Concurrent amplification of cyclin E and CDK2 genes in colorectal carcinomas

The genetic changes of cyclin A, Dl, E and CDK2 were examined in human colorectal carcinomas by Southern-blot analysis. Gene amplification of cyclin E was detected in 5 of 53 (9.4%) primary colorectal carcinoma tissues. Interestingly, in 3 of 5 tumors showing cyclin E gene amplification, the CDK2 gene was amplified simultaneously with rearrangements. No obvious correlation was detected between gene amplification and clinico-pathological features of colorectal carcinomas. Out of 7 colon carcinoma cell lines, 2 showed gene amplification of cyclin E without gene amplification of CDK2. No amplification of cyclin A or Dl gene was found in any of the colorectal carcinoma tissues or colon carcinoma cell lines. Our results suggest that the concurrent amplification of cyclin E and CDK2 genes may play a role in colorectal carcinogenesis. © 1995 Wiley-Liss Inc.     

Cyclin gene amplification and overexpression in breast and ovarian cancers: Evidence for the selection of cyclin D1 in breast and cyclin E in ovarian tumors

Evidence of the involvement of cyclin genes in genetic alterations in human cancer is growing. In the present study, we investigated the amplification, in human breast and ovarian cancer, of 5 cyclin genes; cyclin A, cyclin D1, cyclin D2, cyclin D3 and cyclin E. For this purpose, a series of 1,171 breast and 237 ovarian tumors tested for DNA amplification by Southern blotting and a subset of 132 breast and 22 ovarian cancers were analyzed for RNA expression levels by slot-blot and Northern blotting. In breast tumors, only cyclin D1 was found to be activated in a sizeable fraction of the tumors (amplification 12.6%, overexpression 19%). Cyclin A, D2, D3, and E genes never, or only on rare occasions, showed increased DNA copy numbers and were never found overexpressed at the RNA level. Amplification of cyclin D1 correlated with ER⁺ breast cancer and the presence of lymph-node metastasis. Interestingly, we were also able to determine an association with invasive lobular carcinoma. Our data suggest that cyclin D1 activation determines the evolution of a particular subset of estrogen-responsive tumors. Data obtained in ovarian tumors contrasted with observations in breast cancer. Cyclin D1 DNA amplification was much less frequent in ovarian than in breast tumors (3.3% vs. 12.6%), whereas cyclin E amplification and overexpression were observed in a significant number of cases (12.5% and 18.0% respectively). Cyclin A, cyclin D2 and D3 rarely showed anomalies at the DNA level and were never overexpressed. No clear correlation could be observed between amplification of the cyclin E gene and tumor type, stage or grade in ovarian cancer. Data presented here suggest distinct pathways of cyclin activation in human breast and ovarian cancer. © 1996 Wiley-Liss, Inc.     

Induction of centrosome amplification and chromosome instability in human bladder cancer cells by p53 mutation and cyclin E overexpression

Centrosome amplification frequently occurs in human cancers and is a major cause of chromosome instability (CIN). In mouse cells, centrosome amplification can be readily induced by loss or mutational inactivation of p53. In human cells, however, silencing of endogenous p53 alone does not induce centrosome amplification or CIN, although high degrees of correlation between p53 mutation and CIN/centrosome amplification in human cancer can be detected, suggesting the presence of additional regulatory mechanism(s) in human cells that ensures the numeral integrity of centrosomes and genomic integrity. Cyclin E, a regulatory subunit for CDK2 that plays a key role in centrosome duplication, frequently is overexpressed in human cancers. We found that cyclin E overexpression, together with loss of p53, efficiently induces centrosome amplification and CIN in human bladder cancer cells but not by either cyclin E overexpression or loss of p53 alone. We extended these findings to bladder cancer specimens and found that centrosome amplification is strongly correlated with concomitant occurrence of cyclin E overexpression and p53 inactivation but not with either cyclin E overexpression or p53 inactivation alone. Because cyclin E expression is strictly controlled in human cells compared with mouse cells, our findings suggest that this stringent regulation of cyclin E expression plays an additional role underlying numeral homeostasis of centrosomes in human cells and that deregulation of cyclin E expression, together with inactivation of p53, results in centrosome amplification.     

Prognostic significance of cyclin E overexpression in resected non-small cell lung cancer

Cyclin E plays a pivotal role in the regulation of G1-S transition and relates to malignant transformation of the cells. However, the clinical significance of cyclin E expression in patients with non-small cell lung cancer remains unknown. We examined the expression of cyclin E in 242 resected non-small cell lung cancer in pathological stages I-IIIa and analyzed its relation to clinicopathological factors. Cylin E overexpressions were observed frequently in deeply invasive tumors. Multivariate analysis revealed that complete resection, pathological stage, and cyclin E expression were independent prognostic indicators. When cyclin E and proliferating cell nuclear antigen are combined, the cases negative for both had a significantly better prognosis than the other cases. We concluded that cyclin E overexpression relates to deeply invasive tumors and is correlated with poor prognosis. New therapeutic options may be provided by combination of cyclin E expression and proliferating cell nuclear antigen overexpression.     

细胞周期素D1的过度表达和扩增与卵巢癌关系的研究

目的：研究细胞周期素D1（CyclinD1)蛋白的表达和基因的扩增及其与卵巢癌发生发展的关系。方法：采用免疫组化和差异聚合酶链反应（DPCR）技术对35例卵巢癌进行CyclinD1检测。结果：CyclinD1蛋白在卵巢癌中的表达阳性率为68.6%(24/35)，高于良性疾病卵巢组织的25.7%(9/35)，且与卵巢癌的转移密切相关。卵巢癌组织CyclinD1基因扩增的阳性率为54.3%(19/35)，同样高于良性疾病卵巢组织的22.9%(8/35)。结论：CyclinD1基因在卵巢癌的发生发展中，尤其是在癌转移的过程中起重要的促进作用，CyclinD1的过度表达和扩增与卵巢癌细胞的高增殖活性密切相关。     

cyclinE、CDK2在子宫平滑肌肿瘤中的表达

引言子宫平滑肌肿瘤(uterine smooth muscletumors,USMTs)是妇女最常见的肿瘤。细胞周期素(cyclinE)是G1期的周期蛋白,与细胞周期素依赖性激酶2(CDK2)在G1期末结合而发挥作用,促进细胞进入S期。近年来,在多种肿瘤的研究中发现有cyclinE、CDK2表达的异常,但其在USMTs中的研究,国内文献尚未见报道。增殖细胞核抗原(PCNA)是反映细胞,特别是恶性肿瘤细胞增殖活性的一个指标。本研究拟通过免疫组织化学方法探讨cyclinE、CDK2及PCNA在USMTs中的表达及临床意义。1资料与方法1.1临床资料选取华中科技大学同济医学院附属同济医院病理科1992年7月~2004年10月存档的因USMTs而手术切除子宫的蜡块标本75例,其中,良性子宫平滑肌瘤(usual leiomyoma,UL)35例,交界性子宫平滑肌瘤(borderline leiomyoma,BLM)22例,子宫平滑肌肉瘤(leiomyosarcoma,LMS)18例。于手术室另取正常子宫平滑肌组织(Myometrium,M)20例,4%多聚甲醛固定,石蜡包埋常规处理。1.2试剂鼠抗人cyclinE单克...     

Gene amplification is a mechanism of Six1 overexpression in breast cancer

The Six1 homeoprotein plays a critical role in expanding progenitor populations during normal development via its stimulation of proliferation and inhibition of apoptosis. Overexpression of Six1 is observed in several tumor types, suggesting that when expressed out of context, Six1 may contribute to tumorigenesis by reinstating properties normally conveyed on developing cells. Indeed, Six1 contributes to tumor cell proliferation both in breast cancer and in rhabdomyosarcomas, in which it is also implicated in metastasis. Whereas Six1 overexpression has been reported in several tumor types, the mechanism responsible for its overexpression has not previously been examined. Here we show that a change in gene dosage may contribute to Six1 mRNA overexpression. Significant Six1 gene amplification and overrepresentation occurs in numerous breast cancer cell lines as compared with normal mammary epithelial cells, and the changes in gene dosage correlate with increased Six1 mRNA levels. Of 214 human infiltrating ductal breast carcinomas examined for Six1 gene dosage, 4.7% show Six1 amplification/overrepresentation, and tumors that exhibit an increase in Six1 gene dosage overexpress Six1 mRNA. These data implicate Six1 gene amplification/overrepresentation as a mechanism of Six1 mRNA overexpression in human breast cancer.     

Prostate cancer cell lines lack amplification: overexpression of HER2

The potential overexpression of HER2 in prostate cancer cells has attended significant interest during the past few years, both as potential target for HER2 pathway focused therapy and as a mechanism involved in the progression to androgen independence. Conflicting results have been reported concerning HER2 status on clinical material, differences which generally have been attributed to methodological differences. Nevertheless, HER2 has been utilized for targeted therapy of prostate cancer in a number of preclinical studies and is still regarded as an exciting target molecule. In this study, the HER2 status of three widely used prostate cancer cell lines and corresponding xenografts has been analysed. By use of validated and FDA approved analytical staining techniques none of these cell lines or xenografts were shown to overexpress/amplify HER2, as demonstrated by immunohistochemistry and fluorescense in situ hybridization. These findings are important for the interpretation and understanding of the therapeutic effects when developing drugs targeting HER2 in prostate cancer cell lines and also emphasize the importance of using broad and validated analytical techniques.     

p27, cyclin E,and CDK2 expression in normal and cancerous endometrium

The objective was to investigate the immunohistochemical expression of p27, cyclin E, and CDK2 in normal and cancerous endometrium. Expression of p27 in premenopausal normal endometrium was significantly higher than that in postmenopausal normal endometrium (p=0.019). A significantly lower amount of p27 staining was observed in endometrial cancer tissues from premenopausal women than in normal premenopausal endometrium (p=0.015). Cyclin E expression in premenopausal normal endometrium was significantly higher than that in postmenopausal normal endometrium (p=0.003). A significantly higher amount of cyclin E staining was observed in endometrial cancer tissues from postmenopausal women than in normal postmenopausal endometrium (p=0.017). Regarding menopausal status, no significant difference in CDK2 staining was observed between cancerous and normal endometrium. There was a positive significant correlation between cyclin E and CDK2 expression levels in endometrial cancers (p<0.05). Western blot analysis confirmed elevated p27 protein levels in samples with positive p27 immunostaining. Considerable levels of p27 mRNA were detected in all normal and cancerous samples examined by semi-quantitative PCR. No significant relationship was found between telomerase activity and its association with p27 and cyclin E expression in endometrial cancers. These findings suggested that the decreased expression of p27 caused by post-translational mechanism might play an important role in endometrial cancer development in premenopausal women. In addition, increased cyclin E expression may play an important role in endometrial cancer development in postmenopausal women.     

Validation of cyclin D1/CDK4 as an anticancer drug target in MCF-7 breast cancer cells: Effect of regulated overexpression of cyclin D1 and siRNA-mediated inhibition of endogenous cyclin D1 and CDK4 expression

Summary We have examined the role of cyclin D1 and cyclin-dependent kinase-4 (CDK4) in the cell cycle progression and proliferation of MCF-7 breast cancer cells. Forced expression of cyclin D1 using a tetracycline-regulated expression system, and suppression of endogenous cyclin D1 and CDK4 using small interfering RNA (siRNA) were used to validate this protein complex as a drug target in cancer drug discovery. Overexpression of cyclin D1 increased both phosphorylation of the retinoblastoma gene product (RB) and passage through the G1–S phase transition, resulting in increased proliferation of cells. When cyclin D1 expression was shut off, growth rates fell below those seen in control cell lines transfected with the vector, indicating an increased dependence on this protein for proliferation. Inhibition of endogenous cyclin D1 or CDK4 expression by RNA interference resulted in hypophosphorylation of RB and accumulation of cells in G1. These results support the prevailing view that pharmacological inhibition of cyclin D1/CDK4 complexes is a useful strategy to inhibit the growth of tumors. Furthermore, since MCF-7 cells appear to be dependent on this pathway for their continued proliferation, it is a suitable cell line to test novel cyclin D1/CDK4 inhibitors.     

胃癌患者FGFR2过表达和扩增与预后相关性Meta分析

目的 多项研究表明,纤维细胞生长因子受体2型(fibroblast growth factor receptor type 2,FGFR2)过表达和扩增与胃癌预后相关,但各研究间结论却存在差异.为明确胃癌患者FGFR2活化在胃癌预后中的意义,通过回顾已发表的相关研究进行Meta分析.方法 检索Medline、Embase、Coehrane Library、万方数据库、维普数据库以及中国知网中相关文献,依据纳入、排除标准收集检测FGFR2过表达或扩增在胃癌患者预后中的相关研究,按照纽卡斯尔-渥太华病例对照研究质量评价量表(Newcastle-Ottawa quality assessment scale,NOS)对所纳入文献进行质量评估.Meta分析通过软件Stata 12.0进行,应用风险比(hazard ratio,HR)和95％CI来合并结局指标,Begg's检验评估文献可能存在的发表偏倚.结果 共有10个研究纳入系统评价,总计4 269例胃癌患者.所有研究均涉及单因素分析,合并结果显示,有FGFR2过表达或扩增的胃癌患者相对无FGFR2活化的患者而言,其总生存期(overall survivals,OS)的HR为2.06,95％CI为1.75～2.42.其中,有3个研究(5个样本)涉及多因素分析,合并结果显示,有FGFR2过表达或扩增的胃癌患者相对无FGFR2活化的患者而言,其OS的HR为2.04,95％CI为1.55～2.62.结论 胃癌患者FGFR2过表达和扩增与预后相关,FGFR2是影响胃癌患者预后的独立危险因素,能增加患者的死亡风险.     

Cyclin E amplification/overexpression is associated with poor prognosis in gastric cancer

We describe the correlation between cyclin E and HER2 amplification/overexpression and the clinical outcome in 87 patients with gastric cancer (GC) treated with surgery and adjuvant treatment at our centre. We observed that cyclin E and HER2 amplification/overexpression are not mutually exclusive, and that cyclin E amplification/overexpression correlates with poor prognosis. The co-amplification of cyclin E and HER2 in GC warrants prospective evaluation given the reported role of cyclin E in limiting the effectiveness of anti-HER2 therapies.     

Cell cycle progression without cyclin E/CDK2: breaking down the walls of dogma

G1 is the phase of the cell cycle wherein the cell is responsive to growth factor-dependent signals. As such, G1 regulation is frequently disrupted in cancer through deregulation of cyclin/CDK activity; deregulation of G1 phase provides tumorigenic cells with a growth advantage. Cyclin E, the regulatory cyclin for CDK2, is considered a requisite regulator of G1 progression. Cyclin E is overexpressed in cancer, suggesting that cyclin E/CDK2 deregulation contributes to tumorigenesis. Two papers now challenge both the concept that cyclin E/CDK2 is a requisite component of the cell cycle machine and efforts to develop cyclin E/CDK2 inhibitors as antiproliferative therapeutics.     

Frequent cyclin D1 gene amplification and protein overexpression in oral epithelial dysplasias

Amplification of the cyclin D1 gene has been identified in 17-55% of head and neck squamous cell carcinoma. In some tumors, this alteration has been associated with decreased survival and increased recurrence rates. In precancerous lesions of the mouth, the frequency of cyclin D1 gene amplification is not known. In addition, it is unknown whether amplification of the gene translates to overexpressed cyclin D1 protein in these lesions. We examined 59 formalin-fixed, paraffin embedded tissue biopsies of oral epithelial dysplasias (OED) and 25 oral squamous cell carcinoma (SCC) from the floor of the mouth for cyclin D1 gene and protein levels. Genomic DNA was extracted from laser microdissected lesional tissue and a duplex, quantitative PCR assay was used to determine the amplification of the cyclin D1 gene relative to interferon-gamma. Cyclin D1 protein expression was determined using immunohistochemistry and counting positive nuclei by computer image analysis. We found cyclin D1 gene amplification in 41% of mild, 45% of moderate and 24% of severe OEDs. Cyclin D1 was amplified in 36% of SCC. Overexpression of cyclin D1 protein was identified in 29% of mild, 47% of moderate, 29% of severe OED's, and in 32% of SCC. Overexpression of cyclin D1 protein was identified in similar proportions of all grades of dysplasia and SCC. There were statistically significant correlations identified between gene and protein levels in all categories of disease. We concluded that amplification of the cyclin D1 gene is frequent in OED and that duplex, quantitative polymerase chain reaction is a reliable method to detect this change in routinely processed biopsies. The strong correlation between cyclin D1 gene amplification and protein levels suggests that this method may be suitable to assess cyclin D1 gene status in tissues not suitable for protein analysis.     

Cyclin E overexpression in epithelial ovarian cancer characterizes an etiologic subgroup.

BACKGROUND: The objective of this study was to determine whether cyclin E overexpression defines an etiologically distinct subgroup of ovarian cancer. METHODS: We analyzed data from 538 epithelial ovarian cancer cases and 629 controls enrolled in a population-based case-control study. Cyclin E protein overexpression was assessed using immunohistochemistry. Case-control and case-case comparisons were done to evaluate the relationship between cyclin E overexpression and epidemiologic risk factors. Logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals (95% CI) while adjusting for potential confounders. RESULTS: Case-control comparisons showed ovarian cancers with and without cyclin E overexpression have different associations with several epidemiologic risk factors. A dose-response relationship was observed between lifetime ovulatory cycles (LOC) and ovarian cancer that overexpressed cyclin E [OR, 1.8; 95% CI, 1.1-3.0 for moderately high LOC (265-390 cycles) and OR, 2.7; 95% CI, 1.6-4.5 for high LOC (>390 cycles) compared with low LOC (<265 cycles)], but no relationship was seen with cancers that lacked overexpression. The most important components of the LOC variable contributing to the differences in the association with the cyclin E subgroups of ovarian cancer were months of oral contraceptive use and months pregnant. CONCLUSIONS: Cyclin E overexpression is associated with a high number of LOC, largely influenced by oral contraceptive use and pregnancy. This suggests that cyclin E overexpression is a molecular signature characteristic of ovarian cancer cases that may arise via a pathway that involves ovulation-induced alterations.     

Gene amplification and overexpression of PRDM14 in breast cancers

Several genes that encode PR (PRDI-BF1 and RIZ) domain proteins (PRDM) have been linked to human cancers. To explore the role of the PR domain family genes in breast carcinogenesis, we examined the expression profiles of 16 members of the PRDM gene family in a panel of breast cancer cell lines and primary breast cancer specimens using semiquantitative real-time PCR. We found that PRDM14 mRNA is overexpressed in about two thirds of breast cancers; moreover, immunohistochemical analysis showed that expression of PRDM14 protein is also up-regulated. Analysis of the gene copy number revealed that PRDM14 is a target of gene amplification on chromosome 8q13, which is a region where gene amplification has frequently been detected in various human tumors. Introduction of PRDM14 into cancer cells enhanced cell growth and reduced their sensitivity to chemotherapeutic drugs. Conversely, knockdown of PRDM14 by siRNA induced apoptosis in breast cancer cells and increased their sensitivity to chemotherapeutic drugs, suggesting that up-regulated expression of PRDM14 may play an important role in the proliferation of breast cancer cells. That little or no expression of PRDM14 is seen in noncancerous tissues suggests that PRDM14 could be an ideal therapeutic target for the treatment of breast cancer.     

Prognostic significance of cyclin D1 amplification and overexpression in oral squamous cell carcinomas

Amplification and overexpression of cyclin D1 (CCND1) have been reported as independent prognostic indicators of several tumors. To investigate the association between CCND1 amplification and overexpression in oral squamous cell carcinomas (OSCCs), and to determine which is more reliable as a prognostic indicator, fluorescence in situ hybridization (FISH) on fine-needle aspiration (FNA) biopsies and immunohistochemistry were performed on 41 primary OSCCs (26 males, 15 females; mean age; 58.4 years, range 21-89 years). Thirteen patients were stage I, 13 were stage II, nine were stage III, and six were stage IV. CCND1 amplification and overexpression was detected in 13 (31.7%) and 27 (65.9%) of 41 cases. CCND1 was overexpressed in all cases showing CCND1 amplification. On the other hand, CCND1 overexpression was also detected in 14 of 28 cases (50.0%) lacked such amplification. Statistical analysis showed that the correlation between CCND1 overexpression and decreased survival just failed to reach statistical significance, and CCND1 amplification and nodal status were independent prognostic indicators. In conclusion, it will be necessary to investigate the other pathways that regulate CCND1 expression besides CCND1 amplification. From the present study, CCND1 amplification is a more reliable prognostic indicator than CCND1 overexpression in OSCCs.     

Gene amplification and protein overexpression of EGFR and ERBB2 in sinonasal squamous cell carcinoma

BACKGROUND:

Sinonasal squamous cell carcinomas (SNSCCs) are rare tumors with no etiologic link to tobacco or alcohol, as opposed to other squamous cell carcinomas of the head and neck. Despite improvements in the field of surgery and radiotherapy, patients with these tumors still face a very unfavorable prognosis, partly because of their localization in a complex anatomic area, which has special relevance for surgery and postoperative treatment. Therefore, there is a need for new therapeutic possibilities for patients with these tumors.

METHODS:

Gene copy numbers of epidermal growth factor receptor (EGFR) and v‐erb‐b2 erythroblastic leukemia viral oncogene homolog 2 (ERBB2) were analyzed by fluorescence in situ hybridization and multiplex ligand‐dependent probe amplification, and protein expression was evaluated by immunohistochemistry in 54 SNSCC specimens. The results were correlated with clinicopathologic and follow‐up data.

RESULTS:

EGFR gene copy number increases were observed in 20 of 45 tumors (44%), and 21 of 54 tumors (39%) had EGFR protein overexpression. Eight of 38 tumors (21%) had ERBB2 copy number increases, and 4 of 54 tumors (7%) exhibited elevated protein expression levels. Both copy number increases and protein overexpression of EGFR and ERBB2 were mutually exclusive. v‐Ki‐ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations were absent in 37 tumors that were analyzed.

CONCLUSIONS:

A substantial proportion of SNSCCs carried alterations in EGFR or ERBB2. Together with the absence of KRAS mutations, these findings indicate that therapies targeting these molecules may be promising additions to the therapeutic options for patients with SNSCC. Cancer 2012;. © 2011 American Cancer Society.     

EphA2 overexpression is associated with angiogenesis in ovarian cancer

BACKGROUND: EphA2 is overexpressed in the majority of ovarian cancers and predicts poor clinical outcome. Based on EphA2's emerging role in angiogenesis, we hypothesized that tumors overexpressing EphA2 demonstrate greater microvessel density (MVD) and matrix metalloproteinase (MMP) expression. METHODS: After Institutional Review Board (IRB) approval, 77 invasive epithelial ovarian tumors were analyzed for CD31, EphA2, MMP-2, MMP-9, and MT1-MMP expression. RESULTS: The median age of the patients was 59 years (range, 34-83). EphA2 was overexpressed in 76% of tumors and was associated with advanced-stage disease (P < .001) and high-grade histology (P = .04). MVD was stratified into high (>12.7 vessels/high-power field [HPF]) versus low (相似文献