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1.
The spindle checkpoint, the primary mechanism to ensure that two daughter cells receive the same amount of DNA, is compromised in many malignant tumors and has been implicated as a contributor to aneuploidy and carcinogenesis. The extent of expression and subcellular localization of the spindle proteins Aurora A, Mad2, and BUBR1 varies considerably in different immunohistochemical (IHC) reports from archival tumor tissues. Given the conflicting reports in the literature about the localization of these proteins, we examined the subcellular localization of Aurora kinase A, Mad2, and BUBR1 in normal and cancerous human tissues by IHC. In normal tissues, Aurora A was mainly localized to the nucleus when monoclonal or purified polyclonal antibodies were used, and Mad2 was localized to the nucleus, whereas BUBR1 was localized to the cytoplasm. In malignant tissues, Aurora A showed additional staining in the cytoplasm in the majority of tumors analyzed. Furthermore, BUBR1 was also localized to both the nucleus and cytoplasm in a significant fraction of tumors. Subcellular localization of Mad2 was similar in normal and malignant tissues. Thus, the validity of some earlier IHC studies of Aurora A, Mad2, and BUBR1 should be reconsidered, indicating that high-quality antibodies and a high-alkaline antigen-retrieval technique are required to achieve optimal results. We conclude that the subcellular localizations of these spindle proteins are different, although they have overlapping biological functions, and that Aurora A and BUBR1 undergo a shift in the subcellular localization during malignant transformation.  相似文献   

2.
3.
Gallbladder carcinomas are rare but highly lethal neoplasms. We examined the expression of five cell-cycle-related molecules (p53, RB, cyclin D1, p27, Ki-67), and MSH2, in 46 carcinomas, 14 adenomas, 15 low-grade dysplasias, 9 intestinal metaplasias and 20 normal gallbladder epithelia. The expression of these molecules was altered in gallbladder carcinomas and adenomas. In gallbladder carcinomas we observed increased expression of p53, cyclin D1, Ki-67, and MSH2 together with decreased expression of RB and p27 protein. Aberrant expression of cyclin D1 and reduced expression of RB were noted in adenomas, and expression of cyclin D1 was elevated in low-grade dysplasias. However, there was no change in the levels of these cell-cycle molecules in metaplasia. Expression of p53, p27, Ki-67, and MSH2 was correlated with clinical stage (P<0.05) and there was also a correlation between the expression of Ki-67 and MSH-2 and patient age (P<0.05). These results suggest that altered expression of cell-cycle molecules p53, cyclin D1, RB, p27, and of MSH-2 is involved in the progression of gallbladder carcinomas.  相似文献   

4.

Purpose

Identifying among nephroblastoma those with a high propensity for distant metastases using cell cycle markers: cyclin E as a regulator of progression through the cell cycle and Ki-67 as a tumor proliferation marker, since both are often deregulated in many human malignancies.

Methodology/Principal Findings

A staining index (SI) was obtained by immunohistochemistry using anti-cyclin E and anti-Ki-67 antibodies in paraffin sections of 54 postchemotherapy nephroblastoma including 42 nephroblastoma without metastasis and 12 with metastases. Median cyclin E and Ki-67 SI were 46% and 33% in blastemal cells, 30% and 10% in stromal cells, 37% and 29.5% in epithelial cells. The highest values were found for anaplastic nephroblastoma. A correlation between cyclin E and Ki-67 SI was found for the blastemal component and for the epithelial component. Univariate analysis showed prognostic significance for metastases with cyclin E SI in stromal cells, epithelial cells and blastemal cells (p = 0.03, p = 0.01 and p = 0.002, respectively) as well as with Ki-67 SI in blastema (p<10−4). The most striking data were that both cyclin E SI and blastemal Ki-67 SI discriminated between patients with metastases and patients without metastasis among intermediate-risk nephroblastoma.

Conclusions

Our findings show that a high cyclin E SI in all components of nephroblastoma is correlated with tumor aggressiveness and metastases, and that assessment of its expression may have prognostic value in the categorization of nephroblastoma.  相似文献   

5.
The histological criteria for cervical intraepithelial neoplastic lesions and their follow-ups have been established, but their reproducibility, specificity and sensibility are not certain. Immunohistochemical markers provide more information on each specific case, in order to facilitate its classification and, eventually, its prognosis. Using immunohistochemical techniques, this study analyzes the prognostic value of three markers (Ki-67, c-erbB2 and Cyclin D1) in cases of low grade squamous intraepithelial neoplasia (CIN-I), high grade squamous intraepithelial neoplasia (CIN-III), and infiltrating squamous cell carcinoma (SCC) taken from a group of cervical samples. In situ hybridization was performed in order to detect high-risk HPV. High risk HPV was demonstrated in 82%, 89% and 100% of the LGSIL, HGSIL and SCC cases, respectively. C-erbB2 expression was detected in 9%, 33% and 50% of the LSIL, HGSIL and SCC cases, respectively. The Ki-67 LI was 25%, 68% and 65.5% in the LGSIL, HGSIL and SCC cases, respectively. Nuclear Cyclin D1 expression was seen in 82%, 11% and 30% of the CIN-I,CIN-III and SCC cases, respectively. We observed that the cytoplasmic cyclin D1 expression increased with the severity of the lesion instead of the nuclear expression decreasing with the progression of the pathology. Nuclear and cytoplasmic Cyclin D1 expression seemed to be related to HPV high risk infection. We concluded that Cyclin D1, cerbB2 and The Ki-67 LI expression changed in relation to the severity of the lesion and that they could be helpful in making a differential diagnosis.  相似文献   

6.
Monoclonal antibodies (MAb) to a 36 KD protein, proliferating cell nuclear antigen (PCNA/cyclin), have been previously shown to be capable of identifying proliferating cells in vitro as well as in alcohol-fixed, paraffin-embedded tissue specimens. The routine use of these anti-PCNA/cyclin MAb in investigative studies and in diagnostic pathology requires a clearer understanding of the distribution of PCNA/cyclin in the different cell populations found in tissue specimens. We therefore compared the ability of MAb to three nucleus-associated proliferation markers (MAb 19A2 to PCNA/cyclin; Ki-67 to an undefined proliferation-related marker; BU-1 to 5'-bromodeoxyuridine (BrdU) incorporated into DNA) to identify the proliferating cell fraction of various cells in vitro. The cell lines were chosen to represent a spectrum of proliferation rates (high to low) and cell lineage (mesenchymal vs epithelial, non-transformed vs malignant): (a) HeLa and A-431 (two malignant carcinoma cell lines with high proliferation rates); (b) SK-5 (a non-transformed fibroblast cell line with a low proliferation rate); (c) HUVE (a non-transformed human umbilical vein endothelial cell line with a low proliferation rate). Single and double labeling immunofluorescence studies were performed after uniform 1-hr incubations with BrdU. Comparison of the overlapping distributions of detectable PCNA/cyclin expression and BrdU incorporation demonstrated substantial qualitative and quantitative differences between the different cell lines. In two of the four cell lines (HeLa, A-431) the BrdU staining distributions formed inclusive subsets of the PCNA-positive cell populations. In the HUVE cell line the two populations overlapped incompletely. In one cell line, SK-5, the two populations were mutually exclusive. MAb Ki-67 demonstrated a pattern in the SK-5 cell line that was strongly predictive of PCNA positivity, while showing no associated patterns in the other three cell lines. We conclude that PCNA/cyclin expression detected by MAb may define different cell subpopulations in different cell types relative to those incorporating BrdU or expressing the target antigen for Ki-67. This has implications for the clinical study of mixed cell populations using these antibodies.  相似文献   

7.
The purpose of the present study was to analyse clinical correlation between HPV type 16 and 18 infection, expression of p53, cyclin D1, Ki-67, c-erbB2 and EGFr gene products in cervical cancer cells as well as their nuclear ploidy. The morphological parameters evaluated, such as differentiation of carcinomas, vascular invasion, ploidy and expression of oncogenic proteins, indicate the increased biological malignancy of HPV 16/18-positive carcinomas. The majority of them were poorly differentiated, revealed significantly higher frequence of vascular invasion (p<0.05), were more frequently aneuploid and showed overexpression of cyclin D1. The comparison of the data obtained with the mortality rate of the patients suggests that the overexpression of EGFr and moderate expression of Ki-67 seem to be unfavorable prognostic factors, regardless of the presence of HPV 16/18.  相似文献   

8.
The deubiquitinating enzyme USP2a has shown oncogenic properties in many cancer types by impairing ubiquitination of FASN, MDM2, MDMX or Aurora A. Aberrant expression of USP2a has been linked to progression of human tumors, particularly prostate cancer. However, little is known about the role of USP2a or its mechanism of action in bladder cancer. Here, we provide evidence that USP2a is an oncoprotein in bladder cancer cells. Enforced expression of USP2a caused enhanced proliferation, invasion, migration and resistance to several chemotherapeutic reagents, while USP2a loss resulted in slower proliferation, greater chemosensitivity and reduced migratory/invasive capability compared with control cells. USP2a, but not a catalytically inactive mutant, enhanced proliferation in immortalized TRT-HU1 normal human bladder epithelial cells. USP2a bound to cyclin A1 and prevented cyclin A1 ubiquitination, leading to accumulation of cyclin A1 by a block in degradation. Enforced expression of wild type USP2a, but not an inactive USP2a mutant, resulted in cyclin A1 accumulation and increased cell proliferation. We conclude that USP2a impairs ubiquitination and stabilizes an important cell cycle regulator, cyclin A1, raising the possibility of USP2a targeting as a therapeutic strategy against bladder tumors in combination with chemotherapy.  相似文献   

9.
Abstract. Neoplastic transformation of mouse mammary epithelial cells is the result of several identifiable phenotypic changes which presumably require sequential genetic alterations. In our model system, mammary cells progress from a mortal state (virgin duct) to several morphologically distinct intermediate states. The intermediate states are distinct cell populations that are phenotypically identified as immortal, non-tumourigenic (i.e. EL11), weakly tumourigenic ductal/alveolar hyperplasia (i.e. EL12) and moderately tumourigenic alveolar hyperplasiaa (i.e. TM12) to invasive tumours (i.e. EL12T/TM12T). We have studied the changes in total cyclin A and B1 levels, cyclin A and B1 complexed to cdc2, cyclin B1cdc2 kinase activity and cyclin D proteins in EL11 and EL12 immortalized outgrowth lines. Results revealed increased levels in total cyclin B1(> 5-fold), cyclin B1/cdc2 (3–4-fold) and cyclin B1/cdc2 kinase activity (2–3.5-fold) in EL11 and EL12 phenotypes when compared to control mammary gland (virgin). No changes in the levels of total cyclin A or cycln A associated to cdc2 were observed. Cyclin D1, D2 and D3 protein levels were low in the EL11 immortal ductal outgrowth. Exposure to hormones via a pituitary isograft stimulated the synthesis of cyclin D1 and D2 but not D3 associated to cdk4 as well as total cdk4 proteins. Bromodeoxyuridine (BrdUrd) labelling indices showed marked increases in immortal ductal outgrowths (EL11 and EL12) when compared to virgin, suggesting that epithelial cells are cycling in these cell populations. Even in the presence of hormone stimulation, EL11 outgrowths were not tumourigenic, suggesting that other events are necessary to drive the cells to a tumourigenic phenotype. The results suggest that increased levels of cyclin B1 and cyclin B1-cdc2 kinase activities are early events and may be an important marker for the immortalized phenotype.  相似文献   

10.
Fifty-seven cases of T-cell lymphomas (TCL) including 5 lymphoblastic (T-LBL) and 52 peripheral TCL (PTCL) were analyzed by immunohistochemistry for the expression of p53, mdm2, p21, Rb, cyclin D1, cyclin A, cyclin B1, and Ki67/MIB1 proteins and 39/52 PTCL were also analyzed for the expression of p16 protein and for the presence of apoptotic cells by the TUNEL method. The aim was to search for abnormal immunoprofiles of p53 and Rb growth control pathways and to determine the proliferative activity and the apoptotic index of TCL. Abnormal overexpression of p53, p21 and mdm2, in comparison to normal lymph nodes, was found in 12/57, 10/57 and 2/57 cases of TCL, respectively. Abnormal loss of Rb and p16 expression was found in 1/57 and 2/39 cases, respectively, whereas abnormal overexpression of cyclin D1 was not detected in any of the 57 cases. Our data revealed entity-related p53/p21/mdm2 phenotypes. Indeed, most nodal and cutaneous CD30+ anaplastic large cell lymphomas (ALCL) showed concomitant overexpression of p53 and p21 proteins (7/8 cases), and mdm2 was overexpressed in 2 p53-positive nodal ALCL. In contrast, overexpression of p53 was found in 3/17 cases of nodal peripheral TCL unspecified (PTCL-UC) and 2/7 non-ALCL cutaneous pleomorphic TCL. Overexpression of p21 protein was detected in 2/3 p53-positive PTCL-UC and in 1/2 p53-positive non-ALCL cutaneous pleomorphic TCL. Finally, all the remaining 25 cases of TCL did not show p53 and p21 overexpression. Overall, the p53+/p21+ phenotype in 10/57 TCL suggests wild-type p53 capable of inducing p21 expression. The highest apoptotic index (AI) was found in ALCL and a positive correlation between apoptotic index and Ki67 index (p<0.001) was detected. Ki67, cyclin A and cyclin B1 expression was found in all 57 TCL and on the basis of the combined use of these 3 variables, 3 groups of proliferative activity could be determined: a) high in ALCL and T-LBL, b) low in mycosis fungoides (MF) and gammadelta hepatosplenic TCL, and c) intermediate in the remaining TCL entities. The proliferative activity in the 12 p53 overexpressing cases was higher in comparison to the 45 p53-negative cases. Ki67 expresion in more than 25% of tumour cells showed significant correlation with p53 overexpression (p<0.001). Rb expression tended to be parallel to Ki67, cyclin A and cyclin B1 expression in all but one case of nodal PTCL-UC which displayed loss of RB expression. Interestingly, this case was p53-negative, whereas the p53-positive cases were Rb-positive. These findings suggest that different pathogenetic routes may function in some TCL, involving either the p53 or, less frequently, the Rb pathways.  相似文献   

11.
The deubiquitinating enzyme USP2a has shown oncogenic properties in many cancer types by impairing ubiquitination of FASN, MDM2, MDMX or Aurora A. Aberrant expression of USP2a has been linked to progression of human tumors, particularly prostate cancer. However, little is known about the role of USP2a or its mechanism of action in bladder cancer. Here, we provide evidence that USP2a is an oncoprotein in bladder cancer cells. Enforced expression of USP2a caused enhanced proliferation, invasion, migration and resistance to several chemotherapeutic reagents, while USP2a loss resulted in slower proliferation, greater chemosensitivity and reduced migratory/invasive capability compared with control cells. USP2a, but not a catalytically inactive mutant, enhanced proliferation in immortalized TRT-HU1 normal human bladder epithelial cells. USP2a bound to cyclin A1 and prevented cyclin A1 ubiquitination, leading to accumulation of cyclin A1 by a block in degradation. Enforced expression of wild-type USP2a, but not an inactive USP2a mutant, resulted in cyclin A1 accumulation and increased cell proliferation. We conclude that USP2a impairs ubiquitination and stabilizes an important cell cycle regulator, cyclin A1, raising the possibility of USP2a targeting as a therapeutic strategy against bladder tumors in combination with chemotherapy.Key words: USP2a, cyclin A1, bladder cancer, cisplatin resistance, deubiquitination  相似文献   

12.
Defect in cell cycle control is a hallmark character of cancer. We have investigated the association of Ki67 labeling index, cyclin E and CDC25A expressions with clinical follow-up data in breast carcinomas. Flow cytometry was used to detect gene amplification of cyclins in 44 tumor tissue with invasive breast carcinomas. Multivariate Cox proportional hazard ratio test was used to show the correlations. Cyclin E or CDC25A were upregulated in 34% of the tumors. Among the whole total material, expression of cyclin E and of CDC25A were found upregulated in 31.9% and 39.4% of cells, respectively. Both CDC25A and cyclin E protein expression levels were correlated with Ki67 expression level (p < 0.001). In addition, the expression of CDC25A was associated significantly with poor survival (P = 0.028), whereas no correlation was found with cyclin E. These findings suggest a possible prognostic value for CDC25A as a cell cycle marker and may imply in characteristic of high risk breast cancer patients.  相似文献   

13.
The immunohistochemical expression of p53, p21, Rb, p16, cyclin D1, Ki67, cyclin A, cyclin B1, p27, bcl2, bax, and bak proteins and the apoptotic index (Al) were investigated in 20 normal thymuses (8 adults, 3 adolescents, 5 infants and 4 newborns). The expressions of Rb, Ki67, cyclin A and cyclin B1 were overlapping, being high in the cortex with a tendency for decreased expression toward the medulla. Apoptotic cells were mainly detected in the cortex and the corticomedullary junction, rarely being present in Hassall's corpuscles. The mean values of Ki67, cyclin A, and cyclin B1 expression in thymuses were 77.2%, 32.2% and 21.4% (newborns), 62.4%, 33.7% and 18.5% (infants), 56.9%, 23.4% and 18.9% (adolescents) and 38.7%, 21.7% and 14.6% (adults), respectively. The mean values of AI in thymuses from newborns, infants, adolescents and adults were 1.4%, 2.9%, 2.7% and 3.8%, respectively. This decrease in proliferation and increase in apoptosis may account for the process of thymic involution. P16 expression was widespread with most of Hassall's corpuscles being p16-positive. P16-positive cells and Hassall's corpuscles increased with the increase in age, in keeping with the suggested role of p16 in cellular senescence. P27 expression was undetectable in subcapsular thymocytes with a tendency for increased expression toward the medulla. The expressions of Ki67, cyclin A and cyclin B1 were inversly related with that of p27, consistent with previous evidence that p27 concentration is reduced when the cell-cycle progresses. P21 and much less frequently p53 proteins were mainly detected in a part of the subcapsular cortical epithelial cells. These findings suggest that a) in thymocytes, the apoptotic pathway is mostly p53-independent and the function of p21 as a negative regulator of the cell cycle must be redundant to other negative regulators, such as p16 and p27 which were abundantly detected in thymocytes and b) in some thymic epithelial cells, the p21 expression may be induced by p53, but in most of them seems to be p53-independent. Most of Hassall's corpuscles were p21-positive, consistent with previous evidence that these structures represent end stages of maturation of thymic medullary epithelium and that p21 protein is involved in the process of terminal differentiation. Cyclin D1 positivity was found in some macrophages. Bcl2 expression was mainly seen in medullary thymocytes, reflecting the surviving thymocytes in this region. The expressions of Bax and bak were more widespread in both the medulla and cortex, suggesting that these proteins play a broader role than bcl2 in the regulation of thymic apoptosis.  相似文献   

14.
Nek2A (NIMA-related kinases 2A) has been known as an important centrosome regulatory factor. The aim of this study was to investigate the expression of Nek2A and the role it played in different stages of breast cancer. We detected the expression of Nek2A in both mRNA and protein levels in MCF10 cell lines including MCF-10A, MCF-10DCIS.com, MCF-10CA1a and in human breast samples which contained normal breast tissue (NBT), breast ductal carcinoma in situ (DCIS), and invasive ductal carcinoma (IDC). Our study revealed that the mRNA and protein expression of Nek2A were significantly up-regulated in MCF-10DCIS.com and MCF-10CA1a cell lines as well as in human primary breast cancer tissue (DCIS and IDC). Our study also presented a correlation between Nek2A mRNA expression and some clinic pathological factors. We found that Nek2A mRNA expression was associated with molecular subtypes, ER, PR and Ki-67 immunoreactivity (P<0.05) in DCIS and associated with histological grade, lymph node metastasis, molecular subtypes, c-erbB-2, and Ki-67 expression (P<0.05) in IDC. In addition, we observed that ectopic expression of Nek2A in "normal" immortalized MCF-10A breast epithelial cell resulted in increased Nek2A which lead to abnormal centrosomes. Furthermore, knockdown of Nek2A in MCF-10DCIS.com could remarkably inhibit cell proliferation and induce cell cycle arrest in MCF-10DCIS.com cell line. These data suggested that Nek2A might bear a close relationship with development and progression of breast carcinoma, and highlighted its role as a novel potential biomarker for diagnosis and a possible therapeutic target for human breast cancer especially for DCIS.  相似文献   

15.
OBJECTIVE: To compare the relationship between Her-2/neu in the invasive and in situ components of carcinoma. STUDY DESIGN: Using immunohistochemistry, this study compares the Her-2/neu status in the in situ and invasive components of 200 cases of ductal carcinoma of the breast. A 0-3+ grading scale was used to semiquantitate Her-2/neu protein expression. RESULTS: Twenty-five cases (12.5%) demonstrated a difference of 2 or more grades between the in situ and invasive components. The in situ component always showed higher expression of Her-2/neu than did the invasive component when protein expression was discordant. Comedo carcinoma was the in situ component in 12 of the 25 discordances in Her-2/neu expression. CONCLUSION: Significant heterogeneity exists between Her-2/neu expression in the in situ component and invasive components of adenocarcinoma of the breast. When discordance exists, the in situ component shows higher levels of expression.  相似文献   

16.
The aim of the study was an evaluation of expression of D1 cyclin and Ki-67 proteins in tissue of human papillary thyroid carcinoma (PTC) in a group of papillary microcarcinomas and in a group of PTC with a degree of staging higher than pT1a in TNM classification. We performed immunohistochemical staining and found no statistical differences between groups. These results suggest that changes of expression of D1 cyclin are an early event in tumorigenesis.  相似文献   

17.
18.
摘要 目的:探讨血清人附睾蛋白4(HE4)、血管内皮生长因子(VEGF)、单核细胞趋化因子-1(MCP-1)及CC趋化因子配体20(CCL20)与乳腺癌患者保乳术后局部复发的关系。方法:选择2015年7月~2018年7月期间本院收治的乳腺癌患者312例作为研究对象,均符合保乳术手术指征,成功实施乳腺癌保乳术,所有患者均随访3年。检测两组血清HE4、VEGF、MCP-1、CCL20水平情况,单因素及多因素Logistic回归分析影响术后局部复发的因素。使用受试者工作特征(ROC)曲线分析HE4、VEGF、MCP-1、CCL20水平单独及联合检测对保乳术后局部复发的预测价值。结果:随访过程中失访6例,剩余的306例患者根据随访结果,分为局部复发组27例、无局部复发组279例,局部复发率为8.82%。局部复发组的血清HE4、VEGF、MCP-1、CCL20水平均高于无局部复发组(P<0.05)。单因素分析结果显示,乳腺癌患者保乳术后局部复发与年龄、淋巴结转移、切缘状态、人表皮生长因子受体2(Her-2)、细胞增殖相关抗原(Ki-67)、术后规范化疗、术后足程放疗有关(P<0.05)。多因素Logistic回归分析结果显示术后规范化疗、年龄偏高、术后足程放疗是保乳术后局部复发的保护因素,HE4、VEGF、MCP-1、CCL20水平偏高,切缘状态、Her-2、Ki-67阳性以及淋巴结转移是保乳术后局部复发的危险因素(P<0.05)。HE4、VEGF、MCP-1、CCL20联合应用预测乳腺癌患者保乳术后局部复发的效能高于单一指标应用。结论:乳腺癌保乳术后局部复发患者体内HE4、VEGF、MCP-1、CCL20水平高表达,四指标联合检测可辅助预测保乳术后局部复发。且乳腺癌患者保乳术后复发还受到切缘状态、Her-2、Ki-67等多种因素的影响。  相似文献   

19.
Eukaryotic cells have evolved a mechanism that delays the progression of mitosis until condensed chromosomes are properly positioned on the mitotic spindle. To understand the molecular basis of such monitoring mechanism in human cells, we have been studying genes that regulate the mitotic checkpoint. Our early studies have led to the cloning of a full-length cDNA encoding MAD3-like protein (also termed BUBR1/MAD3/SSK1). Dot blot analyses show that BUBR1 mRNA is expressed in tissues with a high mitotic index but not in differentiated tissues. Western blot analyses show that in asynchronous cells, BUBR1 protein primarily exhibits a molecular mass of 120 kDa, and its expression is detected in most cell lines examined. In addition, BUBR1 is present during various stages of the cell cycle. As cells enter later S and G2, BUBR1 levels are increased significantly. Nocodazole-arrested mitotic cells obtained by mechanical shake-off contain BUBR1 antigen with a slower mobility on denaturing SDS gels. Phosphatase treatment restores the slowly migrating band to the interphase state, indicating that the slow mobility of the BUBR1 antigen is attributable to phosphorylation. Furthermore, purified recombinant His6-BUBR1 is capable of autophosphorylation. Our studies indicate that BUBR1 phosphorylation status is regulated during spindle disruption. Considering its strong homology to BUB1 protein kinase, BUBR1 may also play an important role in mitotic checkpoint control by phosphorylation of a critical cellular component(s) of the mitotic checkpoint pathway.  相似文献   

20.
Diabetic encephalopathy may lead to cognitive deficits in diabetic patients and diminish quality of life. It has been shown that protracted hyperglycaemia is directly associated with neuronal apoptosis, which is involved in diabetic encephalopathy. The anaphase‐promoting complex (APC) is essential for the survival of post‐mitotic neurons. In our previous study, we found that the mitotic arrest deficient protein MAD2B, one of APC inhibitors, was expressed in neurons in central nervous system. However, whether MAD2B is involved in hyperglycaemia‐induced apoptosis and thus takes part in diabetic encephalopathy is still unknown. To address this issue, we first explored the expression of MAD2B and cyclin B1 detected by immunofluorescence and Western blot. It was found that hyperglycaemia remarkably increased the expression of MAD2B and accumulation of cyclin B1 in cortices of diabetes mellitus rat model and in cultured primary neurons. To further explore the role of MAD2B in hyperglycaemia‐induced neuronal injury, we depleted MAD2B expression by a specifically targeted shRNA against MAD2B. We observed that MAD2B deficiency alleviated cyclin B1 expression and apoptotic neuronal death. These results demonstrate that MAD2B expression is the main culprit for accumulation of cyclin B1 and apoptosis in neurons under high glucose. Moreover, inhibition of the expression of MAD2B prevented neurons from entering an aberrant S phase that led differentiated neurons into apoptotic cell death. These results suggest that hyperglycaemia induced neuronal apoptosis through inducing expression of MAD2B, which represents a novel mechanism of diabetic encephalopathy.  相似文献   

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