肾母细胞瘤MIB-1（Ki-67增殖指数）和p27kip1表达及与预后的关系

目的:探讨肾母细胞瘤MIB-1（Ki-67增殖指数）和细胞周期蛋白依赖性激酶抑制剂p27kip1的表达及与预后的关系。方法:经医院伦理委员会批准,连续纳入2008年1月至2013年8月在我院就诊的肾母细胞瘤患者样本作为研究对象,观察p27kip1和MIB-1阳性表达与患者临床特征的关系。结果:肿瘤组织中MIB-1阳性表达率高于正常肾组织,p27kip1阳性表达率低于正常肾组织,差异均有统计学意义（P＜0.05）。MIB-1和p27kip1表达与性别、年龄、病理分型、发病部位等均无相关性（P＞0.05）,与临床分期存在相关性（P＜0.05）。MIB-1表达阳性患者中位生存时间低于阴性患者,而p27kip1表达阴性患者中位生存时间低于阳性患者（χ2=6.979、15.247,P=0.008、0.000）。结论:MIB-1表达增加和p27kip1表达降低与肾母细胞瘤的发生、发展、预后密切相关,临床应根据其表达情况进行针对性干预,以改善患者的预后。     

Frequent loss of expression of the cyclin-dependent kinase inhibitor p27(Kip1) in estrogen-related Endometrial adenocarcinomas.

PURPOSE: p27(Kip1) is a member of the Cip1/Kip1 family of cyclin-dependent kinase inhibitors and is a potential tumor suppressor gene. Low levels of p27 are associated with poor prognosis in a variety of gynecological tumors, including breast, ovarian, and cervical carcinomas. The role of p27 in endometrial cancer remains controversial. EXPERIMENTAL DESIGN: In the present study, p27 protein expression was investigated by immunohistochemistry in a series of 217 endometrial adenocarcinomas and, where present, in synchronous normal endometrium, simple and complex hyperplasia (with or without atypia), and cystic atrophy. The relationship between p27 expression and clinical outcome was also evaluated. RESULTS: Immunohistochemical analysis revealed a significant loss of p27 expression from normal (33%) through hyperplastic endometrium (50%) to endometrial adenocarcinomas (71%; P 相似文献   

Reduced expression and altered subcellular localization of the cyclin-dependent kinase inhibitor p27(Kip1) in human colon cancer

The p27(Kip1) protein is a negative regulator of the cell cycle and a potential tumor suppressor gene. Reduced expression of the p27(Kip1) protein has been reported in several human tumors and has been associated with higher tumor grade and increased mortality in breast, lung, colon, prostate, bladder, and gastric cancers. On the other hand, increased expression of the p27(Kip1) protein, in the absence of gene mutation, has been observed in primary colon and breast cancers. It was recently suggested that sequestration in the cytoplasm might be an alternative way to inactivate p27(Kip1)-associated inhibitory activity. This study was undertaken to further evaluate p27(Kip1) expression in primary colon tumors and to verify whether differences exist between normal and cancer tissues in terms of subcellular localization of this protein. Both normal and neoplastic tissues expressed variable amounts of the p27(Kip1) protein, as assessed by western blot analyses. Although the mean values were not different between tumor and normal mucosa samples, the expression of total p27(Kip1) was reduced in a subset of tumors. Decreased levels of total p27(Kip1) were associated with high tumor grade (P=0.03) and stage (P=0.04). Moreover, while there was no significant difference in nuclear p27(Kip1), the amount of p27(Kip1) in the cytoplasmic fraction was significantly higher in the tumor samples than in the normal mucosa samples (P=0.0001). These results suggest that p27(Kip1) expression is lost in a subset of colorectal tumors and that alterations in the subcellular localization of this protein might play a role in colon carcinogenesis.     

The prognosis in spindle-cell sarcoma depends on the expression of cyclin-dependent kinase inhibitor p27(Kip1) and cyclin E

The aim of the present study was to examine the prognostic significance of p27^Kip1 and cyclin E expression in patients with spindle-cell soft tissue sarcomas. In 46 cases of spindle-cell sarcoma including 17 pre-operative biopsy materials, the expression of p27^Kip1 and cyclin e was immunohistochemically examined. The expression of p27^Kip1 decreased in the nuclei of metastatic primary tumor cells (stage IV), whereas the expression of cyclin E increased in those lesions. On univariate analysis, when the expression of p27^Kip1 and cyclin E was analyzed together, patients with spindle-cell sarcoma exhibiting low expression of p27^Kip1 and high expression of cyclin E showed lower distant-metastasis-free survival (DMFS) and overall survival (OS) than those with other combinations of the two parameters (both P <0.0001). Multivariate analysis revealed that patients with low p27^Kip1 and high cyclin E expression also showed a decrease in DMFS ( P =0.0007, relative risk=21.3) and OS (P=0.005, relative risk=20.8). These results suggest that the combination analysis of p27^Kip1 and cyclin E expression even in biopsy specimens allows the prediction of the clinical behavior of spindle-cell sarcoma. (Cancer Sci 2003; 94: 412–417)     

Pirh2 promotes ubiquitin-dependent degradation of the cyclin-dependent kinase inhibitor p27Kip1

The cyclin-dependent kinase inhibitor p27(Kip1) is degraded in late G(1) phase by the ubiquitin-proteasome pathway, allowing cells to enter S phase. Due to accelerated degradation of p27(Kip1), various human cancers express low levels of p27(Kip1) associated with poor prognosis. S-phase kinase-associated protein 2, the F-box protein component of an SCF ubiquitin ligase complex, is implicated in degradation of p27(Kip1) during S-G(2) phases. Recently, Kip1 ubiquitination-promoting complex has been reported as another ubiquitin ligase that targets cytoplasmic p27(Kip1) exported from the nucleus in G(0)-G(1) phases. Here, we identified a RING-H2-type ubiquitin ligase, Pirh2, as a p27(Kip1)-interacting protein. Endogenous Pirh2 physically interacted with endogenous p27(Kip1) in mammalian cells. Pirh2 directly ubiquitinated p27(Kip1) in an intact RING finger domain-dependent manner in vivo, as well as in vitro. Ablation of endogenous Pirh2 by small interfering RNA increased the steady-state level of p27(Kip1) and decelerated p27(Kip1) turnover. Depletion of Pirh2 induced accumulation of p27(Kip1) in both the nucleus and cytoplasm. Pirh2 expression was induced from late G(1)-S phase, whereas p27(Kip1) was decreased in synchronization with accumulation of Pirh2. Furthermore, reduction of Pirh2 resulted in an impairment of p27(Kip1) degradation and an inhibition of cell cycle progression at G(1)-S transition in a p53-independent manner. Overall, the results indicate that Pirh2 acts as a negative regulator of p27(Kip1) function by promoting ubiquitin-dependent proteasomal degradation.     

Caspase-induced proteolysis of the cyclin-dependent kinase inhibitor p27Kip1 mediates its anti-apoptotic activity.

The caspase-mediated cleavage of a limited number of cellular proteins is a common feature of apoptotic cell death. This cleavage usually inhibits the function of the target protein or generates peptides that actively contribute to the death process. In the present study, we demonstrate that the cyclin-dependent kinase inhibitor p27Kip1 is cleaved by caspases in human leukemic cells exposed to apoptotic stimuli. We have shown recently that p27Kip1 overexpression delayed leukemic cell death in response to cytotoxic drugs. In transient transfection experiments, the p23 and the p15 N-terminal peptides generated by p27Kip1 proteolysis demonstrate an anti-apoptotic effect similar to that induced by the wild-type protein, whereas cleavage-resistant mutants have lost their protective effect. Moreover, stable transfection of a cleavage-resistant mutant of p27Kip1 sensitizes leukemic cells to drug-induced cell death. Altogether, these results indicate that proteolysis of p27Kip1 triggered by caspases mediates the anti-apoptotic activity of the protein.     

Low expression of p27(Kip1), a cyclin-dependent kinase inhibitor, is a marker of poor prognosis in synovial sarcoma

BACKGROUND: Low expression of p27(kip1), a dominant cyclin-dependent kinase inhibitor involved in G1-S transition of the cell cycle, recently has been reported to be associated with aggressive tumor growth. It has been shown that active cell proliferation alludes to poor prognosis in patients with synovial sarcoma. However, to the authors' knowledge, little is known about the clinicopathologic significance of p27(kip1) in synovial sarcoma. METHODS: p27(kip1) expression was examined immunohistochemically in 55 cases of primary synovial sarcoma, and the relations between p27(kip1) expression and several cell proliferation markers, i.e., mitotic index (MI), Ki-67 labeling index (Ki-67 LI), and clinicopathologic parameters related to poor prognosis, were determined. Univariate and multivariate survival analyses were performed to evaluate the prognostic significance of p27(kip1) expression in synovial sarcomas. RESULTS: p27(kip1) labeling index (p27(kip1) LI) correlated inversely with MI (r = -0.44, P = 0.0007) and Ki-67 LI (r = -0.63, P < 0.0001). Of the clinicopathologic parameters examined, tumor necrosis (P = 0.019) and American Joint Committee on Cancer (AJCC) stage (P = 0.021) correlated significantly with p27(kip1) LI. Survival analysis showed that p27(kip1) LI was an independent prognostic factor for overall survival in patients with synovial sarcoma (P = 0.0031). CONCLUSIONS: The study results suggested that low expression of p27(kip1) may be useful as a marker of poor-prognosis synovial sarcoma.     

Cyclin-dependent kinase inhibitor p27(Kip1) expression in transitional cell carcinoma of renal pelvis and ureter

We examined the expression and significance of p27^Kip1 protein in 79 patients with transitional cell carcinoma of the renal pelvis and ureter. Immunohistochemical staining of archival tissue specimens was done using a labeled streptavidin–biotin–peroxidase method. There was no significant association between p27^Kip1 labeling index and histologic grade or pathologic stage. Patients with p27^Kip1 labeling indices of 27 or greater had more favorable prognoses in comparison to those with p27^kip1 labeling indices less than 27 (P<0.01). Multivariate analysis indicated that p27^Kip1 had an independent predictive prognostic value (P<0.05). The p27^Kip1 may be a novel prognostic marker for transitional cell carcinoma of the renal pelvis and ureter.     

The cyclin-dependent kinase inhibitor p27Kip1 is localized to the cytosol in Swiss/3T3 cells.

p27Kip1 plays an important role in cell cycle progression by negatively regulating the activity of cyclin-Cdk complexes. To understand how p27Kip1 functions, the level and subcellular location of p27Kip1 in Swiss/3T3 cells following serum stimulation of quiescent cells was examined. Surprisingly, p27Kip1 was observed exclusively in the cytosol throughout G1 and into early S phase. However, as expected, p27Kip1 in the cytosolic fraction was greatly reduced following serum stimulation and reached very low levels by late G1. The decline in the level of p27Kip1 corresponded in time to an increase in the nuclear level of both Cdk2 and cyclin E. In quiescent 3T3 cells Cdk2 was inactive and co-precipitated with p27Kip1. After serum stimulation, both nuclear and cytosolic Cdk2 was activated and this corresponded to the decline in p27Kip1. Overexpression of p27Kip1 allowed accumulation of the inhibitor in the nucleus but inhibited entry of Cdk2 into the nucleus following serum stimulation. The subcellular localization of p27Kip1 was also examined in a variety of other mammalian cells. In all the cell lines examined the preponderance of p27Kip1 was found in the cytosolic fraction. However, a substantial level of nuclear p27Kip1 was observed for several cell lines. In a primary mixed glial cell culture p27Kip1 was localized to the nucleus. The results suggest that cytosolic p27Kip1 has a functional role in regulating cell cycle progression, possibly through inhibiting transport of cyclin E-Cdk 2 complexes into the nucleus.     

Bortezomib (Velcade) induces p27Kip1 expression through S-phase kinase protein 2 degradation in colorectal cancer

S-phase kinase protein 2 (SKP2), an F-box protein, targets cell cycle regulators including cycle-dependent kinase inhibitor p27Kip1 via ubiquitin-mediated degradation. SKP2 is frequently overexpressed in a variety of cancers. We investigated the role of SKP2 and its ubiquitin-proteasome pathway in colorectal carcinoma using a panel of cell lines, clinical samples, and the NUDE mouse model. Using immunohistochemical analysis on a large tissue microarray of 448 samples, an inverse association of SKP2 expression with p27Kip1 protein levels was seen. A colorectal cancer (CRC) subset with high level of SKP2 and low level of p27Kip1 showed a decreased overall survival (P = 0.0057). Treatment of CRC cell lines with bortezomib or expression of small interfering RNA of SKP2 causes down-regulation of SKP2 and accumulation of p27Kip1. Furthermore, treatment of CRC cells with bortezomib causes apoptosis by involving the mitochondrial pathway and activation of caspases. In addition, treatment of CRC cells with bortezomib down-regulated the expression of XIAP, cIAP1, and survivin. Finally, treatment of CRC cell line xenografts with bortezomib resulted in growth inhibition of tumors in NUDE mice via down-regulation of SKP2 and accumulation of p27Kip1. Altogether, our results suggest that SKP2 and the ubiquitin-proteasome pathway may be potential targets for therapeutic intervention for treatment of CRC.     

Expression of cyclin-dependent kinase inhibitor p27/Kip1 and AP-1 coactivator p38/Jab1 correlates with differentiation of embryonal rhabdomyosarcoma.

Cyclin-dependent kinase (CDK) inhibitor p27/Kip1 (p27) is a diagnostic and prognostic marker of various malignancies. Low expression of p27 reflects poor differentiation and poor prognosis, and an inverse correlation between the expression of p27 and degree of tumor malignancy has been reported. Because p27 mutation is extremely rare in human tumors, it is important to study the expression of p27 and its inactivator, p38/Jab1 (JAB1). Here we analyzed the expression of p27 and JAB1 by immunohistochemistry in embryonal rhabdomyosarcoma (E-RMS). We first confirmed the expression of p27 and JAB1 in normal human tonsillar epithelium, and observed a coordinated expression pattern depending on cell differentiation. Subsequently, specimens of eight poorly- and three well-differentiated E-RMS were examined for the expression of p27 and JAB1. The analyses revealed that four out of eight poorly-differentiated E-RMS were negative for p27, with positivity for nuclear JAB (NJAB) (- / + for p27/NJAB) in three and negativity for any JAB-1 expression ( - / -) in one. The remaining four poorly-differentiated E-RMS expressed p27 in the nuclei, together with predominant NJAB (+ / +). In three well-differentiated E-RMS, only one expressed nuclear p27 and all of these three expressed no NJAB (+ / - for p27/NJAB), but expressed predominant cytoplasmic JAB1 (CJAB). These findings suggest that JAB1 may play an important role in determining the differentiation stage of rhabdomyosarcoma cells by modulating the activity of CDK inhibitor p27.     

Prognostic implications of expression of the cell cycle inhibitor protein p27Kip1

Mitogenic and growth inhibitory signals influence the activity of a family of cyclin dependent kinases (cdks). p27 is an important cdk inhibitor, acting in G1 to inhibit cyclin-cdks. As negative growth regulators, the cdk inhibitors may function as tumor suppressors. While the p16 gene plays a tumor suppressor role in cancers, p27 gene mutations have been identified only rarely. While high levels of p27 protein are expressed in normal human mammary epithelium, loss of p27 is frequent and is of independent prognostic significance in breast cancers. Low p27 is also a poor prognostic factor in colon, gastric, esophageal, lung, and prostate carcinomas, and enhanced proteasomal degradation may underlie loss of p27 in tumor cells. Loss of p27 has not been significantly correlated with tumor proliferation in a number of studies and may reflect alterations in differentiation and adhesion-dependent growth regulation germane to oncogenesis and tumor progression. Efforts to confirm the prognostic value of p27 are under way in a number of large breast cancer studies. These studies may also indicate whether loss of p27 in association with other traditional or novel markers has greater prognostic potential than each factor alone. p27 immunostaining is inexpensive and reliable and may become part of the routine histopathologic processing of tumors in the near future. Widespread application of p27 in prognostic testing will require greater uniformity in scoring techniques and determination of the cut off levels which distinguish individuals at high and low risk of cancer recurrence and death. Finally, the greatest utility of p27 may lie in the information it sheds on the biology of aberrant growth regulation in breast cancer and the potential to use this in the generation of novel therapeutic strategies.     

Gene delivery of cyclin-dependent kinase inhibitors p21 Waf1 and p27 Kip1 suppresses proliferation of MCF-7 breast cancer cells in vitro

Background

Because tumorigenesis depends on a variety of oncogenes, symphyseal study of combined genes may lead to more significant knowledge about tumorigenesis and progression. Combined deficiency of p21 and p27 proteins in mice is linked to more aggressive spontaneous tumorigenesis. We investigated the effect of the transfected p21 ^Waf1 -p27 ^Kip1 gene on centrosome duplication, cell proliferation, and apoptosis of MCF-7, a breast cancer cell line.

Methods

The pIRES-p21 ^Waf1 , pIRES-p27 ^Kip1 , and pIRES-p21 ^Waf1 -p27 ^Kip1 genes were transfected into MCF-7 cells by lipofection. The effect on proliferation was evaluated by MTT assay and clone-formation assay. Cell cycle and apoptosis were analyzed by flow cytometry. Apoptosis was tested by flow cytometry and TUNEL assay. Centrosome duplication was detected by use of indirect immunofluorescence microscopy.

Results

The results showed that the pIRES-p21 ^Waf1 , pIRES-p27 ^Kip1 , and pIRES-p21 ^Waf1 -p27 ^Kip1 significantly inhibited proliferation of MCF-7 cells, followed by accumulation of MCF-7 cells in cycle G₁, induced apoptosis, and a decrease in the proportion of MCF-7 cells which contained abnormal centrosomes. Compared with p21 ^Waf1 or p27 ^Kip1 alone, combination of p21 ^Waf1 and p27 ^Kip1 had a much more significant effect (P < 0.05).

Conclusion

Altogether, these results indicate that the p21 ^Waf1 -p27 ^Kip1 gene combination has a more obvious antitumor effect than p21 ^Waf1 or p27 ^Kip1 alone. This study provides preclinical evidence that combination of p21 ^Waf1 and p27 ^Kip1 could be a novel and promising therapeutic approach to treatment of breast cancer with suppressed p21 ^Waf1 and p27 ^Kip1 expression.     

Frequent loss of expression of the cyclin-dependent kinase inhibitor p27 in epithelial ovarian cancer.

p27Kip1 is a member of the Cip1/Kip1 family of cyclin-dependent kinase inhibitors and is a potential tumor suppressor gene. Low levels of p27 are associated with poor prognosis in a variety of tumors, including breast, colon, prostate, and lung carcinomas. In the present study, p27 protein expression was investigated by immunohistochemistry and Western blot analysis in a series of 82 epithelial ovarian tumors [16 classified as low malignant potential (LMP) and 66 classified as primary ovarian adenocarcinomas]. Immunohistochemical analysis revealed frequent loss of p27 expression in primary ovarian adenocarcinomas (33%), with respect to LMP tumors (6%; P = 0.0009). In addition to nuclear staining, cytoplasmic localization of p27 was noted in 45 (55%) of 82 cases. p27 levels inversely correlated with cdk2 kinase activity in a representative subset of tumors. When the clinical outcome of the patients was evaluated in relationship to p27 status, we observed a significant correlation between presence of p27 staining and a longer time to progression (P = 0.032 by log-rank test). These data indicate that loss of p27 is a frequent event in ovarian carcinomas as compared with LMP tumors, suggesting that these tumor types may have different pathogenesis. p27 levels may also represent a useful prognostic marker for predicting disease recurrence in primary ovarian carcinomas.     

Jun activation domain-binding protein 1 expression in breast cancer inversely correlates with the cell cycle inhibitor p27(Kip1)

The Jun activation domain-binding protein 1 (JAB1), aside from being an activator protein 1 coactivator, is involved in degradation of the cyclin-dependent kinase inhibitor p27. We examined JAB1 and p27 protein expression in invasive breast carcinoma specimens and the association of this expression with clinical outcome. JAB1 was detected immunohistochemically in 43 of 53 (81%) tumors; 32 (60%) breast carcinomas showed high JAB1 expression (>50% of cells positive) and reduced or absent p27 levels (P = 0.02, Mann-Whitney U test). Tumors with high p27 expression were rarely positive for JAB1. All eight patients with JAB1-negative tumors had no evidence of relapse or disease progression at a median follow-up of 70 months. Immunoblotting showed strong JAB1 expression in breast carcinoma samples but not in paired normal breast epithelial samples. Targeted overexpression of JAB1 by regulated adenovirus in breast cancer cell lines also reduced p27 levels by accelerating degradation of p27. Thus, the JAB1:p27 ratio may be a novel indicator of aggressive, high-grade tumor behavior, and control of JAB1 could be a novel target for experimental therapies.