human active kinetochore, and inappropriate expression of the centromere proteins could be a major cause of CIN. We have previously shown that CENP-A was overexpressed in primary human colorectal cancer. In this study, we show that CENP-H was also up-regulated in all of 15 primary human colorectal cancer tissues as well as in CIN tumor cell lines. Surprisingly, transient transfection of CENP-H expression plasmid into the diploid cell line HCT116 remarkably induced aneupoidy. Moreover, CENP-H stable transfectant of mouse embryonic fibroblast/3T3 cell lines showed aberrant interphase micronuclei, characteristic of chromosome missegregation. In these CENP-H overexpressed cells, CENP-H completely disappeared from the centromere of mitotic chromosomes, which might be the cause of the chromosome segregation defect. These results suggest that the aberrant expression and localization of a kinetochore protein CENP-H plays an important role in the aneuploidy frequently observed in colorectal cancers.     

Centromere fission, not telomere erosion, triggers chromosomal instability in human carcinomas

The majority of sporadic carcinomas suffer from a kind of genetic instability in which chromosome number changes occur together with segmental defects. This means that changes involving intact chromosomes accompany breakage-induced alterations. Whereas the causes of aneuploidy are described in detail, the origins of chromosome breakage in sporadic carcinomas remain disputed. The three main pathways of chromosomal instability (CIN) proposed until now (random breakage, telomere fusion and centromere fission) are largely based on animal models and in vitro experiments, and recent studies revealed several discrepancies between animal models and human cancer. Here, we discuss how the experimental systems translate to human carcinomas and compare the theoretical breakage products to data from patient material and cancer cell lines. The majority of chromosomal defects in human carcinomas comprises pericentromeric breaks that are captured by healthy telomeres, and only a minor proportion of chromosome fusions can be attributed to telomere erosion or random breakage. Centromere fission, not telomere erosion, is therefore the most probably trigger of CIN and early carcinogenesis. Similar centromere-telomere fusions might drive a subset of congenital defects and evolutionary chromosome changes.     

Targeting the kinetochore for mitosis-specific inhibitors

Microtubule poisons such as taxol and vinblastine are widely used to treat a variety of cancers. These drugs are believed to kill cells by blocking mitosis. However, there is a critical need to identify new drugs because tumors can often become refractory to treatment with existing drugs. Studies over the past decade on chromosome segregation have uncovered a plethora of novel proteins that function specifically in mitosis. Centrosomes and kinetochores are two organelles that specify formation of the spindle and the attachment of chromosomes to the spindle, respectively. The focus of this review is to highlight the kinetochore as a rich source of targets for the development of mitosis-specific drugs.     

Prognostic relevance of Centromere protein H expression in esophageal carcinoma

Background  

Many kinetochore proteins have been shown to be associated with human cancers. The aim of the present study was to clarify the expression of Centromere protein H (CENP-H), one of the fundamental components of the human active kinetochore, in esophageal carcinoma and its correlation with clinicopathological features.     

着丝粒蛋白F与恶性肿瘤的关系

着丝粒蛋白F（CENP-F）是细胞周期依赖性的着丝粒蛋白,其表达和定位具有严格的细胞周期性。CENP-F在肿瘤发生中起重要作用。CENP-F在多种肿瘤中表达上调,是重要的细胞增殖标志物,研究显示与肿瘤的发生、发展、侵袭、复发与预后等相关,是一个有价值的肿瘤预后指标和潜在治疗靶点。     

着丝粒蛋白F在脑胶质瘤中的表达及其意义

目的：检测着丝粒蛋白F（CENP—F）在脑胶质瘤中的表达，探讨其临床意义。方法：采用免疫组化方法检测64例脑胶质瘤和10例正常脑组织石蜡包埋标本中CENP—F的表达。结果：CENP—F在64例脑胶质瘤中表达阳性率为76．6％．在10例正常脑组织中仅30．0％，差异有统计学意义（P〈0．01）。CENP—F的表达在不同性别、年龄、肿瘤部位、肿瘤直径、瘤周水肿及病理分类中差异无统计学意义（P〉0．05），在不同病理分级中差异有统计学意义（P〈0．05），高分级组较低分级组表达高。结论：CENP—F在脑胶质瘤中高表达，与肿瘤病理分级有关，对判断脑胶质瘤生物学特性有一定意义。     

INCENP (Inner Centromere Protein) is Overexpressed in High Grade Non-Hodgkin B-cell Lymphomas

Inner centromere protein (INCENP) is a member of the Chromosomal Passenger Complex (CPC), which is a four member protein complex essential for proper completion of mitosis and cell division (cytokinesis). Inappropriate chromosomal segregation and cytokinesis due to deregulated expression of chromosome passenger proteins may lead to aneuploidy and cancer including lymphomas. According to our knowledge this is the first study investigating immunohistochemical expression of INCENP in lymphoma cases and cancer tissues in general. Our purpose was to characterize the expression of INCENP in cases of non-Hodgkin B-cell lymphomas, to compare the immunoreactivity between low and high grades and to evaluate the correlation between INCENP and MIB-1 labeling indices. We examined INCENP and MIB-1 immunoreactivity in paraffin sections of 55 samples of non-Hodgkin B-cell lymphomas, obtained from 55 patients, 31 men and 24 women. Thirty were of high grade and 25 were of low grade. Our results showed significantly higher nuclear immunohistochemical expression of INCENP in high grade B-cell lymphomas versus low grade ones. Also INCENP expression was significantly correlated with MIB-1 labeling index. Taken together our results point to a possible association between increased INCENP immunostaining and B-cell lymphoma aggressiveness and also stress the need for further investigating the expression of INCENP and other mitotic regulatory proteins in lymphomas and other malignant neoplasms.     

ZW10相互作用着丝粒蛋白对神经母细胞瘤增殖的影响及机制研究

目的:探讨ZW10相互作用着丝粒蛋白(ZW10 interacting kinetochore protein, ZWINT)对神经母细胞瘤(neuroblastoma, NB)细胞增殖的影响及作用机制。方法:利用NB数据集分析ZWINT表达水平与NB预后及临床分期的关系。EdU实验、流式细胞术和γH2AX免疫荧光染色分别检测干扰ZWINT表达对NB细胞增殖、周期分布和DNA损伤修复能力的影响。免疫组织化学/蛋白质印记(Western blot)检测MYCN扩增和无扩增组织及细胞系中ZWINT的表达情况。荧光定量PCR(qRT-PCR)和Western blot检测干扰/过表达MYCN对ZWINT表达的影响。在线预测ZWINT的启动子区域MYCN的结合位点,ChIP-PCR和荧光素酶实验验证MYCN靶向调控ZWINT表达。强力霉素诱导Tet-on MYCN SH-SY-5Y细胞过表达MYCN同时干扰ZWINT表达,检测ZWINT对MYCN介导的细胞增殖、周期和DNA损伤修复功能的影响。结果:ZWINT表达水平与NB患儿总生存率、无事件生存率呈负相关,其表达随NB分期升高而增高。ZWIN...     

17-AAG, an Hsp90 inhibitor, causes kinetochore defects: a novel mechanism by which 17-AAG inhibits cell proliferation

The Hsp90 inhibitor 17-allylaminogeldanamycin (17-AAG), which is currently in clinical trials, is thought to exert antitumor activity by simultaneously targeting several oncogenic signaling pathways. Here we report a novel mechanism by which 17-AAG inhibits cell proliferation, and we provide the first evidence that HSP90 is required for the assembly of kinetochore protein complexes in humans. 17-AAG caused delocalization of several kinetochore proteins including CENP-I and CENP-H but excluding CENP-B and CENP-C. Consistently, 17-AAG induced a mitotic arrest that depends on the spindle checkpoint and induced misalignment of chromosomes and aneuploidy. We found that HSP90 associates with SGT1 (suppressor of G2 allele of skp1; SUGT1) in human cells and that depletion of SGT1 sensitizes HeLa cells to 17-AAG. Overexpression of SGT1 restored the localization of specific kinetochore proteins and chromosome alignment in cells treated with 17-AAG. Biochemical and genetic results suggest that HSP90, through its interaction with SGT1 (SUGT1), is required for kinetochore assembly. Furthermore, time-course experiments revealed that transient treatment with 17-AAG between late S and G2/M phases causes substantial delocalization of CENP-H and CENP-I, a finding that strongly suggests that HSP90 participates in kinetochore assembly in a cell cycle-dependent manner.     

The mitotic checkpoint kinase NEK2A regulates kinetochore microtubule attachment stability

Loss or gain of whole chromosome, the form of chromosome instability commonly associated with cancers is thought to arise from aberrant chromosome segregation during cell division. Chromosome segregation in mitosis is orchestrated by the interaction of kinetochores with spindle microtubules. Our studies show that NEK2A is a kinetochore-associated protein kinase essential for faithful chromosome segregation. However, it was unclear how NEK2A ensures accurate chromosome segregation in mitosis. Here we show that NEK2A-mediated Hec1 (highly expressed in cancer) phosphorylation is essential for faithful kinetochore microtubule attachments in mitosis. Using phospho-specific antibody, our studies show that NEK2A phosphorylates Hec1 at Ser165 during mitosis. Although such phosphorylation is not required for assembly of Hec1 to the kinetochore, expression of non-phosphorylatable mutant Hec1(S165) perturbed chromosome congression and resulted in a dramatic increase in microtubule attachment errors, including syntelic and monotelic attachments. Our in vitro reconstitution experiment demonstrated that Hec1 binds to microtubule in low affinity and phosphorylation by NEK2A, which prevents aberrant kinetochore-microtubule connections in vivo, increases the affinity of the Ndc80 complex for microtubules in vitro. Thus, our studies illustrate a novel regulatory mechanism in which NEK2A kinase operates a faithful chromosome attachment to spindle microtubule, which prevents chromosome instability during cell division.     

Circulating IgA immune complexes in head and neck cancer, nasopharyngeal carcinoma, lung cancer, and colon cancer

A double antibody enzyme-linked immunosorbent assay (ELISA) was developed to quantitate circulating immune complexed IgA (IgA IC) in human serum. The serum panel for this study consisted of normal blood donors, benign surgery (BS), head and neck cancer (HN), nasopharyngeal carcinoma (NPC), lung cancer (LC), and colon cancer (CC) patients. Immune complexes (IC) were isolated from these sera by precipitation with 3.5% polyethylene glycol (PEG), washed and then redissolved in 0.1 M phosphate-buffered saline pH 7.2. The amount of IgA IC present were then quantified using the double antibody IgA ELISA. This assay was found to be both sensitive (26.0 ng/ml) and reproducible (intra-assay coefficient of variation 4.0%). The mean IgA IC for each cancer group tested (HN = 11.38 +/- 12.54 micrograms/ml; NPC = 13.36 +/- 17.56 micrograms/ml; LC = 17.39 +/- 13.04 micrograms/ml; CC = 26.50 +/- 4.60 micrograms/ml) were significantly elevated (P = 0.001) over both the normals (5.12 +/- 4.09 micrograms/ml) and the benign surgery controls (5.92 +/- 5.04 micrograms/ml). In addition to providing a new tumor marker the presence of high levels of IgA IC in cancer patients could provide a source of tumor-specific antibody as well as antigen and provide reagents to study immune regulation in cancer patients.     

Cannabinoids, endocannabinoids, and cancer

The endocannabinoid system consists of an array of endogenously produced bioactive lipids that activate cannabinoid receptors. Although the primary focus of endocannabinoid biology has been on neurological and psychiatric effects, recent work has revealed several important interactions between the endocannabinoid system and cancer. Several different types of cancer have abnormal regulation of the endocannabinoid system that contributes to cancer progression and correlates to clinical outcomes. Modulation of the endocannabinoid system by pharmacological agents in various cancer types reveals that it can mediate antiproliferative and apoptotic effects by both cannabinoid receptor-dependent and -independent pathways. Selective agonists and antagonists of the cannabinoid receptors, inhibitors of endocannabinoid hydrolysis, and cannabinoid analogs have been utilized to probe the pathways involved in the effects of the endocannabinoid system on cancer cell apoptosis, proliferation, migration, adhesion, and invasion. The antiproliferative and apoptotic effects produced by some of these pharmacological probes reveal that the endocannabinoid system is a promising new target for the development of novel chemotherapeutics to treat cancer.     

Viruses, oncogenes, and cancer

Our current theories of virus-induced cellular transformation have changed with the emerging recognition that all normal cells contain proto-oncogenes which convert to oncogenes and induce transformation when activated and/or amplified. Cellular oncogenes have been identified by homology to the transforming genes of acute retroviruses and by the transforming activity of tumor cell DNA in transfection assays. More than two dozen cellular oncogenes identified to date constitute a heterogeneous group of genes which are remarkably conserved among highly diverse species. Expression of proto-oncogenes is linked to normal growth and development; whereas their expression as oncogenes due to gene mutation, rearrangement, amplification or other processes leading to altered or overexpression is associated with the development of tumors. Functions of oncogene proteins are being identified. These include unique protein kinase activity, growth factor/growth factor receptor properties, and the presence of DNA-binding polypeptides. It also appears that cooperation between several activated cellular oncogenes may be required in the multistep process of oncogenesis. Our recent in vitro experimental evidence supports that human cell carcinogenesis is indeed a multistep process. In addition, the involvement of the activated cellular transforming genes met and H-ras in chemically induced human cell carcinogenesis has been shown. Advancement in molecular biology of oncogenes and their products is likely to result in improvements in cancer diagnosis and cancer therapy.